compat/regex/regexec.c

   1 /* Extended regular expression matching and search library.
   2    Copyright (C) 2002-2005, 2007, 2009, 2010 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Isamu Hasegawa <isamu@yamato.ibm.com>.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19    02110-1301 USA.  */
  20
  21 static reg_errcode_t match_ctx_init (re_match_context_t *cache, int eflags,
  22                                      int n) internal_function;
  23 static void match_ctx_clean (re_match_context_t *mctx) internal_function;
  24 static void match_ctx_free (re_match_context_t *cache) internal_function;
  25 static reg_errcode_t match_ctx_add_entry (re_match_context_t *cache, int node,
  26                                           int str_idx, int from, int to)
  27      internal_function;
  28 static int search_cur_bkref_entry (const re_match_context_t *mctx, int str_idx)
  29      internal_function;
  30 static reg_errcode_t match_ctx_add_subtop (re_match_context_t *mctx, int node,
  31                                            int str_idx) internal_function;
  32 static re_sub_match_last_t * match_ctx_add_sublast (re_sub_match_top_t *subtop,
  33                                                    int node, int str_idx)
  34      internal_function;
  35 static void sift_ctx_init (re_sift_context_t *sctx, re_dfastate_t **sifted_sts,
  36                            re_dfastate_t **limited_sts, int last_node,
  37                            int last_str_idx)
  38      internal_function;
  39 static reg_errcode_t re_search_internal (const regex_t *preg,
  40                                          const char *string, int length,
  41                                          int start, int range, int stop,
  42                                          size_t nmatch, regmatch_t pmatch[],
  43                                          int eflags);
  44 static int re_search_2_stub (struct re_pattern_buffer *bufp,
  45                              const char *string1, int length1,
  46                              const char *string2, int length2,
  47                              int start, int range, struct re_registers *regs,
  48                              int stop, int ret_len);
  49 static int re_search_stub (struct re_pattern_buffer *bufp,
  50                            const char *string, int length, int start,
  51                            int range, int stop, struct re_registers *regs,
  52                            int ret_len);
  53 static unsigned re_copy_regs (struct re_registers *regs, regmatch_t *pmatch,
  54                               int nregs, int regs_allocated);
  55 static reg_errcode_t prune_impossible_nodes (re_match_context_t *mctx);
  56 static int check_matching (re_match_context_t *mctx, int fl_longest_match,
  57                            int *p_match_first) internal_function;
  58 static int check_halt_state_context (const re_match_context_t *mctx,
  59                                      const re_dfastate_t *state, int idx)
  60      internal_function;
  61 static void update_regs (const re_dfa_t *dfa, regmatch_t *pmatch,
  62                          regmatch_t *prev_idx_match, int cur_node,
  63                          int cur_idx, int nmatch) internal_function;
  64 static reg_errcode_t push_fail_stack (struct re_fail_stack_t *fs,
  65                                       int str_idx, int dest_node, int nregs,
  66                                       regmatch_t *regs,
  67                                       re_node_set *eps_via_nodes)
  68      internal_function;
  69 static reg_errcode_t set_regs (const regex_t *preg,
  70                                const re_match_context_t *mctx,
  71                                size_t nmatch, regmatch_t *pmatch,
  72                                int fl_backtrack) internal_function;
  73 static reg_errcode_t free_fail_stack_return (struct re_fail_stack_t *fs)
  74      internal_function;
  75
  76 #ifdef RE_ENABLE_I18N
  77 static int sift_states_iter_mb (const re_match_context_t *mctx,
  78                                 re_sift_context_t *sctx,
  79                                 int node_idx, int str_idx, int max_str_idx)
  80      internal_function;
  81 #endif /* RE_ENABLE_I18N */
  82 static reg_errcode_t sift_states_backward (const re_match_context_t *mctx,
  83                                            re_sift_context_t *sctx)
  84      internal_function;
  85 static reg_errcode_t build_sifted_states (const re_match_context_t *mctx,
  86                                           re_sift_context_t *sctx, int str_idx,
  87                                           re_node_set *cur_dest)
  88      internal_function;
  89 static reg_errcode_t update_cur_sifted_state (const re_match_context_t *mctx,
  90                                               re_sift_context_t *sctx,
  91                                               int str_idx,
  92                                               re_node_set *dest_nodes)
  93      internal_function;
  94 static reg_errcode_t add_epsilon_src_nodes (const re_dfa_t *dfa,
  95                                             re_node_set *dest_nodes,
  96                                             const re_node_set *candidates)
  97      internal_function;
  98 static int check_dst_limits (const re_match_context_t *mctx,
  99                              re_node_set *limits,
 100                              int dst_node, int dst_idx, int src_node,
 101                              int src_idx) internal_function;
 102 static int check_dst_limits_calc_pos_1 (const re_match_context_t *mctx,
 103                                         int boundaries, int subexp_idx,
 104                                         int from_node, int bkref_idx)
 105      internal_function;
 106 static int check_dst_limits_calc_pos (const re_match_context_t *mctx,
 107                                       int limit, int subexp_idx,
 108                                       int node, int str_idx,
 109                                       int bkref_idx) internal_function;
 110 static reg_errcode_t check_subexp_limits (const re_dfa_t *dfa,
 111                                           re_node_set *dest_nodes,
 112                                           const re_node_set *candidates,
 113                                           re_node_set *limits,
 114                                           struct re_backref_cache_entry *bkref_ents,
 115                                           int str_idx) internal_function;
 116 static reg_errcode_t sift_states_bkref (const re_match_context_t *mctx,
 117                                         re_sift_context_t *sctx,
 118                                         int str_idx, const re_node_set *candidates)
 119      internal_function;
 120 static reg_errcode_t merge_state_array (const re_dfa_t *dfa,
 121                                         re_dfastate_t **dst,
 122                                         re_dfastate_t **src, int num)
 123      internal_function;
 124 static re_dfastate_t *find_recover_state (reg_errcode_t *err,
 125                                          re_match_context_t *mctx) internal_function;
 126 static re_dfastate_t *transit_state (reg_errcode_t *err,
 127                                      re_match_context_t *mctx,
 128                                      re_dfastate_t *state) internal_function;
 129 static re_dfastate_t *merge_state_with_log (reg_errcode_t *err,
 130                                             re_match_context_t *mctx,
 131                                             re_dfastate_t *next_state)
 132      internal_function;
 133 static reg_errcode_t check_subexp_matching_top (re_match_context_t *mctx,
 134                                                 re_node_set *cur_nodes,
 135                                                 int str_idx) internal_function;
 136 #if 0
 137 static re_dfastate_t *transit_state_sb (reg_errcode_t *err,
 138                                         re_match_context_t *mctx,
 139                                         re_dfastate_t *pstate)
 140      internal_function;
 141 #endif
 142 #ifdef RE_ENABLE_I18N
 143 static reg_errcode_t transit_state_mb (re_match_context_t *mctx,
 144                                        re_dfastate_t *pstate)
 145      internal_function;
 146 #endif /* RE_ENABLE_I18N */
 147 static reg_errcode_t transit_state_bkref (re_match_context_t *mctx,
 148                                           const re_node_set *nodes)
 149      internal_function;
 150 static reg_errcode_t get_subexp (re_match_context_t *mctx,
 151                                  int bkref_node, int bkref_str_idx)
 152      internal_function;
 153 static reg_errcode_t get_subexp_sub (re_match_context_t *mctx,
 154                                      const re_sub_match_top_t *sub_top,
 155                                      re_sub_match_last_t *sub_last,
 156                                      int bkref_node, int bkref_str)
 157      internal_function;
 158 static int find_subexp_node (const re_dfa_t *dfa, const re_node_set *nodes,
 159                              int subexp_idx, int type) internal_function;
 160 static reg_errcode_t check_arrival (re_match_context_t *mctx,
 161                                     state_array_t *path, int top_node,
 162                                     int top_str, int last_node, int last_str,
 163                                     int type) internal_function;
 164 static reg_errcode_t check_arrival_add_next_nodes (re_match_context_t *mctx,
 165                                                    int str_idx,
 166                                                    re_node_set *cur_nodes,
 167                                                    re_node_set *next_nodes)
 168      internal_function;
 169 static reg_errcode_t check_arrival_expand_ecl (const re_dfa_t *dfa,
 170                                                re_node_set *cur_nodes,
 171                                                int ex_subexp, int type)
 172      internal_function;
 173 static reg_errcode_t check_arrival_expand_ecl_sub (const re_dfa_t *dfa,
 174                                                    re_node_set *dst_nodes,
 175                                                    int target, int ex_subexp,
 176                                                    int type) internal_function;
 177 static reg_errcode_t expand_bkref_cache (re_match_context_t *mctx,
 178                                          re_node_set *cur_nodes, int cur_str,
 179                                          int subexp_num, int type)
 180      internal_function;
 181 static int build_trtable (const re_dfa_t *dfa,
 182                           re_dfastate_t *state) internal_function;
 183 #ifdef RE_ENABLE_I18N
 184 static int check_node_accept_bytes (const re_dfa_t *dfa, int node_idx,
 185                                     const re_string_t *input, int idx)
 186      internal_function;
 187 # ifdef _LIBC
 188 static unsigned int find_collation_sequence_value (const unsigned char *mbs,
 189                                                    size_t name_len)
 190      internal_function;
 191 # endif /* _LIBC */
 192 #endif /* RE_ENABLE_I18N */
 193 static int group_nodes_into_DFAstates (const re_dfa_t *dfa,
 194                                        const re_dfastate_t *state,
 195                                        re_node_set *states_node,
 196                                        bitset_t *states_ch) internal_function;
 197 static int check_node_accept (const re_match_context_t *mctx,
 198                               const re_token_t *node, int idx)
 199      internal_function;
 200 static reg_errcode_t extend_buffers (re_match_context_t *mctx)
 201      internal_function;
 202 \f
 203 /* Entry point for POSIX code.  */
 204
 205 /* regexec searches for a given pattern, specified by PREG, in the
 206    string STRING.
 207
 208    If NMATCH is zero or REG_NOSUB was set in the cflags argument to
 209    `regcomp', we ignore PMATCH.  Otherwise, we assume PMATCH has at
 210    least NMATCH elements, and we set them to the offsets of the
 211    corresponding matched substrings.
 212
 213    EFLAGS specifies `execution flags' which affect matching: if
 214    REG_NOTBOL is set, then ^ does not match at the beginning of the
 215    string; if REG_NOTEOL is set, then $ does not match at the end.
 216
 217    We return 0 if we find a match and REG_NOMATCH if not.  */
 218
 219 int
 220 regexec (
 221         const regex_t *__restrict preg,
 222         const char *__restrict string,
 223         size_t nmatch,
 224         regmatch_t pmatch[],
 225         int eflags)
 226 {
 227   reg_errcode_t err;
 228   int start, length;
 229
 230   if (eflags & ~(REG_NOTBOL | REG_NOTEOL | REG_STARTEND))
 231     return REG_BADPAT;
 232
 233   if (eflags & REG_STARTEND)
 234     {
 235       start = pmatch[0].rm_so;
 236       length = pmatch[0].rm_eo;
 237     }
 238   else
 239     {
 240       start = 0;
 241       length = strlen (string);
 242     }
 243
 244   __libc_lock_lock (dfa->lock);
 245   if (preg->no_sub)
 246     err = re_search_internal (preg, string, length, start, length - start,
 247                               length, 0, NULL, eflags);
 248   else
 249     err = re_search_internal (preg, string, length, start, length - start,
 250                               length, nmatch, pmatch, eflags);
 251   __libc_lock_unlock (dfa->lock);
 252   return err != REG_NOERROR;
 253 }
 254
 255 #ifdef _LIBC
 256 # include <shlib-compat.h>
 257 versioned_symbol (libc, __regexec, regexec, GLIBC_2_3_4);
 258
 259 # if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_3_4)
 260 __typeof__ (__regexec) __compat_regexec;
 261
 262 int
 263 attribute_compat_text_section
 264 __compat_regexec (const regex_t *__restrict preg,
 265                   const char *__restrict string, size_t nmatch,
 266                   regmatch_t pmatch[], int eflags)
 267 {
 268   return regexec (preg, string, nmatch, pmatch,
 269                   eflags & (REG_NOTBOL | REG_NOTEOL));
 270 }
 271 compat_symbol (libc, __compat_regexec, regexec, GLIBC_2_0);
 272 # endif
 273 #endif
 274
 275 /* Entry points for GNU code.  */
 276
 277 /* re_match, re_search, re_match_2, re_search_2
 278
 279    The former two functions operate on STRING with length LENGTH,
 280    while the later two operate on concatenation of STRING1 and STRING2
 281    with lengths LENGTH1 and LENGTH2, respectively.
 282
 283    re_match() matches the compiled pattern in BUFP against the string,
 284    starting at index START.
 285
 286    re_search() first tries matching at index START, then it tries to match
 287    starting from index START + 1, and so on.  The last start position tried
 288    is START + RANGE.  (Thus RANGE = 0 forces re_search to operate the same
 289    way as re_match().)
 290
 291    The parameter STOP of re_{match,search}_2 specifies that no match exceeding
 292    the first STOP characters of the concatenation of the strings should be
 293    concerned.
 294
 295    If REGS is not NULL, and BUFP->no_sub is not set, the offsets of the match
 296    and all groups is stroed in REGS.  (For the "_2" variants, the offsets are
 297    computed relative to the concatenation, not relative to the individual
 298    strings.)
 299
 300    On success, re_match* functions return the length of the match, re_search*
 301    return the position of the start of the match.  Return value -1 means no
 302    match was found and -2 indicates an internal error.  */
 303
 304 int
 305 re_match (struct re_pattern_buffer *bufp,
 306           const char *string,
 307           int length,
 308           int start,
 309           struct re_registers *regs)
 310 {
 311   return re_search_stub (bufp, string, length, start, 0, length, regs, 1);
 312 }
 313 #ifdef _LIBC
 314 weak_alias (__re_match, re_match)
 315 #endif
 316
 317 int
 318 re_search (struct re_pattern_buffer *bufp,
 319            const char *string,
 320            int length, int start, int range,
 321            struct re_registers *regs)
 322 {
 323   return re_search_stub (bufp, string, length, start, range, length, regs, 0);
 324 }
 325 #ifdef _LIBC
 326 weak_alias (__re_search, re_search)
 327 #endif
 328
 329 int
 330 re_match_2 (struct re_pattern_buffer *bufp,
 331             const char *string1, int length1,
 332             const char *string2, int length2, int start,
 333             struct re_registers *regs, int stop)
 334 {
 335   return re_search_2_stub (bufp, string1, length1, string2, length2,
 336                            start, 0, regs, stop, 1);
 337 }
 338 #ifdef _LIBC
 339 weak_alias (__re_match_2, re_match_2)
 340 #endif
 341
 342 int
 343 re_search_2 (struct re_pattern_buffer *bufp,
 344              const char *string1, int length1,
 345              const char *string2, int length2, int start,
 346              int range, struct re_registers *regs,  int stop)
 347 {
 348   return re_search_2_stub (bufp, string1, length1, string2, length2,
 349                            start, range, regs, stop, 0);
 350 }
 351 #ifdef _LIBC
 352 weak_alias (__re_search_2, re_search_2)
 353 #endif
 354
 355 static int
 356 re_search_2_stub (struct re_pattern_buffer *bufp,
 357                   const char *string1, int length1,
 358                   const char *string2, int length2, int start,
 359                   int range, struct re_registers *regs,
 360                   int stop, int ret_len)
 361 {
 362   const char *str;
 363   int rval;
 364   int len = length1 + length2;
 365   int free_str = 0;
 366
 367   if (BE (length1 < 0 || length2 < 0 || stop < 0, 0))
 368     return -2;
 369
 370   /* Concatenate the strings.  */
 371   if (length2 > 0)
 372     if (length1 > 0)
 373       {
 374         char *s = re_malloc (char, len);
 375
 376         if (BE (s == NULL, 0))
 377           return -2;
 378         memcpy (s, string1, length1);
 379         memcpy (s + length1, string2, length2);
 380         str = s;
 381         free_str = 1;
 382       }
 383     else
 384       str = string2;
 385   else
 386     str = string1;
 387
 388   rval = re_search_stub (bufp, str, len, start, range, stop, regs, ret_len);
 389   if (free_str)
 390     re_free ((char *) str);
 391   return rval;
 392 }
 393
 394 /* The parameters have the same meaning as those of re_search.
 395    Additional parameters:
 396    If RET_LEN is nonzero the length of the match is returned (re_match style);
 397    otherwise the position of the match is returned.  */
 398
 399 static int
 400 re_search_stub (struct re_pattern_buffer *bufp,
 401                 const char *string, int length, int start,
 402                 int range, int stop,
 403                 struct re_registers *regs, int ret_len)
 404 {
 405   reg_errcode_t result;
 406   regmatch_t *pmatch;
 407   int nregs, rval;
 408   int eflags = 0;
 409
 410   /* Check for out-of-range.  */
 411   if (BE (start < 0 || start > length, 0))
 412     return -1;
 413   if (BE (start + range > length, 0))
 414     range = length - start;
 415   else if (BE (start + range < 0, 0))
 416     range = -start;
 417
 418   __libc_lock_lock (dfa->lock);
 419
 420   eflags |= (bufp->not_bol) ? REG_NOTBOL : 0;
 421   eflags |= (bufp->not_eol) ? REG_NOTEOL : 0;
 422
 423   /* Compile fastmap if we haven't yet.  */
 424   if (range > 0 && bufp->fastmap != NULL && !bufp->fastmap_accurate)
 425     re_compile_fastmap (bufp);
 426
 427   if (BE (bufp->no_sub, 0))
 428     regs = NULL;
 429
 430   /* We need at least 1 register.  */
 431   if (regs == NULL)
 432     nregs = 1;
 433   else if (BE (bufp->regs_allocated == REGS_FIXED &&
 434                regs->num_regs < bufp->re_nsub + 1, 0))
 435     {
 436       nregs = regs->num_regs;
 437       if (BE (nregs < 1, 0))
 438         {
 439           /* Nothing can be copied to regs.  */
 440           regs = NULL;
 441           nregs = 1;
 442         }
 443     }
 444   else
 445     nregs = bufp->re_nsub + 1;
 446   pmatch = re_malloc (regmatch_t, nregs);
 447   if (BE (pmatch == NULL, 0))
 448     {
 449       rval = -2;
 450       goto out;
 451     }
 452
 453   result = re_search_internal (bufp, string, length, start, range, stop,
 454                                nregs, pmatch, eflags);
 455
 456   rval = 0;
 457
 458   /* I hope we needn't fill their regs with -1's when no match was found.  */
 459   if (result != REG_NOERROR)
 460     rval = -1;
 461   else if (regs != NULL)
 462     {
 463       /* If caller wants register contents data back, copy them.  */
 464       bufp->regs_allocated = re_copy_regs (regs, pmatch, nregs,
 465                                            bufp->regs_allocated);
 466       if (BE (bufp->regs_allocated == REGS_UNALLOCATED, 0))
 467         rval = -2;
 468     }
 469
 470   if (BE (rval == 0, 1))
 471     {
 472       if (ret_len)
 473         {
 474           assert (pmatch[0].rm_so == start);
 475           rval = pmatch[0].rm_eo - start;
 476         }
 477       else
 478         rval = pmatch[0].rm_so;
 479     }
 480   re_free (pmatch);
 481  out:
 482   __libc_lock_unlock (dfa->lock);
 483   return rval;
 484 }
 485
 486 static unsigned
 487 re_copy_regs (struct re_registers *regs,
 488               regmatch_t *pmatch,
 489               int nregs, int regs_allocated)
 490 {
 491   int rval = REGS_REALLOCATE;
 492   int i;
 493   int need_regs = nregs + 1;
 494   /* We need one extra element beyond `num_regs' for the `-1' marker GNU code
 495      uses.  */
 496
 497   /* Have the register data arrays been allocated?  */
 498   if (regs_allocated == REGS_UNALLOCATED)
 499     { /* No.  So allocate them with malloc.  */
 500       regs->start = re_malloc (regoff_t, need_regs);
 501       if (BE (regs->start == NULL, 0))
 502         return REGS_UNALLOCATED;
 503       regs->end = re_malloc (regoff_t, need_regs);
 504       if (BE (regs->end == NULL, 0))
 505         {
 506           re_free (regs->start);
 507           return REGS_UNALLOCATED;
 508         }
 509       regs->num_regs = need_regs;
 510     }
 511   else if (regs_allocated == REGS_REALLOCATE)
 512     { /* Yes.  If we need more elements than were already
 513          allocated, reallocate them.  If we need fewer, just
 514          leave it alone.  */
 515       if (BE (need_regs > regs->num_regs, 0))
 516         {
 517           regoff_t *new_start = re_realloc (regs->start, regoff_t, need_regs);
 518           regoff_t *new_end;
 519           if (BE (new_start == NULL, 0))
 520             return REGS_UNALLOCATED;
 521           new_end = re_realloc (regs->end, regoff_t, need_regs);
 522           if (BE (new_end == NULL, 0))
 523             {
 524               re_free (new_start);
 525               return REGS_UNALLOCATED;
 526             }
 527           regs->start = new_start;
 528           regs->end = new_end;
 529           regs->num_regs = need_regs;
 530         }
 531     }
 532   else
 533     {
 534       assert (regs_allocated == REGS_FIXED);
 535       /* This function may not be called with REGS_FIXED and nregs too big.  */
 536       assert (regs->num_regs >= nregs);
 537       rval = REGS_FIXED;
 538     }
 539
 540   /* Copy the regs.  */
 541   for (i = 0; i < nregs; ++i)
 542     {
 543       regs->start[i] = pmatch[i].rm_so;
 544       regs->end[i] = pmatch[i].rm_eo;
 545     }
 546   for ( ; i < regs->num_regs; ++i)
 547     regs->start[i] = regs->end[i] = -1;
 548
 549   return rval;
 550 }
 551
 552 /* Set REGS to hold NUM_REGS registers, storing them in STARTS and
 553    ENDS.  Subsequent matches using PATTERN_BUFFER and REGS will use
 554    this memory for recording register information.  STARTS and ENDS
 555    must be allocated using the malloc library routine, and must each
 556    be at least NUM_REGS * sizeof (regoff_t) bytes long.
 557
 558    If NUM_REGS == 0, then subsequent matches should allocate their own
 559    register data.
 560
 561    Unless this function is called, the first search or match using
 562    PATTERN_BUFFER will allocate its own register data, without
 563    freeing the old data.  */
 564
 565 void
 566 re_set_registers (struct re_pattern_buffer *bufp,
 567                   struct re_registers *regs,
 568                   unsigned num_regs,
 569                   regoff_t *starts,
 570                   regoff_t *ends)
 571 {
 572   if (num_regs)
 573     {
 574       bufp->regs_allocated = REGS_REALLOCATE;
 575       regs->num_regs = num_regs;
 576       regs->start = starts;
 577       regs->end = ends;
 578     }
 579   else
 580     {
 581       bufp->regs_allocated = REGS_UNALLOCATED;
 582       regs->num_regs = 0;
 583       regs->start = regs->end = (regoff_t *) 0;
 584     }
 585 }
 586 #ifdef _LIBC
 587 weak_alias (__re_set_registers, re_set_registers)
 588 #endif
 589 \f
 590 /* Entry points compatible with 4.2 BSD regex library.  We don't define
 591    them unless specifically requested.  */
 592
 593 #if defined _REGEX_RE_COMP || defined _LIBC
 594 int
 595 # ifdef _LIBC
 596 weak_function
 597 # endif
 598 re_exec (s)
 599      const char *s;
 600 {
 601   return 0 == regexec (&re_comp_buf, s, 0, NULL, 0);
 602 }
 603 #endif /* _REGEX_RE_COMP */
 604 \f
 605 /* Internal entry point.  */
 606
 607 /* Searches for a compiled pattern PREG in the string STRING, whose
 608    length is LENGTH.  NMATCH, PMATCH, and EFLAGS have the same
 609    mingings with regexec.  START, and RANGE have the same meanings
 610    with re_search.
 611    Return REG_NOERROR if we find a match, and REG_NOMATCH if not,
 612    otherwise return the error code.
 613    Note: We assume front end functions already check ranges.
 614    (START + RANGE >= 0 && START + RANGE <= LENGTH)  */
 615
 616 static reg_errcode_t
 617 re_search_internal (const regex_t *preg,
 618                     const char *string,
 619                     int length, int start, int range, int stop,
 620                     size_t nmatch, regmatch_t pmatch[],
 621                     int eflags)
 622 {
 623   reg_errcode_t err;
 624   const re_dfa_t *dfa = (const re_dfa_t *) preg->buffer;
 625   int left_lim, right_lim, incr;
 626   int fl_longest_match, match_first, match_kind, match_last = -1;
 627   int extra_nmatch;
 628   int sb, ch;
 629 #if defined _LIBC || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L)
 630   re_match_context_t mctx = { .dfa = dfa };
 631 #else
 632   re_match_context_t mctx;
 633 #endif
 634   char *fastmap = (preg->fastmap != NULL && preg->fastmap_accurate
 635                    && range && !preg->can_be_null) ? preg->fastmap : NULL;
 636   RE_TRANSLATE_TYPE t = preg->translate;
 637
 638 #if !(defined _LIBC || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
 639   memset (&mctx, '\0', sizeof (re_match_context_t));
 640   mctx.dfa = dfa;
 641 #endif
 642
 643   extra_nmatch = (nmatch > preg->re_nsub) ? nmatch - (preg->re_nsub + 1) : 0;
 644   nmatch -= extra_nmatch;
 645
 646   /* Check if the DFA haven't been compiled.  */
 647   if (BE (preg->used == 0 || dfa->init_state == NULL
 648           || dfa->init_state_word == NULL || dfa->init_state_nl == NULL
 649           || dfa->init_state_begbuf == NULL, 0))
 650     return REG_NOMATCH;
 651
 652 #ifdef DEBUG
 653   /* We assume front-end functions already check them.  */
 654   assert (start + range >= 0 && start + range <= length);
 655 #endif
 656
 657   /* If initial states with non-begbuf contexts have no elements,
 658      the regex must be anchored.  If preg->newline_anchor is set,
 659      we'll never use init_state_nl, so do not check it.  */
 660   if (dfa->init_state->nodes.nelem == 0
 661       && dfa->init_state_word->nodes.nelem == 0
 662       && (dfa->init_state_nl->nodes.nelem == 0
 663           || !preg->newline_anchor))
 664     {
 665       if (start != 0 && start + range != 0)
 666         return REG_NOMATCH;
 667       start = range = 0;
 668     }
 669
 670   /* We must check the longest matching, if nmatch > 0.  */
 671   fl_longest_match = (nmatch != 0 || dfa->nbackref);
 672
 673   err = re_string_allocate (&mctx.input, string, length, dfa->nodes_len + 1,
 674                             preg->translate, preg->syntax & RE_ICASE, dfa);
 675   if (BE (err != REG_NOERROR, 0))
 676     goto free_return;
 677   mctx.input.stop = stop;
 678   mctx.input.raw_stop = stop;
 679   mctx.input.newline_anchor = preg->newline_anchor;
 680
 681   err = match_ctx_init (&mctx, eflags, dfa->nbackref * 2);
 682   if (BE (err != REG_NOERROR, 0))
 683     goto free_return;
 684
 685   /* We will log all the DFA states through which the dfa pass,
 686      if nmatch > 1, or this dfa has "multibyte node", which is a
 687      back-reference or a node which can accept multibyte character or
 688      multi character collating element.  */
 689   if (nmatch > 1 || dfa->has_mb_node)
 690     {
 691       /* Avoid overflow.  */
 692       if (BE (SIZE_MAX / sizeof (re_dfastate_t *) <= mctx.input.bufs_len, 0))
 693         {
 694           err = REG_ESPACE;
 695           goto free_return;
 696         }
 697
 698       mctx.state_log = re_malloc (re_dfastate_t *, mctx.input.bufs_len + 1);
 699       if (BE (mctx.state_log == NULL, 0))
 700         {
 701           err = REG_ESPACE;
 702           goto free_return;
 703         }
 704     }
 705   else
 706     mctx.state_log = NULL;
 707
 708   match_first = start;
 709   mctx.input.tip_context = (eflags & REG_NOTBOL) ? CONTEXT_BEGBUF
 710                            : CONTEXT_NEWLINE | CONTEXT_BEGBUF;
 711
 712   /* Check incrementally whether of not the input string match.  */
 713   incr = (range < 0) ? -1 : 1;
 714   left_lim = (range < 0) ? start + range : start;
 715   right_lim = (range < 0) ? start : start + range;
 716   sb = dfa->mb_cur_max == 1;
 717   match_kind =
 718     (fastmap
 719      ? ((sb || !(preg->syntax & RE_ICASE || t) ? 4 : 0)
 720         | (range >= 0 ? 2 : 0)
 721         | (t != NULL ? 1 : 0))
 722      : 8);
 723
 724   for (;; match_first += incr)
 725     {
 726       err = REG_NOMATCH;
 727       if (match_first < left_lim || right_lim < match_first)
 728         goto free_return;
 729
 730       /* Advance as rapidly as possible through the string, until we
 731          find a plausible place to start matching.  This may be done
 732          with varying efficiency, so there are various possibilities:
 733          only the most common of them are specialized, in order to
 734          save on code size.  We use a switch statement for speed.  */
 735       switch (match_kind)
 736         {
 737         case 8:
 738           /* No fastmap.  */
 739           break;
 740
 741         case 7:
 742           /* Fastmap with single-byte translation, match forward.  */
 743           while (BE (match_first < right_lim, 1)
 744                  && !fastmap[t[(unsigned char) string[match_first]]])
 745             ++match_first;
 746           goto forward_match_found_start_or_reached_end;
 747
 748         case 6:
 749           /* Fastmap without translation, match forward.  */
 750           while (BE (match_first < right_lim, 1)
 751                  && !fastmap[(unsigned char) string[match_first]])
 752             ++match_first;
 753
 754         forward_match_found_start_or_reached_end:
 755           if (BE (match_first == right_lim, 0))
 756             {
 757               ch = match_first >= length
 758                        ? 0 : (unsigned char) string[match_first];
 759               if (!fastmap[t ? t[ch] : ch])
 760                 goto free_return;
 761             }
 762           break;
 763
 764         case 4:
 765         case 5:
 766           /* Fastmap without multi-byte translation, match backwards.  */
 767           while (match_first >= left_lim)
 768             {
 769               ch = match_first >= length
 770                        ? 0 : (unsigned char) string[match_first];
 771               if (fastmap[t ? t[ch] : ch])
 772                 break;
 773               --match_first;
 774             }
 775           if (match_first < left_lim)
 776             goto free_return;
 777           break;
 778
 779         default:
 780           /* In this case, we can't determine easily the current byte,
 781              since it might be a component byte of a multibyte
 782              character.  Then we use the constructed buffer instead.  */
 783           for (;;)
 784             {
 785               /* If MATCH_FIRST is out of the valid range, reconstruct the
 786                  buffers.  */
 787               unsigned int offset = match_first - mctx.input.raw_mbs_idx;
 788               if (BE (offset >= (unsigned int) mctx.input.valid_raw_len, 0))
 789                 {
 790                   err = re_string_reconstruct (&mctx.input, match_first,
 791                                                eflags);
 792                   if (BE (err != REG_NOERROR, 0))
 793                     goto free_return;
 794
 795                   offset = match_first - mctx.input.raw_mbs_idx;
 796                 }
 797               /* If MATCH_FIRST is out of the buffer, leave it as '\0'.
 798                  Note that MATCH_FIRST must not be smaller than 0.  */
 799               ch = (match_first >= length
 800                     ? 0 : re_string_byte_at (&mctx.input, offset));
 801               if (fastmap[ch])
 802                 break;
 803               match_first += incr;
 804               if (match_first < left_lim || match_first > right_lim)
 805                 {
 806                   err = REG_NOMATCH;
 807                   goto free_return;
 808                 }
 809             }
 810           break;
 811         }
 812
 813       /* Reconstruct the buffers so that the matcher can assume that
 814          the matching starts from the beginning of the buffer.  */
 815       err = re_string_reconstruct (&mctx.input, match_first, eflags);
 816       if (BE (err != REG_NOERROR, 0))
 817         goto free_return;
 818
 819 #ifdef RE_ENABLE_I18N
 820      /* Don't consider this char as a possible match start if it part,
 821         yet isn't the head, of a multibyte character.  */
 822       if (!sb && !re_string_first_byte (&mctx.input, 0))
 823         continue;
 824 #endif
 825
 826       /* It seems to be appropriate one, then use the matcher.  */
 827       /* We assume that the matching starts from 0.  */
 828       mctx.state_log_top = mctx.nbkref_ents = mctx.max_mb_elem_len = 0;
 829       match_last = check_matching (&mctx, fl_longest_match,
 830                                    range >= 0 ? &match_first : NULL);
 831       if (match_last != -1)
 832         {
 833           if (BE (match_last == -2, 0))
 834             {
 835               err = REG_ESPACE;
 836               goto free_return;
 837             }
 838           else
 839             {
 840               mctx.match_last = match_last;
 841               if ((!preg->no_sub && nmatch > 1) || dfa->nbackref)
 842                 {
 843                   re_dfastate_t *pstate = mctx.state_log[match_last];
 844                   mctx.last_node = check_halt_state_context (&mctx, pstate,
 845                                                              match_last);
 846                 }
 847               if ((!preg->no_sub && nmatch > 1 && dfa->has_plural_match)
 848                   || dfa->nbackref)
 849                 {
 850                   err = prune_impossible_nodes (&mctx);
 851                   if (err == REG_NOERROR)
 852                     break;
 853                   if (BE (err != REG_NOMATCH, 0))
 854                     goto free_return;
 855                   match_last = -1;
 856                 }
 857               else
 858                 break; /* We found a match.  */
 859             }
 860         }
 861
 862       match_ctx_clean (&mctx);
 863     }
 864
 865 #ifdef DEBUG
 866   assert (match_last != -1);
 867   assert (err == REG_NOERROR);
 868 #endif
 869
 870   /* Set pmatch[] if we need.  */
 871   if (nmatch > 0)
 872     {
 873       int reg_idx;
 874
 875       /* Initialize registers.  */
 876       for (reg_idx = 1; reg_idx < nmatch; ++reg_idx)
 877         pmatch[reg_idx].rm_so = pmatch[reg_idx].rm_eo = -1;
 878
 879       /* Set the points where matching start/end.  */
 880       pmatch[0].rm_so = 0;
 881       pmatch[0].rm_eo = mctx.match_last;
 882
 883       if (!preg->no_sub && nmatch > 1)
 884         {
 885           err = set_regs (preg, &mctx, nmatch, pmatch,
 886                           dfa->has_plural_match && dfa->nbackref > 0);
 887           if (BE (err != REG_NOERROR, 0))
 888             goto free_return;
 889         }
 890
 891       /* At last, add the offset to the each registers, since we slided
 892          the buffers so that we could assume that the matching starts
 893          from 0.  */
 894       for (reg_idx = 0; reg_idx < nmatch; ++reg_idx)
 895         if (pmatch[reg_idx].rm_so != -1)
 896           {
 897 #ifdef RE_ENABLE_I18N
 898             if (BE (mctx.input.offsets_needed != 0, 0))
 899               {
 900                 pmatch[reg_idx].rm_so =
 901                   (pmatch[reg_idx].rm_so == mctx.input.valid_len
 902                    ? mctx.input.valid_raw_len
 903                    : mctx.input.offsets[pmatch[reg_idx].rm_so]);
 904                 pmatch[reg_idx].rm_eo =
 905                   (pmatch[reg_idx].rm_eo == mctx.input.valid_len
 906                    ? mctx.input.valid_raw_len
 907                    : mctx.input.offsets[pmatch[reg_idx].rm_eo]);
 908               }
 909 #else
 910             assert (mctx.input.offsets_needed == 0);
 911 #endif
 912             pmatch[reg_idx].rm_so += match_first;
 913             pmatch[reg_idx].rm_eo += match_first;
 914           }
 915       for (reg_idx = 0; reg_idx < extra_nmatch; ++reg_idx)
 916         {
 917           pmatch[nmatch + reg_idx].rm_so = -1;
 918           pmatch[nmatch + reg_idx].rm_eo = -1;
 919         }
 920
 921       if (dfa->subexp_map)
 922         for (reg_idx = 0; reg_idx + 1 < nmatch; reg_idx++)
 923           if (dfa->subexp_map[reg_idx] != reg_idx)
 924             {
 925               pmatch[reg_idx + 1].rm_so
 926                 = pmatch[dfa->subexp_map[reg_idx] + 1].rm_so;
 927               pmatch[reg_idx + 1].rm_eo
 928                 = pmatch[dfa->subexp_map[reg_idx] + 1].rm_eo;
 929             }
 930     }
 931
 932  free_return:
 933   re_free (mctx.state_log);
 934   if (dfa->nbackref)
 935     match_ctx_free (&mctx);
 936   re_string_destruct (&mctx.input);
 937   return err;
 938 }
 939
 940 static reg_errcode_t
 941 prune_impossible_nodes (re_match_context_t *mctx)
 942 {
 943   const re_dfa_t *const dfa = mctx->dfa;
 944   int halt_node, match_last;
 945   reg_errcode_t ret;
 946   re_dfastate_t **sifted_states;
 947   re_dfastate_t **lim_states = NULL;
 948   re_sift_context_t sctx;
 949 #ifdef DEBUG
 950   assert (mctx->state_log != NULL);
 951 #endif
 952   match_last = mctx->match_last;
 953   halt_node = mctx->last_node;
 954
 955   /* Avoid overflow.  */
 956   if (BE (SIZE_MAX / sizeof (re_dfastate_t *) <= match_last, 0))
 957     return REG_ESPACE;
 958
 959   sifted_states = re_malloc (re_dfastate_t *, match_last + 1);
 960   if (BE (sifted_states == NULL, 0))
 961     {
 962       ret = REG_ESPACE;
 963       goto free_return;
 964     }
 965   if (dfa->nbackref)
 966     {
 967       lim_states = re_malloc (re_dfastate_t *, match_last + 1);
 968       if (BE (lim_states == NULL, 0))
 969         {
 970           ret = REG_ESPACE;
 971           goto free_return;
 972         }
 973       while (1)
 974         {
 975           memset (lim_states, '\0',
 976                   sizeof (re_dfastate_t *) * (match_last + 1));
 977           sift_ctx_init (&sctx, sifted_states, lim_states, halt_node,
 978                          match_last);
 979           ret = sift_states_backward (mctx, &sctx);
 980           re_node_set_free (&sctx.limits);
 981           if (BE (ret != REG_NOERROR, 0))
 982               goto free_return;
 983           if (sifted_states[0] != NULL || lim_states[0] != NULL)
 984             break;
 985           do
 986             {
 987               --match_last;
 988               if (match_last < 0)
 989                 {
 990                   ret = REG_NOMATCH;
 991                   goto free_return;
 992                 }
 993             } while (mctx->state_log[match_last] == NULL
 994                      || !mctx->state_log[match_last]->halt);
 995           halt_node = check_halt_state_context (mctx,
 996                                                 mctx->state_log[match_last],
 997                                                 match_last);
 998         }
 999       ret = merge_state_array (dfa, sifted_states, lim_states,
1000                                match_last + 1);
1001       re_free (lim_states);
1002       lim_states = NULL;
1003       if (BE (ret != REG_NOERROR, 0))
1004         goto free_return;
1005     }
1006   else
1007     {
1008       sift_ctx_init (&sctx, sifted_states, lim_states, halt_node, match_last);
1009       ret = sift_states_backward (mctx, &sctx);
1010       re_node_set_free (&sctx.limits);
1011       if (BE (ret != REG_NOERROR, 0))
1012         goto free_return;
1013       if (sifted_states[0] == NULL)
1014         {
1015           ret = REG_NOMATCH;
1016           goto free_return;
1017         }
1018     }
1019   re_free (mctx->state_log);
1020   mctx->state_log = sifted_states;
1021   sifted_states = NULL;
1022   mctx->last_node = halt_node;
1023   mctx->match_last = match_last;
1024   ret = REG_NOERROR;
1025  free_return:
1026   re_free (sifted_states);
1027   re_free (lim_states);
1028   return ret;
1029 }
1030
1031 /* Acquire an initial state and return it.
1032    We must select appropriate initial state depending on the context,
1033    since initial states may have constraints like "\<", "^", etc..  */
1034
1035 static inline re_dfastate_t *
1036 __attribute ((always_inline)) internal_function
1037 acquire_init_state_context (reg_errcode_t *err, const re_match_context_t *mctx,
1038                             int idx)
1039 {
1040   const re_dfa_t *const dfa = mctx->dfa;
1041   if (dfa->init_state->has_constraint)
1042     {
1043       unsigned int context;
1044       context = re_string_context_at (&mctx->input, idx - 1, mctx->eflags);
1045       if (IS_WORD_CONTEXT (context))
1046         return dfa->init_state_word;
1047       else if (IS_ORDINARY_CONTEXT (context))
1048         return dfa->init_state;
1049       else if (IS_BEGBUF_CONTEXT (context) && IS_NEWLINE_CONTEXT (context))
1050         return dfa->init_state_begbuf;
1051       else if (IS_NEWLINE_CONTEXT (context))
1052         return dfa->init_state_nl;
1053       else if (IS_BEGBUF_CONTEXT (context))
1054         {
1055           /* It is relatively rare case, then calculate on demand.  */
1056           return re_acquire_state_context (err, dfa,
1057                                            dfa->init_state->entrance_nodes,
1058                                            context);
1059         }
1060       else
1061         /* Must not happen?  */
1062         return dfa->init_state;
1063     }
1064   else
1065     return dfa->init_state;
1066 }
1067
1068 /* Check whether the regular expression match input string INPUT or not,
1069    and return the index where the matching end, return -1 if not match,
1070    or return -2 in case of an error.
1071    FL_LONGEST_MATCH means we want the POSIX longest matching.
1072    If P_MATCH_FIRST is not NULL, and the match fails, it is set to the
1073    next place where we may want to try matching.
1074    Note that the matcher assume that the matching starts from the current
1075    index of the buffer.  */
1076
1077 static int
1078 internal_function
1079 check_matching (re_match_context_t *mctx, int fl_longest_match,
1080                 int *p_match_first)
1081 {
1082   const re_dfa_t *const dfa = mctx->dfa;
1083   reg_errcode_t err;
1084   int match = 0;
1085   int match_last = -1;
1086   int cur_str_idx = re_string_cur_idx (&mctx->input);
1087   re_dfastate_t *cur_state;
1088   int at_init_state = p_match_first != NULL;
1089   int next_start_idx = cur_str_idx;
1090
1091   err = REG_NOERROR;
1092   cur_state = acquire_init_state_context (&err, mctx, cur_str_idx);
1093   /* An initial state must not be NULL (invalid).  */
1094   if (BE (cur_state == NULL, 0))
1095     {
1096       assert (err == REG_ESPACE);
1097       return -2;
1098     }
1099
1100   if (mctx->state_log != NULL)
1101     {
1102       mctx->state_log[cur_str_idx] = cur_state;
1103
1104       /* Check OP_OPEN_SUBEXP in the initial state in case that we use them
1105          later.  E.g. Processing back references.  */
1106       if (BE (dfa->nbackref, 0))
1107         {
1108           at_init_state = 0;
1109           err = check_subexp_matching_top (mctx, &cur_state->nodes, 0);
1110           if (BE (err != REG_NOERROR, 0))
1111             return err;
1112
1113           if (cur_state->has_backref)
1114             {
1115               err = transit_state_bkref (mctx, &cur_state->nodes);
1116               if (BE (err != REG_NOERROR, 0))
1117                 return err;
1118             }
1119         }
1120     }
1121
1122   /* If the RE accepts NULL string.  */
1123   if (BE (cur_state->halt, 0))
1124     {
1125       if (!cur_state->has_constraint
1126           || check_halt_state_context (mctx, cur_state, cur_str_idx))
1127         {
1128           if (!fl_longest_match)
1129             return cur_str_idx;
1130           else
1131             {
1132               match_last = cur_str_idx;
1133               match = 1;
1134             }
1135         }
1136     }
1137
1138   while (!re_string_eoi (&mctx->input))
1139     {
1140       re_dfastate_t *old_state = cur_state;
1141       int next_char_idx = re_string_cur_idx (&mctx->input) + 1;
1142
1143       if (BE (next_char_idx >= mctx->input.bufs_len, 0)
1144           || (BE (next_char_idx >= mctx->input.valid_len, 0)
1145               && mctx->input.valid_len < mctx->input.len))
1146         {
1147           err = extend_buffers (mctx);
1148           if (BE (err != REG_NOERROR, 0))
1149             {
1150               assert (err == REG_ESPACE);
1151               return -2;
1152             }
1153         }
1154
1155       cur_state = transit_state (&err, mctx, cur_state);
1156       if (mctx->state_log != NULL)
1157         cur_state = merge_state_with_log (&err, mctx, cur_state);
1158
1159       if (cur_state == NULL)
1160         {
1161           /* Reached the invalid state or an error.  Try to recover a valid
1162              state using the state log, if available and if we have not
1163              already found a valid (even if not the longest) match.  */
1164           if (BE (err != REG_NOERROR, 0))
1165             return -2;
1166
1167           if (mctx->state_log == NULL
1168               || (match && !fl_longest_match)
1169               || (cur_state = find_recover_state (&err, mctx)) == NULL)
1170             break;
1171         }
1172
1173       if (BE (at_init_state, 0))
1174         {
1175           if (old_state == cur_state)
1176             next_start_idx = next_char_idx;
1177           else
1178             at_init_state = 0;
1179         }
1180
1181       if (cur_state->halt)
1182         {
1183           /* Reached a halt state.
1184              Check the halt state can satisfy the current context.  */
1185           if (!cur_state->has_constraint
1186               || check_halt_state_context (mctx, cur_state,
1187                                            re_string_cur_idx (&mctx->input)))
1188             {
1189               /* We found an appropriate halt state.  */
1190               match_last = re_string_cur_idx (&mctx->input);
1191               match = 1;
1192
1193               /* We found a match, do not modify match_first below.  */
1194               p_match_first = NULL;
1195               if (!fl_longest_match)
1196                 break;
1197             }
1198         }
1199     }
1200
1201   if (p_match_first)
1202     *p_match_first += next_start_idx;
1203
1204   return match_last;
1205 }
1206
1207 /* Check NODE match the current context.  */
1208
1209 static int
1210 internal_function
1211 check_halt_node_context (const re_dfa_t *dfa, int node, unsigned int context)
1212 {
1213   re_token_type_t type = dfa->nodes[node].type;
1214   unsigned int constraint = dfa->nodes[node].constraint;
1215   if (type != END_OF_RE)
1216     return 0;
1217   if (!constraint)
1218     return 1;
1219   if (NOT_SATISFY_NEXT_CONSTRAINT (constraint, context))
1220     return 0;
1221   return 1;
1222 }
1223
1224 /* Check the halt state STATE match the current context.
1225    Return 0 if not match, if the node, STATE has, is a halt node and
1226    match the context, return the node.  */
1227
1228 static int
1229 internal_function
1230 check_halt_state_context (const re_match_context_t *mctx,
1231                           const re_dfastate_t *state, int idx)
1232 {
1233   int i;
1234   unsigned int context;
1235 #ifdef DEBUG
1236   assert (state->halt);
1237 #endif
1238   context = re_string_context_at (&mctx->input, idx, mctx->eflags);
1239   for (i = 0; i < state->nodes.nelem; ++i)
1240     if (check_halt_node_context (mctx->dfa, state->nodes.elems[i], context))
1241       return state->nodes.elems[i];
1242   return 0;
1243 }
1244
1245 /* Compute the next node to which "NFA" transit from NODE("NFA" is a NFA
1246    corresponding to the DFA).
1247    Return the destination node, and update EPS_VIA_NODES, return -1 in case
1248    of errors.  */
1249
1250 static int
1251 internal_function
1252 proceed_next_node (const re_match_context_t *mctx, int nregs, regmatch_t *regs,
1253                    int *pidx, int node, re_node_set *eps_via_nodes,
1254                    struct re_fail_stack_t *fs)
1255 {
1256   const re_dfa_t *const dfa = mctx->dfa;
1257   int i, err;
1258   if (IS_EPSILON_NODE (dfa->nodes[node].type))
1259     {
1260       re_node_set *cur_nodes = &mctx->state_log[*pidx]->nodes;
1261       re_node_set *edests = &dfa->edests[node];
1262       int dest_node;
1263       err = re_node_set_insert (eps_via_nodes, node);
1264       if (BE (err < 0, 0))
1265         return -2;
1266       /* Pick up a valid destination, or return -1 if none is found.  */
1267       for (dest_node = -1, i = 0; i < edests->nelem; ++i)
1268         {
1269           int candidate = edests->elems[i];
1270           if (!re_node_set_contains (cur_nodes, candidate))
1271             continue;
1272           if (dest_node == -1)
1273             dest_node = candidate;
1274
1275           else
1276             {
1277               /* In order to avoid infinite loop like "(a*)*", return the second
1278                  epsilon-transition if the first was already considered.  */
1279               if (re_node_set_contains (eps_via_nodes, dest_node))
1280                 return candidate;
1281
1282               /* Otherwise, push the second epsilon-transition on the fail stack.  */
1283               else if (fs != NULL
1284                        && push_fail_stack (fs, *pidx, candidate, nregs, regs,
1285                                            eps_via_nodes))
1286                 return -2;
1287
1288               /* We know we are going to exit.  */
1289               break;
1290             }
1291         }
1292       return dest_node;
1293     }
1294   else
1295     {
1296       int naccepted = 0;
1297       re_token_type_t type = dfa->nodes[node].type;
1298
1299 #ifdef RE_ENABLE_I18N
1300       if (dfa->nodes[node].accept_mb)
1301         naccepted = check_node_accept_bytes (dfa, node, &mctx->input, *pidx);
1302       else
1303 #endif /* RE_ENABLE_I18N */
1304       if (type == OP_BACK_REF)
1305         {
1306           int subexp_idx = dfa->nodes[node].opr.idx + 1;
1307           naccepted = regs[subexp_idx].rm_eo - regs[subexp_idx].rm_so;
1308           if (fs != NULL)
1309             {
1310               if (regs[subexp_idx].rm_so == -1 || regs[subexp_idx].rm_eo == -1)
1311                 return -1;
1312               else if (naccepted)
1313                 {
1314                   char *buf = (char *) re_string_get_buffer (&mctx->input);
1315                   if (memcmp (buf + regs[subexp_idx].rm_so, buf + *pidx,
1316                               naccepted) != 0)
1317                     return -1;
1318                 }
1319             }
1320
1321           if (naccepted == 0)
1322             {
1323               int dest_node;
1324               err = re_node_set_insert (eps_via_nodes, node);
1325               if (BE (err < 0, 0))
1326                 return -2;
1327               dest_node = dfa->edests[node].elems[0];
1328               if (re_node_set_contains (&mctx->state_log[*pidx]->nodes,
1329                                         dest_node))
1330                 return dest_node;
1331             }
1332         }
1333
1334       if (naccepted != 0
1335           || check_node_accept (mctx, dfa->nodes + node, *pidx))
1336         {
1337           int dest_node = dfa->nexts[node];
1338           *pidx = (naccepted == 0) ? *pidx + 1 : *pidx + naccepted;
1339           if (fs && (*pidx > mctx->match_last || mctx->state_log[*pidx] == NULL
1340                      || !re_node_set_contains (&mctx->state_log[*pidx]->nodes,
1341                                                dest_node)))
1342             return -1;
1343           re_node_set_empty (eps_via_nodes);
1344           return dest_node;
1345         }
1346     }
1347   return -1;
1348 }
1349
1350 static reg_errcode_t
1351 internal_function
1352 push_fail_stack (struct re_fail_stack_t *fs, int str_idx, int dest_node,
1353                  int nregs, regmatch_t *regs, re_node_set *eps_via_nodes)
1354 {
1355   reg_errcode_t err;
1356   int num = fs->num++;
1357   if (fs->num == fs->alloc)
1358     {
1359       struct re_fail_stack_ent_t *new_array;
1360       new_array = realloc (fs->stack, (sizeof (struct re_fail_stack_ent_t)
1361                                        * fs->alloc * 2));
1362       if (new_array == NULL)
1363         return REG_ESPACE;
1364       fs->alloc *= 2;
1365       fs->stack = new_array;
1366     }
1367   fs->stack[num].idx = str_idx;
1368   fs->stack[num].node = dest_node;
1369   fs->stack[num].regs = re_malloc (regmatch_t, nregs);
1370   if (fs->stack[num].regs == NULL)
1371     return REG_ESPACE;
1372   memcpy (fs->stack[num].regs, regs, sizeof (regmatch_t) * nregs);
1373   err = re_node_set_init_copy (&fs->stack[num].eps_via_nodes, eps_via_nodes);
1374   return err;
1375 }
1376
1377 static int
1378 internal_function
1379 pop_fail_stack (struct re_fail_stack_t *fs, int *pidx, int nregs,
1380                 regmatch_t *regs, re_node_set *eps_via_nodes)
1381 {
1382   int num = --fs->num;
1383   assert (num >= 0);
1384   *pidx = fs->stack[num].idx;
1385   memcpy (regs, fs->stack[num].regs, sizeof (regmatch_t) * nregs);
1386   re_node_set_free (eps_via_nodes);
1387   re_free (fs->stack[num].regs);
1388   *eps_via_nodes = fs->stack[num].eps_via_nodes;
1389   return fs->stack[num].node;
1390 }
1391
1392 /* Set the positions where the subexpressions are starts/ends to registers
1393    PMATCH.
1394    Note: We assume that pmatch[0] is already set, and
1395    pmatch[i].rm_so == pmatch[i].rm_eo == -1 for 0 < i < nmatch.  */
1396
1397 static reg_errcode_t
1398 internal_function
1399 set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch,
1400           regmatch_t *pmatch, int fl_backtrack)
1401 {
1402   const re_dfa_t *dfa = (const re_dfa_t *) preg->buffer;
1403   int idx, cur_node;
1404   re_node_set eps_via_nodes;
1405   struct re_fail_stack_t *fs;
1406   struct re_fail_stack_t fs_body = { 0, 2, NULL };
1407   regmatch_t *prev_idx_match;
1408   int prev_idx_match_malloced = 0;
1409
1410 #ifdef DEBUG
1411   assert (nmatch > 1);
1412   assert (mctx->state_log != NULL);
1413 #endif
1414   if (fl_backtrack)
1415     {
1416       fs = &fs_body;
1417       fs->stack = re_malloc (struct re_fail_stack_ent_t, fs->alloc);
1418       if (fs->stack == NULL)
1419         return REG_ESPACE;
1420     }
1421   else
1422     fs = NULL;
1423
1424   cur_node = dfa->init_node;
1425   re_node_set_init_empty (&eps_via_nodes);
1426
1427 #ifdef HAVE_ALLOCA
1428   if (__libc_use_alloca (nmatch * sizeof (regmatch_t)))
1429     prev_idx_match = (regmatch_t *) alloca (nmatch * sizeof (regmatch_t));
1430   else
1431 #endif
1432     {
1433       prev_idx_match = re_malloc (regmatch_t, nmatch);
1434       if (prev_idx_match == NULL)
1435         {
1436           free_fail_stack_return (fs);
1437           return REG_ESPACE;
1438         }
1439       prev_idx_match_malloced = 1;
1440     }
1441   memcpy (prev_idx_match, pmatch, sizeof (regmatch_t) * nmatch);
1442
1443   for (idx = pmatch[0].rm_so; idx <= pmatch[0].rm_eo ;)
1444     {
1445       update_regs (dfa, pmatch, prev_idx_match, cur_node, idx, nmatch);
1446
1447       if (idx == pmatch[0].rm_eo && cur_node == mctx->last_node)
1448         {
1449           int reg_idx;
1450           if (fs)
1451             {
1452               for (reg_idx = 0; reg_idx < nmatch; ++reg_idx)
1453                 if (pmatch[reg_idx].rm_so > -1 && pmatch[reg_idx].rm_eo == -1)
1454                   break;
1455               if (reg_idx == nmatch)
1456                 {
1457                   re_node_set_free (&eps_via_nodes);
1458                   if (prev_idx_match_malloced)
1459                     re_free (prev_idx_match);
1460                   return free_fail_stack_return (fs);
1461                 }
1462               cur_node = pop_fail_stack (fs, &idx, nmatch, pmatch,
1463                                          &eps_via_nodes);
1464             }
1465           else
1466             {
1467               re_node_set_free (&eps_via_nodes);
1468               if (prev_idx_match_malloced)
1469                 re_free (prev_idx_match);
1470               return REG_NOERROR;
1471             }
1472         }
1473
1474       /* Proceed to next node.  */
1475       cur_node = proceed_next_node (mctx, nmatch, pmatch, &idx, cur_node,
1476                                     &eps_via_nodes, fs);
1477
1478       if (BE (cur_node < 0, 0))
1479         {
1480           if (BE (cur_node == -2, 0))
1481             {
1482               re_node_set_free (&eps_via_nodes);
1483               if (prev_idx_match_malloced)
1484                 re_free (prev_idx_match);
1485               free_fail_stack_return (fs);
1486               return REG_ESPACE;
1487             }
1488           if (fs)
1489             cur_node = pop_fail_stack (fs, &idx, nmatch, pmatch,
1490                                        &eps_via_nodes);
1491           else
1492             {
1493               re_node_set_free (&eps_via_nodes);
1494               if (prev_idx_match_malloced)
1495                 re_free (prev_idx_match);
1496               return REG_NOMATCH;
1497             }
1498         }
1499     }
1500   re_node_set_free (&eps_via_nodes);
1501   if (prev_idx_match_malloced)
1502     re_free (prev_idx_match);
1503   return free_fail_stack_return (fs);
1504 }
1505
1506 static reg_errcode_t
1507 internal_function
1508 free_fail_stack_return (struct re_fail_stack_t *fs)
1509 {
1510   if (fs)
1511     {
1512       int fs_idx;
1513       for (fs_idx = 0; fs_idx < fs->num; ++fs_idx)
1514         {
1515           re_node_set_free (&fs->stack[fs_idx].eps_via_nodes);
1516           re_free (fs->stack[fs_idx].regs);
1517         }
1518       re_free (fs->stack);
1519     }
1520   return REG_NOERROR;
1521 }
1522
1523 static void
1524 internal_function
1525 update_regs (const re_dfa_t *dfa, regmatch_t *pmatch,
1526              regmatch_t *prev_idx_match, int cur_node, int cur_idx, int nmatch)
1527 {
1528   int type = dfa->nodes[cur_node].type;
1529   if (type == OP_OPEN_SUBEXP)
1530     {
1531       int reg_num = dfa->nodes[cur_node].opr.idx + 1;
1532
1533       /* We are at the first node of this sub expression.  */
1534       if (reg_num < nmatch)
1535         {
1536           pmatch[reg_num].rm_so = cur_idx;
1537           pmatch[reg_num].rm_eo = -1;
1538         }
1539     }
1540   else if (type == OP_CLOSE_SUBEXP)
1541     {
1542       int reg_num = dfa->nodes[cur_node].opr.idx + 1;
1543       if (reg_num < nmatch)
1544         {
1545           /* We are at the last node of this sub expression.  */
1546           if (pmatch[reg_num].rm_so < cur_idx)
1547             {
1548               pmatch[reg_num].rm_eo = cur_idx;
1549               /* This is a non-empty match or we are not inside an optional
1550                  subexpression.  Accept this right away.  */
1551               memcpy (prev_idx_match, pmatch, sizeof (regmatch_t) * nmatch);
1552             }
1553           else
1554             {
1555               if (dfa->nodes[cur_node].opt_subexp
1556                   && prev_idx_match[reg_num].rm_so != -1)
1557                 /* We transited through an empty match for an optional
1558                    subexpression, like (a?)*, and this is not the subexp's
1559                    first match.  Copy back the old content of the registers
1560                    so that matches of an inner subexpression are undone as
1561                    well, like in ((a?))*.  */
1562                 memcpy (pmatch, prev_idx_match, sizeof (regmatch_t) * nmatch);
1563               else
1564                 /* We completed a subexpression, but it may be part of
1565                    an optional one, so do not update PREV_IDX_MATCH.  */
1566                 pmatch[reg_num].rm_eo = cur_idx;
1567             }
1568         }
1569     }
1570 }
1571
1572 /* This function checks the STATE_LOG from the SCTX->last_str_idx to 0
1573    and sift the nodes in each states according to the following rules.
1574    Updated state_log will be wrote to STATE_LOG.
1575
1576    Rules: We throw away the Node `a' in the STATE_LOG[STR_IDX] if...
1577      1. When STR_IDX == MATCH_LAST(the last index in the state_log):
1578         If `a' isn't the LAST_NODE and `a' can't epsilon transit to
1579         the LAST_NODE, we throw away the node `a'.
1580      2. When 0 <= STR_IDX < MATCH_LAST and `a' accepts
1581         string `s' and transit to `b':
1582         i. If 'b' isn't in the STATE_LOG[STR_IDX+strlen('s')], we throw
1583            away the node `a'.
1584         ii. If 'b' is in the STATE_LOG[STR_IDX+strlen('s')] but 'b' is
1585             thrown away, we throw away the node `a'.
1586      3. When 0 <= STR_IDX < MATCH_LAST and 'a' epsilon transit to 'b':
1587         i. If 'b' isn't in the STATE_LOG[STR_IDX], we throw away the
1588            node `a'.
1589         ii. If 'b' is in the STATE_LOG[STR_IDX] but 'b' is thrown away,
1590             we throw away the node `a'.  */
1591
1592 #define STATE_NODE_CONTAINS(state,node) \
1593   ((state) != NULL && re_node_set_contains (&(state)->nodes, node))
1594
1595 static reg_errcode_t
1596 internal_function
1597 sift_states_backward (const re_match_context_t *mctx, re_sift_context_t *sctx)
1598 {
1599   reg_errcode_t err;
1600   int null_cnt = 0;
1601   int str_idx = sctx->last_str_idx;
1602   re_node_set cur_dest;
1603
1604 #ifdef DEBUG
1605   assert (mctx->state_log != NULL && mctx->state_log[str_idx] != NULL);
1606 #endif
1607
1608   /* Build sifted state_log[str_idx].  It has the nodes which can epsilon
1609      transit to the last_node and the last_node itself.  */
1610   err = re_node_set_init_1 (&cur_dest, sctx->last_node);
1611   if (BE (err != REG_NOERROR, 0))
1612     return err;
1613   err = update_cur_sifted_state (mctx, sctx, str_idx, &cur_dest);
1614   if (BE (err != REG_NOERROR, 0))
1615     goto free_return;
1616
1617   /* Then check each states in the state_log.  */
1618   while (str_idx > 0)
1619     {
1620       /* Update counters.  */
1621       null_cnt = (sctx->sifted_states[str_idx] == NULL) ? null_cnt + 1 : 0;
1622       if (null_cnt > mctx->max_mb_elem_len)
1623         {
1624           memset (sctx->sifted_states, '\0',
1625                   sizeof (re_dfastate_t *) * str_idx);
1626           re_node_set_free (&cur_dest);
1627           return REG_NOERROR;
1628         }
1629       re_node_set_empty (&cur_dest);
1630       --str_idx;
1631
1632       if (mctx->state_log[str_idx])
1633         {
1634           err = build_sifted_states (mctx, sctx, str_idx, &cur_dest);
1635           if (BE (err != REG_NOERROR, 0))
1636             goto free_return;
1637         }
1638
1639       /* Add all the nodes which satisfy the following conditions:
1640          - It can epsilon transit to a node in CUR_DEST.
1641          - It is in CUR_SRC.
1642          And update state_log.  */
1643       err = update_cur_sifted_state (mctx, sctx, str_idx, &cur_dest);
1644       if (BE (err != REG_NOERROR, 0))
1645         goto free_return;
1646     }
1647   err = REG_NOERROR;
1648  free_return:
1649   re_node_set_free (&cur_dest);
1650   return err;
1651 }
1652
1653 static reg_errcode_t
1654 internal_function
1655 build_sifted_states (const re_match_context_t *mctx, re_sift_context_t *sctx,
1656                      int str_idx, re_node_set *cur_dest)
1657 {
1658   const re_dfa_t *const dfa = mctx->dfa;
1659   const re_node_set *cur_src = &mctx->state_log[str_idx]->non_eps_nodes;
1660   int i;
1661
1662   /* Then build the next sifted state.
1663      We build the next sifted state on `cur_dest', and update
1664      `sifted_states[str_idx]' with `cur_dest'.
1665      Note:
1666      `cur_dest' is the sifted state from `state_log[str_idx + 1]'.
1667      `cur_src' points the node_set of the old `state_log[str_idx]'
1668      (with the epsilon nodes pre-filtered out).  */
1669   for (i = 0; i < cur_src->nelem; i++)
1670     {
1671       int prev_node = cur_src->elems[i];
1672       int naccepted = 0;
1673       int ret;
1674
1675 #ifdef DEBUG
1676       re_token_type_t type = dfa->nodes[prev_node].type;
1677       assert (!IS_EPSILON_NODE (type));
1678 #endif
1679 #ifdef RE_ENABLE_I18N
1680       /* If the node may accept `multi byte'.  */
1681       if (dfa->nodes[prev_node].accept_mb)
1682         naccepted = sift_states_iter_mb (mctx, sctx, prev_node,
1683                                          str_idx, sctx->last_str_idx);
1684 #endif /* RE_ENABLE_I18N */
1685
1686       /* We don't check backreferences here.
1687          See update_cur_sifted_state().  */
1688       if (!naccepted
1689           && check_node_accept (mctx, dfa->nodes + prev_node, str_idx)
1690           && STATE_NODE_CONTAINS (sctx->sifted_states[str_idx + 1],
1691                                   dfa->nexts[prev_node]))
1692         naccepted = 1;
1693
1694       if (naccepted == 0)
1695         continue;
1696
1697       if (sctx->limits.nelem)
1698         {
1699           int to_idx = str_idx + naccepted;
1700           if (check_dst_limits (mctx, &sctx->limits,
1701                                 dfa->nexts[prev_node], to_idx,
1702                                 prev_node, str_idx))
1703             continue;
1704         }
1705       ret = re_node_set_insert (cur_dest, prev_node);
1706       if (BE (ret == -1, 0))
1707         return REG_ESPACE;
1708     }
1709
1710   return REG_NOERROR;
1711 }
1712
1713 /* Helper functions.  */
1714
1715 static reg_errcode_t
1716 internal_function
1717 clean_state_log_if_needed (re_match_context_t *mctx, int next_state_log_idx)
1718 {
1719   int top = mctx->state_log_top;
1720
1721   if (next_state_log_idx >= mctx->input.bufs_len
1722       || (next_state_log_idx >= mctx->input.valid_len
1723           && mctx->input.valid_len < mctx->input.len))
1724     {
1725       reg_errcode_t err;
1726       err = extend_buffers (mctx);
1727       if (BE (err != REG_NOERROR, 0))
1728         return err;
1729     }
1730
1731   if (top < next_state_log_idx)
1732     {
1733       memset (mctx->state_log + top + 1, '\0',
1734               sizeof (re_dfastate_t *) * (next_state_log_idx - top));
1735       mctx->state_log_top = next_state_log_idx;
1736     }
1737   return REG_NOERROR;
1738 }
1739
1740 static reg_errcode_t
1741 internal_function
1742 merge_state_array (const re_dfa_t *dfa, re_dfastate_t **dst,
1743                    re_dfastate_t **src, int num)
1744 {
1745   int st_idx;
1746   reg_errcode_t err;
1747   for (st_idx = 0; st_idx < num; ++st_idx)
1748     {
1749       if (dst[st_idx] == NULL)
1750         dst[st_idx] = src[st_idx];
1751       else if (src[st_idx] != NULL)
1752         {
1753           re_node_set merged_set;
1754           err = re_node_set_init_union (&merged_set, &dst[st_idx]->nodes,
1755                                         &src[st_idx]->nodes);
1756           if (BE (err != REG_NOERROR, 0))
1757             return err;
1758           dst[st_idx] = re_acquire_state (&err, dfa, &merged_set);
1759           re_node_set_free (&merged_set);
1760           if (BE (err != REG_NOERROR, 0))
1761             return err;
1762         }
1763     }
1764   return REG_NOERROR;
1765 }
1766
1767 static reg_errcode_t
1768 internal_function
1769 update_cur_sifted_state (const re_match_context_t *mctx,
1770                          re_sift_context_t *sctx, int str_idx,
1771                          re_node_set *dest_nodes)
1772 {
1773   const re_dfa_t *const dfa = mctx->dfa;
1774   reg_errcode_t err = REG_NOERROR;
1775   const re_node_set *candidates;
1776   candidates = ((mctx->state_log[str_idx] == NULL) ? NULL
1777                 : &mctx->state_log[str_idx]->nodes);
1778
1779   if (dest_nodes->nelem == 0)
1780     sctx->sifted_states[str_idx] = NULL;
1781   else
1782     {
1783       if (candidates)
1784         {
1785           /* At first, add the nodes which can epsilon transit to a node in
1786              DEST_NODE.  */
1787           err = add_epsilon_src_nodes (dfa, dest_nodes, candidates);
1788           if (BE (err != REG_NOERROR, 0))
1789             return err;
1790
1791           /* Then, check the limitations in the current sift_context.  */
1792           if (sctx->limits.nelem)
1793             {
1794               err = check_subexp_limits (dfa, dest_nodes, candidates, &sctx->limits,
1795                                          mctx->bkref_ents, str_idx);
1796               if (BE (err != REG_NOERROR, 0))
1797                 return err;
1798             }
1799         }
1800
1801       sctx->sifted_states[str_idx] = re_acquire_state (&err, dfa, dest_nodes);
1802       if (BE (err != REG_NOERROR, 0))
1803         return err;
1804     }
1805
1806   if (candidates && mctx->state_log[str_idx]->has_backref)
1807     {
1808       err = sift_states_bkref (mctx, sctx, str_idx, candidates);
1809       if (BE (err != REG_NOERROR, 0))
1810         return err;
1811     }
1812   return REG_NOERROR;
1813 }
1814
1815 static reg_errcode_t
1816 internal_function
1817 add_epsilon_src_nodes (const re_dfa_t *dfa, re_node_set *dest_nodes,
1818                        const re_node_set *candidates)
1819 {
1820   reg_errcode_t err = REG_NOERROR;
1821   int i;
1822
1823   re_dfastate_t *state = re_acquire_state (&err, dfa, dest_nodes);
1824   if (BE (err != REG_NOERROR, 0))
1825     return err;
1826
1827   if (!state->inveclosure.alloc)
1828     {
1829       err = re_node_set_alloc (&state->inveclosure, dest_nodes->nelem);
1830       if (BE (err != REG_NOERROR, 0))
1831         return REG_ESPACE;
1832       for (i = 0; i < dest_nodes->nelem; i++)
1833         {
1834           err = re_node_set_merge (&state->inveclosure,
1835                                    dfa->inveclosures + dest_nodes->elems[i]);
1836           if (BE (err != REG_NOERROR, 0))
1837             return REG_ESPACE;
1838         }
1839     }
1840   return re_node_set_add_intersect (dest_nodes, candidates,
1841                                     &state->inveclosure);
1842 }
1843
1844 static reg_errcode_t
1845 internal_function
1846 sub_epsilon_src_nodes (const re_dfa_t *dfa, int node, re_node_set *dest_nodes,
1847                        const re_node_set *candidates)
1848 {
1849     int ecl_idx;
1850     reg_errcode_t err;
1851     re_node_set *inv_eclosure = dfa->inveclosures + node;
1852     re_node_set except_nodes;
1853     re_node_set_init_empty (&except_nodes);
1854     for (ecl_idx = 0; ecl_idx < inv_eclosure->nelem; ++ecl_idx)
1855       {
1856         int cur_node = inv_eclosure->elems[ecl_idx];
1857         if (cur_node == node)
1858           continue;
1859         if (IS_EPSILON_NODE (dfa->nodes[cur_node].type))
1860           {
1861             int edst1 = dfa->edests[cur_node].elems[0];
1862             int edst2 = ((dfa->edests[cur_node].nelem > 1)
1863                          ? dfa->edests[cur_node].elems[1] : -1);
1864             if ((!re_node_set_contains (inv_eclosure, edst1)
1865                  && re_node_set_contains (dest_nodes, edst1))
1866                 || (edst2 > 0
1867                     && !re_node_set_contains (inv_eclosure, edst2)
1868                     && re_node_set_contains (dest_nodes, edst2)))
1869               {
1870                 err = re_node_set_add_intersect (&except_nodes, candidates,
1871                                                  dfa->inveclosures + cur_node);
1872                 if (BE (err != REG_NOERROR, 0))
1873                   {
1874                     re_node_set_free (&except_nodes);
1875                     return err;
1876                   }
1877               }
1878           }
1879       }
1880     for (ecl_idx = 0; ecl_idx < inv_eclosure->nelem; ++ecl_idx)
1881       {
1882         int cur_node = inv_eclosure->elems[ecl_idx];
1883         if (!re_node_set_contains (&except_nodes, cur_node))
1884           {
1885             int idx = re_node_set_contains (dest_nodes, cur_node) - 1;
1886             re_node_set_remove_at (dest_nodes, idx);
1887           }
1888       }
1889     re_node_set_free (&except_nodes);
1890     return REG_NOERROR;
1891 }
1892
1893 static int
1894 internal_function
1895 check_dst_limits (const re_match_context_t *mctx, re_node_set *limits,
1896                   int dst_node, int dst_idx, int src_node, int src_idx)
1897 {
1898   const re_dfa_t *const dfa = mctx->dfa;
1899   int lim_idx, src_pos, dst_pos;
1900
1901   int dst_bkref_idx = search_cur_bkref_entry (mctx, dst_idx);
1902   int src_bkref_idx = search_cur_bkref_entry (mctx, src_idx);
1903   for (lim_idx = 0; lim_idx < limits->nelem; ++lim_idx)
1904     {
1905       int subexp_idx;
1906       struct re_backref_cache_entry *ent;
1907       ent = mctx->bkref_ents + limits->elems[lim_idx];
1908       subexp_idx = dfa->nodes[ent->node].opr.idx;
1909
1910       dst_pos = check_dst_limits_calc_pos (mctx, limits->elems[lim_idx],
1911                                            subexp_idx, dst_node, dst_idx,
1912                                            dst_bkref_idx);
1913       src_pos = check_dst_limits_calc_pos (mctx, limits->elems[lim_idx],
1914                                            subexp_idx, src_node, src_idx,
1915                                            src_bkref_idx);
1916
1917       /* In case of:
1918          <src> <dst> ( <subexp> )
1919          ( <subexp> ) <src> <dst>
1920          ( <subexp1> <src> <subexp2> <dst> <subexp3> )  */
1921       if (src_pos == dst_pos)
1922         continue; /* This is unrelated limitation.  */
1923       else
1924         return 1;
1925     }
1926   return 0;
1927 }
1928
1929 static int
1930 internal_function
1931 check_dst_limits_calc_pos_1 (const re_match_context_t *mctx, int boundaries,
1932                              int subexp_idx, int from_node, int bkref_idx)
1933 {
1934   const re_dfa_t *const dfa = mctx->dfa;
1935   const re_node_set *eclosures = dfa->eclosures + from_node;
1936   int node_idx;
1937
1938   /* Else, we are on the boundary: examine the nodes on the epsilon
1939      closure.  */
1940   for (node_idx = 0; node_idx < eclosures->nelem; ++node_idx)
1941     {
1942       int node = eclosures->elems[node_idx];
1943       switch (dfa->nodes[node].type)
1944         {
1945         case OP_BACK_REF:
1946           if (bkref_idx != -1)
1947             {
1948               struct re_backref_cache_entry *ent = mctx->bkref_ents + bkref_idx;
1949               do
1950                 {
1951                   int dst, cpos;
1952
1953                   if (ent->node != node)
1954                     continue;
1955
1956                   if (subexp_idx < BITSET_WORD_BITS
1957                       && !(ent->eps_reachable_subexps_map
1958                            & ((bitset_word_t) 1 << subexp_idx)))
1959                     continue;
1960
1961                   /* Recurse trying to reach the OP_OPEN_SUBEXP and
1962                      OP_CLOSE_SUBEXP cases below.  But, if the
1963                      destination node is the same node as the source
1964                      node, don't recurse because it would cause an
1965                      infinite loop: a regex that exhibits this behavior
1966                      is ()\1*\1*  */
1967                   dst = dfa->edests[node].elems[0];
1968                   if (dst == from_node)
1969                     {
1970                       if (boundaries & 1)
1971                         return -1;
1972                       else /* if (boundaries & 2) */
1973                         return 0;
1974                     }
1975
1976                   cpos =
1977                     check_dst_limits_calc_pos_1 (mctx, boundaries, subexp_idx,
1978                                                  dst, bkref_idx);
1979                   if (cpos == -1 /* && (boundaries & 1) */)
1980                     return -1;
1981                   if (cpos == 0 && (boundaries & 2))
1982                     return 0;
1983
1984                   if (subexp_idx < BITSET_WORD_BITS)
1985                     ent->eps_reachable_subexps_map
1986                       &= ~((bitset_word_t) 1 << subexp_idx);
1987                 }
1988               while (ent++->more);
1989             }
1990           break;
1991
1992         case OP_OPEN_SUBEXP:
1993           if ((boundaries & 1) && subexp_idx == dfa->nodes[node].opr.idx)
1994             return -1;
1995           break;
1996
1997         case OP_CLOSE_SUBEXP:
1998           if ((boundaries & 2) && subexp_idx == dfa->nodes[node].opr.idx)
1999             return 0;
2000           break;
2001
2002         default:
2003             break;
2004         }
2005     }
2006
2007   return (boundaries & 2) ? 1 : 0;
2008 }
2009
2010 static int
2011 internal_function
2012 check_dst_limits_calc_pos (const re_match_context_t *mctx, int limit,
2013                            int subexp_idx, int from_node, int str_idx,
2014                            int bkref_idx)
2015 {
2016   struct re_backref_cache_entry *lim = mctx->bkref_ents + limit;
2017   int boundaries;
2018
2019   /* If we are outside the range of the subexpression, return -1 or 1.  */
2020   if (str_idx < lim->subexp_from)
2021     return -1;
2022
2023   if (lim->subexp_to < str_idx)
2024     return 1;
2025
2026   /* If we are within the subexpression, return 0.  */
2027   boundaries = (str_idx == lim->subexp_from);
2028   boundaries |= (str_idx == lim->subexp_to) << 1;
2029   if (boundaries == 0)
2030     return 0;
2031
2032   /* Else, examine epsilon closure.  */
2033   return check_dst_limits_calc_pos_1 (mctx, boundaries, subexp_idx,
2034                                       from_node, bkref_idx);
2035 }
2036
2037 /* Check the limitations of sub expressions LIMITS, and remove the nodes
2038    which are against limitations from DEST_NODES. */
2039
2040 static reg_errcode_t
2041 internal_function
2042 check_subexp_limits (const re_dfa_t *dfa, re_node_set *dest_nodes,
2043                      const re_node_set *candidates, re_node_set *limits,
2044                      struct re_backref_cache_entry *bkref_ents, int str_idx)
2045 {
2046   reg_errcode_t err;
2047   int node_idx, lim_idx;
2048
2049   for (lim_idx = 0; lim_idx < limits->nelem; ++lim_idx)
2050     {
2051       int subexp_idx;
2052       struct re_backref_cache_entry *ent;
2053       ent = bkref_ents + limits->elems[lim_idx];
2054
2055       if (str_idx <= ent->subexp_from || ent->str_idx < str_idx)
2056         continue; /* This is unrelated limitation.  */
2057
2058       subexp_idx = dfa->nodes[ent->node].opr.idx;
2059       if (ent->subexp_to == str_idx)
2060         {
2061           int ops_node = -1;
2062           int cls_node = -1;
2063           for (node_idx = 0; node_idx < dest_nodes->nelem; ++node_idx)
2064             {
2065               int node = dest_nodes->elems[node_idx];
2066               re_token_type_t type = dfa->nodes[node].type;
2067               if (type == OP_OPEN_SUBEXP
2068                   && subexp_idx == dfa->nodes[node].opr.idx)
2069                 ops_node = node;
2070               else if (type == OP_CLOSE_SUBEXP
2071                        && subexp_idx == dfa->nodes[node].opr.idx)
2072                 cls_node = node;
2073             }
2074
2075           /* Check the limitation of the open subexpression.  */
2076           /* Note that (ent->subexp_to = str_idx != ent->subexp_from).  */
2077           if (ops_node >= 0)
2078             {
2079               err = sub_epsilon_src_nodes (dfa, ops_node, dest_nodes,
2080                                            candidates);
2081               if (BE (err != REG_NOERROR, 0))
2082                 return err;
2083             }
2084
2085           /* Check the limitation of the close subexpression.  */
2086           if (cls_node >= 0)
2087             for (node_idx = 0; node_idx < dest_nodes->nelem; ++node_idx)
2088               {
2089                 int node = dest_nodes->elems[node_idx];
2090                 if (!re_node_set_contains (dfa->inveclosures + node,
2091                                            cls_node)
2092                     && !re_node_set_contains (dfa->eclosures + node,
2093                                               cls_node))
2094                   {
2095                     /* It is against this limitation.
2096                        Remove it form the current sifted state.  */
2097                     err = sub_epsilon_src_nodes (dfa, node, dest_nodes,
2098                                                  candidates);
2099                     if (BE (err != REG_NOERROR, 0))
2100                       return err;
2101                     --node_idx;
2102                   }
2103               }
2104         }
2105       else /* (ent->subexp_to != str_idx)  */
2106         {
2107           for (node_idx = 0; node_idx < dest_nodes->nelem; ++node_idx)
2108             {
2109               int node = dest_nodes->elems[node_idx];
2110               re_token_type_t type = dfa->nodes[node].type;
2111               if (type == OP_CLOSE_SUBEXP || type == OP_OPEN_SUBEXP)
2112                 {
2113                   if (subexp_idx != dfa->nodes[node].opr.idx)
2114                     continue;
2115                   /* It is against this limitation.
2116                      Remove it form the current sifted state.  */
2117                   err = sub_epsilon_src_nodes (dfa, node, dest_nodes,
2118                                                candidates);
2119                   if (BE (err != REG_NOERROR, 0))
2120                     return err;
2121                 }
2122             }
2123         }
2124     }
2125   return REG_NOERROR;
2126 }
2127
2128 static reg_errcode_t
2129 internal_function
2130 sift_states_bkref (const re_match_context_t *mctx, re_sift_context_t *sctx,
2131                    int str_idx, const re_node_set *candidates)
2132 {
2133   const re_dfa_t *const dfa = mctx->dfa;
2134   reg_errcode_t err;
2135   int node_idx, node;
2136   re_sift_context_t local_sctx;
2137   int first_idx = search_cur_bkref_entry (mctx, str_idx);
2138
2139   if (first_idx == -1)
2140     return REG_NOERROR;
2141
2142   local_sctx.sifted_states = NULL; /* Mark that it hasn't been initialized.  */
2143
2144   for (node_idx = 0; node_idx < candidates->nelem; ++node_idx)
2145     {
2146       int enabled_idx;
2147       re_token_type_t type;
2148       struct re_backref_cache_entry *entry;
2149       node = candidates->elems[node_idx];
2150       type = dfa->nodes[node].type;
2151       /* Avoid infinite loop for the REs like "()\1+".  */
2152       if (node == sctx->last_node && str_idx == sctx->last_str_idx)
2153         continue;
2154       if (type != OP_BACK_REF)
2155         continue;
2156
2157       entry = mctx->bkref_ents + first_idx;
2158       enabled_idx = first_idx;
2159       do
2160         {
2161           int subexp_len;
2162           int to_idx;
2163           int dst_node;
2164           int ret;
2165           re_dfastate_t *cur_state;
2166
2167           if (entry->node != node)
2168             continue;
2169           subexp_len = entry->subexp_to - entry->subexp_from;
2170           to_idx = str_idx + subexp_len;
2171           dst_node = (subexp_len ? dfa->nexts[node]
2172                       : dfa->edests[node].elems[0]);
2173
2174           if (to_idx > sctx->last_str_idx
2175               || sctx->sifted_states[to_idx] == NULL
2176               || !STATE_NODE_CONTAINS (sctx->sifted_states[to_idx], dst_node)
2177               || check_dst_limits (mctx, &sctx->limits, node,
2178                                    str_idx, dst_node, to_idx))
2179             continue;
2180
2181           if (local_sctx.sifted_states == NULL)
2182             {
2183               local_sctx = *sctx;
2184               err = re_node_set_init_copy (&local_sctx.limits, &sctx->limits);
2185               if (BE (err != REG_NOERROR, 0))
2186                 goto free_return;
2187             }
2188           local_sctx.last_node = node;
2189           local_sctx.last_str_idx = str_idx;
2190           ret = re_node_set_insert (&local_sctx.limits, enabled_idx);
2191           if (BE (ret < 0, 0))
2192             {
2193               err = REG_ESPACE;
2194               goto free_return;
2195             }
2196           cur_state = local_sctx.sifted_states[str_idx];
2197           err = sift_states_backward (mctx, &local_sctx);
2198           if (BE (err != REG_NOERROR, 0))
2199             goto free_return;
2200           if (sctx->limited_states != NULL)
2201             {
2202               err = merge_state_array (dfa, sctx->limited_states,
2203                                        local_sctx.sifted_states,
2204                                        str_idx + 1);
2205               if (BE (err != REG_NOERROR, 0))
2206                 goto free_return;
2207             }
2208           local_sctx.sifted_states[str_idx] = cur_state;
2209           re_node_set_remove (&local_sctx.limits, enabled_idx);
2210
2211           /* mctx->bkref_ents may have changed, reload the pointer.  */
2212           entry = mctx->bkref_ents + enabled_idx;
2213         }
2214       while (enabled_idx++, entry++->more);
2215     }
2216   err = REG_NOERROR;
2217  free_return:
2218   if (local_sctx.sifted_states != NULL)
2219     {
2220       re_node_set_free (&local_sctx.limits);
2221     }
2222
2223   return err;
2224 }
2225
2226
2227 #ifdef RE_ENABLE_I18N
2228 static int
2229 internal_function
2230 sift_states_iter_mb (const re_match_context_t *mctx, re_sift_context_t *sctx,
2231                      int node_idx, int str_idx, int max_str_idx)
2232 {
2233   const re_dfa_t *const dfa = mctx->dfa;
2234   int naccepted;
2235   /* Check the node can accept `multi byte'.  */
2236   naccepted = check_node_accept_bytes (dfa, node_idx, &mctx->input, str_idx);
2237   if (naccepted > 0 && str_idx + naccepted <= max_str_idx &&
2238       !STATE_NODE_CONTAINS (sctx->sifted_states[str_idx + naccepted],
2239                             dfa->nexts[node_idx]))
2240     /* The node can't accept the `multi byte', or the
2241        destination was already thrown away, then the node
2242        couldn't accept the current input `multi byte'.   */
2243     naccepted = 0;
2244   /* Otherwise, it is sure that the node could accept
2245      `naccepted' bytes input.  */
2246   return naccepted;
2247 }
2248 #endif /* RE_ENABLE_I18N */
2249
2250 \f
2251 /* Functions for state transition.  */
2252
2253 /* Return the next state to which the current state STATE will transit by
2254    accepting the current input byte, and update STATE_LOG if necessary.
2255    If STATE can accept a multibyte char/collating element/back reference
2256    update the destination of STATE_LOG.  */
2257
2258 static re_dfastate_t *
2259 internal_function
2260 transit_state (reg_errcode_t *err, re_match_context_t *mctx,
2261                re_dfastate_t *state)
2262 {
2263   re_dfastate_t **trtable;
2264   unsigned char ch;
2265
2266 #ifdef RE_ENABLE_I18N
2267   /* If the current state can accept multibyte.  */
2268   if (BE (state->accept_mb, 0))
2269     {
2270       *err = transit_state_mb (mctx, state);
2271       if (BE (*err != REG_NOERROR, 0))
2272         return NULL;
2273     }
2274 #endif /* RE_ENABLE_I18N */
2275
2276   /* Then decide the next state with the single byte.  */
2277 #if 0
2278   if (0)
2279     /* don't use transition table  */
2280     return transit_state_sb (err, mctx, state);
2281 #endif
2282
2283   /* Use transition table  */
2284   ch = re_string_fetch_byte (&mctx->input);
2285   for (;;)
2286     {
2287       trtable = state->trtable;
2288       if (BE (trtable != NULL, 1))
2289         return trtable[ch];
2290
2291       trtable = state->word_trtable;
2292       if (BE (trtable != NULL, 1))
2293         {
2294           unsigned int context;
2295           context
2296             = re_string_context_at (&mctx->input,
2297                                     re_string_cur_idx (&mctx->input) - 1,
2298                                     mctx->eflags);
2299           if (IS_WORD_CONTEXT (context))
2300             return trtable[ch + SBC_MAX];
2301           else
2302             return trtable[ch];
2303         }
2304
2305       if (!build_trtable (mctx->dfa, state))
2306         {
2307           *err = REG_ESPACE;
2308           return NULL;
2309         }
2310
2311       /* Retry, we now have a transition table.  */
2312     }
2313 }
2314
2315 /* Update the state_log if we need */
2316 static re_dfastate_t *
2317 internal_function
2318 merge_state_with_log (reg_errcode_t *err, re_match_context_t *mctx,
2319                       re_dfastate_t *next_state)
2320 {
2321   const re_dfa_t *const dfa = mctx->dfa;
2322   int cur_idx = re_string_cur_idx (&mctx->input);
2323
2324   if (cur_idx > mctx->state_log_top)
2325     {
2326       mctx->state_log[cur_idx] = next_state;
2327       mctx->state_log_top = cur_idx;
2328     }
2329   else if (mctx->state_log[cur_idx] == NULL)
2330     {
2331       mctx->state_log[cur_idx] = next_state;
2332     }
2333   else
2334     {
2335       re_dfastate_t *pstate;
2336       unsigned int context;
2337       re_node_set next_nodes, *log_nodes, *table_nodes = NULL;
2338       /* If (state_log[cur_idx] != 0), it implies that cur_idx is
2339          the destination of a multibyte char/collating element/
2340          back reference.  Then the next state is the union set of
2341          these destinations and the results of the transition table.  */
2342       pstate = mctx->state_log[cur_idx];
2343       log_nodes = pstate->entrance_nodes;
2344       if (next_state != NULL)
2345         {
2346           table_nodes = next_state->entrance_nodes;
2347           *err = re_node_set_init_union (&next_nodes, table_nodes,
2348                                              log_nodes);
2349           if (BE (*err != REG_NOERROR, 0))
2350             return NULL;
2351         }
2352       else
2353         next_nodes = *log_nodes;
2354       /* Note: We already add the nodes of the initial state,
2355          then we don't need to add them here.  */
2356
2357       context = re_string_context_at (&mctx->input,
2358                                       re_string_cur_idx (&mctx->input) - 1,
2359                                       mctx->eflags);
2360       next_state = mctx->state_log[cur_idx]
2361         = re_acquire_state_context (err, dfa, &next_nodes, context);
2362       /* We don't need to check errors here, since the return value of
2363          this function is next_state and ERR is already set.  */
2364
2365       if (table_nodes != NULL)
2366         re_node_set_free (&next_nodes);
2367     }
2368
2369   if (BE (dfa->nbackref, 0) && next_state != NULL)
2370     {
2371       /* Check OP_OPEN_SUBEXP in the current state in case that we use them
2372          later.  We must check them here, since the back references in the
2373          next state might use them.  */
2374       *err = check_subexp_matching_top (mctx, &next_state->nodes,
2375                                         cur_idx);
2376       if (BE (*err != REG_NOERROR, 0))
2377         return NULL;
2378
2379       /* If the next state has back references.  */
2380       if (next_state->has_backref)
2381         {
2382           *err = transit_state_bkref (mctx, &next_state->nodes);
2383           if (BE (*err != REG_NOERROR, 0))
2384             return NULL;
2385           next_state = mctx->state_log[cur_idx];
2386         }
2387     }
2388
2389   return next_state;
2390 }
2391
2392 /* Skip bytes in the input that correspond to part of a
2393    multi-byte match, then look in the log for a state
2394    from which to restart matching.  */
2395 static re_dfastate_t *
2396 internal_function
2397 find_recover_state (reg_errcode_t *err, re_match_context_t *mctx)
2398 {
2399   re_dfastate_t *cur_state;
2400   do
2401     {
2402       int max = mctx->state_log_top;
2403       int cur_str_idx = re_string_cur_idx (&mctx->input);
2404
2405       do
2406         {
2407           if (++cur_str_idx > max)
2408             return NULL;
2409           re_string_skip_bytes (&mctx->input, 1);
2410         }
2411       while (mctx->state_log[cur_str_idx] == NULL);
2412
2413       cur_state = merge_state_with_log (err, mctx, NULL);
2414     }
2415   while (*err == REG_NOERROR && cur_state == NULL);
2416   return cur_state;
2417 }
2418
2419 /* Helper functions for transit_state.  */
2420
2421 /* From the node set CUR_NODES, pick up the nodes whose types are
2422    OP_OPEN_SUBEXP and which have corresponding back references in the regular
2423    expression. And register them to use them later for evaluating the
2424    correspoding back references.  */
2425
2426 static reg_errcode_t
2427 internal_function
2428 check_subexp_matching_top (re_match_context_t *mctx, re_node_set *cur_nodes,
2429                            int str_idx)
2430 {
2431   const re_dfa_t *const dfa = mctx->dfa;
2432   int node_idx;
2433   reg_errcode_t err;
2434
2435   /* TODO: This isn't efficient.
2436            Because there might be more than one nodes whose types are
2437            OP_OPEN_SUBEXP and whose index is SUBEXP_IDX, we must check all
2438            nodes.
2439            E.g. RE: (a){2}  */
2440   for (node_idx = 0; node_idx < cur_nodes->nelem; ++node_idx)
2441     {
2442       int node = cur_nodes->elems[node_idx];
2443       if (dfa->nodes[node].type == OP_OPEN_SUBEXP
2444           && dfa->nodes[node].opr.idx < BITSET_WORD_BITS
2445           && (dfa->used_bkref_map
2446               & ((bitset_word_t) 1 << dfa->nodes[node].opr.idx)))
2447         {
2448           err = match_ctx_add_subtop (mctx, node, str_idx);
2449           if (BE (err != REG_NOERROR, 0))
2450             return err;
2451         }
2452     }
2453   return REG_NOERROR;
2454 }
2455
2456 #if 0
2457 /* Return the next state to which the current state STATE will transit by
2458    accepting the current input byte.  */
2459
2460 static re_dfastate_t *
2461 transit_state_sb (reg_errcode_t *err, re_match_context_t *mctx,
2462                   re_dfastate_t *state)
2463 {
2464   const re_dfa_t *const dfa = mctx->dfa;
2465   re_node_set next_nodes;
2466   re_dfastate_t *next_state;
2467   int node_cnt, cur_str_idx = re_string_cur_idx (&mctx->input);
2468   unsigned int context;
2469
2470   *err = re_node_set_alloc (&next_nodes, state->nodes.nelem + 1);
2471   if (BE (*err != REG_NOERROR, 0))
2472     return NULL;
2473   for (node_cnt = 0; node_cnt < state->nodes.nelem; ++node_cnt)
2474     {
2475       int cur_node = state->nodes.elems[node_cnt];
2476       if (check_node_accept (mctx, dfa->nodes + cur_node, cur_str_idx))
2477         {
2478           *err = re_node_set_merge (&next_nodes,
2479                                     dfa->eclosures + dfa->nexts[cur_node]);
2480           if (BE (*err != REG_NOERROR, 0))
2481             {
2482               re_node_set_free (&next_nodes);
2483               return NULL;
2484             }
2485         }
2486     }
2487   context = re_string_context_at (&mctx->input, cur_str_idx, mctx->eflags);
2488   next_state = re_acquire_state_context (err, dfa, &next_nodes, context);
2489   /* We don't need to check errors here, since the return value of
2490      this function is next_state and ERR is already set.  */
2491
2492   re_node_set_free (&next_nodes);
2493   re_string_skip_bytes (&mctx->input, 1);
2494   return next_state;
2495 }
2496 #endif
2497
2498 #ifdef RE_ENABLE_I18N
2499 static reg_errcode_t
2500 internal_function
2501 transit_state_mb (re_match_context_t *mctx, re_dfastate_t *pstate)
2502 {
2503   const re_dfa_t *const dfa = mctx->dfa;
2504   reg_errcode_t err;
2505   int i;
2506
2507   for (i = 0; i < pstate->nodes.nelem; ++i)
2508     {
2509       re_node_set dest_nodes, *new_nodes;
2510       int cur_node_idx = pstate->nodes.elems[i];
2511       int naccepted, dest_idx;
2512       unsigned int context;
2513       re_dfastate_t *dest_state;
2514
2515       if (!dfa->nodes[cur_node_idx].accept_mb)
2516         continue;
2517
2518       if (dfa->nodes[cur_node_idx].constraint)
2519         {
2520           context = re_string_context_at (&mctx->input,
2521                                           re_string_cur_idx (&mctx->input),
2522                                           mctx->eflags);
2523           if (NOT_SATISFY_NEXT_CONSTRAINT (dfa->nodes[cur_node_idx].constraint,
2524                                            context))
2525             continue;
2526         }
2527
2528       /* How many bytes the node can accept?  */
2529       naccepted = check_node_accept_bytes (dfa, cur_node_idx, &mctx->input,
2530                                            re_string_cur_idx (&mctx->input));
2531       if (naccepted == 0)
2532         continue;
2533
2534       /* The node can accepts `naccepted' bytes.  */
2535       dest_idx = re_string_cur_idx (&mctx->input) + naccepted;
2536       mctx->max_mb_elem_len = ((mctx->max_mb_elem_len < naccepted) ? naccepted
2537                                : mctx->max_mb_elem_len);
2538       err = clean_state_log_if_needed (mctx, dest_idx);
2539       if (BE (err != REG_NOERROR, 0))
2540         return err;
2541 #ifdef DEBUG
2542       assert (dfa->nexts[cur_node_idx] != -1);
2543 #endif
2544       new_nodes = dfa->eclosures + dfa->nexts[cur_node_idx];
2545
2546       dest_state = mctx->state_log[dest_idx];
2547       if (dest_state == NULL)
2548         dest_nodes = *new_nodes;
2549       else
2550         {
2551           err = re_node_set_init_union (&dest_nodes,
2552                                         dest_state->entrance_nodes, new_nodes);
2553           if (BE (err != REG_NOERROR, 0))
2554             return err;
2555         }
2556       context = re_string_context_at (&mctx->input, dest_idx - 1,
2557                                       mctx->eflags);
2558       mctx->state_log[dest_idx]
2559         = re_acquire_state_context (&err, dfa, &dest_nodes, context);
2560       if (dest_state != NULL)
2561         re_node_set_free (&dest_nodes);
2562       if (BE (mctx->state_log[dest_idx] == NULL && err != REG_NOERROR, 0))
2563         return err;
2564     }
2565   return REG_NOERROR;
2566 }
2567 #endif /* RE_ENABLE_I18N */
2568
2569 static reg_errcode_t
2570 internal_function
2571 transit_state_bkref (re_match_context_t *mctx, const re_node_set *nodes)
2572 {
2573   const re_dfa_t *const dfa = mctx->dfa;
2574   reg_errcode_t err;
2575   int i;
2576   int cur_str_idx = re_string_cur_idx (&mctx->input);
2577
2578   for (i = 0; i < nodes->nelem; ++i)
2579     {
2580       int dest_str_idx, prev_nelem, bkc_idx;
2581       int node_idx = nodes->elems[i];
2582       unsigned int context;
2583       const re_token_t *node = dfa->nodes + node_idx;
2584       re_node_set *new_dest_nodes;
2585
2586       /* Check whether `node' is a backreference or not.  */
2587       if (node->type != OP_BACK_REF)
2588         continue;
2589
2590       if (node->constraint)
2591         {
2592           context = re_string_context_at (&mctx->input, cur_str_idx,
2593                                           mctx->eflags);
2594           if (NOT_SATISFY_NEXT_CONSTRAINT (node->constraint, context))
2595             continue;
2596         }
2597
2598       /* `node' is a backreference.
2599          Check the substring which the substring matched.  */
2600       bkc_idx = mctx->nbkref_ents;
2601       err = get_subexp (mctx, node_idx, cur_str_idx);
2602       if (BE (err != REG_NOERROR, 0))
2603         goto free_return;
2604
2605       /* And add the epsilon closures (which is `new_dest_nodes') of
2606          the backreference to appropriate state_log.  */
2607 #ifdef DEBUG
2608       assert (dfa->nexts[node_idx] != -1);
2609 #endif
2610       for (; bkc_idx < mctx->nbkref_ents; ++bkc_idx)
2611         {
2612           int subexp_len;
2613           re_dfastate_t *dest_state;
2614           struct re_backref_cache_entry *bkref_ent;
2615           bkref_ent = mctx->bkref_ents + bkc_idx;
2616           if (bkref_ent->node != node_idx || bkref_ent->str_idx != cur_str_idx)
2617             continue;
2618           subexp_len = bkref_ent->subexp_to - bkref_ent->subexp_from;
2619           new_dest_nodes = (subexp_len == 0
2620                             ? dfa->eclosures + dfa->edests[node_idx].elems[0]
2621                             : dfa->eclosures + dfa->nexts[node_idx]);
2622           dest_str_idx = (cur_str_idx + bkref_ent->subexp_to
2623                           - bkref_ent->subexp_from);
2624           context = re_string_context_at (&mctx->input, dest_str_idx - 1,
2625                                           mctx->eflags);
2626           dest_state = mctx->state_log[dest_str_idx];
2627           prev_nelem = ((mctx->state_log[cur_str_idx] == NULL) ? 0
2628                         : mctx->state_log[cur_str_idx]->nodes.nelem);
2629           /* Add `new_dest_node' to state_log.  */
2630           if (dest_state == NULL)
2631             {
2632               mctx->state_log[dest_str_idx]
2633                 = re_acquire_state_context (&err, dfa, new_dest_nodes,
2634                                             context);
2635               if (BE (mctx->state_log[dest_str_idx] == NULL
2636                       && err != REG_NOERROR, 0))
2637                 goto free_return;
2638             }
2639           else
2640             {
2641               re_node_set dest_nodes;
2642               err = re_node_set_init_union (&dest_nodes,
2643                                             dest_state->entrance_nodes,
2644                                             new_dest_nodes);
2645               if (BE (err != REG_NOERROR, 0))
2646                 {
2647                   re_node_set_free (&dest_nodes);
2648                   goto free_return;
2649                 }
2650               mctx->state_log[dest_str_idx]
2651                 = re_acquire_state_context (&err, dfa, &dest_nodes, context);
2652               re_node_set_free (&dest_nodes);
2653               if (BE (mctx->state_log[dest_str_idx] == NULL
2654                       && err != REG_NOERROR, 0))
2655                 goto free_return;
2656             }
2657           /* We need to check recursively if the backreference can epsilon
2658              transit.  */
2659           if (subexp_len == 0
2660               && mctx->state_log[cur_str_idx]->nodes.nelem > prev_nelem)
2661             {
2662               err = check_subexp_matching_top (mctx, new_dest_nodes,
2663                                                cur_str_idx);
2664               if (BE (err != REG_NOERROR, 0))
2665                 goto free_return;
2666               err = transit_state_bkref (mctx, new_dest_nodes);
2667               if (BE (err != REG_NOERROR, 0))
2668                 goto free_return;
2669             }
2670         }
2671     }
2672   err = REG_NOERROR;
2673  free_return:
2674   return err;
2675 }
2676
2677 /* Enumerate all the candidates which the backreference BKREF_NODE can match
2678    at BKREF_STR_IDX, and register them by match_ctx_add_entry().
2679    Note that we might collect inappropriate candidates here.
2680    However, the cost of checking them strictly here is too high, then we
2681    delay these checking for prune_impossible_nodes().  */
2682
2683 static reg_errcode_t
2684 internal_function
2685 get_subexp (re_match_context_t *mctx, int bkref_node, int bkref_str_idx)
2686 {
2687   const re_dfa_t *const dfa = mctx->dfa;
2688   int subexp_num, sub_top_idx;
2689   const char *buf = (const char *) re_string_get_buffer (&mctx->input);
2690   /* Return if we have already checked BKREF_NODE at BKREF_STR_IDX.  */
2691   int cache_idx = search_cur_bkref_entry (mctx, bkref_str_idx);
2692   if (cache_idx != -1)
2693     {
2694       const struct re_backref_cache_entry *entry
2695         = mctx->bkref_ents + cache_idx;
2696       do
2697         if (entry->node == bkref_node)
2698           return REG_NOERROR; /* We already checked it.  */
2699       while (entry++->more);
2700     }
2701
2702   subexp_num = dfa->nodes[bkref_node].opr.idx;
2703
2704   /* For each sub expression  */
2705   for (sub_top_idx = 0; sub_top_idx < mctx->nsub_tops; ++sub_top_idx)
2706     {
2707       reg_errcode_t err;
2708       re_sub_match_top_t *sub_top = mctx->sub_tops[sub_top_idx];
2709       re_sub_match_last_t *sub_last;
2710       int sub_last_idx, sl_str, bkref_str_off;
2711
2712       if (dfa->nodes[sub_top->node].opr.idx != subexp_num)
2713         continue; /* It isn't related.  */
2714
2715       sl_str = sub_top->str_idx;
2716       bkref_str_off = bkref_str_idx;
2717       /* At first, check the last node of sub expressions we already
2718          evaluated.  */
2719       for (sub_last_idx = 0; sub_last_idx < sub_top->nlasts; ++sub_last_idx)
2720         {
2721           int sl_str_diff;
2722           sub_last = sub_top->lasts[sub_last_idx];
2723           sl_str_diff = sub_last->str_idx - sl_str;
2724           /* The matched string by the sub expression match with the substring
2725              at the back reference?  */
2726           if (sl_str_diff > 0)
2727             {
2728               if (BE (bkref_str_off + sl_str_diff > mctx->input.valid_len, 0))
2729                 {
2730                   /* Not enough chars for a successful match.  */
2731                   if (bkref_str_off + sl_str_diff > mctx->input.len)
2732                     break;
2733
2734                   err = clean_state_log_if_needed (mctx,
2735                                                    bkref_str_off
2736                                                    + sl_str_diff);
2737                   if (BE (err != REG_NOERROR, 0))
2738                     return err;
2739                   buf = (const char *) re_string_get_buffer (&mctx->input);
2740                 }
2741               if (memcmp (buf + bkref_str_off, buf + sl_str, sl_str_diff) != 0)
2742                 /* We don't need to search this sub expression any more.  */
2743                 break;
2744             }
2745           bkref_str_off += sl_str_diff;
2746           sl_str += sl_str_diff;
2747           err = get_subexp_sub (mctx, sub_top, sub_last, bkref_node,
2748                                 bkref_str_idx);
2749
2750           /* Reload buf, since the preceding call might have reallocated
2751              the buffer.  */
2752           buf = (const char *) re_string_get_buffer (&mctx->input);
2753
2754           if (err == REG_NOMATCH)
2755             continue;
2756           if (BE (err != REG_NOERROR, 0))
2757             return err;
2758         }
2759
2760       if (sub_last_idx < sub_top->nlasts)
2761         continue;
2762       if (sub_last_idx > 0)
2763         ++sl_str;
2764       /* Then, search for the other last nodes of the sub expression.  */
2765       for (; sl_str <= bkref_str_idx; ++sl_str)
2766         {
2767           int cls_node, sl_str_off;
2768           const re_node_set *nodes;
2769           sl_str_off = sl_str - sub_top->str_idx;
2770           /* The matched string by the sub expression match with the substring
2771              at the back reference?  */
2772           if (sl_str_off > 0)
2773             {
2774               if (BE (bkref_str_off >= mctx->input.valid_len, 0))
2775                 {
2776                   /* If we are at the end of the input, we cannot match.  */
2777                   if (bkref_str_off >= mctx->input.len)
2778                     break;
2779
2780                   err = extend_buffers (mctx);
2781                   if (BE (err != REG_NOERROR, 0))
2782                     return err;
2783
2784                   buf = (const char *) re_string_get_buffer (&mctx->input);
2785                 }
2786               if (buf [bkref_str_off++] != buf[sl_str - 1])
2787                 break; /* We don't need to search this sub expression
2788                           any more.  */
2789             }
2790           if (mctx->state_log[sl_str] == NULL)
2791             continue;
2792           /* Does this state have a ')' of the sub expression?  */
2793           nodes = &mctx->state_log[sl_str]->nodes;
2794           cls_node = find_subexp_node (dfa, nodes, subexp_num,
2795                                        OP_CLOSE_SUBEXP);
2796           if (cls_node == -1)
2797             continue; /* No.  */
2798           if (sub_top->path == NULL)
2799             {
2800               sub_top->path = calloc (sizeof (state_array_t),
2801                                       sl_str - sub_top->str_idx + 1);
2802               if (sub_top->path == NULL)
2803                 return REG_ESPACE;
2804             }
2805           /* Can the OP_OPEN_SUBEXP node arrive the OP_CLOSE_SUBEXP node
2806              in the current context?  */
2807           err = check_arrival (mctx, sub_top->path, sub_top->node,
2808                                sub_top->str_idx, cls_node, sl_str,
2809                                OP_CLOSE_SUBEXP);
2810           if (err == REG_NOMATCH)
2811               continue;
2812           if (BE (err != REG_NOERROR, 0))
2813               return err;
2814           sub_last = match_ctx_add_sublast (sub_top, cls_node, sl_str);
2815           if (BE (sub_last == NULL, 0))
2816             return REG_ESPACE;
2817           err = get_subexp_sub (mctx, sub_top, sub_last, bkref_node,
2818                                 bkref_str_idx);
2819           if (err == REG_NOMATCH)
2820             continue;
2821         }
2822     }
2823   return REG_NOERROR;
2824 }
2825
2826 /* Helper functions for get_subexp().  */
2827
2828 /* Check SUB_LAST can arrive to the back reference BKREF_NODE at BKREF_STR.
2829    If it can arrive, register the sub expression expressed with SUB_TOP
2830    and SUB_LAST.  */
2831
2832 static reg_errcode_t
2833 internal_function
2834 get_subexp_sub (re_match_context_t *mctx, const re_sub_match_top_t *sub_top,
2835                 re_sub_match_last_t *sub_last, int bkref_node, int bkref_str)
2836 {
2837   reg_errcode_t err;
2838   int to_idx;
2839   /* Can the subexpression arrive the back reference?  */
2840   err = check_arrival (mctx, &sub_last->path, sub_last->node,
2841                        sub_last->str_idx, bkref_node, bkref_str,
2842                        OP_OPEN_SUBEXP);
2843   if (err != REG_NOERROR)
2844     return err;
2845   err = match_ctx_add_entry (mctx, bkref_node, bkref_str, sub_top->str_idx,
2846                              sub_last->str_idx);
2847   if (BE (err != REG_NOERROR, 0))
2848     return err;
2849   to_idx = bkref_str + sub_last->str_idx - sub_top->str_idx;
2850   return clean_state_log_if_needed (mctx, to_idx);
2851 }
2852
2853 /* Find the first node which is '(' or ')' and whose index is SUBEXP_IDX.
2854    Search '(' if FL_OPEN, or search ')' otherwise.
2855    TODO: This function isn't efficient...
2856          Because there might be more than one nodes whose types are
2857          OP_OPEN_SUBEXP and whose index is SUBEXP_IDX, we must check all
2858          nodes.
2859          E.g. RE: (a){2}  */
2860
2861 static int
2862 internal_function
2863 find_subexp_node (const re_dfa_t *dfa, const re_node_set *nodes,
2864                   int subexp_idx, int type)
2865 {
2866   int cls_idx;
2867   for (cls_idx = 0; cls_idx < nodes->nelem; ++cls_idx)
2868     {
2869       int cls_node = nodes->elems[cls_idx];
2870       const re_token_t *node = dfa->nodes + cls_node;
2871       if (node->type == type
2872           && node->opr.idx == subexp_idx)
2873         return cls_node;
2874     }
2875   return -1;
2876 }
2877
2878 /* Check whether the node TOP_NODE at TOP_STR can arrive to the node
2879    LAST_NODE at LAST_STR.  We record the path onto PATH since it will be
2880    heavily reused.
2881    Return REG_NOERROR if it can arrive, or REG_NOMATCH otherwise.  */
2882
2883 static reg_errcode_t
2884 internal_function
2885 check_arrival (re_match_context_t *mctx, state_array_t *path, int top_node,
2886                int top_str, int last_node, int last_str, int type)
2887 {
2888   const re_dfa_t *const dfa = mctx->dfa;
2889   reg_errcode_t err = REG_NOERROR;
2890   int subexp_num, backup_cur_idx, str_idx, null_cnt;
2891   re_dfastate_t *cur_state = NULL;
2892   re_node_set *cur_nodes, next_nodes;
2893   re_dfastate_t **backup_state_log;
2894   unsigned int context;
2895
2896   subexp_num = dfa->nodes[top_node].opr.idx;
2897   /* Extend the buffer if we need.  */
2898   if (BE (path->alloc < last_str + mctx->max_mb_elem_len + 1, 0))
2899     {
2900       re_dfastate_t **new_array;
2901       int old_alloc = path->alloc;
2902       path->alloc += last_str + mctx->max_mb_elem_len + 1;
2903       new_array = re_realloc (path->array, re_dfastate_t *, path->alloc);
2904       if (BE (new_array == NULL, 0))
2905         {
2906           path->alloc = old_alloc;
2907           return REG_ESPACE;
2908         }
2909       path->array = new_array;
2910       memset (new_array + old_alloc, '\0',
2911               sizeof (re_dfastate_t *) * (path->alloc - old_alloc));
2912     }
2913
2914   str_idx = path->next_idx ? path->next_idx : top_str;
2915
2916   /* Temporary modify MCTX.  */
2917   backup_state_log = mctx->state_log;
2918   backup_cur_idx = mctx->input.cur_idx;
2919   mctx->state_log = path->array;
2920   mctx->input.cur_idx = str_idx;
2921
2922   /* Setup initial node set.  */
2923   context = re_string_context_at (&mctx->input, str_idx - 1, mctx->eflags);
2924   if (str_idx == top_str)
2925     {
2926       err = re_node_set_init_1 (&next_nodes, top_node);
2927       if (BE (err != REG_NOERROR, 0))
2928         return err;
2929       err = check_arrival_expand_ecl (dfa, &next_nodes, subexp_num, type);
2930       if (BE (err != REG_NOERROR, 0))
2931         {
2932           re_node_set_free (&next_nodes);
2933           return err;
2934         }
2935     }
2936   else
2937     {
2938       cur_state = mctx->state_log[str_idx];
2939       if (cur_state && cur_state->has_backref)
2940         {
2941           err = re_node_set_init_copy (&next_nodes, &cur_state->nodes);
2942           if (BE (err != REG_NOERROR, 0))
2943             return err;
2944         }
2945       else
2946         re_node_set_init_empty (&next_nodes);
2947     }
2948   if (str_idx == top_str || (cur_state && cur_state->has_backref))
2949     {
2950       if (next_nodes.nelem)
2951         {
2952           err = expand_bkref_cache (mctx, &next_nodes, str_idx,
2953                                     subexp_num, type);
2954           if (BE (err != REG_NOERROR, 0))
2955             {
2956               re_node_set_free (&next_nodes);
2957               return err;
2958             }
2959         }
2960       cur_state = re_acquire_state_context (&err, dfa, &next_nodes, context);
2961       if (BE (cur_state == NULL && err != REG_NOERROR, 0))
2962         {
2963           re_node_set_free (&next_nodes);
2964           return err;
2965         }
2966       mctx->state_log[str_idx] = cur_state;
2967     }
2968
2969   for (null_cnt = 0; str_idx < last_str && null_cnt <= mctx->max_mb_elem_len;)
2970     {
2971       re_node_set_empty (&next_nodes);
2972       if (mctx->state_log[str_idx + 1])
2973         {
2974           err = re_node_set_merge (&next_nodes,
2975                                    &mctx->state_log[str_idx + 1]->nodes);
2976           if (BE (err != REG_NOERROR, 0))
2977             {
2978               re_node_set_free (&next_nodes);
2979               return err;
2980             }
2981         }
2982       if (cur_state)
2983         {
2984           err = check_arrival_add_next_nodes (mctx, str_idx,
2985                                               &cur_state->non_eps_nodes,
2986                                               &next_nodes);
2987           if (BE (err != REG_NOERROR, 0))
2988             {
2989               re_node_set_free (&next_nodes);
2990               return err;
2991             }
2992         }
2993       ++str_idx;
2994       if (next_nodes.nelem)
2995         {
2996           err = check_arrival_expand_ecl (dfa, &next_nodes, subexp_num, type);
2997           if (BE (err != REG_NOERROR, 0))
2998             {
2999               re_node_set_free (&next_nodes);
3000               return err;
3001             }
3002           err = expand_bkref_cache (mctx, &next_nodes, str_idx,
3003                                     subexp_num, type);
3004           if (BE (err != REG_NOERROR, 0))
3005             {
3006               re_node_set_free (&next_nodes);
3007               return err;
3008             }
3009         }
3010       context = re_string_context_at (&mctx->input, str_idx - 1, mctx->eflags);
3011       cur_state = re_acquire_state_context (&err, dfa, &next_nodes, context);
3012       if (BE (cur_state == NULL && err != REG_NOERROR, 0))
3013         {
3014           re_node_set_free (&next_nodes);
3015           return err;
3016         }
3017       mctx->state_log[str_idx] = cur_state;
3018       null_cnt = cur_state == NULL ? null_cnt + 1 : 0;
3019     }
3020   re_node_set_free (&next_nodes);
3021   cur_nodes = (mctx->state_log[last_str] == NULL ? NULL
3022                : &mctx->state_log[last_str]->nodes);
3023   path->next_idx = str_idx;
3024
3025   /* Fix MCTX.  */
3026   mctx->state_log = backup_state_log;
3027   mctx->input.cur_idx = backup_cur_idx;
3028
3029   /* Then check the current node set has the node LAST_NODE.  */
3030   if (cur_nodes != NULL && re_node_set_contains (cur_nodes, last_node))
3031     return REG_NOERROR;
3032
3033   return REG_NOMATCH;
3034 }
3035
3036 /* Helper functions for check_arrival.  */
3037
3038 /* Calculate the destination nodes of CUR_NODES at STR_IDX, and append them
3039    to NEXT_NODES.
3040    TODO: This function is similar to the functions transit_state*(),
3041          however this function has many additional works.
3042          Can't we unify them?  */
3043
3044 static reg_errcode_t
3045 internal_function
3046 check_arrival_add_next_nodes (re_match_context_t *mctx, int str_idx,
3047                               re_node_set *cur_nodes, re_node_set *next_nodes)
3048 {
3049   const re_dfa_t *const dfa = mctx->dfa;
3050   int result;
3051   int cur_idx;
3052 #ifdef RE_ENABLE_I18N
3053   reg_errcode_t err = REG_NOERROR;
3054 #endif
3055   re_node_set union_set;
3056   re_node_set_init_empty (&union_set);
3057   for (cur_idx = 0; cur_idx < cur_nodes->nelem; ++cur_idx)
3058     {
3059       int naccepted = 0;
3060       int cur_node = cur_nodes->elems[cur_idx];
3061 #ifdef DEBUG
3062       re_token_type_t type = dfa->nodes[cur_node].type;
3063       assert (!IS_EPSILON_NODE (type));
3064 #endif
3065 #ifdef RE_ENABLE_I18N
3066       /* If the node may accept `multi byte'.  */
3067       if (dfa->nodes[cur_node].accept_mb)
3068         {
3069           naccepted = check_node_accept_bytes (dfa, cur_node, &mctx->input,
3070                                                str_idx);
3071           if (naccepted > 1)
3072             {
3073               re_dfastate_t *dest_state;
3074               int next_node = dfa->nexts[cur_node];
3075               int next_idx = str_idx + naccepted;
3076               dest_state = mctx->state_log[next_idx];
3077               re_node_set_empty (&union_set);
3078               if (dest_state)
3079                 {
3080                   err = re_node_set_merge (&union_set, &dest_state->nodes);
3081                   if (BE (err != REG_NOERROR, 0))
3082                     {
3083                       re_node_set_free (&union_set);
3084                       return err;
3085                     }
3086                 }
3087               result = re_node_set_insert (&union_set, next_node);
3088               if (BE (result < 0, 0))
3089                 {
3090                   re_node_set_free (&union_set);
3091                   return REG_ESPACE;
3092                 }
3093               mctx->state_log[next_idx] = re_acquire_state (&err, dfa,
3094                                                             &union_set);
3095               if (BE (mctx->state_log[next_idx] == NULL
3096                       && err != REG_NOERROR, 0))
3097                 {
3098                   re_node_set_free (&union_set);
3099                   return err;
3100                 }
3101             }
3102         }
3103 #endif /* RE_ENABLE_I18N */
3104       if (naccepted
3105           || check_node_accept (mctx, dfa->nodes + cur_node, str_idx))
3106         {
3107           result = re_node_set_insert (next_nodes, dfa->nexts[cur_node]);
3108           if (BE (result < 0, 0))
3109             {
3110               re_node_set_free (&union_set);
3111               return REG_ESPACE;
3112             }
3113         }
3114     }
3115   re_node_set_free (&union_set);
3116   return REG_NOERROR;
3117 }
3118
3119 /* For all the nodes in CUR_NODES, add the epsilon closures of them to
3120    CUR_NODES, however exclude the nodes which are:
3121     - inside the sub expression whose number is EX_SUBEXP, if FL_OPEN.
3122     - out of the sub expression whose number is EX_SUBEXP, if !FL_OPEN.
3123 */
3124
3125 static reg_errcode_t
3126 internal_function
3127 check_arrival_expand_ecl (const re_dfa_t *dfa, re_node_set *cur_nodes,
3128                           int ex_subexp, int type)
3129 {
3130   reg_errcode_t err;
3131   int idx, outside_node;
3132   re_node_set new_nodes;
3133 #ifdef DEBUG
3134   assert (cur_nodes->nelem);
3135 #endif
3136   err = re_node_set_alloc (&new_nodes, cur_nodes->nelem);
3137   if (BE (err != REG_NOERROR, 0))
3138     return err;
3139   /* Create a new node set NEW_NODES with the nodes which are epsilon
3140      closures of the node in CUR_NODES.  */
3141
3142   for (idx = 0; idx < cur_nodes->nelem; ++idx)
3143     {
3144       int cur_node = cur_nodes->elems[idx];
3145       const re_node_set *eclosure = dfa->eclosures + cur_node;
3146       outside_node = find_subexp_node (dfa, eclosure, ex_subexp, type);
3147       if (outside_node == -1)
3148         {
3149           /* There are no problematic nodes, just merge them.  */
3150           err = re_node_set_merge (&new_nodes, eclosure);
3151           if (BE (err != REG_NOERROR, 0))
3152             {
3153               re_node_set_free (&new_nodes);
3154               return err;
3155             }
3156         }
3157       else
3158         {
3159           /* There are problematic nodes, re-calculate incrementally.  */
3160           err = check_arrival_expand_ecl_sub (dfa, &new_nodes, cur_node,
3161                                               ex_subexp, type);
3162           if (BE (err != REG_NOERROR, 0))
3163             {
3164               re_node_set_free (&new_nodes);
3165               return err;
3166             }
3167         }
3168     }
3169   re_node_set_free (cur_nodes);
3170   *cur_nodes = new_nodes;
3171   return REG_NOERROR;
3172 }
3173
3174 /* Helper function for check_arrival_expand_ecl.
3175    Check incrementally the epsilon closure of TARGET, and if it isn't
3176    problematic append it to DST_NODES.  */
3177
3178 static reg_errcode_t
3179 internal_function
3180 check_arrival_expand_ecl_sub (const re_dfa_t *dfa, re_node_set *dst_nodes,
3181                               int target, int ex_subexp, int type)
3182 {
3183   int cur_node;
3184   for (cur_node = target; !re_node_set_contains (dst_nodes, cur_node);)
3185     {
3186       int err;
3187
3188       if (dfa->nodes[cur_node].type == type
3189           && dfa->nodes[cur_node].opr.idx == ex_subexp)
3190         {
3191           if (type == OP_CLOSE_SUBEXP)
3192             {
3193               err = re_node_set_insert (dst_nodes, cur_node);
3194               if (BE (err == -1, 0))
3195                 return REG_ESPACE;
3196             }
3197           break;
3198         }
3199       err = re_node_set_insert (dst_nodes, cur_node);
3200       if (BE (err == -1, 0))
3201         return REG_ESPACE;
3202       if (dfa->edests[cur_node].nelem == 0)
3203         break;
3204       if (dfa->edests[cur_node].nelem == 2)
3205         {
3206           err = check_arrival_expand_ecl_sub (dfa, dst_nodes,
3207                                               dfa->edests[cur_node].elems[1],
3208                                               ex_subexp, type);
3209           if (BE (err != REG_NOERROR, 0))
3210             return err;
3211         }
3212       cur_node = dfa->edests[cur_node].elems[0];
3213     }
3214   return REG_NOERROR;
3215 }
3216
3217
3218 /* For all the back references in the current state, calculate the
3219    destination of the back references by the appropriate entry
3220    in MCTX->BKREF_ENTS.  */
3221
3222 static reg_errcode_t
3223 internal_function
3224 expand_bkref_cache (re_match_context_t *mctx, re_node_set *cur_nodes,
3225                     int cur_str, int subexp_num, int type)
3226 {
3227   const re_dfa_t *const dfa = mctx->dfa;
3228   reg_errcode_t err;
3229   int cache_idx_start = search_cur_bkref_entry (mctx, cur_str);
3230   struct re_backref_cache_entry *ent;
3231
3232   if (cache_idx_start == -1)
3233     return REG_NOERROR;
3234
3235  restart:
3236   ent = mctx->bkref_ents + cache_idx_start;
3237   do
3238     {
3239       int to_idx, next_node;
3240
3241       /* Is this entry ENT is appropriate?  */
3242       if (!re_node_set_contains (cur_nodes, ent->node))
3243         continue; /* No.  */
3244
3245       to_idx = cur_str + ent->subexp_to - ent->subexp_from;
3246       /* Calculate the destination of the back reference, and append it
3247          to MCTX->STATE_LOG.  */
3248       if (to_idx == cur_str)
3249         {
3250           /* The backreference did epsilon transit, we must re-check all the
3251              node in the current state.  */
3252           re_node_set new_dests;
3253           reg_errcode_t err2, err3;
3254           next_node = dfa->edests[ent->node].elems[0];
3255           if (re_node_set_contains (cur_nodes, next_node))
3256             continue;
3257           err = re_node_set_init_1 (&new_dests, next_node);
3258           err2 = check_arrival_expand_ecl (dfa, &new_dests, subexp_num, type);
3259           err3 = re_node_set_merge (cur_nodes, &new_dests);
3260           re_node_set_free (&new_dests);
3261           if (BE (err != REG_NOERROR || err2 != REG_NOERROR
3262                   || err3 != REG_NOERROR, 0))
3263             {
3264               err = (err != REG_NOERROR ? err
3265                      : (err2 != REG_NOERROR ? err2 : err3));
3266               return err;
3267             }
3268           /* TODO: It is still inefficient...  */
3269           goto restart;
3270         }
3271       else
3272         {
3273           re_node_set union_set;
3274           next_node = dfa->nexts[ent->node];
3275           if (mctx->state_log[to_idx])
3276             {
3277               int ret;
3278               if (re_node_set_contains (&mctx->state_log[to_idx]->nodes,
3279                                         next_node))
3280                 continue;
3281               err = re_node_set_init_copy (&union_set,
3282                                            &mctx->state_log[to_idx]->nodes);
3283               ret = re_node_set_insert (&union_set, next_node);
3284               if (BE (err != REG_NOERROR || ret < 0, 0))
3285                 {
3286                   re_node_set_free (&union_set);
3287                   err = err != REG_NOERROR ? err : REG_ESPACE;
3288                   return err;
3289                 }
3290             }
3291           else
3292             {
3293               err = re_node_set_init_1 (&union_set, next_node);
3294               if (BE (err != REG_NOERROR, 0))
3295                 return err;
3296             }
3297           mctx->state_log[to_idx] = re_acquire_state (&err, dfa, &union_set);
3298           re_node_set_free (&union_set);
3299           if (BE (mctx->state_log[to_idx] == NULL
3300                   && err != REG_NOERROR, 0))
3301             return err;
3302         }
3303     }
3304   while (ent++->more);
3305   return REG_NOERROR;
3306 }
3307
3308 /* Build transition table for the state.
3309    Return 1 if succeeded, otherwise return NULL.  */
3310
3311 static int
3312 internal_function
3313 build_trtable (const re_dfa_t *dfa, re_dfastate_t *state)
3314 {
3315   reg_errcode_t err;
3316   int i, j, ch, need_word_trtable = 0;
3317   bitset_word_t elem, mask;
3318   bool dests_node_malloced = false;
3319   bool dest_states_malloced = false;
3320   int ndests; /* Number of the destination states from `state'.  */
3321   re_dfastate_t **trtable;
3322   re_dfastate_t **dest_states = NULL, **dest_states_word, **dest_states_nl;
3323   re_node_set follows, *dests_node;
3324   bitset_t *dests_ch;
3325   bitset_t acceptable;
3326
3327   struct dests_alloc
3328   {
3329     re_node_set dests_node[SBC_MAX];
3330     bitset_t dests_ch[SBC_MAX];
3331   } *dests_alloc;
3332
3333   /* We build DFA states which corresponds to the destination nodes
3334      from `state'.  `dests_node[i]' represents the nodes which i-th
3335      destination state contains, and `dests_ch[i]' represents the
3336      characters which i-th destination state accepts.  */
3337 #ifdef HAVE_ALLOCA
3338   if (__libc_use_alloca (sizeof (struct dests_alloc)))
3339     dests_alloc = (struct dests_alloc *) alloca (sizeof (struct dests_alloc));
3340   else
3341 #endif
3342     {
3343       dests_alloc = re_malloc (struct dests_alloc, 1);
3344       if (BE (dests_alloc == NULL, 0))
3345         return 0;
3346       dests_node_malloced = true;
3347     }
3348   dests_node = dests_alloc->dests_node;
3349   dests_ch = dests_alloc->dests_ch;
3350
3351   /* Initialize transiton table.  */
3352   state->word_trtable = state->trtable = NULL;
3353
3354   /* At first, group all nodes belonging to `state' into several
3355      destinations.  */
3356   ndests = group_nodes_into_DFAstates (dfa, state, dests_node, dests_ch);
3357   if (BE (ndests <= 0, 0))
3358     {
3359       if (dests_node_malloced)
3360         free (dests_alloc);
3361       /* Return 0 in case of an error, 1 otherwise.  */
3362       if (ndests == 0)
3363         {
3364           state->trtable = (re_dfastate_t **)
3365             calloc (sizeof (re_dfastate_t *), SBC_MAX);
3366           return 1;
3367         }
3368       return 0;
3369     }
3370
3371   err = re_node_set_alloc (&follows, ndests + 1);
3372   if (BE (err != REG_NOERROR, 0))
3373     goto out_free;
3374
3375   /* Avoid arithmetic overflow in size calculation.  */
3376   if (BE ((((SIZE_MAX - (sizeof (re_node_set) + sizeof (bitset_t)) * SBC_MAX)
3377             / (3 * sizeof (re_dfastate_t *)))
3378            < ndests),
3379           0))
3380     goto out_free;
3381
3382 #ifdef HAVE_ALLOCA
3383   if (__libc_use_alloca ((sizeof (re_node_set) + sizeof (bitset_t)) * SBC_MAX
3384                          + ndests * 3 * sizeof (re_dfastate_t *)))
3385     dest_states = (re_dfastate_t **)
3386       alloca (ndests * 3 * sizeof (re_dfastate_t *));
3387   else
3388 #endif
3389     {
3390       dest_states = (re_dfastate_t **)
3391         malloc (ndests * 3 * sizeof (re_dfastate_t *));
3392       if (BE (dest_states == NULL, 0))
3393         {
3394 out_free:
3395           if (dest_states_malloced)
3396             free (dest_states);
3397           re_node_set_free (&follows);
3398           for (i = 0; i < ndests; ++i)
3399             re_node_set_free (dests_node + i);
3400           if (dests_node_malloced)
3401             free (dests_alloc);
3402           return 0;
3403         }
3404       dest_states_malloced = true;
3405     }
3406   dest_states_word = dest_states + ndests;
3407   dest_states_nl = dest_states_word + ndests;
3408   bitset_empty (acceptable);
3409
3410   /* Then build the states for all destinations.  */
3411   for (i = 0; i < ndests; ++i)
3412     {
3413       int next_node;
3414       re_node_set_empty (&follows);
3415       /* Merge the follows of this destination states.  */
3416       for (j = 0; j < dests_node[i].nelem; ++j)
3417         {
3418           next_node = dfa->nexts[dests_node[i].elems[j]];
3419           if (next_node != -1)
3420             {
3421               err = re_node_set_merge (&follows, dfa->eclosures + next_node);
3422               if (BE (err != REG_NOERROR, 0))
3423                 goto out_free;
3424             }
3425         }
3426       dest_states[i] = re_acquire_state_context (&err, dfa, &follows, 0);
3427       if (BE (dest_states[i] == NULL && err != REG_NOERROR, 0))
3428         goto out_free;
3429       /* If the new state has context constraint,
3430          build appropriate states for these contexts.  */
3431       if (dest_states[i]->has_constraint)
3432         {
3433           dest_states_word[i] = re_acquire_state_context (&err, dfa, &follows,
3434                                                           CONTEXT_WORD);
3435           if (BE (dest_states_word[i] == NULL && err != REG_NOERROR, 0))
3436             goto out_free;
3437
3438           if (dest_states[i] != dest_states_word[i] && dfa->mb_cur_max > 1)
3439             need_word_trtable = 1;
3440
3441           dest_states_nl[i] = re_acquire_state_context (&err, dfa, &follows,
3442                                                         CONTEXT_NEWLINE);
3443           if (BE (dest_states_nl[i] == NULL && err != REG_NOERROR, 0))
3444             goto out_free;
3445         }
3446       else
3447         {
3448           dest_states_word[i] = dest_states[i];
3449           dest_states_nl[i] = dest_states[i];
3450         }
3451       bitset_merge (acceptable, dests_ch[i]);
3452     }
3453
3454   if (!BE (need_word_trtable, 0))
3455     {
3456       /* We don't care about whether the following character is a word
3457          character, or we are in a single-byte character set so we can
3458          discern by looking at the character code: allocate a
3459          256-entry transition table.  */
3460       trtable = state->trtable =
3461         (re_dfastate_t **) calloc (sizeof (re_dfastate_t *), SBC_MAX);
3462       if (BE (trtable == NULL, 0))
3463         goto out_free;
3464
3465       /* For all characters ch...:  */
3466       for (i = 0; i < BITSET_WORDS; ++i)
3467         for (ch = i * BITSET_WORD_BITS, elem = acceptable[i], mask = 1;
3468              elem;
3469              mask <<= 1, elem >>= 1, ++ch)
3470           if (BE (elem & 1, 0))
3471             {
3472               /* There must be exactly one destination which accepts
3473                  character ch.  See group_nodes_into_DFAstates.  */
3474               for (j = 0; (dests_ch[j][i] & mask) == 0; ++j)
3475                 ;
3476
3477               /* j-th destination accepts the word character ch.  */
3478               if (dfa->word_char[i] & mask)
3479                 trtable[ch] = dest_states_word[j];
3480               else
3481                 trtable[ch] = dest_states[j];
3482             }
3483     }
3484   else
3485     {
3486       /* We care about whether the following character is a word
3487          character, and we are in a multi-byte character set: discern
3488          by looking at the character code: build two 256-entry
3489          transition tables, one starting at trtable[0] and one
3490          starting at trtable[SBC_MAX].  */
3491       trtable = state->word_trtable =
3492         (re_dfastate_t **) calloc (sizeof (re_dfastate_t *), 2 * SBC_MAX);
3493       if (BE (trtable == NULL, 0))
3494         goto out_free;
3495
3496       /* For all characters ch...:  */
3497       for (i = 0; i < BITSET_WORDS; ++i)
3498         for (ch = i * BITSET_WORD_BITS, elem = acceptable[i], mask = 1;
3499              elem;
3500              mask <<= 1, elem >>= 1, ++ch)
3501           if (BE (elem & 1, 0))
3502             {
3503               /* There must be exactly one destination which accepts
3504                  character ch.  See group_nodes_into_DFAstates.  */
3505               for (j = 0; (dests_ch[j][i] & mask) == 0; ++j)
3506                 ;
3507
3508               /* j-th destination accepts the word character ch.  */
3509               trtable[ch] = dest_states[j];
3510               trtable[ch + SBC_MAX] = dest_states_word[j];
3511             }
3512     }
3513
3514   /* new line */
3515   if (bitset_contain (acceptable, NEWLINE_CHAR))
3516     {
3517       /* The current state accepts newline character.  */
3518       for (j = 0; j < ndests; ++j)
3519         if (bitset_contain (dests_ch[j], NEWLINE_CHAR))
3520           {
3521             /* k-th destination accepts newline character.  */
3522             trtable[NEWLINE_CHAR] = dest_states_nl[j];
3523             if (need_word_trtable)
3524               trtable[NEWLINE_CHAR + SBC_MAX] = dest_states_nl[j];
3525             /* There must be only one destination which accepts
3526                newline.  See group_nodes_into_DFAstates.  */
3527             break;
3528           }
3529     }
3530
3531   if (dest_states_malloced)
3532     free (dest_states);
3533
3534   re_node_set_free (&follows);
3535   for (i = 0; i < ndests; ++i)
3536     re_node_set_free (dests_node + i);
3537
3538   if (dests_node_malloced)
3539     free (dests_alloc);
3540
3541   return 1;
3542 }
3543
3544 /* Group all nodes belonging to STATE into several destinations.
3545    Then for all destinations, set the nodes belonging to the destination
3546    to DESTS_NODE[i] and set the characters accepted by the destination
3547    to DEST_CH[i].  This function return the number of destinations.  */
3548
3549 static int
3550 internal_function
3551 group_nodes_into_DFAstates (const re_dfa_t *dfa, const re_dfastate_t *state,
3552                             re_node_set *dests_node, bitset_t *dests_ch)
3553 {
3554   reg_errcode_t err;
3555   int result;
3556   int i, j, k;
3557   int ndests; /* Number of the destinations from `state'.  */
3558   bitset_t accepts; /* Characters a node can accept.  */
3559   const re_node_set *cur_nodes = &state->nodes;
3560   bitset_empty (accepts);
3561   ndests = 0;
3562
3563   /* For all the nodes belonging to `state',  */
3564   for (i = 0; i < cur_nodes->nelem; ++i)
3565     {
3566       re_token_t *node = &dfa->nodes[cur_nodes->elems[i]];
3567       re_token_type_t type = node->type;
3568       unsigned int constraint = node->constraint;
3569
3570       /* Enumerate all single byte character this node can accept.  */
3571       if (type == CHARACTER)
3572         bitset_set (accepts, node->opr.c);
3573       else if (type == SIMPLE_BRACKET)
3574         {
3575           bitset_merge (accepts, node->opr.sbcset);
3576         }
3577       else if (type == OP_PERIOD)
3578         {
3579 #ifdef RE_ENABLE_I18N
3580           if (dfa->mb_cur_max > 1)
3581             bitset_merge (accepts, dfa->sb_char);
3582           else
3583 #endif
3584             bitset_set_all (accepts);
3585           if (!(dfa->syntax & RE_DOT_NEWLINE))
3586             bitset_clear (accepts, '\n');
3587           if (dfa->syntax & RE_DOT_NOT_NULL)
3588             bitset_clear (accepts, '\0');
3589         }
3590 #ifdef RE_ENABLE_I18N
3591       else if (type == OP_UTF8_PERIOD)
3592         {
3593           memset (accepts, '\xff', sizeof (bitset_t) / 2);
3594           if (!(dfa->syntax & RE_DOT_NEWLINE))
3595             bitset_clear (accepts, '\n');
3596           if (dfa->syntax & RE_DOT_NOT_NULL)
3597             bitset_clear (accepts, '\0');
3598         }
3599 #endif
3600       else
3601         continue;
3602
3603       /* Check the `accepts' and sift the characters which are not
3604          match it the context.  */
3605       if (constraint)
3606         {
3607           if (constraint & NEXT_NEWLINE_CONSTRAINT)
3608             {
3609               bool accepts_newline = bitset_contain (accepts, NEWLINE_CHAR);
3610               bitset_empty (accepts);
3611               if (accepts_newline)
3612                 bitset_set (accepts, NEWLINE_CHAR);
3613               else
3614                 continue;
3615             }
3616           if (constraint & NEXT_ENDBUF_CONSTRAINT)
3617             {
3618               bitset_empty (accepts);
3619               continue;
3620             }
3621
3622           if (constraint & NEXT_WORD_CONSTRAINT)
3623             {
3624               bitset_word_t any_set = 0;
3625               if (type == CHARACTER && !node->word_char)
3626                 {
3627                   bitset_empty (accepts);
3628                   continue;
3629                 }
3630 #ifdef RE_ENABLE_I18N
3631               if (dfa->mb_cur_max > 1)
3632                 for (j = 0; j < BITSET_WORDS; ++j)
3633                   any_set |= (accepts[j] &= (dfa->word_char[j] | ~dfa->sb_char[j]));
3634               else
3635 #endif
3636                 for (j = 0; j < BITSET_WORDS; ++j)
3637                   any_set |= (accepts[j] &= dfa->word_char[j]);
3638               if (!any_set)
3639                 continue;
3640             }
3641           if (constraint & NEXT_NOTWORD_CONSTRAINT)
3642             {
3643               bitset_word_t any_set = 0;
3644               if (type == CHARACTER && node->word_char)
3645                 {
3646                   bitset_empty (accepts);
3647                   continue;
3648                 }
3649 #ifdef RE_ENABLE_I18N
3650               if (dfa->mb_cur_max > 1)
3651                 for (j = 0; j < BITSET_WORDS; ++j)
3652                   any_set |= (accepts[j] &= ~(dfa->word_char[j] & dfa->sb_char[j]));
3653               else
3654 #endif
3655                 for (j = 0; j < BITSET_WORDS; ++j)
3656                   any_set |= (accepts[j] &= ~dfa->word_char[j]);
3657               if (!any_set)
3658                 continue;
3659             }
3660         }
3661
3662       /* Then divide `accepts' into DFA states, or create a new
3663          state.  Above, we make sure that accepts is not empty.  */
3664       for (j = 0; j < ndests; ++j)
3665         {
3666           bitset_t intersec; /* Intersection sets, see below.  */
3667           bitset_t remains;
3668           /* Flags, see below.  */
3669           bitset_word_t has_intersec, not_subset, not_consumed;
3670
3671           /* Optimization, skip if this state doesn't accept the character.  */
3672           if (type == CHARACTER && !bitset_contain (dests_ch[j], node->opr.c))
3673             continue;
3674
3675           /* Enumerate the intersection set of this state and `accepts'.  */
3676           has_intersec = 0;
3677           for (k = 0; k < BITSET_WORDS; ++k)
3678             has_intersec |= intersec[k] = accepts[k] & dests_ch[j][k];
3679           /* And skip if the intersection set is empty.  */
3680           if (!has_intersec)
3681             continue;
3682
3683           /* Then check if this state is a subset of `accepts'.  */
3684           not_subset = not_consumed = 0;
3685           for (k = 0; k < BITSET_WORDS; ++k)
3686             {
3687               not_subset |= remains[k] = ~accepts[k] & dests_ch[j][k];
3688               not_consumed |= accepts[k] = accepts[k] & ~dests_ch[j][k];
3689             }
3690
3691           /* If this state isn't a subset of `accepts', create a
3692              new group state, which has the `remains'. */
3693           if (not_subset)
3694             {
3695               bitset_copy (dests_ch[ndests], remains);
3696               bitset_copy (dests_ch[j], intersec);
3697               err = re_node_set_init_copy (dests_node + ndests, &dests_node[j]);
3698               if (BE (err != REG_NOERROR, 0))
3699                 goto error_return;
3700               ++ndests;
3701             }
3702
3703           /* Put the position in the current group. */
3704           result = re_node_set_insert (&dests_node[j], cur_nodes->elems[i]);
3705           if (BE (result < 0, 0))
3706             goto error_return;
3707
3708           /* If all characters are consumed, go to next node. */
3709           if (!not_consumed)
3710             break;
3711         }
3712       /* Some characters remain, create a new group. */
3713       if (j == ndests)
3714         {
3715           bitset_copy (dests_ch[ndests], accepts);
3716           err = re_node_set_init_1 (dests_node + ndests, cur_nodes->elems[i]);
3717           if (BE (err != REG_NOERROR, 0))
3718             goto error_return;
3719           ++ndests;
3720           bitset_empty (accepts);
3721         }
3722     }
3723   return ndests;
3724  error_return:
3725   for (j = 0; j < ndests; ++j)
3726     re_node_set_free (dests_node + j);
3727   return -1;
3728 }
3729
3730 #ifdef RE_ENABLE_I18N
3731 /* Check how many bytes the node `dfa->nodes[node_idx]' accepts.
3732    Return the number of the bytes the node accepts.
3733    STR_IDX is the current index of the input string.
3734
3735    This function handles the nodes which can accept one character, or
3736    one collating element like '.', '[a-z]', opposite to the other nodes
3737    can only accept one byte.  */
3738
3739 static int
3740 internal_function
3741 check_node_accept_bytes (const re_dfa_t *dfa, int node_idx,
3742                          const re_string_t *input, int str_idx)
3743 {
3744   const re_token_t *node = dfa->nodes + node_idx;
3745   int char_len, elem_len;
3746   int i;
3747   wint_t wc;
3748
3749   if (BE (node->type == OP_UTF8_PERIOD, 0))
3750     {
3751       unsigned char c = re_string_byte_at (input, str_idx), d;
3752       if (BE (c < 0xc2, 1))
3753         return 0;
3754
3755       if (str_idx + 2 > input->len)
3756         return 0;
3757
3758       d = re_string_byte_at (input, str_idx + 1);
3759       if (c < 0xe0)
3760         return (d < 0x80 || d > 0xbf) ? 0 : 2;
3761       else if (c < 0xf0)
3762         {
3763           char_len = 3;
3764           if (c == 0xe0 && d < 0xa0)
3765             return 0;
3766         }
3767       else if (c < 0xf8)
3768         {
3769           char_len = 4;
3770           if (c == 0xf0 && d < 0x90)
3771             return 0;
3772         }
3773       else if (c < 0xfc)
3774         {
3775           char_len = 5;
3776           if (c == 0xf8 && d < 0x88)
3777             return 0;
3778         }
3779       else if (c < 0xfe)
3780         {
3781           char_len = 6;
3782           if (c == 0xfc && d < 0x84)
3783             return 0;
3784         }
3785       else
3786         return 0;
3787
3788       if (str_idx + char_len > input->len)
3789         return 0;
3790
3791       for (i = 1; i < char_len; ++i)
3792         {
3793           d = re_string_byte_at (input, str_idx + i);
3794           if (d < 0x80 || d > 0xbf)
3795             return 0;
3796         }
3797       return char_len;
3798     }
3799
3800   char_len = re_string_char_size_at (input, str_idx);
3801   if (node->type == OP_PERIOD)
3802     {
3803       if (char_len <= 1)
3804         return 0;
3805       /* FIXME: I don't think this if is needed, as both '\n'
3806          and '\0' are char_len == 1.  */
3807       /* '.' accepts any one character except the following two cases.  */
3808       if ((!(dfa->syntax & RE_DOT_NEWLINE) &&
3809            re_string_byte_at (input, str_idx) == '\n') ||
3810           ((dfa->syntax & RE_DOT_NOT_NULL) &&
3811            re_string_byte_at (input, str_idx) == '\0'))
3812         return 0;
3813       return char_len;
3814     }
3815
3816   elem_len = re_string_elem_size_at (input, str_idx);
3817   wc = __btowc(*(input->mbs+str_idx));
3818   if (((elem_len <= 1 && char_len <= 1) || char_len == 0) && (wc != WEOF && wc < SBC_MAX))
3819     return 0;
3820
3821   if (node->type == COMPLEX_BRACKET)
3822     {
3823       const re_charset_t *cset = node->opr.mbcset;
3824 # ifdef _LIBC
3825       const unsigned char *pin
3826         = ((const unsigned char *) re_string_get_buffer (input) + str_idx);
3827       int j;
3828       uint32_t nrules;
3829 # endif /* _LIBC */
3830       int match_len = 0;
3831       wchar_t wc = ((cset->nranges || cset->nchar_classes || cset->nmbchars)
3832                     ? re_string_wchar_at (input, str_idx) : 0);
3833
3834       /* match with multibyte character?  */
3835       for (i = 0; i < cset->nmbchars; ++i)
3836         if (wc == cset->mbchars[i])
3837           {
3838             match_len = char_len;
3839             goto check_node_accept_bytes_match;
3840           }
3841       /* match with character_class?  */
3842       for (i = 0; i < cset->nchar_classes; ++i)
3843         {
3844           wctype_t wt = cset->char_classes[i];
3845           if (__iswctype (wc, wt))
3846             {
3847               match_len = char_len;
3848               goto check_node_accept_bytes_match;
3849             }
3850         }
3851
3852 # ifdef _LIBC
3853       nrules = _NL_CURRENT_WORD (LC_COLLATE, _NL_COLLATE_NRULES);
3854       if (nrules != 0)
3855         {
3856           unsigned int in_collseq = 0;
3857           const int32_t *table, *indirect;
3858           const unsigned char *weights, *extra;
3859           const char *collseqwc;
3860           /* This #include defines a local function!  */
3861 #  include <locale/weight.h>
3862
3863           /* match with collating_symbol?  */
3864           if (cset->ncoll_syms)
3865             extra = (const unsigned char *)
3866               _NL_CURRENT (LC_COLLATE, _NL_COLLATE_SYMB_EXTRAMB);
3867           for (i = 0; i < cset->ncoll_syms; ++i)
3868             {
3869               const unsigned char *coll_sym = extra + cset->coll_syms[i];
3870               /* Compare the length of input collating element and
3871                  the length of current collating element.  */
3872               if (*coll_sym != elem_len)
3873                 continue;
3874               /* Compare each bytes.  */
3875               for (j = 0; j < *coll_sym; j++)
3876                 if (pin[j] != coll_sym[1 + j])
3877                   break;
3878               if (j == *coll_sym)
3879                 {
3880                   /* Match if every bytes is equal.  */
3881                   match_len = j;
3882                   goto check_node_accept_bytes_match;
3883                 }
3884             }
3885
3886           if (cset->nranges)
3887             {
3888               if (elem_len <= char_len)
3889                 {
3890                   collseqwc = _NL_CURRENT (LC_COLLATE, _NL_COLLATE_COLLSEQWC);
3891                   in_collseq = __collseq_table_lookup (collseqwc, wc);
3892                 }
3893               else
3894                 in_collseq = find_collation_sequence_value (pin, elem_len);
3895             }
3896           /* match with range expression?  */
3897           for (i = 0; i < cset->nranges; ++i)
3898             if (cset->range_starts[i] <= in_collseq
3899                 && in_collseq <= cset->range_ends[i])
3900               {
3901                 match_len = elem_len;
3902                 goto check_node_accept_bytes_match;
3903               }
3904
3905           /* match with equivalence_class?  */
3906           if (cset->nequiv_classes)
3907             {
3908               const unsigned char *cp = pin;
3909               table = (const int32_t *)
3910                 _NL_CURRENT (LC_COLLATE, _NL_COLLATE_TABLEMB);
3911               weights = (const unsigned char *)
3912                 _NL_CURRENT (LC_COLLATE, _NL_COLLATE_WEIGHTMB);
3913               extra = (const unsigned char *)
3914                 _NL_CURRENT (LC_COLLATE, _NL_COLLATE_EXTRAMB);
3915               indirect = (const int32_t *)
3916                 _NL_CURRENT (LC_COLLATE, _NL_COLLATE_INDIRECTMB);
3917               int32_t idx = findidx (&cp);
3918               if (idx > 0)
3919                 for (i = 0; i < cset->nequiv_classes; ++i)
3920                   {
3921                     int32_t equiv_class_idx = cset->equiv_classes[i];
3922                     size_t weight_len = weights[idx & 0xffffff];
3923                     if (weight_len == weights[equiv_class_idx & 0xffffff]
3924                         && (idx >> 24) == (equiv_class_idx >> 24))
3925                       {
3926                         int cnt = 0;
3927
3928                         idx &= 0xffffff;
3929                         equiv_class_idx &= 0xffffff;
3930
3931                         while (cnt <= weight_len
3932                                && (weights[equiv_class_idx + 1 + cnt]
3933                                    == weights[idx + 1 + cnt]))
3934                           ++cnt;
3935                         if (cnt > weight_len)
3936                           {
3937                             match_len = elem_len;
3938                             goto check_node_accept_bytes_match;
3939                           }
3940                       }
3941                   }
3942             }
3943         }
3944       else
3945 # endif /* _LIBC */
3946         {
3947           /* match with range expression?  */
3948 #if __GNUC__ >= 2
3949           wchar_t cmp_buf[] = {L'\0', L'\0', wc, L'\0', L'\0', L'\0'};
3950 #else
3951           wchar_t cmp_buf[] = {L'\0', L'\0', L'\0', L'\0', L'\0', L'\0'};
3952           cmp_buf[2] = wc;
3953 #endif
3954           for (i = 0; i < cset->nranges; ++i)
3955             {
3956               cmp_buf[0] = cset->range_starts[i];
3957               cmp_buf[4] = cset->range_ends[i];
3958               if (wcscoll (cmp_buf, cmp_buf + 2) <= 0
3959                   && wcscoll (cmp_buf + 2, cmp_buf + 4) <= 0)
3960                 {
3961                   match_len = char_len;
3962                   goto check_node_accept_bytes_match;
3963                 }
3964             }
3965         }
3966     check_node_accept_bytes_match:
3967       if (!cset->non_match)
3968         return match_len;
3969       else
3970         {
3971           if (match_len > 0)
3972             return 0;
3973           else
3974             return (elem_len > char_len) ? elem_len : char_len;
3975         }
3976     }
3977   return 0;
3978 }
3979
3980 # ifdef _LIBC
3981 static unsigned int
3982 internal_function
3983 find_collation_sequence_value (const unsigned char *mbs, size_t mbs_len)
3984 {
3985   uint32_t nrules = _NL_CURRENT_WORD (LC_COLLATE, _NL_COLLATE_NRULES);
3986   if (nrules == 0)
3987     {
3988       if (mbs_len == 1)
3989         {
3990           /* No valid character.  Match it as a single byte character.  */
3991           const unsigned char *collseq = (const unsigned char *)
3992             _NL_CURRENT (LC_COLLATE, _NL_COLLATE_COLLSEQMB);
3993           return collseq[mbs[0]];
3994         }
3995       return UINT_MAX;
3996     }
3997   else
3998     {
3999       int32_t idx;
4000       const unsigned char *extra = (const unsigned char *)
4001         _NL_CURRENT (LC_COLLATE, _NL_COLLATE_SYMB_EXTRAMB);
4002       int32_t extrasize = (const unsigned char *)
4003         _NL_CURRENT (LC_COLLATE, _NL_COLLATE_SYMB_EXTRAMB + 1) - extra;
4004
4005       for (idx = 0; idx < extrasize;)
4006         {
4007           int mbs_cnt, found = 0;
4008           int32_t elem_mbs_len;
4009           /* Skip the name of collating element name.  */
4010           idx = idx + extra[idx] + 1;
4011           elem_mbs_len = extra[idx++];
4012           if (mbs_len == elem_mbs_len)
4013             {
4014               for (mbs_cnt = 0; mbs_cnt < elem_mbs_len; ++mbs_cnt)
4015                 if (extra[idx + mbs_cnt] != mbs[mbs_cnt])
4016                   break;
4017               if (mbs_cnt == elem_mbs_len)
4018                 /* Found the entry.  */
4019                 found = 1;
4020             }
4021           /* Skip the byte sequence of the collating element.  */
4022           idx += elem_mbs_len;
4023           /* Adjust for the alignment.  */
4024           idx = (idx + 3) & ~3;
4025           /* Skip the collation sequence value.  */
4026           idx += sizeof (uint32_t);
4027           /* Skip the wide char sequence of the collating element.  */
4028           idx = idx + sizeof (uint32_t) * (extra[idx] + 1);
4029           /* If we found the entry, return the sequence value.  */
4030           if (found)
4031             return *(uint32_t *) (extra + idx);
4032           /* Skip the collation sequence value.  */
4033           idx += sizeof (uint32_t);
4034         }
4035       return UINT_MAX;
4036     }
4037 }
4038 # endif /* _LIBC */
4039 #endif /* RE_ENABLE_I18N */
4040
4041 /* Check whether the node accepts the byte which is IDX-th
4042    byte of the INPUT.  */
4043
4044 static int
4045 internal_function
4046 check_node_accept (const re_match_context_t *mctx, const re_token_t *node,
4047                    int idx)
4048 {
4049   unsigned char ch;
4050   ch = re_string_byte_at (&mctx->input, idx);
4051   switch (node->type)
4052     {
4053     case CHARACTER:
4054       if (node->opr.c != ch)
4055         return 0;
4056       break;
4057
4058     case SIMPLE_BRACKET:
4059       if (!bitset_contain (node->opr.sbcset, ch))
4060         return 0;
4061       break;
4062
4063 #ifdef RE_ENABLE_I18N
4064     case OP_UTF8_PERIOD:
4065       if (ch >= 0x80)
4066         return 0;
4067       /* FALLTHROUGH */
4068 #endif
4069     case OP_PERIOD:
4070       if ((ch == '\n' && !(mctx->dfa->syntax & RE_DOT_NEWLINE))
4071           || (ch == '\0' && (mctx->dfa->syntax & RE_DOT_NOT_NULL)))
4072         return 0;
4073       break;
4074
4075     default:
4076       return 0;
4077     }
4078
4079   if (node->constraint)
4080     {
4081       /* The node has constraints.  Check whether the current context
4082          satisfies the constraints.  */
4083       unsigned int context = re_string_context_at (&mctx->input, idx,
4084                                                    mctx->eflags);
4085       if (NOT_SATISFY_NEXT_CONSTRAINT (node->constraint, context))
4086         return 0;
4087     }
4088
4089   return 1;
4090 }
4091
4092 /* Extend the buffers, if the buffers have run out.  */
4093
4094 static reg_errcode_t
4095 internal_function
4096 extend_buffers (re_match_context_t *mctx)
4097 {
4098   reg_errcode_t ret;
4099   re_string_t *pstr = &mctx->input;
4100
4101   /* Avoid overflow.  */
4102   if (BE (INT_MAX / 2 / sizeof (re_dfastate_t *) <= pstr->bufs_len, 0))
4103     return REG_ESPACE;
4104
4105   /* Double the lengthes of the buffers.  */
4106   ret = re_string_realloc_buffers (pstr, pstr->bufs_len * 2);
4107   if (BE (ret != REG_NOERROR, 0))
4108     return ret;
4109
4110   if (mctx->state_log != NULL)
4111     {
4112       /* And double the length of state_log.  */
4113       /* XXX We have no indication of the size of this buffer.  If this
4114          allocation fail we have no indication that the state_log array
4115          does not have the right size.  */
4116       re_dfastate_t **new_array = re_realloc (mctx->state_log, re_dfastate_t *,
4117                                               pstr->bufs_len + 1);
4118       if (BE (new_array == NULL, 0))
4119         return REG_ESPACE;
4120       mctx->state_log = new_array;
4121     }
4122
4123   /* Then reconstruct the buffers.  */
4124   if (pstr->icase)
4125     {
4126 #ifdef RE_ENABLE_I18N
4127       if (pstr->mb_cur_max > 1)
4128         {
4129           ret = build_wcs_upper_buffer (pstr);
4130           if (BE (ret != REG_NOERROR, 0))
4131             return ret;
4132         }
4133       else
4134 #endif /* RE_ENABLE_I18N  */
4135         build_upper_buffer (pstr);
4136     }
4137   else
4138     {
4139 #ifdef RE_ENABLE_I18N
4140       if (pstr->mb_cur_max > 1)
4141         build_wcs_buffer (pstr);
4142       else
4143 #endif /* RE_ENABLE_I18N  */
4144         {
4145           if (pstr->trans != NULL)
4146             re_string_translate_buffer (pstr);
4147         }
4148     }
4149   return REG_NOERROR;
4150 }
4151
4152 \f
4153 /* Functions for matching context.  */
4154
4155 /* Initialize MCTX.  */
4156
4157 static reg_errcode_t
4158 internal_function
4159 match_ctx_init (re_match_context_t *mctx, int eflags, int n)
4160 {
4161   mctx->eflags = eflags;
4162   mctx->match_last = -1;
4163   if (n > 0)
4164     {
4165       mctx->bkref_ents = re_malloc (struct re_backref_cache_entry, n);
4166       mctx->sub_tops = re_malloc (re_sub_match_top_t *, n);
4167       if (BE (mctx->bkref_ents == NULL || mctx->sub_tops == NULL, 0))
4168         return REG_ESPACE;
4169     }
4170   /* Already zero-ed by the caller.
4171      else
4172        mctx->bkref_ents = NULL;
4173      mctx->nbkref_ents = 0;
4174      mctx->nsub_tops = 0;  */
4175   mctx->abkref_ents = n;
4176   mctx->max_mb_elem_len = 1;
4177   mctx->asub_tops = n;
4178   return REG_NOERROR;
4179 }
4180
4181 /* Clean the entries which depend on the current input in MCTX.
4182    This function must be invoked when the matcher changes the start index
4183    of the input, or changes the input string.  */
4184
4185 static void
4186 internal_function
4187 match_ctx_clean (re_match_context_t *mctx)
4188 {
4189   int st_idx;
4190   for (st_idx = 0; st_idx < mctx->nsub_tops; ++st_idx)
4191     {
4192       int sl_idx;
4193       re_sub_match_top_t *top = mctx->sub_tops[st_idx];
4194       for (sl_idx = 0; sl_idx < top->nlasts; ++sl_idx)
4195         {
4196           re_sub_match_last_t *last = top->lasts[sl_idx];
4197           re_free (last->path.array);
4198           re_free (last);
4199         }
4200       re_free (top->lasts);
4201       if (top->path)
4202         {
4203           re_free (top->path->array);
4204           re_free (top->path);
4205         }
4206       free (top);
4207     }
4208
4209   mctx->nsub_tops = 0;
4210   mctx->nbkref_ents = 0;
4211 }
4212
4213 /* Free all the memory associated with MCTX.  */
4214
4215 static void
4216 internal_function
4217 match_ctx_free (re_match_context_t *mctx)
4218 {
4219   /* First, free all the memory associated with MCTX->SUB_TOPS.  */
4220   match_ctx_clean (mctx);
4221   re_free (mctx->sub_tops);
4222   re_free (mctx->bkref_ents);
4223 }
4224
4225 /* Add a new backreference entry to MCTX.
4226    Note that we assume that caller never call this function with duplicate
4227    entry, and call with STR_IDX which isn't smaller than any existing entry.
4228 */
4229
4230 static reg_errcode_t
4231 internal_function
4232 match_ctx_add_entry (re_match_context_t *mctx, int node, int str_idx, int from,
4233                      int to)
4234 {
4235   if (mctx->nbkref_ents >= mctx->abkref_ents)
4236     {
4237       struct re_backref_cache_entry* new_entry;
4238       new_entry = re_realloc (mctx->bkref_ents, struct re_backref_cache_entry,
4239                               mctx->abkref_ents * 2);
4240       if (BE (new_entry == NULL, 0))
4241         {
4242           re_free (mctx->bkref_ents);
4243           return REG_ESPACE;
4244         }
4245       mctx->bkref_ents = new_entry;
4246       memset (mctx->bkref_ents + mctx->nbkref_ents, '\0',
4247               sizeof (struct re_backref_cache_entry) * mctx->abkref_ents);
4248       mctx->abkref_ents *= 2;
4249     }
4250   if (mctx->nbkref_ents > 0
4251       && mctx->bkref_ents[mctx->nbkref_ents - 1].str_idx == str_idx)
4252     mctx->bkref_ents[mctx->nbkref_ents - 1].more = 1;
4253
4254   mctx->bkref_ents[mctx->nbkref_ents].node = node;
4255   mctx->bkref_ents[mctx->nbkref_ents].str_idx = str_idx;
4256   mctx->bkref_ents[mctx->nbkref_ents].subexp_from = from;
4257   mctx->bkref_ents[mctx->nbkref_ents].subexp_to = to;
4258
4259   /* This is a cache that saves negative results of check_dst_limits_calc_pos.
4260      If bit N is clear, means that this entry won't epsilon-transition to
4261      an OP_OPEN_SUBEXP or OP_CLOSE_SUBEXP for the N+1-th subexpression.  If
4262      it is set, check_dst_limits_calc_pos_1 will recurse and try to find one
4263      such node.
4264
4265      A backreference does not epsilon-transition unless it is empty, so set
4266      to all zeros if FROM != TO.  */
4267   mctx->bkref_ents[mctx->nbkref_ents].eps_reachable_subexps_map
4268     = (from == to ? ~0 : 0);
4269
4270   mctx->bkref_ents[mctx->nbkref_ents++].more = 0;
4271   if (mctx->max_mb_elem_len < to - from)
4272     mctx->max_mb_elem_len = to - from;
4273   return REG_NOERROR;
4274 }
4275
4276 /* Search for the first entry which has the same str_idx, or -1 if none is
4277    found.  Note that MCTX->BKREF_ENTS is already sorted by MCTX->STR_IDX.  */
4278
4279 static int
4280 internal_function
4281 search_cur_bkref_entry (const re_match_context_t *mctx, int str_idx)
4282 {
4283   int left, right, mid, last;
4284   last = right = mctx->nbkref_ents;
4285   for (left = 0; left < right;)
4286     {
4287       mid = (left + right) / 2;
4288       if (mctx->bkref_ents[mid].str_idx < str_idx)
4289         left = mid + 1;
4290       else
4291         right = mid;
4292     }
4293   if (left < last && mctx->bkref_ents[left].str_idx == str_idx)
4294     return left;
4295   else
4296     return -1;
4297 }
4298
4299 /* Register the node NODE, whose type is OP_OPEN_SUBEXP, and which matches
4300    at STR_IDX.  */
4301
4302 static reg_errcode_t
4303 internal_function
4304 match_ctx_add_subtop (re_match_context_t *mctx, int node, int str_idx)
4305 {
4306 #ifdef DEBUG
4307   assert (mctx->sub_tops != NULL);
4308   assert (mctx->asub_tops > 0);
4309 #endif
4310   if (BE (mctx->nsub_tops == mctx->asub_tops, 0))
4311     {
4312       int new_asub_tops = mctx->asub_tops * 2;
4313       re_sub_match_top_t **new_array = re_realloc (mctx->sub_tops,
4314                                                    re_sub_match_top_t *,
4315                                                    new_asub_tops);
4316       if (BE (new_array == NULL, 0))
4317         return REG_ESPACE;
4318       mctx->sub_tops = new_array;
4319       mctx->asub_tops = new_asub_tops;
4320     }
4321   mctx->sub_tops[mctx->nsub_tops] = calloc (1, sizeof (re_sub_match_top_t));
4322   if (BE (mctx->sub_tops[mctx->nsub_tops] == NULL, 0))
4323     return REG_ESPACE;
4324   mctx->sub_tops[mctx->nsub_tops]->node = node;
4325   mctx->sub_tops[mctx->nsub_tops++]->str_idx = str_idx;
4326   return REG_NOERROR;
4327 }
4328
4329 /* Register the node NODE, whose type is OP_CLOSE_SUBEXP, and which matches
4330    at STR_IDX, whose corresponding OP_OPEN_SUBEXP is SUB_TOP.  */
4331
4332 static re_sub_match_last_t *
4333 internal_function
4334 match_ctx_add_sublast (re_sub_match_top_t *subtop, int node, int str_idx)
4335 {
4336   re_sub_match_last_t *new_entry;
4337   if (BE (subtop->nlasts == subtop->alasts, 0))
4338     {
4339       int new_alasts = 2 * subtop->alasts + 1;
4340       re_sub_match_last_t **new_array = re_realloc (subtop->lasts,
4341                                                     re_sub_match_last_t *,
4342                                                     new_alasts);
4343       if (BE (new_array == NULL, 0))
4344         return NULL;
4345       subtop->lasts = new_array;
4346       subtop->alasts = new_alasts;
4347     }
4348   new_entry = calloc (1, sizeof (re_sub_match_last_t));
4349   if (BE (new_entry != NULL, 1))
4350     {
4351       subtop->lasts[subtop->nlasts] = new_entry;
4352       new_entry->node = node;
4353       new_entry->str_idx = str_idx;
4354       ++subtop->nlasts;
4355     }
4356   return new_entry;
4357 }
4358
4359 static void
4360 internal_function
4361 sift_ctx_init (re_sift_context_t *sctx, re_dfastate_t **sifted_sts,
4362                re_dfastate_t **limited_sts, int last_node, int last_str_idx)
4363 {
4364   sctx->sifted_states = sifted_sts;
4365   sctx->limited_states = limited_sts;
4366   sctx->last_node = last_node;
4367   sctx->last_str_idx = last_str_idx;
4368   re_node_set_init_empty (&sctx->limits);
4369 }