external/bsd/mdocml/dist/apropos_db.c

   1 /*      $Vendor-Id: apropos_db.c,v 1.31 2012/03/24 01:46:25 kristaps Exp $ */
   2 /*
   3  * Copyright (c) 2011, 2012 Kristaps Dzonsons <kristaps@bsd.lv>
   4  * Copyright (c) 2011 Ingo Schwarze <schwarze@openbsd.org>
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18 #ifdef HAVE_CONFIG_H
  19 #include "config.h"
  20 #endif
  21
  22 #include <assert.h>
  23 #include <fcntl.h>
  24 #include <regex.h>
  25 #include <stdarg.h>
  26 #include <stdint.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30
  31 #if defined(__linux__)
  32 # include <endian.h>
  33 # include <db_185.h>
  34 #elif defined(__APPLE__)
  35 # include <libkern/OSByteOrder.h>
  36 # include <db.h>
  37 #else
  38 # include <db.h>
  39 #endif
  40
  41 #include "mandocdb.h"
  42 #include "apropos_db.h"
  43 #include "mandoc.h"
  44
  45 #define RESFREE(_x) \
  46         do { \
  47                 free((_x)->file); \
  48                 free((_x)->cat); \
  49                 free((_x)->title); \
  50                 free((_x)->arch); \
  51                 free((_x)->desc); \
  52                 free((_x)->matches); \
  53         } while (/*CONSTCOND*/0)
  54
  55 struct  expr {
  56         int              regex; /* is regex? */
  57         int              index; /* index in match array */
  58         uint64_t         mask; /* type-mask */
  59         int              and; /* is rhs of logical AND? */
  60         char            *v; /* search value */
  61         regex_t          re; /* compiled re, if regex */
  62         struct expr     *next; /* next in sequence */
  63         struct expr     *subexpr;
  64 };
  65
  66 struct  type {
  67         uint64_t         mask;
  68         const char      *name;
  69 };
  70
  71 struct  rectree {
  72         struct res      *node; /* record array for dir tree */
  73         int              len; /* length of record array */
  74 };
  75
  76 static  const struct type types[] = {
  77         { TYPE_An, "An" },
  78         { TYPE_Ar, "Ar" },
  79         { TYPE_At, "At" },
  80         { TYPE_Bsx, "Bsx" },
  81         { TYPE_Bx, "Bx" },
  82         { TYPE_Cd, "Cd" },
  83         { TYPE_Cm, "Cm" },
  84         { TYPE_Dv, "Dv" },
  85         { TYPE_Dx, "Dx" },
  86         { TYPE_Em, "Em" },
  87         { TYPE_Er, "Er" },
  88         { TYPE_Ev, "Ev" },
  89         { TYPE_Fa, "Fa" },
  90         { TYPE_Fl, "Fl" },
  91         { TYPE_Fn, "Fn" },
  92         { TYPE_Fn, "Fo" },
  93         { TYPE_Ft, "Ft" },
  94         { TYPE_Fx, "Fx" },
  95         { TYPE_Ic, "Ic" },
  96         { TYPE_In, "In" },
  97         { TYPE_Lb, "Lb" },
  98         { TYPE_Li, "Li" },
  99         { TYPE_Lk, "Lk" },
 100         { TYPE_Ms, "Ms" },
 101         { TYPE_Mt, "Mt" },
 102         { TYPE_Nd, "Nd" },
 103         { TYPE_Nm, "Nm" },
 104         { TYPE_Nx, "Nx" },
 105         { TYPE_Ox, "Ox" },
 106         { TYPE_Pa, "Pa" },
 107         { TYPE_Rs, "Rs" },
 108         { TYPE_Sh, "Sh" },
 109         { TYPE_Ss, "Ss" },
 110         { TYPE_St, "St" },
 111         { TYPE_Sy, "Sy" },
 112         { TYPE_Tn, "Tn" },
 113         { TYPE_Va, "Va" },
 114         { TYPE_Va, "Vt" },
 115         { TYPE_Xr, "Xr" },
 116         { UINT64_MAX, "any" },
 117         { 0, NULL }
 118 };
 119
 120 static  DB      *btree_open(void);
 121 static  int      btree_read(const DBT *, const DBT *,
 122                         const struct mchars *,
 123                         uint64_t *, recno_t *, char **);
 124 static  int      expreval(const struct expr *, int *);
 125 static  void     exprexec(const struct expr *,
 126                         const char *, uint64_t, struct res *);
 127 static  int      exprmark(const struct expr *,
 128                         const char *, uint64_t, int *);
 129 static  struct expr *exprexpr(int, char *[], int *, int *, size_t *);
 130 static  struct expr *exprterm(char *, int);
 131 static  DB      *index_open(void);
 132 static  int      index_read(const DBT *, const DBT *, int,
 133                         const struct mchars *, struct res *);
 134 static  void     norm_string(const char *,
 135                         const struct mchars *, char **);
 136 static  size_t   norm_utf8(unsigned int, char[7]);
 137 static  int      single_search(struct rectree *, const struct opts *,
 138                         const struct expr *, size_t terms,
 139                         struct mchars *, int);
 140
 141 /*
 142  * Open the keyword mandoc-db database.
 143  */
 144 static DB *
 145 btree_open(void)
 146 {
 147         BTREEINFO        info;
 148         DB              *db;
 149
 150         memset(&info, 0, sizeof(BTREEINFO));
 151         info.lorder = 4321;
 152         info.flags = R_DUP;
 153
 154         db = dbopen(MANDOC_DB, O_RDONLY, 0, DB_BTREE, &info);
 155         if (NULL != db)
 156                 return(db);
 157
 158         return(NULL);
 159 }
 160
 161 /*
 162  * Read a keyword from the database and normalise it.
 163  * Return 0 if the database is insane, else 1.
 164  */
 165 static int
 166 btree_read(const DBT *k, const DBT *v, const struct mchars *mc,
 167                 uint64_t *mask, recno_t *rec, char **buf)
 168 {
 169         uint64_t         vbuf[2];
 170
 171         /* Are our sizes sane? */
 172         if (k->size < 2 || sizeof(vbuf) != v->size)
 173                 return(0);
 174
 175         /* Is our string nil-terminated? */
 176         if ('\0' != ((const char *)k->data)[(int)k->size - 1])
 177                 return(0);
 178
 179         norm_string((const char *)k->data, mc, buf);
 180         memcpy(vbuf, v->data, v->size);
 181         *mask = betoh64(vbuf[0]);
 182         *rec  = betoh64(vbuf[1]);
 183         return(1);
 184 }
 185
 186 /*
 187  * Take a Unicode codepoint and produce its UTF-8 encoding.
 188  * This isn't the best way to do this, but it works.
 189  * The magic numbers are from the UTF-8 packaging.
 190  * They're not as scary as they seem: read the UTF-8 spec for details.
 191  */
 192 static size_t
 193 norm_utf8(unsigned int cp, char out[7])
 194 {
 195         int              rc;
 196
 197         rc = 0;
 198
 199         if (cp <= 0x0000007F) {
 200                 rc = 1;
 201                 out[0] = (char)cp;
 202         } else if (cp <= 0x000007FF) {
 203                 rc = 2;
 204                 out[0] = (cp >> 6  & 31) | 192;
 205                 out[1] = (cp       & 63) | 128;
 206         } else if (cp <= 0x0000FFFF) {
 207                 rc = 3;
 208                 out[0] = (cp >> 12 & 15) | 224;
 209                 out[1] = (cp >> 6  & 63) | 128;
 210                 out[2] = (cp       & 63) | 128;
 211         } else if (cp <= 0x001FFFFF) {
 212                 rc = 4;
 213                 out[0] = (cp >> 18 & 7) | 240;
 214                 out[1] = (cp >> 12 & 63) | 128;
 215                 out[2] = (cp >> 6  & 63) | 128;
 216                 out[3] = (cp       & 63) | 128;
 217         } else if (cp <= 0x03FFFFFF) {
 218                 rc = 5;
 219                 out[0] = (cp >> 24 & 3) | 248;
 220                 out[1] = (cp >> 18 & 63) | 128;
 221                 out[2] = (cp >> 12 & 63) | 128;
 222                 out[3] = (cp >> 6  & 63) | 128;
 223                 out[4] = (cp       & 63) | 128;
 224         } else if (cp <= 0x7FFFFFFF) {
 225                 rc = 6;
 226                 out[0] = (cp >> 30 & 1) | 252;
 227                 out[1] = (cp >> 24 & 63) | 128;
 228                 out[2] = (cp >> 18 & 63) | 128;
 229                 out[3] = (cp >> 12 & 63) | 128;
 230                 out[4] = (cp >> 6  & 63) | 128;
 231                 out[5] = (cp       & 63) | 128;
 232         } else
 233                 return(0);
 234
 235         out[rc] = '\0';
 236         return((size_t)rc);
 237 }
 238
 239 /*
 240  * Normalise strings from the index and database.
 241  * These strings are escaped as defined by mandoc_char(7) along with
 242  * other goop in mandoc.h (e.g., soft hyphens).
 243  * This function normalises these into a nice UTF-8 string.
 244  * Returns 0 if the database is fucked.
 245  */
 246 static void
 247 norm_string(const char *val, const struct mchars *mc, char **buf)
 248 {
 249         size_t            sz, bsz;
 250         char              utfbuf[7];
 251         const char       *seq, *cpp;
 252         int               len, u, pos;
 253         enum mandoc_esc   esc;
 254         static const char res[] = { '\\', '\t',
 255                                 ASCII_NBRSP, ASCII_HYPH, '\0' };
 256
 257         /* Pre-allocate by the length of the input */
 258
 259         bsz = strlen(val) + 1;
 260         *buf = mandoc_realloc(*buf, bsz);
 261         pos = 0;
 262
 263         while ('\0' != *val) {
 264                 /*
 265                  * Halt on the first escape sequence.
 266                  * This also halts on the end of string, in which case
 267                  * we just copy, fallthrough, and exit the loop.
 268                  */
 269                 if ((sz = strcspn(val, res)) > 0) {
 270                         memcpy(&(*buf)[pos], val, sz);
 271                         pos += (int)sz;
 272                         val += (int)sz;
 273                 }
 274
 275                 if (ASCII_HYPH == *val) {
 276                         (*buf)[pos++] = '-';
 277                         val++;
 278                         continue;
 279                 } else if ('\t' == *val || ASCII_NBRSP == *val) {
 280                         (*buf)[pos++] = ' ';
 281                         val++;
 282                         continue;
 283                 } else if ('\\' != *val)
 284                         break;
 285
 286                 /* Read past the slash. */
 287
 288                 val++;
 289                 u = 0;
 290
 291                 /*
 292                  * Parse the escape sequence and see if it's a
 293                  * predefined character or special character.
 294                  */
 295
 296                 esc = mandoc_escape(&val, &seq, &len);
 297                 if (ESCAPE_ERROR == esc)
 298                         break;
 299
 300                 /*
 301                  * XXX - this just does UTF-8, but we need to know
 302                  * beforehand whether we should do text substitution.
 303                  */
 304
 305                 switch (esc) {
 306                 case (ESCAPE_SPECIAL):
 307                         if (0 != (u = mchars_spec2cp(mc, seq, len)))
 308                                 break;
 309                         /* FALLTHROUGH */
 310                 default:
 311                         continue;
 312                 }
 313
 314                 /*
 315                  * If we have a Unicode codepoint, try to convert that
 316                  * to a UTF-8 byte string.
 317                  */
 318
 319                 cpp = utfbuf;
 320                 if (0 == (sz = norm_utf8(u, utfbuf)))
 321                         continue;
 322
 323                 /* Copy the rendered glyph into the stream. */
 324
 325                 sz = strlen(cpp);
 326                 bsz += sz;
 327
 328                 *buf = mandoc_realloc(*buf, bsz);
 329
 330                 memcpy(&(*buf)[pos], cpp, sz);
 331                 pos += (int)sz;
 332         }
 333
 334         (*buf)[pos] = '\0';
 335 }
 336
 337 /*
 338  * Open the filename-index mandoc-db database.
 339  * Returns NULL if opening failed.
 340  */
 341 static DB *
 342 index_open(void)
 343 {
 344         DB              *db;
 345
 346         db = dbopen(MANDOC_IDX, O_RDONLY, 0, DB_RECNO, NULL);
 347         if (NULL != db)
 348                 return(db);
 349
 350         return(NULL);
 351 }
 352
 353 /*
 354  * Safely unpack from an index file record into the structure.
 355  * Returns 1 if an entry was unpacked, 0 if the database is insane.
 356  */
 357 static int
 358 index_read(const DBT *key, const DBT *val, int index,
 359                 const struct mchars *mc, struct res *rec)
 360 {
 361         size_t           left;
 362         char            *np, *cp;
 363         char             type;
 364
 365 #define INDEX_BREAD(_dst) \
 366         do { \
 367                 if (NULL == (np = memchr(cp, '\0', left))) \
 368                         return(0); \
 369                 norm_string(cp, mc, &(_dst)); \
 370                 left -= (np - cp) + 1; \
 371                 cp = np + 1; \
 372         } while (/* CONSTCOND */ 0)
 373
 374         if (0 == (left = val->size))
 375                 return(0);
 376
 377         cp = val->data;
 378         assert(sizeof(recno_t) == key->size);
 379         memcpy(&rec->rec, key->data, key->size);
 380         rec->volume = index;
 381
 382         if ('d' == (type = *cp++))
 383                 rec->type = RESTYPE_MDOC;
 384         else if ('a' == type)
 385                 rec->type = RESTYPE_MAN;
 386         else if ('c' == type)
 387                 rec->type = RESTYPE_CAT;
 388         else
 389                 return(0);
 390
 391         left--;
 392         INDEX_BREAD(rec->file);
 393         INDEX_BREAD(rec->cat);
 394         INDEX_BREAD(rec->title);
 395         INDEX_BREAD(rec->arch);
 396         INDEX_BREAD(rec->desc);
 397         return(1);
 398 }
 399
 400 /*
 401  * Search mandocdb databases in paths for expression "expr".
 402  * Filter out by "opts".
 403  * Call "res" with the results, which may be zero.
 404  * Return 0 if there was a database error, else return 1.
 405  */
 406 int
 407 apropos_search(int pathsz, char **paths, const struct opts *opts,
 408                 const struct expr *expr, size_t terms, void *arg,
 409                 size_t *sz, struct res **resp,
 410                 void (*res)(struct res *, size_t, void *))
 411 {
 412         struct rectree   tree;
 413         struct mchars   *mc;
 414         int              i, rc;
 415
 416         memset(&tree, 0, sizeof(struct rectree));
 417
 418         rc = 0;
 419         mc = mchars_alloc();
 420         *sz = 0;
 421         *resp = NULL;
 422
 423         /*
 424          * Main loop.  Change into the directory containing manpage
 425          * databases.  Run our expession over each database in the set.
 426          */
 427
 428         for (i = 0; i < pathsz; i++) {
 429                 if (chdir(paths[i]))
 430                         continue;
 431                 if (single_search(&tree, opts, expr, terms, mc, i))
 432                         continue;
 433
 434                 resfree(tree.node, tree.len);
 435                 mchars_free(mc);
 436                 return(0);
 437         }
 438
 439         (*res)(tree.node, tree.len, arg);
 440         *sz = tree.len;
 441         *resp = tree.node;
 442         mchars_free(mc);
 443         return(1);
 444 }
 445
 446 static int
 447 single_search(struct rectree *tree, const struct opts *opts,
 448                 const struct expr *expr, size_t terms,
 449                 struct mchars *mc, int vol)
 450 {
 451         int              root, leaf, ch;
 452         DBT              key, val;
 453         DB              *btree, *idx;
 454         char            *buf;
 455         struct res      *rs;
 456         struct res       r;
 457         uint64_t         mask;
 458         recno_t          rec;
 459
 460         root    = -1;
 461         leaf    = -1;
 462         btree   = NULL;
 463         idx     = NULL;
 464         buf     = NULL;
 465         rs      = tree->node;
 466
 467         memset(&r, 0, sizeof(struct res));
 468
 469         if (NULL == (btree = btree_open()))
 470                 return(1);
 471
 472         if (NULL == (idx = index_open())) {
 473                 (*btree->close)(btree);
 474                 return(1);
 475         }
 476
 477         while (0 == (ch = (*btree->seq)(btree, &key, &val, R_NEXT))) {
 478                 if ( ! btree_read(&key, &val, mc, &mask, &rec, &buf))
 479                         break;
 480
 481                 /*
 482                  * See if this keyword record matches any of the
 483                  * expressions we have stored.
 484                  */
 485                 if ( ! exprmark(expr, buf, mask, NULL))
 486                         continue;
 487
 488                 /*
 489                  * O(log n) scan for prior records.  Since a record
 490                  * number is unbounded, this has decent performance over
 491                  * a complex hash function.
 492                  */
 493
 494                 for (leaf = root; leaf >= 0; )
 495                         if (rec > rs[leaf].rec &&
 496                                         rs[leaf].rhs >= 0)
 497                                 leaf = rs[leaf].rhs;
 498                         else if (rec < rs[leaf].rec &&
 499                                         rs[leaf].lhs >= 0)
 500                                 leaf = rs[leaf].lhs;
 501                         else
 502                                 break;
 503
 504                 /*
 505                  * If we find a record, see if it has already evaluated
 506                  * to true.  If it has, great, just keep going.  If not,
 507                  * try to evaluate it now and continue anyway.
 508                  */
 509
 510                 if (leaf >= 0 && rs[leaf].rec == rec) {
 511                         if (0 == rs[leaf].matched)
 512                                 exprexec(expr, buf, mask, &rs[leaf]);
 513                         continue;
 514                 }
 515
 516                 /*
 517                  * We have a new file to examine.
 518                  * Extract the manpage's metadata from the index
 519                  * database, then begin partial evaluation.
 520                  */
 521
 522                 key.data = &rec;
 523                 key.size = sizeof(recno_t);
 524
 525                 if (0 != (*idx->get)(idx, &key, &val, 0))
 526                         break;
 527
 528                 r.lhs = r.rhs = -1;
 529                 if ( ! index_read(&key, &val, vol, mc, &r))
 530                         break;
 531
 532                 /* XXX: this should be elsewhere, I guess? */
 533
 534                 if (opts->cat && strcasecmp(opts->cat, r.cat))
 535                         continue;
 536
 537                 if (opts->arch && *r.arch)
 538                         if (strcasecmp(opts->arch, r.arch))
 539                                 continue;
 540
 541                 tree->node = rs = mandoc_realloc
 542                         (rs, (tree->len + 1) * sizeof(struct res));
 543
 544                 memcpy(&rs[tree->len], &r, sizeof(struct res));
 545                 memset(&r, 0, sizeof(struct res));
 546                 rs[tree->len].matches =
 547                         mandoc_calloc(terms, sizeof(int));
 548
 549                 exprexec(expr, buf, mask, &rs[tree->len]);
 550
 551                 /* Append to our tree. */
 552
 553                 if (leaf >= 0) {
 554                         if (rec > rs[leaf].rec)
 555                                 rs[leaf].rhs = tree->len;
 556                         else
 557                                 rs[leaf].lhs = tree->len;
 558                 } else
 559                         root = tree->len;
 560
 561                 tree->len++;
 562         }
 563
 564         (*btree->close)(btree);
 565         (*idx->close)(idx);
 566
 567         free(buf);
 568         RESFREE(&r);
 569         return(1 == ch);
 570 }
 571
 572 void
 573 resfree(struct res *rec, size_t sz)
 574 {
 575         size_t           i;
 576
 577         for (i = 0; i < sz; i++)
 578                 RESFREE(&rec[i]);
 579         free(rec);
 580 }
 581
 582 /*
 583  * Compile a list of straight-up terms.
 584  * The arguments are re-written into ~[[:<:]]term[[:>:]], or "term"
 585  * surrounded by word boundaries, then pumped through exprterm().
 586  * Terms are case-insensitive.
 587  * This emulates whatis(1) behaviour.
 588  */
 589 struct expr *
 590 termcomp(int argc, char *argv[], size_t *tt)
 591 {
 592         char            *buf;
 593         int              pos;
 594         struct expr     *e, *next;
 595         size_t           sz;
 596
 597         buf = NULL;
 598         e = NULL;
 599         *tt = 0;
 600
 601         for (pos = argc - 1; pos >= 0; pos--) {
 602                 sz = strlen(argv[pos]) + 18;
 603                 buf = mandoc_realloc(buf, sz);
 604                 strlcpy(buf, "Nm~[[:<:]]", sz);
 605                 strlcat(buf, argv[pos], sz);
 606                 strlcat(buf, "[[:>:]]", sz);
 607                 if (NULL == (next = exprterm(buf, 0))) {
 608                         free(buf);
 609                         exprfree(e);
 610                         return(NULL);
 611                 }
 612                 next->next = e;
 613                 e = next;
 614                 (*tt)++;
 615         }
 616
 617         free(buf);
 618         return(e);
 619 }
 620
 621 /*
 622  * Compile a sequence of logical expressions.
 623  * See apropos.1 for a grammar of this sequence.
 624  */
 625 struct expr *
 626 exprcomp(int argc, char *argv[], size_t *tt)
 627 {
 628         int              pos, lvl;
 629         struct expr     *e;
 630
 631         pos = lvl = 0;
 632         *tt = 0;
 633
 634         e = exprexpr(argc, argv, &pos, &lvl, tt);
 635
 636         if (0 == lvl && pos >= argc)
 637                 return(e);
 638
 639         exprfree(e);
 640         return(NULL);
 641 }
 642
 643 /*
 644  * Compile an array of tokens into an expression.
 645  * An informal expression grammar is defined in apropos(1).
 646  * Return NULL if we fail doing so.  All memory will be cleaned up.
 647  * Return the root of the expression sequence if alright.
 648  */
 649 static struct expr *
 650 exprexpr(int argc, char *argv[], int *pos, int *lvl, size_t *tt)
 651 {
 652         struct expr     *e, *first, *next;
 653         int              log;
 654
 655         first = next = NULL;
 656
 657         for ( ; *pos < argc; (*pos)++) {
 658                 e = next;
 659
 660                 /*
 661                  * Close out a subexpression.
 662                  */
 663
 664                 if (NULL != e && 0 == strcmp(")", argv[*pos])) {
 665                         if (--(*lvl) < 0)
 666                                 goto err;
 667                         break;
 668                 }
 669
 670                 /*
 671                  * Small note: if we're just starting, don't let "-a"
 672                  * and "-o" be considered logical operators: they're
 673                  * just tokens unless pairwise joining, in which case we
 674                  * record their existence (or assume "OR").
 675                  */
 676                 log = 0;
 677
 678                 if (NULL != e && 0 == strcmp("-a", argv[*pos]))
 679                         log = 1;
 680                 else if (NULL != e && 0 == strcmp("-o", argv[*pos]))
 681                         log = 2;
 682
 683                 if (log > 0 && ++(*pos) >= argc)
 684                         goto err;
 685
 686                 /*
 687                  * Now we parse the term part.  This can begin with
 688                  * "-i", in which case the expression is case
 689                  * insensitive.
 690                  */
 691
 692                 if (0 == strcmp("(", argv[*pos])) {
 693                         ++(*pos);
 694                         ++(*lvl);
 695                         next = mandoc_calloc(1, sizeof(struct expr));
 696                         next->subexpr = exprexpr(argc, argv, pos, lvl, tt);
 697                         if (NULL == next->subexpr) {
 698                                 free(next);
 699                                 next = NULL;
 700                         }
 701                 } else if (0 == strcmp("-i", argv[*pos])) {
 702                         if (++(*pos) >= argc)
 703                                 goto err;
 704                         next = exprterm(argv[*pos], 0);
 705                 } else
 706                         next = exprterm(argv[*pos], 1);
 707
 708                 if (NULL == next)
 709                         goto err;
 710
 711                 next->and = log == 1;
 712                 next->index = (int)(*tt)++;
 713
 714                 /* Append to our chain of expressions. */
 715
 716                 if (NULL == first) {
 717                         assert(NULL == e);
 718                         first = next;
 719                 } else {
 720                         assert(NULL != e);
 721                         e->next = next;
 722                 }
 723         }
 724
 725         return(first);
 726 err:
 727         exprfree(first);
 728         return(NULL);
 729 }
 730
 731 /*
 732  * Parse a terminal expression with the grammar as defined in
 733  * apropos(1).
 734  * Return NULL if we fail the parse.
 735  */
 736 static struct expr *
 737 exprterm(char *buf, int cs)
 738 {
 739         struct expr      e;
 740         struct expr     *p;
 741         char            *key;
 742         int              i;
 743
 744         memset(&e, 0, sizeof(struct expr));
 745
 746         /* Choose regex or substring match. */
 747
 748         if (NULL == (e.v = strpbrk(buf, "=~"))) {
 749                 e.regex = 0;
 750                 e.v = buf;
 751         } else {
 752                 e.regex = '~' == *e.v;
 753                 *e.v++ = '\0';
 754         }
 755
 756         /* Determine the record types to search for. */
 757
 758         e.mask = 0;
 759         if (buf < e.v) {
 760                 while (NULL != (key = strsep(&buf, ","))) {
 761                         i = 0;
 762                         while (types[i].mask &&
 763                                         strcmp(types[i].name, key))
 764                                 i++;
 765                         e.mask |= types[i].mask;
 766                 }
 767         }
 768         if (0 == e.mask)
 769                 e.mask = TYPE_Nm | TYPE_Nd;
 770
 771         if (e.regex) {
 772                 i = REG_EXTENDED | REG_NOSUB | (cs ? 0 : REG_ICASE);
 773                 if (regcomp(&e.re, e.v, i))
 774                         return(NULL);
 775         }
 776
 777         e.v = mandoc_strdup(e.v);
 778
 779         p = mandoc_calloc(1, sizeof(struct expr));
 780         memcpy(p, &e, sizeof(struct expr));
 781         return(p);
 782 }
 783
 784 void
 785 exprfree(struct expr *p)
 786 {
 787         struct expr     *pp;
 788
 789         while (NULL != p) {
 790                 if (p->subexpr)
 791                         exprfree(p->subexpr);
 792                 if (p->regex)
 793                         regfree(&p->re);
 794                 free(p->v);
 795                 pp = p->next;
 796                 free(p);
 797                 p = pp;
 798         }
 799 }
 800
 801 static int
 802 exprmark(const struct expr *p, const char *cp,
 803                 uint64_t mask, int *ms)
 804 {
 805
 806         for ( ; p; p = p->next) {
 807                 if (p->subexpr) {
 808                         if (exprmark(p->subexpr, cp, mask, ms))
 809                                 return(1);
 810                         continue;
 811                 } else if ( ! (mask & p->mask))
 812                         continue;
 813
 814                 if (p->regex) {
 815                         if (regexec(&p->re, cp, 0, NULL, 0))
 816                                 continue;
 817                 } else if (NULL == strcasestr(cp, p->v))
 818                         continue;
 819
 820                 if (NULL == ms)
 821                         return(1);
 822                 else
 823                         ms[p->index] = 1;
 824         }
 825
 826         return(0);
 827 }
 828
 829 static int
 830 expreval(const struct expr *p, int *ms)
 831 {
 832         int              match;
 833
 834         /*
 835          * AND has precedence over OR.  Analysis is left-right, though
 836          * it doesn't matter because there are no side-effects.
 837          * Thus, step through pairwise ANDs and accumulate their Boolean
 838          * evaluation.  If we encounter a single true AND collection or
 839          * standalone term, the whole expression is true (by definition
 840          * of OR).
 841          */
 842
 843         for (match = 0; p && ! match; p = p->next) {
 844                 /* Evaluate a subexpression, if applicable. */
 845                 if (p->subexpr && ! ms[p->index])
 846                         ms[p->index] = expreval(p->subexpr, ms);
 847
 848                 match = ms[p->index];
 849                 for ( ; p->next && p->next->and; p = p->next) {
 850                         /* Evaluate a subexpression, if applicable. */
 851                         if (p->next->subexpr && ! ms[p->next->index])
 852                                 ms[p->next->index] =
 853                                         expreval(p->next->subexpr, ms);
 854                         match = match && ms[p->next->index];
 855                 }
 856         }
 857
 858         return(match);
 859 }
 860
 861 /*
 862  * First, update the array of terms for which this expression evaluates
 863  * to true.
 864  * Second, logically evaluate all terms over the updated array of truth
 865  * values.
 866  * If this evaluates to true, mark the expression as satisfied.
 867  */
 868 static void
 869 exprexec(const struct expr *e, const char *cp,
 870                 uint64_t mask, struct res *r)
 871 {
 872
 873         assert(0 == r->matched);
 874         exprmark(e, cp, mask, r->matches);
 875         r->matched = expreval(e, r->matches);
 876 }