src/runner/expr.c

   1 /* expr.c -- arithmetic expression evaluation. */
   2
   3 /* Copyright (C) 1990-2020 Free Software Foundation, Inc.
   4
   5    This file is part of GNU Bush, the Bourne Again SHell.
   6
   7    Bush is free software: you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation, either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    Bush is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with Bush.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 /*
  22  All arithmetic is done as intmax_t integers with no checking for overflow
  23  (though division by 0 is caught and flagged as an error).
  24
  25  The following operators are handled, grouped into a set of levels in
  26  order of decreasing precedence.
  27
  28         "id++", "id--"          [post-increment and post-decrement]
  29         "-", "+"                [(unary operators)]
  30         "++id", "--id"          [pre-increment and pre-decrement]
  31         "!", "~"
  32         "**"                    [(exponentiation)]
  33         "*", "/", "%"
  34         "+", "-"
  35         "<<", ">>"
  36         "<=", ">=", "<", ">"
  37         "==", "!="
  38         "&"
  39         "^"
  40         "|"
  41         "&&"
  42         "||"
  43         "expr ? expr : expr"
  44         "=", "*=", "/=", "%=", "+=", "-=", "<<=", ">>=", "&=", "^=", "|="
  45         ,                       [comma]
  46
  47  (Note that most of these operators have special meaning to bush, and an
  48  entire expression should be quoted, e.g. "a=$a+1" or "a=a+1" to ensure
  49  that it is passed intact to the evaluator when using `let'.  When using
  50  the $[] or $(( )) forms, the text between the `[' and `]' or `((' and `))'
  51  is treated as if in double quotes.)
  52
  53  Sub-expressions within parentheses have a precedence level greater than
  54  all of the above levels and are evaluated first.  Within a single prece-
  55  dence group, evaluation is left-to-right, except for the arithmetic
  56  assignment operator (`='), which is evaluated right-to-left (as in C).
  57
  58  The expression evaluator returns the value of the expression (assignment
  59  statements have as a value what is returned by the RHS).  The `let'
  60  builtin, on the other hand, returns 0 if the last expression evaluates to
  61  a non-zero, and 1 otherwise.
  62
  63  Implementation is a recursive-descent parser.
  64
  65  Chet Ramey
  66  chet@po.cwru.edu
  67 */
  68
  69 #include "config.h"
  70
  71 #include <stdio.h>
  72 #include "bushansi.h"
  73
  74 #if defined (HAVE_UNISTD_H)
  75 #  ifdef _MINIX
  76 #    include <sys/types.h>
  77 #  endif
  78 #  include <unistd.h>
  79 #endif
  80
  81 #include "chartypes.h"
  82 #include "bushintl.h"
  83
  84 #include "shell.h"
  85 #include "var/arrayfunc.h"
  86 #include "runner/execute_cmd.h"
  87 #include "flags.h"
  88 #include "lxrgmr/subst.h"
  89 #include "typemax.h"            /* INTMAX_MAX, INTMAX_MIN */
  90
  91 /* Because of the $((...)) construct, expressions may include newlines.
  92    Here is a macro which accepts newlines, tabs and spaces as whitespace. */
  93 #define cr_whitespace(c) (whitespace(c) || ((c) == '\n'))
  94
  95 /* Size be which the expression stack grows when necessary. */
  96 #define EXPR_STACK_GROW_SIZE 10
  97
  98 /* Maximum amount of recursion allowed.  This prevents a non-integer
  99    variable such as "num=num+2" from infinitely adding to itself when
 100    "let num=num+2" is given. */
 101 #define MAX_EXPR_RECURSION_LEVEL 1024
 102
 103 /* The Tokens.  Singing "The Lion Sleeps Tonight". */
 104
 105 #define EQEQ    1       /* "==" */
 106 #define NEQ     2       /* "!=" */
 107 #define LEQ     3       /* "<=" */
 108 #define GEQ     4       /* ">=" */
 109 #define STR     5       /* string */
 110 #define NUM     6       /* number */
 111 #define LAND    7       /* "&&" Logical AND */
 112 #define LOR     8       /* "||" Logical OR */
 113 #define LSH     9       /* "<<" Left SHift */
 114 #define RSH    10       /* ">>" Right SHift */
 115 #define OP_ASSIGN 11    /* op= expassign as in Posix.2 */
 116 #define COND    12      /* exp1 ? exp2 : exp3 */
 117 #define POWER   13      /* exp1**exp2 */
 118 #define PREINC  14      /* ++var */
 119 #define PREDEC  15      /* --var */
 120 #define POSTINC 16      /* var++ */
 121 #define POSTDEC 17      /* var-- */
 122 #define EQ      '='
 123 #define GT      '>'
 124 #define LT      '<'
 125 #define PLUS    '+'
 126 #define MINUS   '-'
 127 #define MUL     '*'
 128 #define DIV     '/'
 129 #define MOD     '%'
 130 #define NOT     '!'
 131 #define LPAR    '('
 132 #define RPAR    ')'
 133 #define BAND    '&'     /* Bitwise AND */
 134 #define BOR     '|'     /* Bitwise OR. */
 135 #define BXOR    '^'     /* Bitwise eXclusive OR. */
 136 #define BNOT    '~'     /* Bitwise NOT; Two's complement. */
 137 #define QUES    '?'
 138 #define COL     ':'
 139 #define COMMA   ','
 140
 141 /* This should be the function corresponding to the operator with the
 142    highest precedence. */
 143 #define EXP_HIGHEST     expcomma
 144
 145 #ifndef MAX_INT_LEN
 146 #  define MAX_INT_LEN 32
 147 #endif
 148
 149 struct lvalue
 150 {
 151   char *tokstr;         /* possibly-rewritten lvalue if not NULL */
 152   intmax_t tokval;      /* expression evaluated value */
 153   SHELL_VAR *tokvar;    /* variable described by array or var reference */
 154   intmax_t ind;         /* array index if not -1 */
 155 };
 156
 157 /* A structure defining a single expression context. */
 158 typedef struct {
 159   int curtok, lasttok;
 160   char *expression, *tp, *lasttp;
 161   intmax_t tokval;
 162   char *tokstr;
 163   int noeval;
 164   struct lvalue lval;
 165 } EXPR_CONTEXT;
 166
 167 static char     *expression;    /* The current expression */
 168 static char     *tp;            /* token lexical position */
 169 static char     *lasttp;        /* pointer to last token position */
 170 static int      curtok;         /* the current token */
 171 static int      lasttok;        /* the previous token */
 172 static int      assigntok;      /* the OP in OP= */
 173 static char     *tokstr;        /* current token string */
 174 static intmax_t tokval;         /* current token value */
 175 static int      noeval;         /* set to 1 if no assignment to be done */
 176 static procenv_t evalbuf;
 177
 178 /* set to 1 if the expression has already been run through word expansion */
 179 static int      already_expanded;
 180
 181 static struct lvalue curlval = {0, 0, 0, -1};
 182 static struct lvalue lastlval = {0, 0, 0, -1};
 183
 184 static int      _is_arithop PARAMS((int));
 185 static void     readtok PARAMS((void)); /* lexical analyzer */
 186
 187 static void     init_lvalue PARAMS((struct lvalue *));
 188 static struct lvalue *alloc_lvalue PARAMS((void));
 189 static void     free_lvalue PARAMS((struct lvalue *));
 190
 191 static intmax_t expr_streval PARAMS((char *, int, struct lvalue *));
 192 static intmax_t strlong PARAMS((char *));
 193 static void     evalerror PARAMS((const char *));
 194
 195 static void     pushexp PARAMS((void));
 196 static void     popexp PARAMS((void));
 197 static void     expr_unwind PARAMS((void));
 198 static void     expr_bind_variable PARAMS((char *, char *));
 199 #if defined (ARRAY_VARS)
 200 static void     expr_bind_array_element PARAMS((char *, arrayind_t, char *));
 201 #endif
 202
 203 static intmax_t subexpr PARAMS((char *));
 204
 205 static intmax_t expcomma PARAMS((void));
 206 static intmax_t expassign PARAMS((void));
 207 static intmax_t expcond PARAMS((void));
 208 static intmax_t explor PARAMS((void));
 209 static intmax_t expland PARAMS((void));
 210 static intmax_t expbor PARAMS((void));
 211 static intmax_t expbxor PARAMS((void));
 212 static intmax_t expband PARAMS((void));
 213 static intmax_t exp5 PARAMS((void));
 214 static intmax_t exp4 PARAMS((void));
 215 static intmax_t expshift PARAMS((void));
 216 static intmax_t exp3 PARAMS((void));
 217 static intmax_t expmuldiv PARAMS((void));
 218 static intmax_t exppower PARAMS((void));
 219 static intmax_t exp1 PARAMS((void));
 220 static intmax_t exp0 PARAMS((void));
 221
 222 /* Global var which contains the stack of expression contexts. */
 223 static EXPR_CONTEXT **expr_stack;
 224 static int expr_depth;             /* Location in the stack. */
 225 static int expr_stack_size;        /* Number of slots already allocated. */
 226
 227 #if defined (ARRAY_VARS)
 228 extern const char * const bush_badsub_errmsg;
 229 #endif
 230
 231 #define SAVETOK(X) \
 232   do { \
 233     (X)->curtok = curtok; \
 234     (X)->lasttok = lasttok; \
 235     (X)->tp = tp; \
 236     (X)->lasttp = lasttp; \
 237     (X)->tokval = tokval; \
 238     (X)->tokstr = tokstr; \
 239     (X)->noeval = noeval; \
 240     (X)->lval = curlval; \
 241   } while (0)
 242
 243 #define RESTORETOK(X) \
 244   do { \
 245     curtok = (X)->curtok; \
 246     lasttok = (X)->lasttok; \
 247     tp = (X)->tp; \
 248     lasttp = (X)->lasttp; \
 249     tokval = (X)->tokval; \
 250     tokstr = (X)->tokstr; \
 251     noeval = (X)->noeval; \
 252     curlval = (X)->lval; \
 253   } while (0)
 254
 255 /* Push and save away the contents of the globals describing the
 256    current expression context. */
 257 static void
 258 pushexp ()
 259 {
 260   EXPR_CONTEXT *context;
 261
 262   if (expr_depth >= MAX_EXPR_RECURSION_LEVEL)
 263     evalerror (_("expression recursion level exceeded"));
 264
 265   if (expr_depth >= expr_stack_size)
 266     {
 267       expr_stack_size += EXPR_STACK_GROW_SIZE;
 268       expr_stack = (EXPR_CONTEXT **)xrealloc (expr_stack, expr_stack_size * sizeof (EXPR_CONTEXT *));
 269     }
 270
 271   context = (EXPR_CONTEXT *)xmalloc (sizeof (EXPR_CONTEXT));
 272
 273   context->expression = expression;
 274   SAVETOK(context);
 275
 276   expr_stack[expr_depth++] = context;
 277 }
 278
 279 /* Pop the the contents of the expression context stack into the
 280    globals describing the current expression context. */
 281 static void
 282 popexp ()
 283 {
 284   EXPR_CONTEXT *context;
 285
 286   if (expr_depth <= 0)
 287     {
 288       /* See the comment at the top of evalexp() for an explanation of why
 289          this is done. */
 290       expression = lasttp = 0;
 291       evalerror (_("recursion stack underflow"));
 292     }
 293
 294   context = expr_stack[--expr_depth];
 295
 296   expression = context->expression;
 297   RESTORETOK (context);
 298
 299   free (context);
 300 }
 301
 302 static void
 303 expr_unwind ()
 304 {
 305   while (--expr_depth > 0)
 306     {
 307       if (expr_stack[expr_depth]->tokstr)
 308         free (expr_stack[expr_depth]->tokstr);
 309
 310       if (expr_stack[expr_depth]->expression)
 311         free (expr_stack[expr_depth]->expression);
 312
 313       free (expr_stack[expr_depth]);
 314     }
 315   if (expr_depth == 0)
 316     free (expr_stack[expr_depth]);      /* free the allocated EXPR_CONTEXT */
 317
 318   noeval = 0;   /* XXX */
 319 }
 320
 321 static void
 322 expr_bind_variable (lhs, rhs)
 323      char *lhs, *rhs;
 324 {
 325   SHELL_VAR *v;
 326   int aflags;
 327
 328   if (lhs == 0 || *lhs == 0)
 329     return;             /* XXX */
 330
 331 #if defined (ARRAY_VARS)
 332   aflags = (assoc_expand_once && already_expanded) ? ASS_NOEXPAND : 0;
 333 #else
 334   aflags = 0;
 335 #endif
 336   v = bind_int_variable (lhs, rhs, aflags);
 337   if (v && (readonly_p (v) || noassign_p (v)))
 338     sh_longjmp (evalbuf, 1);    /* variable assignment error */
 339   stupidly_hack_special_variables (lhs);
 340 }
 341
 342 #if defined (ARRAY_VARS)
 343 /* This is similar to the logic in arrayfunc.c:valid_array_subscript when
 344    you pass VA_NOEXPAND. */
 345 static int
 346 expr_skipsubscript (vp, cp)
 347      char *vp, *cp;
 348 {
 349   int flags, isassoc;
 350   SHELL_VAR *entry;
 351
 352   isassoc = 0;
 353   entry = 0;
 354   if (assoc_expand_once & already_expanded)
 355     {
 356       *cp = '\0';
 357       isassoc = legal_identifier (vp) && (entry = find_variable (vp)) && assoc_p (entry);
 358       *cp = '[';        /* ] */
 359     }
 360   flags = (isassoc && assoc_expand_once && already_expanded) ? VA_NOEXPAND : 0;
 361   return (skipsubscript (cp, 0, flags));
 362 }
 363
 364 /* Rewrite tok, which is of the form vname[expression], to vname[ind], where
 365    IND is the already-calculated value of expression. */
 366 static void
 367 expr_bind_array_element (tok, ind, rhs)
 368      char *tok;
 369      arrayind_t ind;
 370      char *rhs;
 371 {
 372   char *lhs, *vname;
 373   size_t llen;
 374   char ibuf[INT_STRLEN_BOUND (arrayind_t) + 1], *istr;
 375
 376   istr = fmtumax (ind, 10, ibuf, sizeof (ibuf), 0);
 377   vname = array_variable_name (tok, 0, (char **)NULL, (int *)NULL);
 378
 379   llen = strlen (vname) + sizeof (ibuf) + 3;
 380   lhs = xmalloc (llen);
 381
 382   sprintf (lhs, "%s[%s]", vname, istr);         /* XXX */
 383
 384 /*itrace("expr_bind_array_element: %s=%s", lhs, rhs);*/
 385   expr_bind_variable (lhs, rhs);
 386   free (vname);
 387   free (lhs);
 388 }
 389 #endif /* ARRAY_VARS */
 390
 391 /* Evaluate EXPR, and return the arithmetic result.  If VALIDP is
 392    non-null, a zero is stored into the location to which it points
 393    if the expression is invalid, non-zero otherwise.  If a non-zero
 394    value is returned in *VALIDP, the return value of evalexp() may
 395    be used.
 396
 397    The `while' loop after the longjmp is caught relies on the above
 398    implementation of pushexp and popexp leaving in expr_stack[0] the
 399    values that the variables had when the program started.  That is,
 400    the first things saved are the initial values of the variables that
 401    were assigned at program startup or by the compiler.  Therefore, it is
 402    safe to let the loop terminate when expr_depth == 0, without freeing up
 403    any of the expr_depth[0] stuff. */
 404 intmax_t
 405 evalexp (expr, flags, validp)
 406      char *expr;
 407      int flags;
 408      int *validp;
 409 {
 410   intmax_t val;
 411   int c;
 412   procenv_t oevalbuf;
 413
 414   val = 0;
 415   noeval = 0;
 416   already_expanded = (flags&EXP_EXPANDED);
 417
 418   FASTCOPY (evalbuf, oevalbuf, sizeof (evalbuf));
 419
 420   c = setjmp_nosigs (evalbuf);
 421
 422   if (c)
 423     {
 424       FREE (tokstr);
 425       FREE (expression);
 426       tokstr = expression = (char *)NULL;
 427
 428       expr_unwind ();
 429       expr_depth = 0;   /* XXX - make sure */
 430
 431       /* We copy in case we've called evalexp recursively */
 432       FASTCOPY (oevalbuf, evalbuf, sizeof (evalbuf));
 433
 434       if (validp)
 435         *validp = 0;
 436       return (0);
 437     }
 438
 439   val = subexpr (expr);
 440
 441   if (validp)
 442     *validp = 1;
 443
 444   FASTCOPY (oevalbuf, evalbuf, sizeof (evalbuf));
 445
 446   return (val);
 447 }
 448
 449 static intmax_t
 450 subexpr (expr)
 451      char *expr;
 452 {
 453   intmax_t val;
 454   char *p;
 455
 456   for (p = expr; p && *p && cr_whitespace (*p); p++)
 457     ;
 458
 459   if (p == NULL || *p == '\0')
 460     return (0);
 461
 462   pushexp ();
 463   expression = savestring (expr);
 464   tp = expression;
 465
 466   curtok = lasttok = 0;
 467   tokstr = (char *)NULL;
 468   tokval = 0;
 469   init_lvalue (&curlval);
 470   lastlval = curlval;
 471
 472   readtok ();
 473
 474   val = EXP_HIGHEST ();
 475
 476   if (curtok != 0)
 477     evalerror (_("syntax error in expression"));
 478
 479   FREE (tokstr);
 480   FREE (expression);
 481
 482   popexp ();
 483
 484   return val;
 485 }
 486
 487 static intmax_t
 488 expcomma ()
 489 {
 490   register intmax_t value;
 491
 492   value = expassign ();
 493   while (curtok == COMMA)
 494     {
 495       readtok ();
 496       value = expassign ();
 497     }
 498
 499   return value;
 500 }
 501
 502 static intmax_t
 503 expassign ()
 504 {
 505   register intmax_t value;
 506   char *lhs, *rhs;
 507   arrayind_t lind;
 508 #if defined (HAVE_IMAXDIV)
 509   imaxdiv_t idiv;
 510 #endif
 511
 512   value = expcond ();
 513   if (curtok == EQ || curtok == OP_ASSIGN)
 514     {
 515       int special, op;
 516       intmax_t lvalue;
 517
 518       special = curtok == OP_ASSIGN;
 519
 520       if (lasttok != STR)
 521         evalerror (_("attempted assignment to non-variable"));
 522
 523       if (special)
 524         {
 525           op = assigntok;               /* a OP= b */
 526           lvalue = value;
 527         }
 528
 529       if (tokstr == 0)
 530         evalerror (_("syntax error in variable assignment"));
 531
 532       /* XXX - watch out for pointer aliasing issues here */
 533       lhs = savestring (tokstr);
 534       /* save ind in case rhs is string var and evaluation overwrites it */
 535       lind = curlval.ind;
 536       readtok ();
 537       value = expassign ();
 538
 539       if (special)
 540         {
 541           if ((op == DIV || op == MOD) && value == 0)
 542             {
 543               if (noeval == 0)
 544                 evalerror (_("division by 0"));
 545               else
 546                 value = 1;
 547             }
 548
 549           switch (op)
 550             {
 551             case MUL:
 552               /* Handle INTMAX_MIN and INTMAX_MAX * -1 specially here? */
 553               lvalue *= value;
 554               break;
 555             case DIV:
 556             case MOD:
 557               if (lvalue == INTMAX_MIN && value == -1)
 558                 lvalue = (op == DIV) ? INTMAX_MIN : 0;
 559               else
 560 #if HAVE_IMAXDIV
 561                 {
 562                   idiv = imaxdiv (lvalue, value);
 563                   lvalue = (op == DIV) ? idiv.quot : idiv.rem;
 564                 }
 565 #else
 566                 lvalue = (op == DIV) ? lvalue / value : lvalue % value;
 567 #endif
 568               break;
 569             case PLUS:
 570               lvalue += value;
 571               break;
 572             case MINUS:
 573               lvalue -= value;
 574               break;
 575             case LSH:
 576               lvalue <<= value;
 577               break;
 578             case RSH:
 579               lvalue >>= value;
 580               break;
 581             case BAND:
 582               lvalue &= value;
 583               break;
 584             case BOR:
 585               lvalue |= value;
 586               break;
 587             case BXOR:
 588               lvalue ^= value;
 589               break;
 590             default:
 591               free (lhs);
 592               evalerror (_("bug: bad expassign token"));
 593               break;
 594             }
 595           value = lvalue;
 596         }
 597
 598       rhs = itos (value);
 599       if (noeval == 0)
 600         {
 601 #if defined (ARRAY_VARS)
 602           if (lind != -1)
 603             expr_bind_array_element (lhs, lind, rhs);
 604           else
 605 #endif
 606             expr_bind_variable (lhs, rhs);
 607         }
 608       if (curlval.tokstr && curlval.tokstr == tokstr)
 609         init_lvalue (&curlval);
 610
 611       free (rhs);
 612       free (lhs);
 613       FREE (tokstr);
 614       tokstr = (char *)NULL;            /* For freeing on errors. */
 615     }
 616
 617   return (value);
 618 }
 619
 620 /* Conditional expression (expr?expr:expr) */
 621 static intmax_t
 622 expcond ()
 623 {
 624   intmax_t cval, val1, val2, rval;
 625   int set_noeval;
 626
 627   set_noeval = 0;
 628   rval = cval = explor ();
 629   if (curtok == QUES)           /* found conditional expr */
 630     {
 631       if (cval == 0)
 632         {
 633           set_noeval = 1;
 634           noeval++;
 635         }
 636
 637       readtok ();
 638       if (curtok == 0 || curtok == COL)
 639         evalerror (_("expression expected"));
 640
 641       val1 = EXP_HIGHEST ();
 642
 643       if (set_noeval)
 644         noeval--;
 645       if (curtok != COL)
 646         evalerror (_("`:' expected for conditional expression"));
 647
 648       set_noeval = 0;
 649       if (cval)
 650         {
 651           set_noeval = 1;
 652           noeval++;
 653         }
 654
 655       readtok ();
 656       if (curtok == 0)
 657         evalerror (_("expression expected"));
 658       val2 = expcond ();
 659
 660       if (set_noeval)
 661         noeval--;
 662       rval = cval ? val1 : val2;
 663       lasttok = COND;
 664     }
 665   return rval;
 666 }
 667
 668 /* Logical OR. */
 669 static intmax_t
 670 explor ()
 671 {
 672   register intmax_t val1, val2;
 673   int set_noeval;
 674
 675   val1 = expland ();
 676
 677   while (curtok == LOR)
 678     {
 679       set_noeval = 0;
 680       if (val1 != 0)
 681         {
 682           noeval++;
 683           set_noeval = 1;
 684         }
 685       readtok ();
 686       val2 = expland ();
 687       if (set_noeval)
 688         noeval--;
 689       val1 = val1 || val2;
 690       lasttok = LOR;
 691     }
 692
 693   return (val1);
 694 }
 695
 696 /* Logical AND. */
 697 static intmax_t
 698 expland ()
 699 {
 700   register intmax_t val1, val2;
 701   int set_noeval;
 702
 703   val1 = expbor ();
 704
 705   while (curtok == LAND)
 706     {
 707       set_noeval = 0;
 708       if (val1 == 0)
 709         {
 710           set_noeval = 1;
 711           noeval++;
 712         }
 713       readtok ();
 714       val2 = expbor ();
 715       if (set_noeval)
 716         noeval--;
 717       val1 = val1 && val2;
 718       lasttok = LAND;
 719     }
 720
 721   return (val1);
 722 }
 723
 724 /* Bitwise OR. */
 725 static intmax_t
 726 expbor ()
 727 {
 728   register intmax_t val1, val2;
 729
 730   val1 = expbxor ();
 731
 732   while (curtok == BOR)
 733     {
 734       readtok ();
 735       val2 = expbxor ();
 736       val1 = val1 | val2;
 737       lasttok = NUM;
 738     }
 739
 740   return (val1);
 741 }
 742
 743 /* Bitwise XOR. */
 744 static intmax_t
 745 expbxor ()
 746 {
 747   register intmax_t val1, val2;
 748
 749   val1 = expband ();
 750
 751   while (curtok == BXOR)
 752     {
 753       readtok ();
 754       val2 = expband ();
 755       val1 = val1 ^ val2;
 756       lasttok = NUM;
 757     }
 758
 759   return (val1);
 760 }
 761
 762 /* Bitwise AND. */
 763 static intmax_t
 764 expband ()
 765 {
 766   register intmax_t val1, val2;
 767
 768   val1 = exp5 ();
 769
 770   while (curtok == BAND)
 771     {
 772       readtok ();
 773       val2 = exp5 ();
 774       val1 = val1 & val2;
 775       lasttok = NUM;
 776     }
 777
 778   return (val1);
 779 }
 780
 781 static intmax_t
 782 exp5 ()
 783 {
 784   register intmax_t val1, val2;
 785
 786   val1 = exp4 ();
 787
 788   while ((curtok == EQEQ) || (curtok == NEQ))
 789     {
 790       int op = curtok;
 791
 792       readtok ();
 793       val2 = exp4 ();
 794       if (op == EQEQ)
 795         val1 = (val1 == val2);
 796       else if (op == NEQ)
 797         val1 = (val1 != val2);
 798       lasttok = NUM;
 799     }
 800   return (val1);
 801 }
 802
 803 static intmax_t
 804 exp4 ()
 805 {
 806   register intmax_t val1, val2;
 807
 808   val1 = expshift ();
 809   while ((curtok == LEQ) ||
 810          (curtok == GEQ) ||
 811          (curtok == LT) ||
 812          (curtok == GT))
 813     {
 814       int op = curtok;
 815
 816       readtok ();
 817       val2 = expshift ();
 818
 819       if (op == LEQ)
 820         val1 = val1 <= val2;
 821       else if (op == GEQ)
 822         val1 = val1 >= val2;
 823       else if (op == LT)
 824         val1 = val1 < val2;
 825       else                      /* (op == GT) */
 826         val1 = val1 > val2;
 827       lasttok = NUM;
 828     }
 829   return (val1);
 830 }
 831
 832 /* Left and right shifts. */
 833 static intmax_t
 834 expshift ()
 835 {
 836   register intmax_t val1, val2;
 837
 838   val1 = exp3 ();
 839
 840   while ((curtok == LSH) || (curtok == RSH))
 841     {
 842       int op = curtok;
 843
 844       readtok ();
 845       val2 = exp3 ();
 846
 847       if (op == LSH)
 848         val1 = val1 << val2;
 849       else
 850         val1 = val1 >> val2;
 851       lasttok = NUM;
 852     }
 853
 854   return (val1);
 855 }
 856
 857 static intmax_t
 858 exp3 ()
 859 {
 860   register intmax_t val1, val2;
 861
 862   val1 = expmuldiv ();
 863
 864   while ((curtok == PLUS) || (curtok == MINUS))
 865     {
 866       int op = curtok;
 867
 868       readtok ();
 869       val2 = expmuldiv ();
 870
 871       if (op == PLUS)
 872         val1 += val2;
 873       else if (op == MINUS)
 874         val1 -= val2;
 875       lasttok = NUM;
 876     }
 877   return (val1);
 878 }
 879
 880 static intmax_t
 881 expmuldiv ()
 882 {
 883   register intmax_t val1, val2;
 884 #if defined (HAVE_IMAXDIV)
 885   imaxdiv_t idiv;
 886 #endif
 887
 888   val1 = exppower ();
 889
 890   while ((curtok == MUL) ||
 891          (curtok == DIV) ||
 892          (curtok == MOD))
 893     {
 894       int op = curtok;
 895       char *stp, *sltp;
 896
 897       stp = tp;
 898       readtok ();
 899
 900       val2 = exppower ();
 901
 902       /* Handle division by 0 and twos-complement arithmetic overflow */
 903       if (((op == DIV) || (op == MOD)) && (val2 == 0))
 904         {
 905           if (noeval == 0)
 906             {
 907               sltp = lasttp;
 908               lasttp = stp;
 909               while (lasttp && *lasttp && whitespace (*lasttp))
 910                 lasttp++;
 911               evalerror (_("division by 0"));
 912               lasttp = sltp;
 913             }
 914           else
 915             val2 = 1;
 916         }
 917       else if (op == MOD && val1 == INTMAX_MIN && val2 == -1)
 918         {
 919           val1 = 0;
 920           continue;
 921         }
 922       else if (op == DIV && val1 == INTMAX_MIN && val2 == -1)
 923         val2 = 1;
 924
 925       if (op == MUL)
 926         val1 *= val2;
 927       else if (op == DIV || op == MOD)
 928 #if defined (HAVE_IMAXDIV)
 929         {
 930           idiv = imaxdiv (val1, val2);
 931           val1 = (op == DIV) ? idiv.quot : idiv.rem;
 932         }
 933 #else
 934         val1 = (op == DIV) ? val1 / val2 : val1 % val2;
 935 #endif
 936       lasttok = NUM;
 937     }
 938   return (val1);
 939 }
 940
 941 static intmax_t
 942 ipow (base, exp)
 943      intmax_t base, exp;
 944 {
 945   intmax_t result;
 946
 947   result = 1;
 948   while (exp)
 949     {
 950       if (exp & 1)
 951         result *= base;
 952       exp >>= 1;
 953       base *= base;
 954     }
 955   return result;
 956 }
 957
 958 static intmax_t
 959 exppower ()
 960 {
 961   register intmax_t val1, val2, c;
 962
 963   val1 = exp1 ();
 964   while (curtok == POWER)
 965     {
 966       readtok ();
 967       val2 = exppower ();       /* exponentiation is right-associative */
 968       lasttok = NUM;
 969       if (val2 == 0)
 970         return (1);
 971       if (val2 < 0)
 972         evalerror (_("exponent less than 0"));
 973       val1 = ipow (val1, val2);
 974     }
 975   return (val1);
 976 }
 977
 978 static intmax_t
 979 exp1 ()
 980 {
 981   register intmax_t val;
 982
 983   if (curtok == NOT)
 984     {
 985       readtok ();
 986       val = !exp1 ();
 987       lasttok = NUM;
 988     }
 989   else if (curtok == BNOT)
 990     {
 991       readtok ();
 992       val = ~exp1 ();
 993       lasttok = NUM;
 994     }
 995   else if (curtok == MINUS)
 996     {
 997       readtok ();
 998       val = - exp1 ();
 999       lasttok = NUM;
1000     }
1001   else if (curtok == PLUS)
1002     {
1003       readtok ();
1004       val = exp1 ();
1005       lasttok = NUM;
1006     }
1007   else
1008     val = exp0 ();
1009
1010   return (val);
1011 }
1012
1013 static intmax_t
1014 exp0 ()
1015 {
1016   register intmax_t val = 0, v2;
1017   char *vincdec;
1018   int stok;
1019   EXPR_CONTEXT ec;
1020
1021   /* XXX - might need additional logic here to decide whether or not
1022            pre-increment or pre-decrement is legal at this point. */
1023   if (curtok == PREINC || curtok == PREDEC)
1024     {
1025       stok = lasttok = curtok;
1026       readtok ();
1027       if (curtok != STR)
1028         /* readtok() catches this */
1029         evalerror (_("identifier expected after pre-increment or pre-decrement"));
1030
1031       v2 = tokval + ((stok == PREINC) ? 1 : -1);
1032       vincdec = itos (v2);
1033       if (noeval == 0)
1034         {
1035 #if defined (ARRAY_VARS)
1036           if (curlval.ind != -1)
1037             expr_bind_array_element (curlval.tokstr, curlval.ind, vincdec);
1038           else
1039 #endif
1040             if (tokstr)
1041               expr_bind_variable (tokstr, vincdec);
1042         }
1043       free (vincdec);
1044       val = v2;
1045
1046       curtok = NUM;     /* make sure --x=7 is flagged as an error */
1047       readtok ();
1048     }
1049   else if (curtok == LPAR)
1050     {
1051       /* XXX - save curlval here?  Or entire expression context? */
1052       readtok ();
1053       val = EXP_HIGHEST ();
1054
1055       if (curtok != RPAR) /* ( */
1056         evalerror (_("missing `)'"));
1057
1058       /* Skip over closing paren. */
1059       readtok ();
1060     }
1061   else if ((curtok == NUM) || (curtok == STR))
1062     {
1063       val = tokval;
1064       if (curtok == STR)
1065         {
1066           SAVETOK (&ec);
1067           tokstr = (char *)NULL;        /* keep it from being freed */
1068           noeval = 1;
1069           readtok ();
1070           stok = curtok;
1071
1072           /* post-increment or post-decrement */
1073           if (stok == POSTINC || stok == POSTDEC)
1074             {
1075               /* restore certain portions of EC */
1076               tokstr = ec.tokstr;
1077               noeval = ec.noeval;
1078               curlval = ec.lval;
1079               lasttok = STR;    /* ec.curtok */
1080
1081               v2 = val + ((stok == POSTINC) ? 1 : -1);
1082               vincdec = itos (v2);
1083               if (noeval == 0)
1084                 {
1085 #if defined (ARRAY_VARS)
1086                   if (curlval.ind != -1)
1087                     expr_bind_array_element (curlval.tokstr, curlval.ind, vincdec);
1088                   else
1089 #endif
1090                     expr_bind_variable (tokstr, vincdec);
1091                 }
1092               free (vincdec);
1093               curtok = NUM;     /* make sure x++=7 is flagged as an error */
1094             }
1095           else
1096             {
1097               /* XXX - watch out for pointer aliasing issues here */
1098               if (stok == STR)  /* free new tokstr before old one is restored */
1099                 FREE (tokstr);
1100               RESTORETOK (&ec);
1101             }
1102         }
1103
1104       readtok ();
1105     }
1106   else
1107     evalerror (_("syntax error: operand expected"));
1108
1109   return (val);
1110 }
1111
1112 static void
1113 init_lvalue (lv)
1114      struct lvalue *lv;
1115 {
1116   lv->tokstr = 0;
1117   lv->tokvar = 0;
1118   lv->tokval = lv->ind = -1;
1119 }
1120
1121 static struct lvalue *
1122 alloc_lvalue ()
1123 {
1124   struct lvalue *lv;
1125
1126   lv = xmalloc (sizeof (struct lvalue));
1127   init_lvalue (lv);
1128   return (lv);
1129 }
1130
1131 static void
1132 free_lvalue (lv)
1133      struct lvalue *lv;
1134 {
1135   free (lv);            /* should be inlined */
1136 }
1137
1138 static intmax_t
1139 expr_streval (tok, e, lvalue)
1140      char *tok;
1141      int e;
1142      struct lvalue *lvalue;
1143 {
1144   SHELL_VAR *v;
1145   char *value;
1146   intmax_t tval;
1147   int initial_depth;
1148 #if defined (ARRAY_VARS)
1149   arrayind_t ind;
1150   int tflag, aflag;
1151 #endif
1152
1153 /*itrace("expr_streval: %s: noeval = %d expanded=%d", tok, noeval, already_expanded);*/
1154   /* If we are suppressing evaluation, just short-circuit here instead of
1155      going through the rest of the evaluator. */
1156   if (noeval)
1157     return (0);
1158
1159   initial_depth = expr_depth;
1160
1161 #if defined (ARRAY_VARS)
1162   tflag = assoc_expand_once && already_expanded;        /* for a start */
1163 #endif
1164
1165   /* [[[[[ */
1166 #if defined (ARRAY_VARS)
1167   aflag = (tflag) ? AV_NOEXPAND : 0;
1168   v = (e == ']') ? array_variable_part (tok, tflag, (char **)0, (int *)0) : find_variable (tok);
1169 #else
1170   v = find_variable (tok);
1171 #endif
1172   if (v == 0 && e != ']')
1173     v = find_variable_last_nameref (tok, 0);
1174
1175   if ((v == 0 || invisible_p (v)) && unbound_vars_is_error)
1176     {
1177 #if defined (ARRAY_VARS)
1178       value = (e == ']') ? array_variable_name (tok, tflag, (char **)0, (int *)0) : tok;
1179 #else
1180       value = tok;
1181 #endif
1182
1183       set_exit_status (EXECUTION_FAILURE);
1184       err_unboundvar (value);
1185
1186 #if defined (ARRAY_VARS)
1187       if (e == ']')
1188         FREE (value);   /* array_variable_name returns new memory */
1189 #endif
1190
1191       if (no_longjmp_on_fatal_error && interactive_shell)
1192         sh_longjmp (evalbuf, 1);
1193
1194       if (interactive_shell)
1195         {
1196           expr_unwind ();
1197           top_level_cleanup ();
1198           jump_to_top_level (DISCARD);
1199         }
1200       else
1201         jump_to_top_level (FORCE_EOF);
1202     }
1203
1204 #if defined (ARRAY_VARS)
1205   ind = -1;
1206   /* If the second argument to get_array_value doesn't include AV_ALLOWALL,
1207      we don't allow references like array[@].  In this case, get_array_value
1208      is just like get_variable_value in that it does not return newly-allocated
1209      memory or quote the results.  AFLAG is set above and is either AV_NOEXPAND
1210      or 0. */
1211   value = (e == ']') ? get_array_value (tok, aflag, (int *)NULL, &ind) : get_variable_value (v);
1212 #else
1213   value = get_variable_value (v);
1214 #endif
1215
1216   if (expr_depth < initial_depth)
1217     {
1218       if (no_longjmp_on_fatal_error && interactive_shell)
1219         sh_longjmp (evalbuf, 1);
1220       return (0);
1221     }
1222
1223   tval = (value && *value) ? subexpr (value) : 0;
1224
1225   if (lvalue)
1226     {
1227       lvalue->tokstr = tok;     /* XXX */
1228       lvalue->tokval = tval;
1229       lvalue->tokvar = v;       /* XXX */
1230 #if defined (ARRAY_VARS)
1231       lvalue->ind = ind;
1232 #else
1233       lvalue->ind = -1;
1234 #endif
1235     }
1236
1237   return (tval);
1238 }
1239
1240 static int
1241 _is_multiop (c)
1242      int c;
1243 {
1244   switch (c)
1245     {
1246     case EQEQ:
1247     case NEQ:
1248     case LEQ:
1249     case GEQ:
1250     case LAND:
1251     case LOR:
1252     case LSH:
1253     case RSH:
1254     case OP_ASSIGN:
1255     case COND:
1256     case POWER:
1257     case PREINC:
1258     case PREDEC:
1259     case POSTINC:
1260     case POSTDEC:
1261       return 1;
1262     default:
1263       return 0;
1264     }
1265 }
1266
1267 static int
1268 _is_arithop (c)
1269      int c;
1270 {
1271   switch (c)
1272     {
1273     case EQ:
1274     case GT:
1275     case LT:
1276     case PLUS:
1277     case MINUS:
1278     case MUL:
1279     case DIV:
1280     case MOD:
1281     case NOT:
1282     case LPAR:
1283     case RPAR:
1284     case BAND:
1285     case BOR:
1286     case BXOR:
1287     case BNOT:
1288       return 1;         /* operator tokens */
1289     case QUES:
1290     case COL:
1291     case COMMA:
1292       return 1;         /* questionable */
1293     default:
1294       return 0;         /* anything else is invalid */
1295     }
1296 }
1297
1298 /* Lexical analyzer/token reader for the expression evaluator.  Reads the
1299    next token and puts its value into curtok, while advancing past it.
1300    Updates value of tp.  May also set tokval (for number) or tokstr (for
1301    string). */
1302 static void
1303 readtok ()
1304 {
1305   register char *cp, *xp;
1306   register unsigned char c, c1;
1307   register int e;
1308   struct lvalue lval;
1309
1310   /* Skip leading whitespace. */
1311   cp = tp;
1312   c = e = 0;
1313   while (cp && (c = *cp) && (cr_whitespace (c)))
1314     cp++;
1315
1316   if (c)
1317     cp++;
1318
1319   if (c == '\0')
1320     {
1321       lasttok = curtok;
1322       curtok = 0;
1323       tp = cp;
1324       return;
1325     }
1326   lasttp = tp = cp - 1;
1327
1328   if (legal_variable_starter (c))
1329     {
1330       /* variable names not preceded with a dollar sign are shell variables. */
1331       char *savecp;
1332       char *bakcp;
1333       EXPR_CONTEXT ec;
1334       int peektok;
1335
1336           bakcp = cp;
1337       while (legal_variable_char (c))
1338           {
1339 #if 1
1340                 if (legal_variable_char2 (cp) == 0)
1341                         break;
1342 #else
1343             if (c == ':')
1344                 {
1345                   if (*(cp+1) == ':')
1346                     cp++;
1347                   else
1348                         break;
1349                 }
1350 #endif
1351         c = *cp++;
1352           }
1353       c = *--cp;
1354
1355 #if defined (ARRAY_VARS)
1356       if (c == '[')
1357         {
1358           e = expr_skipsubscript (tp, cp);              /* XXX - was skipsubscript */
1359           if (cp[e] == ']')
1360             {
1361               cp += e + 1;
1362               c = *cp;
1363               e = ']';
1364             }
1365           else
1366             evalerror (bush_badsub_errmsg);
1367         }
1368 #endif /* ARRAY_VARS */
1369
1370       *cp = '\0';
1371       /* XXX - watch out for pointer aliasing issues here */
1372       if (curlval.tokstr && curlval.tokstr == tokstr)
1373         init_lvalue (&curlval);
1374
1375       FREE (tokstr);
1376       tokstr = savestring (tp);
1377       *cp = c;
1378
1379       /* XXX - make peektok part of saved token state? */
1380       SAVETOK (&ec);
1381       tokstr = (char *)NULL;    /* keep it from being freed */
1382       tp = savecp = cp;
1383       noeval = 1;
1384       curtok = STR;
1385       readtok ();
1386       peektok = curtok;
1387       if (peektok == STR)       /* free new tokstr before old one is restored */
1388         FREE (tokstr);
1389       RESTORETOK (&ec);
1390       cp = savecp;
1391
1392       /* The tests for PREINC and PREDEC aren't strictly correct, but they
1393          preserve old behavior if a construct like --x=9 is given. */
1394       if (lasttok == PREINC || lasttok == PREDEC || peektok != EQ)
1395         {
1396           lastlval = curlval;
1397           tokval = expr_streval (tokstr, e, &curlval);
1398         }
1399       else
1400         tokval = 0;
1401
1402       lasttok = curtok;
1403       curtok = STR;
1404     }
1405   else if (DIGIT(c))
1406     {
1407       while (ISALNUM (c) || c == '#' || c == '@' || c == '_')
1408         c = *cp++;
1409
1410       c = *--cp;
1411       *cp = '\0';
1412
1413       tokval = strlong (tp);
1414       *cp = c;
1415       lasttok = curtok;
1416       curtok = NUM;
1417     }
1418   else
1419     {
1420       c1 = *cp++;
1421       if ((c == EQ) && (c1 == EQ))
1422         c = EQEQ;
1423       else if ((c == NOT) && (c1 == EQ))
1424         c = NEQ;
1425       else if ((c == GT) && (c1 == EQ))
1426         c = GEQ;
1427       else if ((c == LT) && (c1 == EQ))
1428         c = LEQ;
1429       else if ((c == LT) && (c1 == LT))
1430         {
1431           if (*cp == '=')       /* a <<= b */
1432             {
1433               assigntok = LSH;
1434               c = OP_ASSIGN;
1435               cp++;
1436             }
1437           else
1438             c = LSH;
1439         }
1440       else if ((c == GT) && (c1 == GT))
1441         {
1442           if (*cp == '=')
1443             {
1444               assigntok = RSH;  /* a >>= b */
1445               c = OP_ASSIGN;
1446               cp++;
1447             }
1448           else
1449             c = RSH;
1450         }
1451       else if ((c == BAND) && (c1 == BAND))
1452         c = LAND;
1453       else if ((c == BOR) && (c1 == BOR))
1454         c = LOR;
1455       else if ((c == '*') && (c1 == '*'))
1456         c = POWER;
1457       else if ((c == '-' || c == '+') && c1 == c && curtok == STR)
1458         c = (c == '-') ? POSTDEC : POSTINC;
1459       else if ((c == '-' || c == '+') && c1 == c && curtok == NUM && (lasttok == PREINC || lasttok == PREDEC))
1460         {
1461           /* This catches something like --FOO++ */
1462           if (c == '-')
1463             evalerror ("--: assignment requires lvalue");
1464           else
1465             evalerror ("++: assignment requires lvalue");
1466         }
1467       else if ((c == '-' || c == '+') && c1 == c)
1468         {
1469           /* Quickly scan forward to see if this is followed by optional
1470              whitespace and an identifier. */
1471           xp = cp;
1472           while (xp && *xp && cr_whitespace (*xp))
1473             xp++;
1474           if (legal_variable_starter ((unsigned char)*xp))
1475             c = (c == '-') ? PREDEC : PREINC;
1476           else
1477             /* Could force parsing as preinc or predec and throw an error */
1478 #if 0
1479             {
1480               /* Posix says unary plus and minus have higher priority than
1481                  preinc and predec. */
1482               /* This catches something like --4++ */
1483               if (c == '-')
1484                 evalerror ("--: assignment requires lvalue");
1485               else
1486                 evalerror ("++: assignment requires lvalue");
1487             }
1488 #else
1489             cp--;       /* not preinc or predec, so unget the character */
1490 #endif
1491         }
1492       else if (c1 == EQ && member (c, "*/%+-&^|"))
1493         {
1494           assigntok = c;        /* a OP= b */
1495           c = OP_ASSIGN;
1496         }
1497       else if (_is_arithop (c) == 0)
1498         {
1499           cp--;
1500           /* use curtok, since it hasn't been copied to lasttok yet */
1501           if (curtok == 0 || _is_arithop (curtok) || _is_multiop (curtok))
1502             evalerror (_("syntax error: operand expected"));
1503           else
1504             evalerror (_("syntax error: invalid arithmetic operator"));
1505         }
1506       else
1507         cp--;                   /* `unget' the character */
1508
1509       /* Should check here to make sure that the current character is one
1510          of the recognized operators and flag an error if not.  Could create
1511          a character map the first time through and check it on subsequent
1512          calls. */
1513       lasttok = curtok;
1514       curtok = c;
1515     }
1516   tp = cp;
1517 }
1518
1519 static void
1520 evalerror (msg)
1521      const char *msg;
1522 {
1523   char *name, *t;
1524
1525   name = this_command_name;
1526   for (t = expression; t && whitespace (*t); t++)
1527     ;
1528   internal_error (_("%s%s%s: %s (error token is \"%s\")"),
1529                    name ? name : "", name ? ": " : "",
1530                    t ? t : "", msg, (lasttp && *lasttp) ? lasttp : "");
1531   sh_longjmp (evalbuf, 1);
1532 }
1533
1534 /* Convert a string to an intmax_t integer, with an arbitrary base.
1535    0nnn -> base 8
1536    0[Xx]nn -> base 16
1537    Anything else: [base#]number (this is implemented to match ksh93)
1538
1539    Base may be >=2 and <=64.  If base is <= 36, the numbers are drawn
1540    from [0-9][a-zA-Z], and lowercase and uppercase letters may be used
1541    interchangeably.  If base is > 36 and <= 64, the numbers are drawn
1542    from [0-9][a-z][A-Z]_@ (a = 10, z = 35, A = 36, Z = 61, @ = 62, _ = 63 --
1543    you get the picture). */
1544
1545 #define VALID_NUMCHAR(c)        (ISALNUM(c) || ((c) == '_') || ((c) == '@'))
1546
1547 static intmax_t
1548 strlong (num)
1549      char *num;
1550 {
1551   register char *s;
1552   register unsigned char c;
1553   int base, foundbase;
1554   intmax_t val;
1555
1556   s = num;
1557
1558   base = 10;
1559   foundbase = 0;
1560   if (*s == '0')
1561     {
1562       s++;
1563
1564       if (*s == '\0')
1565         return 0;
1566
1567        /* Base 16? */
1568       if (*s == 'x' || *s == 'X')
1569         {
1570           base = 16;
1571           s++;
1572         }
1573       else
1574         base = 8;
1575       foundbase++;
1576     }
1577
1578   val = 0;
1579   for (c = *s++; c; c = *s++)
1580     {
1581       if (c == '#')
1582         {
1583           if (foundbase)
1584             evalerror (_("invalid number"));
1585
1586           /* Illegal base specifications raise an evaluation error. */
1587           if (val < 2 || val > 64)
1588             evalerror (_("invalid arithmetic base"));
1589
1590           base = val;
1591           val = 0;
1592           foundbase++;
1593
1594           /* Make sure a base# is followed by a character that can compose a
1595              valid integer constant. Jeremy Townshend <jeremy.townshend@gmail.com> */
1596           if (VALID_NUMCHAR (*s) == 0)
1597             evalerror (_("invalid integer constant"));
1598         }
1599       else if (VALID_NUMCHAR (c))
1600         {
1601           if (DIGIT(c))
1602             c = TODIGIT(c);
1603           else if (c >= 'a' && c <= 'z')
1604             c -= 'a' - 10;
1605           else if (c >= 'A' && c <= 'Z')
1606             c -= 'A' - ((base <= 36) ? 10 : 36);
1607           else if (c == '@')
1608             c = 62;
1609           else if (c == '_')
1610             c = 63;
1611
1612           if (c >= base)
1613             evalerror (_("value too great for base"));
1614
1615           val = (val * base) + c;
1616         }
1617       else
1618         break;
1619     }
1620
1621   return (val);
1622 }
1623
1624 #if defined (EXPR_TEST)
1625 void *
1626 xmalloc (n)
1627      int n;
1628 {
1629   return (malloc (n));
1630 }
1631
1632 void *
1633 xrealloc (s, n)
1634      char *s;
1635      int n;
1636 {
1637   return (realloc (s, n));
1638 }
1639
1640 SHELL_VAR *find_variable () { return 0;}
1641 SHELL_VAR *bind_variable () { return 0; }
1642
1643 char *get_string_value () { return 0; }
1644
1645 procenv_t top_level;
1646
1647 main (argc, argv)
1648      int argc;
1649      char **argv;
1650 {
1651   register int i;
1652   intmax_t v;
1653   int expok;
1654
1655   if (setjmp (top_level))
1656     exit (0);
1657
1658   for (i = 1; i < argc; i++)
1659     {
1660       v = evalexp (argv[i], 0, &expok);
1661       if (expok == 0)
1662         fprintf (stderr, _("%s: expression error\n"), argv[i]);
1663       else
1664         printf ("'%s' -> %ld\n", argv[i], v);
1665     }
1666   exit (0);
1667 }
1668
1669 int
1670 builtin_error (format, arg1, arg2, arg3, arg4, arg5)
1671      char *format;
1672 {
1673   fprintf (stderr, "expr: ");
1674   fprintf (stderr, format, arg1, arg2, arg3, arg4, arg5);
1675   fprintf (stderr, "\n");
1676   return 0;
1677 }
1678
1679 char *
1680 itos (n)
1681      intmax_t n;
1682 {
1683   return ("42");
1684 }
1685
1686 #endif /* EXPR_TEST */
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