source: vendor/bash/3.1-p17/expr.c@ 3275

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1/* expr.c -- arithmetic expression evaluation. */
2
3/* Copyright (C) 1990-2004 Free Software Foundation, Inc.
4
5 This file is part of GNU Bash, the Bourne Again SHell.
6
7 Bash is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
10 any later version.
11
12 Bash is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
15 License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with Bash; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA. */
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 "++id", "--id" [pre-increment and pre-decrement]
30 "-", "+" [(unary operators)]
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 bash, 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@ins.CWRU.Edu
67*/
68
69#include "config.h"
70
71#include <stdio.h>
72#include "bashansi.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 "bashintl.h"
83
84#include "shell.h"
85
86/* Because of the $((...)) construct, expressions may include newlines.
87 Here is a macro which accepts newlines, tabs and spaces as whitespace. */
88#define cr_whitespace(c) (whitespace(c) || ((c) == '\n'))
89
90/* Size be which the expression stack grows when neccessary. */
91#define EXPR_STACK_GROW_SIZE 10
92
93/* Maximum amount of recursion allowed. This prevents a non-integer
94 variable such as "num=num+2" from infinitely adding to itself when
95 "let num=num+2" is given. */
96#define MAX_EXPR_RECURSION_LEVEL 1024
97
98/* The Tokens. Singing "The Lion Sleeps Tonight". */
99
100#define EQEQ 1 /* "==" */
101#define NEQ 2 /* "!=" */
102#define LEQ 3 /* "<=" */
103#define GEQ 4 /* ">=" */
104#define STR 5 /* string */
105#define NUM 6 /* number */
106#define LAND 7 /* "&&" Logical AND */
107#define LOR 8 /* "||" Logical OR */
108#define LSH 9 /* "<<" Left SHift */
109#define RSH 10 /* ">>" Right SHift */
110#define OP_ASSIGN 11 /* op= expassign as in Posix.2 */
111#define COND 12 /* exp1 ? exp2 : exp3 */
112#define POWER 13 /* exp1**exp2 */
113#define PREINC 14 /* ++var */
114#define PREDEC 15 /* --var */
115#define POSTINC 16 /* var++ */
116#define POSTDEC 17 /* var-- */
117#define EQ '='
118#define GT '>'
119#define LT '<'
120#define PLUS '+'
121#define MINUS '-'
122#define MUL '*'
123#define DIV '/'
124#define MOD '%'
125#define NOT '!'
126#define LPAR '('
127#define RPAR ')'
128#define BAND '&' /* Bitwise AND */
129#define BOR '|' /* Bitwise OR. */
130#define BXOR '^' /* Bitwise eXclusive OR. */
131#define BNOT '~' /* Bitwise NOT; Two's complement. */
132#define QUES '?'
133#define COL ':'
134#define COMMA ','
135
136/* This should be the function corresponding to the operator with the
137 highest precedence. */
138#define EXP_HIGHEST expcomma
139
140static char *expression; /* The current expression */
141static char *tp; /* token lexical position */
142static char *lasttp; /* pointer to last token position */
143static int curtok; /* the current token */
144static int lasttok; /* the previous token */
145static int assigntok; /* the OP in OP= */
146static char *tokstr; /* current token string */
147static intmax_t tokval; /* current token value */
148static int noeval; /* set to 1 if no assignment to be done */
149static procenv_t evalbuf;
150
151static void readtok __P((void)); /* lexical analyzer */
152
153static intmax_t expr_streval __P((char *, int));
154static intmax_t strlong __P((char *));
155static void evalerror __P((char *));
156
157static void pushexp __P((void));
158static void popexp __P((void));
159static void expr_unwind __P((void));
160static void expr_bind_variable __P((char *, char *));
161
162static intmax_t subexpr __P((char *));
163
164static intmax_t expcomma __P((void));
165static intmax_t expassign __P((void));
166static intmax_t expcond __P((void));
167static intmax_t explor __P((void));
168static intmax_t expland __P((void));
169static intmax_t expbor __P((void));
170static intmax_t expbxor __P((void));
171static intmax_t expband __P((void));
172static intmax_t exp5 __P((void));
173static intmax_t exp4 __P((void));
174static intmax_t expshift __P((void));
175static intmax_t exp3 __P((void));
176static intmax_t exp2 __P((void));
177static intmax_t exppower __P((void));
178static intmax_t exp1 __P((void));
179static intmax_t exp0 __P((void));
180
181/* A structure defining a single expression context. */
182typedef struct {
183 int curtok, lasttok;
184 char *expression, *tp, *lasttp;
185 intmax_t tokval;
186 char *tokstr;
187 int noeval;
188} EXPR_CONTEXT;
189
190#ifdef INCLUDE_UNUSED
191/* Not used yet. */
192typedef struct {
193 char *tokstr;
194 intmax_t tokval;
195} LVALUE;
196#endif
197
198/* Global var which contains the stack of expression contexts. */
199static EXPR_CONTEXT **expr_stack;
200static int expr_depth; /* Location in the stack. */
201static int expr_stack_size; /* Number of slots already allocated. */
202
203extern char *this_command_name;
204extern int unbound_vars_is_error;
205
206#if defined (ARRAY_VARS)
207extern char *bash_badsub_errmsg;
208#endif
209
210#define SAVETOK(X) \
211 do { \
212 (X)->curtok = curtok; \
213 (X)->lasttok = lasttok; \
214 (X)->tp = tp; \
215 (X)->lasttp = lasttp; \
216 (X)->tokval = tokval; \
217 (X)->tokstr = tokstr; \
218 (X)->noeval = noeval; \
219 } while (0)
220
221#define RESTORETOK(X) \
222 do { \
223 curtok = (X)->curtok; \
224 lasttok = (X)->lasttok; \
225 tp = (X)->tp; \
226 lasttp = (X)->lasttp; \
227 tokval = (X)->tokval; \
228 tokstr = (X)->tokstr; \
229 noeval = (X)->noeval; \
230 } while (0)
231
232/* Push and save away the contents of the globals describing the
233 current expression context. */
234static void
235pushexp ()
236{
237 EXPR_CONTEXT *context;
238
239 if (expr_depth >= MAX_EXPR_RECURSION_LEVEL)
240 evalerror (_("expression recursion level exceeded"));
241
242 if (expr_depth >= expr_stack_size)
243 {
244 expr_stack_size += EXPR_STACK_GROW_SIZE;
245 expr_stack = (EXPR_CONTEXT **)xrealloc (expr_stack, expr_stack_size * sizeof (EXPR_CONTEXT *));
246 }
247
248 context = (EXPR_CONTEXT *)xmalloc (sizeof (EXPR_CONTEXT));
249
250 context->expression = expression;
251 SAVETOK(context);
252
253 expr_stack[expr_depth++] = context;
254}
255
256/* Pop the the contents of the expression context stack into the
257 globals describing the current expression context. */
258static void
259popexp ()
260{
261 EXPR_CONTEXT *context;
262
263 if (expr_depth == 0)
264 evalerror (_("recursion stack underflow"));
265
266 context = expr_stack[--expr_depth];
267
268 expression = context->expression;
269 RESTORETOK (context);
270
271 free (context);
272}
273
274static void
275expr_unwind ()
276{
277 while (--expr_depth > 0)
278 {
279 if (expr_stack[expr_depth]->tokstr)
280 free (expr_stack[expr_depth]->tokstr);
281
282 if (expr_stack[expr_depth]->expression)
283 free (expr_stack[expr_depth]->expression);
284
285 free (expr_stack[expr_depth]);
286 }
287 free (expr_stack[expr_depth]); /* free the allocated EXPR_CONTEXT */
288}
289
290static void
291expr_bind_variable (lhs, rhs)
292 char *lhs, *rhs;
293{
294 (void)bind_int_variable (lhs, rhs);
295 stupidly_hack_special_variables (lhs);
296}
297
298/* Evaluate EXPR, and return the arithmetic result. If VALIDP is
299 non-null, a zero is stored into the location to which it points
300 if the expression is invalid, non-zero otherwise. If a non-zero
301 value is returned in *VALIDP, the return value of evalexp() may
302 be used.
303
304 The `while' loop after the longjmp is caught relies on the above
305 implementation of pushexp and popexp leaving in expr_stack[0] the
306 values that the variables had when the program started. That is,
307 the first things saved are the initial values of the variables that
308 were assigned at program startup or by the compiler. Therefore, it is
309 safe to let the loop terminate when expr_depth == 0, without freeing up
310 any of the expr_depth[0] stuff. */
311intmax_t
312evalexp (expr, validp)
313 char *expr;
314 int *validp;
315{
316 intmax_t val;
317 int c;
318 procenv_t oevalbuf;
319
320 val = 0;
321
322 FASTCOPY (evalbuf, oevalbuf, sizeof (evalbuf));
323
324 c = setjmp (evalbuf);
325
326 if (c)
327 {
328 FREE (tokstr);
329 FREE (expression);
330 tokstr = expression = (char *)NULL;
331
332 expr_unwind ();
333
334 if (validp)
335 *validp = 0;
336 return (0);
337 }
338
339 val = subexpr (expr);
340
341 if (validp)
342 *validp = 1;
343
344 FASTCOPY (oevalbuf, evalbuf, sizeof (evalbuf));
345
346 return (val);
347}
348
349static intmax_t
350subexpr (expr)
351 char *expr;
352{
353 intmax_t val;
354 char *p;
355
356 for (p = expr; p && *p && cr_whitespace (*p); p++)
357 ;
358
359 if (p == NULL || *p == '\0')
360 return (0);
361
362 pushexp ();
363 curtok = lasttok = 0;
364 expression = savestring (expr);
365 tp = expression;
366
367 tokstr = (char *)NULL;
368 tokval = 0;
369
370 readtok ();
371
372 val = EXP_HIGHEST ();
373
374 if (curtok != 0)
375 evalerror (_("syntax error in expression"));
376
377 FREE (tokstr);
378 FREE (expression);
379
380 popexp ();
381
382 return val;
383}
384
385static intmax_t
386expcomma ()
387{
388 register intmax_t value;
389
390 value = expassign ();
391 while (curtok == COMMA)
392 {
393 readtok ();
394 value = expassign ();
395 }
396
397 return value;
398}
399
400static intmax_t
401expassign ()
402{
403 register intmax_t value;
404 char *lhs, *rhs;
405
406 value = expcond ();
407 if (curtok == EQ || curtok == OP_ASSIGN)
408 {
409 int special, op;
410 intmax_t lvalue;
411
412 special = curtok == OP_ASSIGN;
413
414 if (lasttok != STR)
415 evalerror (_("attempted assignment to non-variable"));
416
417 if (special)
418 {
419 op = assigntok; /* a OP= b */
420 lvalue = value;
421 }
422
423 lhs = savestring (tokstr);
424 readtok ();
425 value = expassign ();
426
427 if (special)
428 {
429 switch (op)
430 {
431 case MUL:
432 lvalue *= value;
433 break;
434 case DIV:
435 if (value == 0)
436 evalerror (_("division by 0"));
437 lvalue /= value;
438 break;
439 case MOD:
440 if (value == 0)
441 evalerror (_("division by 0"));
442 lvalue %= value;
443 break;
444 case PLUS:
445 lvalue += value;
446 break;
447 case MINUS:
448 lvalue -= value;
449 break;
450 case LSH:
451 lvalue <<= value;
452 break;
453 case RSH:
454 lvalue >>= value;
455 break;
456 case BAND:
457 lvalue &= value;
458 break;
459 case BOR:
460 lvalue |= value;
461 break;
462 case BXOR:
463 lvalue ^= value;
464 break;
465 default:
466 free (lhs);
467 evalerror (_("bug: bad expassign token"));
468 break;
469 }
470 value = lvalue;
471 }
472
473 rhs = itos (value);
474 if (noeval == 0)
475 expr_bind_variable (lhs, rhs);
476 free (rhs);
477 free (lhs);
478 FREE (tokstr);
479 tokstr = (char *)NULL; /* For freeing on errors. */
480 }
481 return (value);
482}
483
484/* Conditional expression (expr?expr:expr) */
485static intmax_t
486expcond ()
487{
488 intmax_t cval, val1, val2, rval;
489 int set_noeval;
490
491 set_noeval = 0;
492 rval = cval = explor ();
493 if (curtok == QUES) /* found conditional expr */
494 {
495 readtok ();
496 if (curtok == 0 || curtok == COL)
497 evalerror (_("expression expected"));
498 if (cval == 0)
499 {
500 set_noeval = 1;
501 noeval++;
502 }
503
504 val1 = EXP_HIGHEST ();
505
506 if (set_noeval)
507 noeval--;
508 if (curtok != COL)
509 evalerror (_("`:' expected for conditional expression"));
510 readtok ();
511 if (curtok == 0)
512 evalerror (_("expression expected"));
513 set_noeval = 0;
514 if (cval)
515 {
516 set_noeval = 1;
517 noeval++;
518 }
519 val2 = explor ();
520 if (set_noeval)
521 noeval--;
522 rval = cval ? val1 : val2;
523 lasttok = COND;
524 }
525 return rval;
526}
527
528/* Logical OR. */
529static intmax_t
530explor ()
531{
532 register intmax_t val1, val2;
533 int set_noeval;
534
535 val1 = expland ();
536
537 while (curtok == LOR)
538 {
539 set_noeval = 0;
540 if (val1 != 0)
541 {
542 noeval++;
543 set_noeval = 1;
544 }
545 readtok ();
546 val2 = expland ();
547 if (set_noeval)
548 noeval--;
549 val1 = val1 || val2;
550 lasttok = LOR;
551 }
552
553 return (val1);
554}
555
556/* Logical AND. */
557static intmax_t
558expland ()
559{
560 register intmax_t val1, val2;
561 int set_noeval;
562
563 val1 = expbor ();
564
565 while (curtok == LAND)
566 {
567 set_noeval = 0;
568 if (val1 == 0)
569 {
570 set_noeval = 1;
571 noeval++;
572 }
573 readtok ();
574 val2 = expbor ();
575 if (set_noeval)
576 noeval--;
577 val1 = val1 && val2;
578 lasttok = LAND;
579 }
580
581 return (val1);
582}
583
584/* Bitwise OR. */
585static intmax_t
586expbor ()
587{
588 register intmax_t val1, val2;
589
590 val1 = expbxor ();
591
592 while (curtok == BOR)
593 {
594 readtok ();
595 val2 = expbxor ();
596 val1 = val1 | val2;
597 }
598
599 return (val1);
600}
601
602/* Bitwise XOR. */
603static intmax_t
604expbxor ()
605{
606 register intmax_t val1, val2;
607
608 val1 = expband ();
609
610 while (curtok == BXOR)
611 {
612 readtok ();
613 val2 = expband ();
614 val1 = val1 ^ val2;
615 }
616
617 return (val1);
618}
619
620/* Bitwise AND. */
621static intmax_t
622expband ()
623{
624 register intmax_t val1, val2;
625
626 val1 = exp5 ();
627
628 while (curtok == BAND)
629 {
630 readtok ();
631 val2 = exp5 ();
632 val1 = val1 & val2;
633 }
634
635 return (val1);
636}
637
638static intmax_t
639exp5 ()
640{
641 register intmax_t val1, val2;
642
643 val1 = exp4 ();
644
645 while ((curtok == EQEQ) || (curtok == NEQ))
646 {
647 int op = curtok;
648
649 readtok ();
650 val2 = exp4 ();
651 if (op == EQEQ)
652 val1 = (val1 == val2);
653 else if (op == NEQ)
654 val1 = (val1 != val2);
655 }
656 return (val1);
657}
658
659static intmax_t
660exp4 ()
661{
662 register intmax_t val1, val2;
663
664 val1 = expshift ();
665 while ((curtok == LEQ) ||
666 (curtok == GEQ) ||
667 (curtok == LT) ||
668 (curtok == GT))
669 {
670 int op = curtok;
671
672 readtok ();
673 val2 = expshift ();
674
675 if (op == LEQ)
676 val1 = val1 <= val2;
677 else if (op == GEQ)
678 val1 = val1 >= val2;
679 else if (op == LT)
680 val1 = val1 < val2;
681 else /* (op == GT) */
682 val1 = val1 > val2;
683 }
684 return (val1);
685}
686
687/* Left and right shifts. */
688static intmax_t
689expshift ()
690{
691 register intmax_t val1, val2;
692
693 val1 = exp3 ();
694
695 while ((curtok == LSH) || (curtok == RSH))
696 {
697 int op = curtok;
698
699 readtok ();
700 val2 = exp3 ();
701
702 if (op == LSH)
703 val1 = val1 << val2;
704 else
705 val1 = val1 >> val2;
706 }
707
708 return (val1);
709}
710
711static intmax_t
712exp3 ()
713{
714 register intmax_t val1, val2;
715
716 val1 = exp2 ();
717
718 while ((curtok == PLUS) || (curtok == MINUS))
719 {
720 int op = curtok;
721
722 readtok ();
723 val2 = exp2 ();
724
725 if (op == PLUS)
726 val1 += val2;
727 else if (op == MINUS)
728 val1 -= val2;
729 }
730 return (val1);
731}
732
733static intmax_t
734exp2 ()
735{
736 register intmax_t val1, val2;
737
738 val1 = exppower ();
739
740 while ((curtok == MUL) ||
741 (curtok == DIV) ||
742 (curtok == MOD))
743 {
744 int op = curtok;
745
746 readtok ();
747
748 val2 = exppower ();
749
750 if (((op == DIV) || (op == MOD)) && (val2 == 0))
751 evalerror (_("division by 0"));
752
753 if (op == MUL)
754 val1 *= val2;
755 else if (op == DIV)
756 val1 /= val2;
757 else if (op == MOD)
758 val1 %= val2;
759 }
760 return (val1);
761}
762
763static intmax_t
764exppower ()
765{
766 register intmax_t val1, val2, c;
767
768 val1 = exp1 ();
769 while (curtok == POWER)
770 {
771 readtok ();
772 val2 = exppower (); /* exponentiation is right-associative */
773 if (val2 == 0)
774 return (1);
775 if (val2 < 0)
776 evalerror (_("exponent less than 0"));
777 for (c = 1; val2--; c *= val1)
778 ;
779 val1 = c;
780 }
781 return (val1);
782}
783
784static intmax_t
785exp1 ()
786{
787 register intmax_t val;
788
789 if (curtok == NOT)
790 {
791 readtok ();
792 val = !exp1 ();
793 }
794 else if (curtok == BNOT)
795 {
796 readtok ();
797 val = ~exp1 ();
798 }
799 else
800 val = exp0 ();
801
802 return (val);
803}
804
805static intmax_t
806exp0 ()
807{
808 register intmax_t val = 0, v2;
809 char *vincdec;
810 int stok;
811 EXPR_CONTEXT ec;
812
813 /* XXX - might need additional logic here to decide whether or not
814 pre-increment or pre-decrement is legal at this point. */
815 if (curtok == PREINC || curtok == PREDEC)
816 {
817 stok = lasttok = curtok;
818 readtok ();
819 if (curtok != STR)
820 /* readtok() catches this */
821 evalerror (_("identifier expected after pre-increment or pre-decrement"));
822
823 v2 = tokval + ((stok == PREINC) ? 1 : -1);
824 vincdec = itos (v2);
825 if (noeval == 0)
826 expr_bind_variable (tokstr, vincdec);
827 free (vincdec);
828 val = v2;
829
830 curtok = NUM; /* make sure --x=7 is flagged as an error */
831 readtok ();
832 }
833 else if (curtok == MINUS)
834 {
835 readtok ();
836 val = - exp0 ();
837 }
838 else if (curtok == PLUS)
839 {
840 readtok ();
841 val = exp0 ();
842 }
843 else if (curtok == LPAR)
844 {
845 readtok ();
846 val = EXP_HIGHEST ();
847
848 if (curtok != RPAR) /* ( */
849 evalerror (_("missing `)'"));
850
851 /* Skip over closing paren. */
852 readtok ();
853 }
854 else if ((curtok == NUM) || (curtok == STR))
855 {
856 val = tokval;
857 if (curtok == STR)
858 {
859 SAVETOK (&ec);
860 tokstr = (char *)NULL; /* keep it from being freed */
861 noeval = 1;
862 readtok ();
863 stok = curtok;
864
865 /* post-increment or post-decrement */
866 if (stok == POSTINC || stok == POSTDEC)
867 {
868 /* restore certain portions of EC */
869 tokstr = ec.tokstr;
870 noeval = ec.noeval;
871 lasttok = STR; /* ec.curtok */
872
873 v2 = val + ((stok == POSTINC) ? 1 : -1);
874 vincdec = itos (v2);
875 if (noeval == 0)
876 expr_bind_variable (tokstr, vincdec);
877 free (vincdec);
878 curtok = NUM; /* make sure x++=7 is flagged as an error */
879 }
880 else
881 {
882 if (stok == STR) /* free new tokstr before old one is restored */
883 FREE (tokstr);
884 RESTORETOK (&ec);
885 }
886
887 }
888
889 readtok ();
890 }
891 else
892 evalerror (_("syntax error: operand expected"));
893
894 return (val);
895}
896
897static intmax_t
898expr_streval (tok, e)
899 char *tok;
900 int e;
901{
902 SHELL_VAR *v;
903 char *value;
904 intmax_t tval;
905
906 /* [[[[[ */
907#if defined (ARRAY_VARS)
908 v = (e == ']') ? array_variable_part (tok, (char **)0, (int *)0) : find_variable (tok);
909#else
910 v = find_variable (tok);
911#endif
912
913 if ((v == 0 || invisible_p (v)) && unbound_vars_is_error)
914 {
915#if defined (ARRAY_VARS)
916 value = (e == ']') ? array_variable_name (tok, (char **)0, (int *)0) : tok;
917#else
918 value = tok;
919#endif
920
921 err_unboundvar (value);
922
923#if defined (ARRAY_VARS)
924 if (e == ']')
925 FREE (value); /* array_variable_name returns new memory */
926#endif
927
928 if (interactive_shell)
929 {
930 expr_unwind ();
931 jump_to_top_level (DISCARD);
932 }
933 else
934 jump_to_top_level (FORCE_EOF);
935 }
936
937#if defined (ARRAY_VARS)
938 /* Second argument of 0 to get_array_value means that we don't allow
939 references like array[@]. In this case, get_array_value is just
940 like get_variable_value in that it does not return newly-allocated
941 memory or quote the results. */
942 value = (e == ']') ? get_array_value (tok, 0, (int *)NULL) : get_variable_value (v);
943#else
944 value = get_variable_value (v);
945#endif
946
947 tval = (value && *value) ? subexpr (value) : 0;
948
949 return (tval);
950}
951
952/* Lexical analyzer/token reader for the expression evaluator. Reads the
953 next token and puts its value into curtok, while advancing past it.
954 Updates value of tp. May also set tokval (for number) or tokstr (for
955 string). */
956static void
957readtok ()
958{
959 register char *cp, *xp;
960 register unsigned char c, c1;
961 register int e;
962
963 /* Skip leading whitespace. */
964 cp = tp;
965 c = e = 0;
966 while (cp && (c = *cp) && (cr_whitespace (c)))
967 cp++;
968
969 if (c)
970 cp++;
971
972 lasttp = tp = cp - 1;
973
974 if (c == '\0')
975 {
976 lasttok = curtok;
977 curtok = 0;
978 tp = cp;
979 return;
980 }
981
982 if (legal_variable_starter (c))
983 {
984 /* variable names not preceded with a dollar sign are shell variables. */
985 char *savecp;
986 EXPR_CONTEXT ec;
987 int peektok;
988
989 while (legal_variable_char (c))
990 c = *cp++;
991
992 c = *--cp;
993
994#if defined (ARRAY_VARS)
995 if (c == '[')
996 {
997 e = skipsubscript (cp, 0);
998 if (cp[e] == ']')
999 {
1000 cp += e + 1;
1001 c = *cp;
1002 e = ']';
1003 }
1004 else
1005 evalerror (bash_badsub_errmsg);
1006 }
1007#endif /* ARRAY_VARS */
1008
1009 *cp = '\0';
1010 FREE (tokstr);
1011 tokstr = savestring (tp);
1012 *cp = c;
1013
1014 SAVETOK (&ec);
1015 tokstr = (char *)NULL; /* keep it from being freed */
1016 tp = savecp = cp;
1017 noeval = 1;
1018 curtok = STR;
1019 readtok ();
1020 peektok = curtok;
1021 if (peektok == STR) /* free new tokstr before old one is restored */
1022 FREE (tokstr);
1023 RESTORETOK (&ec);
1024 cp = savecp;
1025
1026 /* The tests for PREINC and PREDEC aren't strictly correct, but they
1027 preserve old behavior if a construct like --x=9 is given. */
1028 if (lasttok == PREINC || lasttok == PREDEC || peektok != EQ)
1029 tokval = expr_streval (tokstr, e);
1030 else
1031 tokval = 0;
1032
1033 lasttok = curtok;
1034 curtok = STR;
1035 }
1036 else if (DIGIT(c))
1037 {
1038 while (ISALNUM (c) || c == '#' || c == '@' || c == '_')
1039 c = *cp++;
1040
1041 c = *--cp;
1042 *cp = '\0';
1043
1044 tokval = strlong (tp);
1045 *cp = c;
1046 lasttok = curtok;
1047 curtok = NUM;
1048 }
1049 else
1050 {
1051 c1 = *cp++;
1052 if ((c == EQ) && (c1 == EQ))
1053 c = EQEQ;
1054 else if ((c == NOT) && (c1 == EQ))
1055 c = NEQ;
1056 else if ((c == GT) && (c1 == EQ))
1057 c = GEQ;
1058 else if ((c == LT) && (c1 == EQ))
1059 c = LEQ;
1060 else if ((c == LT) && (c1 == LT))
1061 {
1062 if (*cp == '=') /* a <<= b */
1063 {
1064 assigntok = LSH;
1065 c = OP_ASSIGN;
1066 cp++;
1067 }
1068 else
1069 c = LSH;
1070 }
1071 else if ((c == GT) && (c1 == GT))
1072 {
1073 if (*cp == '=')
1074 {
1075 assigntok = RSH; /* a >>= b */
1076 c = OP_ASSIGN;
1077 cp++;
1078 }
1079 else
1080 c = RSH;
1081 }
1082 else if ((c == BAND) && (c1 == BAND))
1083 c = LAND;
1084 else if ((c == BOR) && (c1 == BOR))
1085 c = LOR;
1086 else if ((c == '*') && (c1 == '*'))
1087 c = POWER;
1088 else if ((c == '-' || c == '+') && c1 == c && curtok == STR)
1089 c = (c == '-') ? POSTDEC : POSTINC;
1090 else if ((c == '-' || c == '+') && c1 == c)
1091 {
1092 /* Quickly scan forward to see if this is followed by optional
1093 whitespace and an identifier. */
1094 xp = cp;
1095 while (xp && *xp && cr_whitespace (*xp))
1096 xp++;
1097 if (legal_variable_starter ((unsigned char)*xp))
1098 c = (c == '-') ? PREDEC : PREINC;
1099 else
1100 cp--; /* not preinc or predec, so unget the character */
1101 }
1102 else if (c1 == EQ && member (c, "*/%+-&^|"))
1103 {
1104 assigntok = c; /* a OP= b */
1105 c = OP_ASSIGN;
1106 }
1107 else
1108 cp--; /* `unget' the character */
1109 lasttok = curtok;
1110 curtok = c;
1111 }
1112 tp = cp;
1113}
1114
1115static void
1116evalerror (msg)
1117 char *msg;
1118{
1119 char *name, *t;
1120
1121 name = this_command_name;
1122 for (t = expression; whitespace (*t); t++)
1123 ;
1124 internal_error ("%s%s%s: %s (error token is \"%s\")",
1125 name ? name : "", name ? ": " : "", t,
1126 msg, (lasttp && *lasttp) ? lasttp : "");
1127 longjmp (evalbuf, 1);
1128}
1129
1130/* Convert a string to an intmax_t integer, with an arbitrary base.
1131 0nnn -> base 8
1132 0[Xx]nn -> base 16
1133 Anything else: [base#]number (this is implemented to match ksh93)
1134
1135 Base may be >=2 and <=64. If base is <= 36, the numbers are drawn
1136 from [0-9][a-zA-Z], and lowercase and uppercase letters may be used
1137 interchangably. If base is > 36 and <= 64, the numbers are drawn
1138 from [0-9][a-z][A-Z]_@ (a = 10, z = 35, A = 36, Z = 61, @ = 62, _ = 63 --
1139 you get the picture). */
1140
1141static intmax_t
1142strlong (num)
1143 char *num;
1144{
1145 register char *s;
1146 register unsigned char c;
1147 int base, foundbase;
1148 intmax_t val;
1149
1150 s = num;
1151
1152 base = 10;
1153 foundbase = 0;
1154 if (*s == '0')
1155 {
1156 s++;
1157
1158 if (*s == '\0')
1159 return 0;
1160
1161 /* Base 16? */
1162 if (*s == 'x' || *s == 'X')
1163 {
1164 base = 16;
1165 s++;
1166 }
1167 else
1168 base = 8;
1169 foundbase++;
1170 }
1171
1172 val = 0;
1173 for (c = *s++; c; c = *s++)
1174 {
1175 if (c == '#')
1176 {
1177 if (foundbase)
1178 evalerror (_("invalid number"));
1179
1180 /* Illegal base specifications raise an evaluation error. */
1181 if (val < 2 || val > 64)
1182 evalerror (_("invalid arithmetic base"));
1183
1184 base = val;
1185 val = 0;
1186 foundbase++;
1187 }
1188 else if (ISALNUM(c) || (c == '_') || (c == '@'))
1189 {
1190 if (DIGIT(c))
1191 c = TODIGIT(c);
1192 else if (c >= 'a' && c <= 'z')
1193 c -= 'a' - 10;
1194 else if (c >= 'A' && c <= 'Z')
1195 c -= 'A' - ((base <= 36) ? 10 : 36);
1196 else if (c == '@')
1197 c = 62;
1198 else if (c == '_')
1199 c = 63;
1200
1201 if (c >= base)
1202 evalerror (_("value too great for base"));
1203
1204 val = (val * base) + c;
1205 }
1206 else
1207 break;
1208 }
1209
1210 return (val);
1211}
1212
1213#if defined (EXPR_TEST)
1214void *
1215xmalloc (n)
1216 int n;
1217{
1218 return (malloc (n));
1219}
1220
1221void *
1222xrealloc (s, n)
1223 char *s;
1224 int n;
1225{
1226 return (realloc (s, n));
1227}
1228
1229SHELL_VAR *find_variable () { return 0;}
1230SHELL_VAR *bind_variable () { return 0; }
1231
1232char *get_string_value () { return 0; }
1233
1234procenv_t top_level;
1235
1236main (argc, argv)
1237 int argc;
1238 char **argv;
1239{
1240 register int i;
1241 intmax_t v;
1242 int expok;
1243
1244 if (setjmp (top_level))
1245 exit (0);
1246
1247 for (i = 1; i < argc; i++)
1248 {
1249 v = evalexp (argv[i], &expok);
1250 if (expok == 0)
1251 fprintf (stderr, "%s: expression error\n", argv[i]);
1252 else
1253 printf ("'%s' -> %ld\n", argv[i], v);
1254 }
1255 exit (0);
1256}
1257
1258int
1259builtin_error (format, arg1, arg2, arg3, arg4, arg5)
1260 char *format;
1261{
1262 fprintf (stderr, "expr: ");
1263 fprintf (stderr, format, arg1, arg2, arg3, arg4, arg5);
1264 fprintf (stderr, "\n");
1265 return 0;
1266}
1267
1268char *
1269itos (n)
1270 intmax_t n;
1271{
1272 return ("42");
1273}
1274
1275#endif /* EXPR_TEST */
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