-
Notifications
You must be signed in to change notification settings - Fork 1
/
expr.c
1573 lines (1343 loc) · 32.2 KB
/
expr.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/* expr.c -- arithmetic expression evaluation. */
/* Copyright (C) 1990-2015 Free Software Foundation, Inc.
This file is part of GNU Bash, the Bourne Again SHell.
Bash is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Bash is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Bash. If not, see <http://www.gnu.org/licenses/>.
*/
/*
All arithmetic is done as intmax_t integers with no checking for overflow
(though division by 0 is caught and flagged as an error).
The following operators are handled, grouped into a set of levels in
order of decreasing precedence.
"id++", "id--" [post-increment and post-decrement]
"++id", "--id" [pre-increment and pre-decrement]
"-", "+" [(unary operators)]
"!", "~"
"**" [(exponentiation)]
"*", "/", "%"
"+", "-"
"<<", ">>"
"<=", ">=", "<", ">"
"==", "!="
"&"
"^"
"|"
"&&"
"||"
"expr ? expr : expr"
"=", "*=", "/=", "%=", "+=", "-=", "<<=", ">>=", "&=", "^=", "|="
, [comma]
(Note that most of these operators have special meaning to bash, and an
entire expression should be quoted, e.g. "a=$a+1" or "a=a+1" to ensure
that it is passed intact to the evaluator when using `let'. When using
the $[] or $(( )) forms, the text between the `[' and `]' or `((' and `))'
is treated as if in double quotes.)
Sub-expressions within parentheses have a precedence level greater than
all of the above levels and are evaluated first. Within a single prece-
dence group, evaluation is left-to-right, except for the arithmetic
assignment operator (`='), which is evaluated right-to-left (as in C).
The expression evaluator returns the value of the expression (assignment
statements have as a value what is returned by the RHS). The `let'
builtin, on the other hand, returns 0 if the last expression evaluates to
a non-zero, and 1 otherwise.
Implementation is a recursive-descent parser.
Chet Ramey
*/
#include "config.h"
#include <stdio.h>
#include "bashansi.h"
#if defined (HAVE_UNISTD_H)
# ifdef _MINIX
# include <sys/types.h>
# endif
# include <unistd.h>
#endif
#include "chartypes.h"
#include "bashintl.h"
#include "shell.h"
#include "typemax.h" /* INTMAX_MAX, INTMAX_MIN */
/* Because of the $((...)) construct, expressions may include newlines.
Here is a macro which accepts newlines, tabs and spaces as whitespace. */
#define cr_whitespace(c) (whitespace(c) || ((c) == '\n'))
/* Size be which the expression stack grows when necessary. */
#define EXPR_STACK_GROW_SIZE 10
/* Maximum amount of recursion allowed. This prevents a non-integer
variable such as "num=num+2" from infinitely adding to itself when
"let num=num+2" is given. */
#define MAX_EXPR_RECURSION_LEVEL 1024
/* The Tokens. Singing "The Lion Sleeps Tonight". */
#define EQEQ 1 /* "==" */
#define NEQ 2 /* "!=" */
#define LEQ 3 /* "<=" */
#define GEQ 4 /* ">=" */
#define STR 5 /* string */
#define NUM 6 /* number */
#define LAND 7 /* "&&" Logical AND */
#define LOR 8 /* "||" Logical OR */
#define LSH 9 /* "<<" Left SHift */
#define RSH 10 /* ">>" Right SHift */
#define OP_ASSIGN 11 /* op= expassign as in Posix.2 */
#define COND 12 /* exp1 ? exp2 : exp3 */
#define POWER 13 /* exp1**exp2 */
#define PREINC 14 /* ++var */
#define PREDEC 15 /* --var */
#define POSTINC 16 /* var++ */
#define POSTDEC 17 /* var-- */
#define EQ '='
#define GT '>'
#define LT '<'
#define PLUS '+'
#define MINUS '-'
#define MUL '*'
#define DIV '/'
#define MOD '%'
#define NOT '!'
#define LPAR '('
#define RPAR ')'
#define BAND '&' /* Bitwise AND */
#define BOR '|' /* Bitwise OR. */
#define BXOR '^' /* Bitwise eXclusive OR. */
#define BNOT '~' /* Bitwise NOT; Two's complement. */
#define QUES '?'
#define COL ':'
#define COMMA ','
/* This should be the function corresponding to the operator with the
highest precedence. */
#define EXP_HIGHEST expcomma
#ifndef MAX_INT_LEN
# define MAX_INT_LEN 32
#endif
struct lvalue
{
char *tokstr; /* possibly-rewritten lvalue if not NULL */
intmax_t tokval; /* expression evaluated value */
SHELL_VAR *tokvar; /* variable described by array or var reference */
intmax_t ind; /* array index if not -1 */
};
/* A structure defining a single expression context. */
typedef struct {
int curtok, lasttok;
char *expression, *tp, *lasttp;
intmax_t tokval;
char *tokstr;
int noeval;
struct lvalue lval;
} EXPR_CONTEXT;
static char *expression; /* The current expression */
static char *tp; /* token lexical position */
static char *lasttp; /* pointer to last token position */
static int curtok; /* the current token */
static int lasttok; /* the previous token */
static int assigntok; /* the OP in OP= */
static char *tokstr; /* current token string */
static intmax_t tokval; /* current token value */
static int noeval; /* set to 1 if no assignment to be done */
static procenv_t evalbuf;
static struct lvalue curlval = {0, 0, 0, -1};
static struct lvalue lastlval = {0, 0, 0, -1};
static int _is_arithop __P((int));
static void readtok __P((void)); /* lexical analyzer */
static void init_lvalue __P((struct lvalue *));
static struct lvalue *alloc_lvalue __P((void));
static void free_lvalue __P((struct lvalue *));
static intmax_t expr_streval __P((char *, int, struct lvalue *));
static intmax_t strlong __P((char *));
static void evalerror __P((const char *));
static void pushexp __P((void));
static void popexp __P((void));
static void expr_unwind __P((void));
static void expr_bind_variable __P((char *, char *));
#if defined (ARRAY_VARS)
static void expr_bind_array_element __P((char *, arrayind_t, char *));
#endif
static intmax_t subexpr __P((char *));
static intmax_t expcomma __P((void));
static intmax_t expassign __P((void));
static intmax_t expcond __P((void));
static intmax_t explor __P((void));
static intmax_t expland __P((void));
static intmax_t expbor __P((void));
static intmax_t expbxor __P((void));
static intmax_t expband __P((void));
static intmax_t exp5 __P((void));
static intmax_t exp4 __P((void));
static intmax_t expshift __P((void));
static intmax_t exp3 __P((void));
static intmax_t exp2 __P((void));
static intmax_t exppower __P((void));
static intmax_t exp1 __P((void));
static intmax_t exp0 __P((void));
/* Global var which contains the stack of expression contexts. */
static EXPR_CONTEXT **expr_stack;
static int expr_depth; /* Location in the stack. */
static int expr_stack_size; /* Number of slots already allocated. */
extern char *this_command_name;
extern int unbound_vars_is_error, last_command_exit_value;
#if defined (ARRAY_VARS)
extern const char * const bash_badsub_errmsg;
#endif
#define SAVETOK(X) \
do { \
(X)->curtok = curtok; \
(X)->lasttok = lasttok; \
(X)->tp = tp; \
(X)->lasttp = lasttp; \
(X)->tokval = tokval; \
(X)->tokstr = tokstr; \
(X)->noeval = noeval; \
(X)->lval = curlval; \
} while (0)
#define RESTORETOK(X) \
do { \
curtok = (X)->curtok; \
lasttok = (X)->lasttok; \
tp = (X)->tp; \
lasttp = (X)->lasttp; \
tokval = (X)->tokval; \
tokstr = (X)->tokstr; \
noeval = (X)->noeval; \
curlval = (X)->lval; \
} while (0)
/* Push and save away the contents of the globals describing the
current expression context. */
static void
pushexp ()
{
EXPR_CONTEXT *context;
if (expr_depth >= MAX_EXPR_RECURSION_LEVEL)
evalerror (_("expression recursion level exceeded"));
if (expr_depth >= expr_stack_size)
{
expr_stack_size += EXPR_STACK_GROW_SIZE;
expr_stack = (EXPR_CONTEXT **)xrealloc (expr_stack, expr_stack_size * sizeof (EXPR_CONTEXT *));
}
context = (EXPR_CONTEXT *)xmalloc (sizeof (EXPR_CONTEXT));
context->expression = expression;
SAVETOK(context);
expr_stack[expr_depth++] = context;
}
/* Pop the the contents of the expression context stack into the
globals describing the current expression context. */
static void
popexp ()
{
EXPR_CONTEXT *context;
if (expr_depth == 0)
evalerror (_("recursion stack underflow"));
context = expr_stack[--expr_depth];
expression = context->expression;
RESTORETOK (context);
free (context);
}
static void
expr_unwind ()
{
while (--expr_depth > 0)
{
if (expr_stack[expr_depth]->tokstr)
free (expr_stack[expr_depth]->tokstr);
if (expr_stack[expr_depth]->expression)
free (expr_stack[expr_depth]->expression);
free (expr_stack[expr_depth]);
}
free (expr_stack[expr_depth]); /* free the allocated EXPR_CONTEXT */
noeval = 0; /* XXX */
}
static void
expr_bind_variable (lhs, rhs)
char *lhs, *rhs;
{
SHELL_VAR *v;
v = bind_int_variable (lhs, rhs);
if (v && (readonly_p (v) || noassign_p (v)))
sh_longjmp (evalbuf, 1); /* variable assignment error */
stupidly_hack_special_variables (lhs);
}
#if defined (ARRAY_VARS)
/* Rewrite tok, which is of the form vname[expression], to vname[ind], where
IND is the already-calculated value of expression. */
static void
expr_bind_array_element (tok, ind, rhs)
char *tok;
arrayind_t ind;
char *rhs;
{
char *lhs, *vname;
size_t llen;
char ibuf[INT_STRLEN_BOUND (arrayind_t) + 1], *istr;
istr = fmtumax (ind, 10, ibuf, sizeof (ibuf), 0);
vname = array_variable_name (tok, (char **)NULL, (int *)NULL);
llen = strlen (vname) + sizeof (ibuf) + 3;
lhs = xmalloc (llen);
sprintf (lhs, "%s[%s]", vname, istr); /* XXX */
/*itrace("expr_bind_array_element: %s=%s", lhs, rhs);*/
expr_bind_variable (lhs, rhs);
free (vname);
free (lhs);
}
#endif /* ARRAY_VARS */
/* Evaluate EXPR, and return the arithmetic result. If VALIDP is
non-null, a zero is stored into the location to which it points
if the expression is invalid, non-zero otherwise. If a non-zero
value is returned in *VALIDP, the return value of evalexp() may
be used.
The `while' loop after the longjmp is caught relies on the above
implementation of pushexp and popexp leaving in expr_stack[0] the
values that the variables had when the program started. That is,
the first things saved are the initial values of the variables that
were assigned at program startup or by the compiler. Therefore, it is
safe to let the loop terminate when expr_depth == 0, without freeing up
any of the expr_depth[0] stuff. */
intmax_t
evalexp (expr, validp)
char *expr;
int *validp;
{
intmax_t val;
int c;
procenv_t oevalbuf;
val = 0;
noeval = 0;
FASTCOPY (evalbuf, oevalbuf, sizeof (evalbuf));
c = setjmp_nosigs (evalbuf);
if (c)
{
FREE (tokstr);
FREE (expression);
tokstr = expression = (char *)NULL;
expr_unwind ();
if (validp)
*validp = 0;
return (0);
}
val = subexpr (expr);
if (validp)
*validp = 1;
FASTCOPY (oevalbuf, evalbuf, sizeof (evalbuf));
return (val);
}
static intmax_t
subexpr (expr)
char *expr;
{
intmax_t val;
char *p;
for (p = expr; p && *p && cr_whitespace (*p); p++)
;
if (p == NULL || *p == '\0')
return (0);
pushexp ();
expression = savestring (expr);
tp = expression;
curtok = lasttok = 0;
tokstr = (char *)NULL;
tokval = 0;
init_lvalue (&curlval);
lastlval = curlval;
readtok ();
val = EXP_HIGHEST ();
if (curtok != 0)
evalerror (_("syntax error in expression"));
FREE (tokstr);
FREE (expression);
popexp ();
return val;
}
static intmax_t
expcomma ()
{
register intmax_t value;
value = expassign ();
while (curtok == COMMA)
{
readtok ();
value = expassign ();
}
return value;
}
static intmax_t
expassign ()
{
register intmax_t value;
char *lhs, *rhs;
arrayind_t lind;
#if defined (HAVE_IMAXDIV)
imaxdiv_t idiv;
#endif
value = expcond ();
if (curtok == EQ || curtok == OP_ASSIGN)
{
int special, op;
intmax_t lvalue;
special = curtok == OP_ASSIGN;
if (lasttok != STR)
evalerror (_("attempted assignment to non-variable"));
if (special)
{
op = assigntok; /* a OP= b */
lvalue = value;
}
/* XXX - watch out for pointer aliasing issues here */
lhs = savestring (tokstr);
/* save ind in case rhs is string var and evaluation overwrites it */
lind = curlval.ind;
readtok ();
value = expassign ();
if (special)
{
if ((op == DIV || op == MOD) && value == 0)
{
if (noeval == 0)
evalerror (_("division by 0"));
else
value = 1;
}
switch (op)
{
case MUL:
lvalue *= value;
break;
case DIV:
case MOD:
if (lvalue == INTMAX_MIN && value == -1)
lvalue = (op == DIV) ? INTMAX_MIN : 0;
else
#if HAVE_IMAXDIV
{
idiv = imaxdiv (lvalue, value);
lvalue = (op == DIV) ? idiv.quot : idiv.rem;
}
#else
lvalue = (op == DIV) ? lvalue / value : lvalue % value;
#endif
break;
case PLUS:
lvalue += value;
break;
case MINUS:
lvalue -= value;
break;
case LSH:
lvalue <<= value;
break;
case RSH:
lvalue >>= value;
break;
case BAND:
lvalue &= value;
break;
case BOR:
lvalue |= value;
break;
case BXOR:
lvalue ^= value;
break;
default:
free (lhs);
evalerror (_("bug: bad expassign token"));
break;
}
value = lvalue;
}
rhs = itos (value);
if (noeval == 0)
{
#if defined (ARRAY_VARS)
if (lind != -1)
expr_bind_array_element (lhs, lind, rhs);
else
#endif
expr_bind_variable (lhs, rhs);
}
if (curlval.tokstr && curlval.tokstr == tokstr)
init_lvalue (&curlval);
free (rhs);
free (lhs);
FREE (tokstr);
tokstr = (char *)NULL; /* For freeing on errors. */
}
return (value);
}
/* Conditional expression (expr?expr:expr) */
static intmax_t
expcond ()
{
intmax_t cval, val1, val2, rval;
int set_noeval;
set_noeval = 0;
rval = cval = explor ();
if (curtok == QUES) /* found conditional expr */
{
if (cval == 0)
{
set_noeval = 1;
noeval++;
}
readtok ();
if (curtok == 0 || curtok == COL)
evalerror (_("expression expected"));
val1 = EXP_HIGHEST ();
if (set_noeval)
noeval--;
if (curtok != COL)
evalerror (_("`:' expected for conditional expression"));
set_noeval = 0;
if (cval)
{
set_noeval = 1;
noeval++;
}
readtok ();
if (curtok == 0)
evalerror (_("expression expected"));
val2 = expcond ();
if (set_noeval)
noeval--;
rval = cval ? val1 : val2;
lasttok = COND;
}
return rval;
}
/* Logical OR. */
static intmax_t
explor ()
{
register intmax_t val1, val2;
int set_noeval;
val1 = expland ();
while (curtok == LOR)
{
set_noeval = 0;
if (val1 != 0)
{
noeval++;
set_noeval = 1;
}
readtok ();
val2 = expland ();
if (set_noeval)
noeval--;
val1 = val1 || val2;
lasttok = LOR;
}
return (val1);
}
/* Logical AND. */
static intmax_t
expland ()
{
register intmax_t val1, val2;
int set_noeval;
val1 = expbor ();
while (curtok == LAND)
{
set_noeval = 0;
if (val1 == 0)
{
set_noeval = 1;
noeval++;
}
readtok ();
val2 = expbor ();
if (set_noeval)
noeval--;
val1 = val1 && val2;
lasttok = LAND;
}
return (val1);
}
/* Bitwise OR. */
static intmax_t
expbor ()
{
register intmax_t val1, val2;
val1 = expbxor ();
while (curtok == BOR)
{
readtok ();
val2 = expbxor ();
val1 = val1 | val2;
lasttok = NUM;
}
return (val1);
}
/* Bitwise XOR. */
static intmax_t
expbxor ()
{
register intmax_t val1, val2;
val1 = expband ();
while (curtok == BXOR)
{
readtok ();
val2 = expband ();
val1 = val1 ^ val2;
lasttok = NUM;
}
return (val1);
}
/* Bitwise AND. */
static intmax_t
expband ()
{
register intmax_t val1, val2;
val1 = exp5 ();
while (curtok == BAND)
{
readtok ();
val2 = exp5 ();
val1 = val1 & val2;
lasttok = NUM;
}
return (val1);
}
static intmax_t
exp5 ()
{
register intmax_t val1, val2;
val1 = exp4 ();
while ((curtok == EQEQ) || (curtok == NEQ))
{
int op = curtok;
readtok ();
val2 = exp4 ();
if (op == EQEQ)
val1 = (val1 == val2);
else if (op == NEQ)
val1 = (val1 != val2);
lasttok = NUM;
}
return (val1);
}
static intmax_t
exp4 ()
{
register intmax_t val1, val2;
val1 = expshift ();
while ((curtok == LEQ) ||
(curtok == GEQ) ||
(curtok == LT) ||
(curtok == GT))
{
int op = curtok;
readtok ();
val2 = expshift ();
if (op == LEQ)
val1 = val1 <= val2;
else if (op == GEQ)
val1 = val1 >= val2;
else if (op == LT)
val1 = val1 < val2;
else /* (op == GT) */
val1 = val1 > val2;
lasttok = NUM;
}
return (val1);
}
/* Left and right shifts. */
static intmax_t
expshift ()
{
register intmax_t val1, val2;
val1 = exp3 ();
while ((curtok == LSH) || (curtok == RSH))
{
int op = curtok;
readtok ();
val2 = exp3 ();
if (op == LSH)
val1 = val1 << val2;
else
val1 = val1 >> val2;
lasttok = NUM;
}
return (val1);
}
static intmax_t
exp3 ()
{
register intmax_t val1, val2;
val1 = exp2 ();
while ((curtok == PLUS) || (curtok == MINUS))
{
int op = curtok;
readtok ();
val2 = exp2 ();
if (op == PLUS)
val1 += val2;
else if (op == MINUS)
val1 -= val2;
lasttok = NUM;
}
return (val1);
}
static intmax_t
exp2 ()
{
register intmax_t val1, val2;
#if defined (HAVE_IMAXDIV)
imaxdiv_t idiv;
#endif
val1 = exppower ();
while ((curtok == MUL) ||
(curtok == DIV) ||
(curtok == MOD))
{
int op = curtok;
char *stp, *sltp;
stp = tp;
readtok ();
val2 = exppower ();
/* Handle division by 0 and twos-complement arithmetic overflow */
if (((op == DIV) || (op == MOD)) && (val2 == 0))
{
if (noeval == 0)
{
sltp = lasttp;
lasttp = stp;
while (lasttp && *lasttp && whitespace (*lasttp))
lasttp++;
evalerror (_("division by 0"));
lasttp = sltp;
}
else
val2 = 1;
}
else if (op == MOD && val1 == INTMAX_MIN && val2 == -1)
{
val1 = 0;
continue;
}
else if (op == DIV && val1 == INTMAX_MIN && val2 == -1)
val2 = 1;
if (op == MUL)
val1 *= val2;
else if (op == DIV || op == MOD)
#if defined (HAVE_IMAXDIV)
{
idiv = imaxdiv (val1, val2);
val1 = (op == DIV) ? idiv.quot : idiv.rem;
}
#else
val1 = (op == DIV) ? val1 / val2 : val1 % val2;
#endif
lasttok = NUM;
}
return (val1);
}
static intmax_t
ipow (base, exp)
intmax_t base, exp;
{
intmax_t result;
result = 1;
while (exp)
{
if (exp & 1)
result *= base;
exp >>= 1;
base *= base;
}
return result;
}
static intmax_t
exppower ()
{
register intmax_t val1, val2, c;
val1 = exp1 ();
while (curtok == POWER)
{
readtok ();
val2 = exppower (); /* exponentiation is right-associative */
lasttok = NUM;
if (val2 == 0)
return (1);
if (val2 < 0)
evalerror (_("exponent less than 0"));
val1 = ipow (val1, val2);
}
return (val1);
}
static intmax_t
exp1 ()
{
register intmax_t val;
if (curtok == NOT)
{
readtok ();
val = !exp1 ();
lasttok = NUM;
}
else if (curtok == BNOT)
{
readtok ();
val = ~exp1 ();
lasttok = NUM;
}
else if (curtok == MINUS)
{
readtok ();
val = - exp1 ();
lasttok = NUM;
}
else if (curtok == PLUS)
{
readtok ();
val = exp1 ();
lasttok = NUM;
}
else
val = exp0 ();
return (val);
}
static intmax_t
exp0 ()
{
register intmax_t val = 0, v2;
char *vincdec;
int stok;
EXPR_CONTEXT ec;
/* XXX - might need additional logic here to decide whether or not
pre-increment or pre-decrement is legal at this point. */
if (curtok == PREINC || curtok == PREDEC)
{
stok = lasttok = curtok;
readtok ();
if (curtok != STR)
/* readtok() catches this */
evalerror (_("identifier expected after pre-increment or pre-decrement"));
v2 = tokval + ((stok == PREINC) ? 1 : -1);
vincdec = itos (v2);
if (noeval == 0)
{
#if defined (ARRAY_VARS)
if (curlval.ind != -1)
expr_bind_array_element (curlval.tokstr, curlval.ind, vincdec);
else
#endif
expr_bind_variable (tokstr, vincdec);
}
free (vincdec);
val = v2;
curtok = NUM; /* make sure --x=7 is flagged as an error */
readtok ();
}
else if (curtok == LPAR)
{
/* XXX - save curlval here? Or entire expression context? */