summaryrefslogtreecommitdiff
path: root/coreutils/expr.c
blob: 51e553dc6baaab5a21e30b9df937815f6d5085d7 (plain)
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
/* vi: set sw=4 ts=4: */
/*
 * Mini expr implementation for busybox
 *
 * based on GNU expr Mike Parker.
 * Copyright (C) 86, 1991-1997, 1999 Free Software Foundation, Inc.
 *
 * Busybox modifications
 * Copyright (c) 2000  Edward Betts <edward@debian.org>.
 * Copyright (C) 2003-2005  Vladimir Oleynik <dzo@simtreas.ru>
 *  - reduced 464 bytes.
 *  - 64 math support
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

/* This program evaluates expressions.  Each token (operator, operand,
 * parenthesis) of the expression must be a separate argument.  The
 * parser used is a reasonably general one, though any incarnation of
 * it is language-specific.  It is especially nice for expressions.
 *
 * No parse tree is needed; a new node is evaluated immediately.
 * One function can handle multiple operators all of equal precedence,
 * provided they all associate ((x op x) op x). */

/* no getopt needed */

#include "busybox.h"
#include "xregex.h"

/* The kinds of value we can have.  */
enum valtype {
	integer,
	string
};
typedef enum valtype TYPE;

#if ENABLE_EXPR_MATH_SUPPORT_64
typedef int64_t arith_t;

#define PF_REZ      "ll"
#define PF_REZ_TYPE (long long)
#define STRTOL(s, e, b) strtoll(s, e, b)
#else
typedef long arith_t;

#define PF_REZ      "l"
#define PF_REZ_TYPE (long)
#define STRTOL(s, e, b) strtol(s, e, b)
#endif

/* TODO: use bb_strtol[l]? It's easier to check for errors... */

/* A value is.... */
struct valinfo {
	TYPE type;			/* Which kind. */
	union {				/* The value itself. */
		arith_t i;
		char *s;
	} u;
};
typedef struct valinfo VALUE;

/* The arguments given to the program, minus the program name.  */
static char **args;

static VALUE *docolon(VALUE * sv, VALUE * pv);
static VALUE *eval(void);
static VALUE *int_value(arith_t i);
static VALUE *str_value(char *s);
static int nextarg(char *str);
static int null(VALUE * v);
static int toarith(VALUE * v);
static void freev(VALUE * v);
static void tostring(VALUE * v);

int expr_main(int argc, char **argv)
{
	VALUE *v;

	if (argc == 1) {
		bb_error_msg_and_die("too few arguments");
	}

	args = argv + 1;

	v = eval();
	if (*args)
		bb_error_msg_and_die("syntax error");

	if (v->type == integer)
		printf("%" PF_REZ "d\n", PF_REZ_TYPE v->u.i);
	else
		puts(v->u.s);

	fflush_stdout_and_exit(null(v));
}

/* Return a VALUE for I.  */

static VALUE *int_value(arith_t i)
{
	VALUE *v;

	v = xmalloc(sizeof(VALUE));
	v->type = integer;
	v->u.i = i;
	return v;
}

/* Return a VALUE for S.  */

static VALUE *str_value(char *s)
{
	VALUE *v;

	v = xmalloc(sizeof(VALUE));
	v->type = string;
	v->u.s = xstrdup(s);
	return v;
}

/* Free VALUE V, including structure components.  */

static void freev(VALUE * v)
{
	if (v->type == string)
		free(v->u.s);
	free(v);
}

/* Return nonzero if V is a null-string or zero-number.  */

static int null(VALUE * v)
{
	if (v->type == integer)
		return v->u.i == 0;
	else				/* string: */
		return v->u.s[0] == '\0' || LONE_CHAR(v->u.s, '0');
}

/* Coerce V to a string value (can't fail).  */

static void tostring(VALUE * v)
{
	if (v->type == integer) {
		v->u.s = xasprintf("%" PF_REZ "d", PF_REZ_TYPE v->u.i);
		v->type = string;
	}
}

/* Coerce V to an integer value.  Return 1 on success, 0 on failure.  */

static int toarith(VALUE * v)
{
	if (v->type == string) {
		arith_t i;
		char *e;

		/* Don't interpret the empty string as an integer.  */
		/* Currently does not worry about overflow or int/long differences. */
		i = STRTOL(v->u.s, &e, 10);
		if ((v->u.s == e) || *e)
			return 0;
		free(v->u.s);
		v->u.i = i;
		v->type = integer;
	}
	return 1;
}

/* Return nonzero if the next token matches STR exactly.
   STR must not be NULL.  */

static int nextarg(char *str)
{
	if (*args == NULL)
		return 0;
	return strcmp(*args, str) == 0;
}

/* The comparison operator handling functions.  */

static int cmp_common(VALUE * l, VALUE * r, int op)
{
	int cmpval;

	if (l->type == string || r->type == string) {
		tostring(l);
		tostring(r);
		cmpval = strcmp(l->u.s, r->u.s);
	} else
		cmpval = l->u.i - r->u.i;
	if (op == '<')
		return cmpval < 0;
	else if (op == ('L' + 'E'))
		return cmpval <= 0;
	else if (op == '=')
		return cmpval == 0;
	else if (op == '!')
		return cmpval != 0;
	else if (op == '>')
		return cmpval > 0;
	else				/* >= */
		return cmpval >= 0;
}

/* The arithmetic operator handling functions.  */

static arith_t arithmetic_common(VALUE * l, VALUE * r, int op)
{
	arith_t li, ri;

	if (!toarith(l) || !toarith(r))
		bb_error_msg_and_die("non-numeric argument");
	li = l->u.i;
	ri = r->u.i;
	if ((op == '/' || op == '%') && ri == 0)
		bb_error_msg_and_die("division by zero");
	if (op == '+')
		return li + ri;
	else if (op == '-')
		return li - ri;
	else if (op == '*')
		return li * ri;
	else if (op == '/')
		return li / ri;
	else
		return li % ri;
}

/* Do the : operator.
   SV is the VALUE for the lhs (the string),
   PV is the VALUE for the rhs (the pattern).  */

static VALUE *docolon(VALUE * sv, VALUE * pv)
{
	VALUE *v;
	regex_t re_buffer;
	const int NMATCH = 2;
	regmatch_t re_regs[NMATCH];

	tostring(sv);
	tostring(pv);

	if (pv->u.s[0] == '^') {
		fprintf(stderr, "\
warning: unportable BRE: `%s': using `^' as the first character\n\
of a basic regular expression is not portable; it is being ignored", pv->u.s);
	}

	memset(&re_buffer, 0, sizeof(re_buffer));
	memset(re_regs, 0, sizeof(*re_regs));
	if (regcomp(&re_buffer, pv->u.s, 0) != 0)
		bb_error_msg_and_die("invalid regular expression");

	/* expr uses an anchored pattern match, so check that there was a
	 * match and that the match starts at offset 0. */
	if (regexec(&re_buffer, sv->u.s, NMATCH, re_regs, 0) != REG_NOMATCH &&
		re_regs[0].rm_so == 0) {
		/* Were \(...\) used? */
		if (re_buffer.re_nsub > 0) {
			sv->u.s[re_regs[1].rm_eo] = '\0';
			v = str_value(sv->u.s + re_regs[1].rm_so);
		} else
			v = int_value(re_regs[0].rm_eo);
	} else {
		/* Match failed -- return the right kind of null.  */
		if (re_buffer.re_nsub > 0)
			v = str_value("");
		else
			v = int_value(0);
	}
	return v;
}

/* Handle bare operands and ( expr ) syntax.  */

static VALUE *eval7(void)
{
	VALUE *v;

	if (!*args)
		bb_error_msg_and_die("syntax error");

	if (nextarg("(")) {
		args++;
		v = eval();
		if (!nextarg(")"))
			bb_error_msg_and_die("syntax error");
		args++;
		return v;
	}

	if (nextarg(")"))
		bb_error_msg_and_die("syntax error");

	return str_value(*args++);
}

/* Handle match, substr, index, length, and quote keywords.  */

static VALUE *eval6(void)
{
	VALUE *l, *r, *v, *i1, *i2;

	if (nextarg("quote")) {
		args++;
		if (!*args)
			bb_error_msg_and_die("syntax error");
		return str_value(*args++);
	} else if (nextarg("length")) {
		args++;
		r = eval6();
		tostring(r);
		v = int_value(strlen(r->u.s));
		freev(r);
		return v;
	} else if (nextarg("match")) {
		args++;
		l = eval6();
		r = eval6();
		v = docolon(l, r);
		freev(l);
		freev(r);
		return v;
	} else if (nextarg("index")) {
		args++;
		l = eval6();
		r = eval6();
		tostring(l);
		tostring(r);
		v = int_value(strcspn(l->u.s, r->u.s) + 1);
		if (v->u.i == (arith_t) strlen(l->u.s) + 1)
			v->u.i = 0;
		freev(l);
		freev(r);
		return v;
	} else if (nextarg("substr")) {
		args++;
		l = eval6();
		i1 = eval6();
		i2 = eval6();
		tostring(l);
		if (!toarith(i1) || !toarith(i2)
			|| i1->u.i > (arith_t) strlen(l->u.s)
			|| i1->u.i <= 0 || i2->u.i <= 0)
			v = str_value("");
		else {
			v = xmalloc(sizeof(VALUE));
			v->type = string;
			v->u.s = xstrndup(l->u.s + i1->u.i - 1, i2->u.i);
		}
		freev(l);
		freev(i1);
		freev(i2);
		return v;
	} else
		return eval7();
}

/* Handle : operator (pattern matching).
   Calls docolon to do the real work.  */

static VALUE *eval5(void)
{
	VALUE *l, *r, *v;

	l = eval6();
	while (nextarg(":")) {
		args++;
		r = eval6();
		v = docolon(l, r);
		freev(l);
		freev(r);
		l = v;
	}
	return l;
}

/* Handle *, /, % operators.  */

static VALUE *eval4(void)
{
	VALUE *l, *r;
	int op;
	arith_t val;

	l = eval5();
	while (1) {
		if (nextarg("*"))
			op = '*';
		else if (nextarg("/"))
			op = '/';
		else if (nextarg("%"))
			op = '%';
		else
			return l;
		args++;
		r = eval5();
		val = arithmetic_common(l, r, op);
		freev(l);
		freev(r);
		l = int_value(val);
	}
}

/* Handle +, - operators.  */

static VALUE *eval3(void)
{
	VALUE *l, *r;
	int op;
	arith_t val;

	l = eval4();
	while (1) {
		if (nextarg("+"))
			op = '+';
		else if (nextarg("-"))
			op = '-';
		else
			return l;
		args++;
		r = eval4();
		val = arithmetic_common(l, r, op);
		freev(l);
		freev(r);
		l = int_value(val);
	}
}

/* Handle comparisons.  */

static VALUE *eval2(void)
{
	VALUE *l, *r;
	int op;
	arith_t val;

	l = eval3();
	while (1) {
		if (nextarg("<"))
			op = '<';
		else if (nextarg("<="))
			op = 'L' + 'E';
		else if (nextarg("=") || nextarg("=="))
			op = '=';
		else if (nextarg("!="))
			op = '!';
		else if (nextarg(">="))
			op = 'G' + 'E';
		else if (nextarg(">"))
			op = '>';
		else
			return l;
		args++;
		r = eval3();
		toarith(l);
		toarith(r);
		val = cmp_common(l, r, op);
		freev(l);
		freev(r);
		l = int_value(val);
	}
}

/* Handle &.  */

static VALUE *eval1(void)
{
	VALUE *l, *r;

	l = eval2();
	while (nextarg("&")) {
		args++;
		r = eval2();
		if (null(l) || null(r)) {
			freev(l);
			freev(r);
			l = int_value(0);
		} else
			freev(r);
	}
	return l;
}

/* Handle |.  */

static VALUE *eval(void)
{
	VALUE *l, *r;

	l = eval1();
	while (nextarg("|")) {
		args++;
		r = eval1();
		if (null(l)) {
			freev(l);
			l = r;
		} else
			freev(r);
	}
	return l;
}