summaryrefslogtreecommitdiff
path: root/coreutils/expr.c (plain)
blob: 55a19aa79c5bdb356f3320d8176a5a5493a42dbc
1/* vi: set sw=4 ts=4: */
2/*
3 * Mini expr implementation for busybox
4 *
5 * based on GNU expr Mike Parker.
6 * Copyright (C) 86, 1991-1997, 1999 Free Software Foundation, Inc.
7 *
8 * Busybox modifications
9 * Copyright (c) 2000 Edward Betts <edward@debian.org>.
10 * Copyright (C) 2003-2005 Vladimir Oleynik <dzo@simtreas.ru>
11 * - reduced 464 bytes.
12 * - 64 math support
13 *
14 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
15 */
16/* This program evaluates expressions. Each token (operator, operand,
17 * parenthesis) of the expression must be a separate argument. The
18 * parser used is a reasonably general one, though any incarnation of
19 * it is language-specific. It is especially nice for expressions.
20 *
21 * No parse tree is needed; a new node is evaluated immediately.
22 * One function can handle multiple operators all of equal precedence,
23 * provided they all associate ((x op x) op x).
24 */
25//config:config EXPR
26//config: bool "expr"
27//config: default y
28//config: help
29//config: expr is used to calculate numbers and print the result
30//config: to standard output.
31//config:
32//config:config EXPR_MATH_SUPPORT_64
33//config: bool "Extend Posix numbers support to 64 bit"
34//config: default y
35//config: depends on EXPR
36//config: help
37//config: Enable 64-bit math support in the expr applet. This will make
38//config: the applet slightly larger, but will allow computation with very
39//config: large numbers.
40
41//applet:IF_EXPR(APPLET(expr, BB_DIR_USR_BIN, BB_SUID_DROP))
42
43//kbuild:lib-$(CONFIG_EXPR) += expr.o
44
45//usage:#define expr_trivial_usage
46//usage: "EXPRESSION"
47//usage:#define expr_full_usage "\n\n"
48//usage: "Print the value of EXPRESSION to stdout\n"
49//usage: "\n"
50//usage: "EXPRESSION may be:\n"
51//usage: " ARG1 | ARG2 ARG1 if it is neither null nor 0, otherwise ARG2\n"
52//usage: " ARG1 & ARG2 ARG1 if neither argument is null or 0, otherwise 0\n"
53//usage: " ARG1 < ARG2 1 if ARG1 is less than ARG2, else 0. Similarly:\n"
54//usage: " ARG1 <= ARG2\n"
55//usage: " ARG1 = ARG2\n"
56//usage: " ARG1 != ARG2\n"
57//usage: " ARG1 >= ARG2\n"
58//usage: " ARG1 > ARG2\n"
59//usage: " ARG1 + ARG2 Sum of ARG1 and ARG2. Similarly:\n"
60//usage: " ARG1 - ARG2\n"
61//usage: " ARG1 * ARG2\n"
62//usage: " ARG1 / ARG2\n"
63//usage: " ARG1 % ARG2\n"
64//usage: " STRING : REGEXP Anchored pattern match of REGEXP in STRING\n"
65//usage: " match STRING REGEXP Same as STRING : REGEXP\n"
66//usage: " substr STRING POS LENGTH Substring of STRING, POS counted from 1\n"
67//usage: " index STRING CHARS Index in STRING where any CHARS is found, or 0\n"
68//usage: " length STRING Length of STRING\n"
69//usage: " quote TOKEN Interpret TOKEN as a string, even if\n"
70//usage: " it is a keyword like 'match' or an\n"
71//usage: " operator like '/'\n"
72//usage: " (EXPRESSION) Value of EXPRESSION\n"
73//usage: "\n"
74//usage: "Beware that many operators need to be escaped or quoted for shells.\n"
75//usage: "Comparisons are arithmetic if both ARGs are numbers, else\n"
76//usage: "lexicographical. Pattern matches return the string matched between\n"
77//usage: "\\( and \\) or null; if \\( and \\) are not used, they return the number\n"
78//usage: "of characters matched or 0."
79
80#include "libbb.h"
81#include "common_bufsiz.h"
82#include "xregex.h"
83
84#if ENABLE_EXPR_MATH_SUPPORT_64
85typedef int64_t arith_t;
86
87#define PF_REZ "ll"
88#define PF_REZ_TYPE (long long)
89#define STRTOL(s, e, b) strtoll(s, e, b)
90#else
91typedef long arith_t;
92
93#define PF_REZ "l"
94#define PF_REZ_TYPE (long)
95#define STRTOL(s, e, b) strtol(s, e, b)
96#endif
97
98/* TODO: use bb_strtol[l]? It's easier to check for errors... */
99
100/* The kinds of value we can have. */
101enum {
102 INTEGER,
103 STRING
104};
105
106/* A value is.... */
107struct valinfo {
108 smallint type; /* Which kind. */
109 union { /* The value itself. */
110 arith_t i;
111 char *s;
112 } u;
113};
114typedef struct valinfo VALUE;
115
116/* The arguments given to the program, minus the program name. */
117struct globals {
118 char **args;
119} FIX_ALIASING;
120#define G (*(struct globals*)bb_common_bufsiz1)
121#define INIT_G() do { setup_common_bufsiz(); } while (0)
122
123/* forward declarations */
124static VALUE *eval(void);
125
126
127/* Return a VALUE for I. */
128
129static VALUE *int_value(arith_t i)
130{
131 VALUE *v;
132
133 v = xzalloc(sizeof(VALUE));
134 if (INTEGER) /* otherwise xzalloc did it already */
135 v->type = INTEGER;
136 v->u.i = i;
137 return v;
138}
139
140/* Return a VALUE for S. */
141
142static VALUE *str_value(const char *s)
143{
144 VALUE *v;
145
146 v = xzalloc(sizeof(VALUE));
147 if (STRING) /* otherwise xzalloc did it already */
148 v->type = STRING;
149 v->u.s = xstrdup(s);
150 return v;
151}
152
153/* Free VALUE V, including structure components. */
154
155static void freev(VALUE *v)
156{
157 if (v->type == STRING)
158 free(v->u.s);
159 free(v);
160}
161
162/* Return nonzero if V is a null-string or zero-number. */
163
164static int null(VALUE *v)
165{
166 if (v->type == INTEGER)
167 return v->u.i == 0;
168 /* STRING: */
169 return v->u.s[0] == '\0' || LONE_CHAR(v->u.s, '0');
170}
171
172/* Coerce V to a STRING value (can't fail). */
173
174static void tostring(VALUE *v)
175{
176 if (v->type == INTEGER) {
177 v->u.s = xasprintf("%" PF_REZ "d", PF_REZ_TYPE v->u.i);
178 v->type = STRING;
179 }
180}
181
182/* Coerce V to an INTEGER value. Return 1 on success, 0 on failure. */
183
184static bool toarith(VALUE *v)
185{
186 if (v->type == STRING) {
187 arith_t i;
188 char *e;
189
190 /* Don't interpret the empty string as an integer. */
191 /* Currently does not worry about overflow or int/long differences. */
192 i = STRTOL(v->u.s, &e, 10);
193 if ((v->u.s == e) || *e)
194 return 0;
195 free(v->u.s);
196 v->u.i = i;
197 v->type = INTEGER;
198 }
199 return 1;
200}
201
202/* Return str[0]+str[1] if the next token matches STR exactly.
203 STR must not be NULL. */
204
205static int nextarg(const char *str)
206{
207 if (*G.args == NULL || strcmp(*G.args, str) != 0)
208 return 0;
209 return (unsigned char)str[0] + (unsigned char)str[1];
210}
211
212/* The comparison operator handling functions. */
213
214static int cmp_common(VALUE *l, VALUE *r, int op)
215{
216 arith_t ll, rr;
217
218 ll = l->u.i;
219 rr = r->u.i;
220 if (l->type == STRING || r->type == STRING) {
221 tostring(l);
222 tostring(r);
223 ll = strcmp(l->u.s, r->u.s);
224 rr = 0;
225 }
226 /* calculating ll - rr and checking the result is prone to overflows.
227 * We'll do it differently: */
228 if (op == '<')
229 return ll < rr;
230 if (op == ('<' + '='))
231 return ll <= rr;
232 if (op == '=' || (op == '=' + '='))
233 return ll == rr;
234 if (op == '!' + '=')
235 return ll != rr;
236 if (op == '>')
237 return ll > rr;
238 /* >= */
239 return ll >= rr;
240}
241
242/* The arithmetic operator handling functions. */
243
244static arith_t arithmetic_common(VALUE *l, VALUE *r, int op)
245{
246 arith_t li, ri;
247
248 if (!toarith(l) || !toarith(r))
249 bb_error_msg_and_die("non-numeric argument");
250 li = l->u.i;
251 ri = r->u.i;
252 if (op == '+')
253 return li + ri;
254 if (op == '-')
255 return li - ri;
256 if (op == '*')
257 return li * ri;
258 if (ri == 0)
259 bb_error_msg_and_die("division by zero");
260 if (op == '/')
261 return li / ri;
262 return li % ri;
263}
264
265/* Do the : operator.
266 SV is the VALUE for the lhs (the string),
267 PV is the VALUE for the rhs (the pattern). */
268
269static VALUE *docolon(VALUE *sv, VALUE *pv)
270{
271 enum { NMATCH = 2 };
272 VALUE *v;
273 regex_t re_buffer;
274 regmatch_t re_regs[NMATCH];
275
276 tostring(sv);
277 tostring(pv);
278
279 if (pv->u.s[0] == '^') {
280 bb_error_msg(
281"warning: '%s': using '^' as the first character\n"
282"of a basic regular expression is not portable; it is ignored", pv->u.s);
283 }
284
285 memset(&re_buffer, 0, sizeof(re_buffer));
286 memset(re_regs, 0, sizeof(re_regs));
287 xregcomp(&re_buffer, pv->u.s, 0);
288
289 /* expr uses an anchored pattern match, so check that there was a
290 * match and that the match starts at offset 0. */
291 if (regexec(&re_buffer, sv->u.s, NMATCH, re_regs, 0) != REG_NOMATCH
292 && re_regs[0].rm_so == 0
293 ) {
294 /* Were \(...\) used? */
295 if (re_buffer.re_nsub > 0 && re_regs[1].rm_so >= 0) {
296 sv->u.s[re_regs[1].rm_eo] = '\0';
297 v = str_value(sv->u.s + re_regs[1].rm_so);
298 } else {
299 v = int_value(re_regs[0].rm_eo);
300 }
301 } else {
302 /* Match failed -- return the right kind of null. */
303 if (re_buffer.re_nsub > 0)
304 v = str_value("");
305 else
306 v = int_value(0);
307 }
308 regfree(&re_buffer);
309 return v;
310}
311
312/* Handle bare operands and ( expr ) syntax. */
313
314static VALUE *eval7(void)
315{
316 VALUE *v;
317
318 if (!*G.args)
319 bb_error_msg_and_die("syntax error");
320
321 if (nextarg("(")) {
322 G.args++;
323 v = eval();
324 if (!nextarg(")"))
325 bb_error_msg_and_die("syntax error");
326 G.args++;
327 return v;
328 }
329
330 if (nextarg(")"))
331 bb_error_msg_and_die("syntax error");
332
333 return str_value(*G.args++);
334}
335
336/* Handle match, substr, index, length, and quote keywords. */
337
338static VALUE *eval6(void)
339{
340 static const char keywords[] ALIGN1 =
341 "quote\0""length\0""match\0""index\0""substr\0";
342
343 VALUE *r, *i1, *i2;
344 static VALUE *l = NULL;
345 static VALUE *v = NULL;
346 int key = *G.args ? index_in_strings(keywords, *G.args) + 1 : 0;
347
348 if (key == 0) /* not a keyword */
349 return eval7();
350 G.args++; /* We have a valid token, so get the next argument. */
351 if (key == 1) { /* quote */
352 if (!*G.args)
353 bb_error_msg_and_die("syntax error");
354 return str_value(*G.args++);
355 }
356 if (key == 2) { /* length */
357 r = eval6();
358 tostring(r);
359 v = int_value(strlen(r->u.s));
360 freev(r);
361 } else
362 l = eval6();
363
364 if (key == 3) { /* match */
365 r = eval6();
366 v = docolon(l, r);
367 freev(l);
368 freev(r);
369 }
370 if (key == 4) { /* index */
371 r = eval6();
372 tostring(l);
373 tostring(r);
374 v = int_value(strcspn(l->u.s, r->u.s) + 1);
375 if (v->u.i == (arith_t) strlen(l->u.s) + 1)
376 v->u.i = 0;
377 freev(l);
378 freev(r);
379 }
380 if (key == 5) { /* substr */
381 i1 = eval6();
382 i2 = eval6();
383 tostring(l);
384 if (!toarith(i1) || !toarith(i2)
385 || i1->u.i > (arith_t) strlen(l->u.s)
386 || i1->u.i <= 0 || i2->u.i <= 0)
387 v = str_value("");
388 else {
389 v = xmalloc(sizeof(VALUE));
390 v->type = STRING;
391 v->u.s = xstrndup(l->u.s + i1->u.i - 1, i2->u.i);
392 }
393 freev(l);
394 freev(i1);
395 freev(i2);
396 }
397 return v;
398}
399
400/* Handle : operator (pattern matching).
401 Calls docolon to do the real work. */
402
403static VALUE *eval5(void)
404{
405 VALUE *l, *r, *v;
406
407 l = eval6();
408 while (nextarg(":")) {
409 G.args++;
410 r = eval6();
411 v = docolon(l, r);
412 freev(l);
413 freev(r);
414 l = v;
415 }
416 return l;
417}
418
419/* Handle *, /, % operators. */
420
421static VALUE *eval4(void)
422{
423 VALUE *l, *r;
424 int op;
425 arith_t val;
426
427 l = eval5();
428 while (1) {
429 op = nextarg("*");
430 if (!op) { op = nextarg("/");
431 if (!op) { op = nextarg("%");
432 if (!op) return l;
433 }}
434 G.args++;
435 r = eval5();
436 val = arithmetic_common(l, r, op);
437 freev(l);
438 freev(r);
439 l = int_value(val);
440 }
441}
442
443/* Handle +, - operators. */
444
445static VALUE *eval3(void)
446{
447 VALUE *l, *r;
448 int op;
449 arith_t val;
450
451 l = eval4();
452 while (1) {
453 op = nextarg("+");
454 if (!op) {
455 op = nextarg("-");
456 if (!op) return l;
457 }
458 G.args++;
459 r = eval4();
460 val = arithmetic_common(l, r, op);
461 freev(l);
462 freev(r);
463 l = int_value(val);
464 }
465}
466
467/* Handle comparisons. */
468
469static VALUE *eval2(void)
470{
471 VALUE *l, *r;
472 int op;
473 arith_t val;
474
475 l = eval3();
476 while (1) {
477 op = nextarg("<");
478 if (!op) { op = nextarg("<=");
479 if (!op) { op = nextarg("=");
480 if (!op) { op = nextarg("==");
481 if (!op) { op = nextarg("!=");
482 if (!op) { op = nextarg(">=");
483 if (!op) { op = nextarg(">");
484 if (!op) return l;
485 }}}}}}
486 G.args++;
487 r = eval3();
488 toarith(l);
489 toarith(r);
490 val = cmp_common(l, r, op);
491 freev(l);
492 freev(r);
493 l = int_value(val);
494 }
495}
496
497/* Handle &. */
498
499static VALUE *eval1(void)
500{
501 VALUE *l, *r;
502
503 l = eval2();
504 while (nextarg("&")) {
505 G.args++;
506 r = eval2();
507 if (null(l) || null(r)) {
508 freev(l);
509 freev(r);
510 l = int_value(0);
511 } else
512 freev(r);
513 }
514 return l;
515}
516
517/* Handle |. */
518
519static VALUE *eval(void)
520{
521 VALUE *l, *r;
522
523 l = eval1();
524 while (nextarg("|")) {
525 G.args++;
526 r = eval1();
527 if (null(l)) {
528 freev(l);
529 l = r;
530 } else
531 freev(r);
532 }
533 return l;
534}
535
536int expr_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
537int expr_main(int argc UNUSED_PARAM, char **argv)
538{
539 VALUE *v;
540
541 INIT_G();
542
543 xfunc_error_retval = 2; /* coreutils compat */
544 G.args = argv + 1;
545 if (*G.args == NULL) {
546 bb_error_msg_and_die("too few arguments");
547 }
548 v = eval();
549 if (*G.args)
550 bb_error_msg_and_die("syntax error");
551 if (v->type == INTEGER)
552 printf("%" PF_REZ "d\n", PF_REZ_TYPE v->u.i);
553 else
554 puts(v->u.s);
555 fflush_stdout_and_exit(null(v));
556}
557
generated by cgit at 2024-05-15 16:03:10 (GMT)