source: MondoRescue/branches/2.2.9/mindi-busybox/coreutils/expr.c@ 2142

Last change on this file since 2142 was 1765, checked in by Bruno Cornec, 16 years ago

Update to busybox 1.7.2

File size: 9.4 KB
Line 
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 tarball for details.
15 */
16
17/* This program evaluates expressions. Each token (operator, operand,
18 * parenthesis) of the expression must be a separate argument. The
19 * parser used is a reasonably general one, though any incarnation of
20 * it is language-specific. It is especially nice for expressions.
21 *
22 * No parse tree is needed; a new node is evaluated immediately.
23 * One function can handle multiple operators all of equal precedence,
24 * provided they all associate ((x op x) op x). */
25
26/* no getopt needed */
27
28#include "libbb.h"
29#include "xregex.h"
30
31/* The kinds of value we can have. */
32enum valtype {
33 integer,
34 string
35};
36typedef enum valtype TYPE;
37
38#if ENABLE_EXPR_MATH_SUPPORT_64
39typedef int64_t arith_t;
40
41#define PF_REZ "ll"
42#define PF_REZ_TYPE (long long)
43#define STRTOL(s, e, b) strtoll(s, e, b)
44#else
45typedef long arith_t;
46
47#define PF_REZ "l"
48#define PF_REZ_TYPE (long)
49#define STRTOL(s, e, b) strtol(s, e, b)
50#endif
51
52/* TODO: use bb_strtol[l]? It's easier to check for errors... */
53
54/* A value is.... */
55struct valinfo {
56 TYPE type; /* Which kind. */
57 union { /* The value itself. */
58 arith_t i;
59 char *s;
60 } u;
61};
62typedef struct valinfo VALUE;
63
64/* The arguments given to the program, minus the program name. */
65struct globals {
66 char **args;
67};
68#define G (*(struct globals*)&bb_common_bufsiz1)
69
70/* forward declarations */
71static VALUE *eval(void);
72
73
74/* Return a VALUE for I. */
75
76static VALUE *int_value(arith_t i)
77{
78 VALUE *v;
79
80 v = xmalloc(sizeof(VALUE));
81 v->type = integer;
82 v->u.i = i;
83 return v;
84}
85
86/* Return a VALUE for S. */
87
88static VALUE *str_value(const char *s)
89{
90 VALUE *v;
91
92 v = xmalloc(sizeof(VALUE));
93 v->type = string;
94 v->u.s = xstrdup(s);
95 return v;
96}
97
98/* Free VALUE V, including structure components. */
99
100static void freev(VALUE * v)
101{
102 if (v->type == string)
103 free(v->u.s);
104 free(v);
105}
106
107/* Return nonzero if V is a null-string or zero-number. */
108
109static int null(VALUE * v)
110{
111 if (v->type == integer)
112 return v->u.i == 0;
113 /* string: */
114 return v->u.s[0] == '\0' || LONE_CHAR(v->u.s, '0');
115}
116
117/* Coerce V to a string value (can't fail). */
118
119static void tostring(VALUE * v)
120{
121 if (v->type == integer) {
122 v->u.s = xasprintf("%" PF_REZ "d", PF_REZ_TYPE v->u.i);
123 v->type = string;
124 }
125}
126
127/* Coerce V to an integer value. Return 1 on success, 0 on failure. */
128
129static bool toarith(VALUE * v)
130{
131 if (v->type == string) {
132 arith_t i;
133 char *e;
134
135 /* Don't interpret the empty string as an integer. */
136 /* Currently does not worry about overflow or int/long differences. */
137 i = STRTOL(v->u.s, &e, 10);
138 if ((v->u.s == e) || *e)
139 return 0;
140 free(v->u.s);
141 v->u.i = i;
142 v->type = integer;
143 }
144 return 1;
145}
146
147/* Return nonzero if the next token matches STR exactly.
148 STR must not be NULL. */
149
150static bool nextarg(const char *str)
151{
152 if (*G.args == NULL)
153 return 0;
154 return strcmp(*G.args, str) == 0;
155}
156
157/* The comparison operator handling functions. */
158
159static int cmp_common(VALUE * l, VALUE * r, int op)
160{
161 int cmpval;
162
163 if (l->type == string || r->type == string) {
164 tostring(l);
165 tostring(r);
166 cmpval = strcmp(l->u.s, r->u.s);
167 } else
168 cmpval = l->u.i - r->u.i;
169 if (op == '<')
170 return cmpval < 0;
171 if (op == ('L' + 'E'))
172 return cmpval <= 0;
173 if (op == '=')
174 return cmpval == 0;
175 if (op == '!')
176 return cmpval != 0;
177 if (op == '>')
178 return cmpval > 0;
179 /* >= */
180 return cmpval >= 0;
181}
182
183/* The arithmetic operator handling functions. */
184
185static arith_t arithmetic_common(VALUE * l, VALUE * r, int op)
186{
187 arith_t li, ri;
188
189 if (!toarith(l) || !toarith(r))
190 bb_error_msg_and_die("non-numeric argument");
191 li = l->u.i;
192 ri = r->u.i;
193 if ((op == '/' || op == '%') && ri == 0)
194 bb_error_msg_and_die("division by zero");
195 if (op == '+')
196 return li + ri;
197 else if (op == '-')
198 return li - ri;
199 else if (op == '*')
200 return li * ri;
201 else if (op == '/')
202 return li / ri;
203 else
204 return li % ri;
205}
206
207/* Do the : operator.
208 SV is the VALUE for the lhs (the string),
209 PV is the VALUE for the rhs (the pattern). */
210
211static VALUE *docolon(VALUE * sv, VALUE * pv)
212{
213 VALUE *v;
214 regex_t re_buffer;
215 const int NMATCH = 2;
216 regmatch_t re_regs[NMATCH];
217
218 tostring(sv);
219 tostring(pv);
220
221 if (pv->u.s[0] == '^') {
222 bb_error_msg("\
223warning: unportable BRE: `%s': using `^' as the first character\n\
224of a basic regular expression is not portable; it is being ignored", pv->u.s);
225 }
226
227 memset(&re_buffer, 0, sizeof(re_buffer));
228 memset(re_regs, 0, sizeof(*re_regs));
229 xregcomp(&re_buffer, pv->u.s, 0);
230
231 /* expr uses an anchored pattern match, so check that there was a
232 * match and that the match starts at offset 0. */
233 if (regexec(&re_buffer, sv->u.s, NMATCH, re_regs, 0) != REG_NOMATCH &&
234 re_regs[0].rm_so == 0) {
235 /* Were \(...\) used? */
236 if (re_buffer.re_nsub > 0) {
237 sv->u.s[re_regs[1].rm_eo] = '\0';
238 v = str_value(sv->u.s + re_regs[1].rm_so);
239 } else
240 v = int_value(re_regs[0].rm_eo);
241 } else {
242 /* Match failed -- return the right kind of null. */
243 if (re_buffer.re_nsub > 0)
244 v = str_value("");
245 else
246 v = int_value(0);
247 }
248//FIXME: sounds like here is a bit missing: regfree(&re_buffer);
249 return v;
250}
251
252/* Handle bare operands and ( expr ) syntax. */
253
254static VALUE *eval7(void)
255{
256 VALUE *v;
257
258 if (!*G.args)
259 bb_error_msg_and_die("syntax error");
260
261 if (nextarg("(")) {
262 G.args++;
263 v = eval();
264 if (!nextarg(")"))
265 bb_error_msg_and_die("syntax error");
266 G.args++;
267 return v;
268 }
269
270 if (nextarg(")"))
271 bb_error_msg_and_die("syntax error");
272
273 return str_value(*G.args++);
274}
275
276/* Handle match, substr, index, length, and quote keywords. */
277
278static VALUE *eval6(void)
279{
280 static const char keywords[] ALIGN1 =
281 "quote\0""length\0""match\0""index\0""substr\0";
282
283 VALUE *r, *i1, *i2;
284 VALUE *l = l; /* silence gcc */
285 VALUE *v = v; /* silence gcc */
286 int key = *G.args ? index_in_strings(keywords, *G.args) + 1 : 0;
287
288 if (key == 0) /* not a keyword */
289 return eval7();
290 G.args++; /* We have a valid token, so get the next argument. */
291 if (key == 1) { /* quote */
292 if (!*G.args)
293 bb_error_msg_and_die("syntax error");
294 return str_value(*G.args++);
295 }
296 if (key == 2) { /* length */
297 r = eval6();
298 tostring(r);
299 v = int_value(strlen(r->u.s));
300 freev(r);
301 } else
302 l = eval6();
303
304 if (key == 3) { /* match */
305 r = eval6();
306 v = docolon(l, r);
307 freev(l);
308 freev(r);
309 }
310 if (key == 4) { /* index */
311 r = eval6();
312 tostring(l);
313 tostring(r);
314 v = int_value(strcspn(l->u.s, r->u.s) + 1);
315 if (v->u.i == (arith_t) strlen(l->u.s) + 1)
316 v->u.i = 0;
317 freev(l);
318 freev(r);
319 }
320 if (key == 5) { /* substr */
321 i1 = eval6();
322 i2 = eval6();
323 tostring(l);
324 if (!toarith(i1) || !toarith(i2)
325 || i1->u.i > (arith_t) strlen(l->u.s)
326 || i1->u.i <= 0 || i2->u.i <= 0)
327 v = str_value("");
328 else {
329 v = xmalloc(sizeof(VALUE));
330 v->type = string;
331 v->u.s = xstrndup(l->u.s + i1->u.i - 1, i2->u.i);
332 }
333 freev(l);
334 freev(i1);
335 freev(i2);
336 }
337 return v;
338
339}
340
341/* Handle : operator (pattern matching).
342 Calls docolon to do the real work. */
343
344static VALUE *eval5(void)
345{
346 VALUE *l, *r, *v;
347
348 l = eval6();
349 while (nextarg(":")) {
350 G.args++;
351 r = eval6();
352 v = docolon(l, r);
353 freev(l);
354 freev(r);
355 l = v;
356 }
357 return l;
358}
359
360/* Handle *, /, % operators. */
361
362static VALUE *eval4(void)
363{
364 VALUE *l, *r;
365 int op;
366 arith_t val;
367
368 l = eval5();
369 while (1) {
370 if (nextarg("*"))
371 op = '*';
372 else if (nextarg("/"))
373 op = '/';
374 else if (nextarg("%"))
375 op = '%';
376 else
377 return l;
378 G.args++;
379 r = eval5();
380 val = arithmetic_common(l, r, op);
381 freev(l);
382 freev(r);
383 l = int_value(val);
384 }
385}
386
387/* Handle +, - operators. */
388
389static VALUE *eval3(void)
390{
391 VALUE *l, *r;
392 int op;
393 arith_t val;
394
395 l = eval4();
396 while (1) {
397 if (nextarg("+"))
398 op = '+';
399 else if (nextarg("-"))
400 op = '-';
401 else
402 return l;
403 G.args++;
404 r = eval4();
405 val = arithmetic_common(l, r, op);
406 freev(l);
407 freev(r);
408 l = int_value(val);
409 }
410}
411
412/* Handle comparisons. */
413
414static VALUE *eval2(void)
415{
416 VALUE *l, *r;
417 int op;
418 arith_t val;
419
420 l = eval3();
421 while (1) {
422 if (nextarg("<"))
423 op = '<';
424 else if (nextarg("<="))
425 op = 'L' + 'E';
426 else if (nextarg("=") || nextarg("=="))
427 op = '=';
428 else if (nextarg("!="))
429 op = '!';
430 else if (nextarg(">="))
431 op = 'G' + 'E';
432 else if (nextarg(">"))
433 op = '>';
434 else
435 return l;
436 G.args++;
437 r = eval3();
438 toarith(l);
439 toarith(r);
440 val = cmp_common(l, r, op);
441 freev(l);
442 freev(r);
443 l = int_value(val);
444 }
445}
446
447/* Handle &. */
448
449static VALUE *eval1(void)
450{
451 VALUE *l, *r;
452
453 l = eval2();
454 while (nextarg("&")) {
455 G.args++;
456 r = eval2();
457 if (null(l) || null(r)) {
458 freev(l);
459 freev(r);
460 l = int_value(0);
461 } else
462 freev(r);
463 }
464 return l;
465}
466
467/* Handle |. */
468
469static VALUE *eval(void)
470{
471 VALUE *l, *r;
472
473 l = eval1();
474 while (nextarg("|")) {
475 G.args++;
476 r = eval1();
477 if (null(l)) {
478 freev(l);
479 l = r;
480 } else
481 freev(r);
482 }
483 return l;
484}
485
486int expr_main(int argc, char **argv);
487int expr_main(int argc, char **argv)
488{
489 VALUE *v;
490
491 if (argc == 1) {
492 bb_error_msg_and_die("too few arguments");
493 }
494
495 G.args = argv + 1;
496
497 v = eval();
498 if (*G.args)
499 bb_error_msg_and_die("syntax error");
500
501 if (v->type == integer)
502 printf("%" PF_REZ "d\n", PF_REZ_TYPE v->u.i);
503 else
504 puts(v->u.s);
505
506 fflush_stdout_and_exit(null(v));
507}
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