projects/linux·blob v2.6.29-rc5 · refs

689 lines · 13.6 KiB

1/*
2 * linux/lib/string.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7/*
8 * stupid library routines.. The optimized versions should generally be found
9 * as inline code in <asm-xx/string.h>
10 *
11 * These are buggy as well..
12 *
13 * * Fri Jun 25 1999, Ingo Oeser <[email protected]>
14 * - Added strsep() which will replace strtok() soon (because strsep() is
15 * reentrant and should be faster). Use only strsep() in new code, please.
16 *
17 * * Sat Feb 09 2002, Jason Thomas <[email protected]>,
18 * Matthew Hawkins <[email protected]>
19 * - Kissed strtok() goodbye
20 */
21
22#include <linux/types.h>
23#include <linux/string.h>
24#include <linux/ctype.h>
25#include <linux/module.h>
26
27#ifndef __HAVE_ARCH_STRNICMP
28/**
29 * strnicmp - Case insensitive, length-limited string comparison
30 * @s1: One string
31 * @s2: The other string
32 * @len: the maximum number of characters to compare
33 */
34int strnicmp(const char *s1, const char *s2, size_t len)
35{
36 /* Yes, Virginia, it had better be unsigned */
37 unsigned char c1, c2;
38
39 c1 = c2 = 0;
40 if (len) {
41 do {
42 c1 = *s1;
43 c2 = *s2;
44 s1++;
45 s2++;
46 if (!c1)
47 break;
48 if (!c2)
49 break;
50 if (c1 == c2)
51 continue;
52 c1 = tolower(c1);
53 c2 = tolower(c2);
54 if (c1 != c2)
55 break;
56 } while (--len);
57 }
58 return (int)c1 - (int)c2;
59}
60EXPORT_SYMBOL(strnicmp);
61#endif
62
63#ifndef __HAVE_ARCH_STRCASECMP
64int strcasecmp(const char *s1, const char *s2)
65{
66 int c1, c2;
67
68 do {
69 c1 = tolower(*s1++);
70 c2 = tolower(*s2++);
71 } while (c1 == c2 && c1 != 0);
72 return c1 - c2;
73}
74EXPORT_SYMBOL(strcasecmp);
75#endif
76
77#ifndef __HAVE_ARCH_STRNCASECMP
78int strncasecmp(const char *s1, const char *s2, size_t n)
79{
80 int c1, c2;
81
82 do {
83 c1 = tolower(*s1++);
84 c2 = tolower(*s2++);
85 } while ((--n > 0) && c1 == c2 && c1 != 0);
86 return c1 - c2;
87}
88EXPORT_SYMBOL(strncasecmp);
89#endif
90
91#ifndef __HAVE_ARCH_STRCPY
92/**
93 * strcpy - Copy a %NUL terminated string
94 * @dest: Where to copy the string to
95 * @src: Where to copy the string from
96 */
97#undef strcpy
98char *strcpy(char *dest, const char *src)
99{
100 char *tmp = dest;
101
102 while ((*dest++ = *src++) != '\0')
103 /* nothing */;
104 return tmp;
105}
106EXPORT_SYMBOL(strcpy);
107#endif
108
109#ifndef __HAVE_ARCH_STRNCPY
110/**
111 * strncpy - Copy a length-limited, %NUL-terminated string
112 * @dest: Where to copy the string to
113 * @src: Where to copy the string from
114 * @count: The maximum number of bytes to copy
115 *
116 * The result is not %NUL-terminated if the source exceeds
117 * @count bytes.
118 *
119 * In the case where the length of @src is less than that of
120 * count, the remainder of @dest will be padded with %NUL.
121 *
122 */
123char *strncpy(char *dest, const char *src, size_t count)
124{
125 char *tmp = dest;
126
127 while (count) {
128 if ((*tmp = *src) != 0)
129 src++;
130 tmp++;
131 count--;
132 }
133 return dest;
134}
135EXPORT_SYMBOL(strncpy);
136#endif
137
138#ifndef __HAVE_ARCH_STRLCPY
139/**
140 * strlcpy - Copy a %NUL terminated string into a sized buffer
141 * @dest: Where to copy the string to
142 * @src: Where to copy the string from
143 * @size: size of destination buffer
144 *
145 * Compatible with *BSD: the result is always a valid
146 * NUL-terminated string that fits in the buffer (unless,
147 * of course, the buffer size is zero). It does not pad
148 * out the result like strncpy() does.
149 */
150size_t strlcpy(char *dest, const char *src, size_t size)
151{
152 size_t ret = strlen(src);
153
154 if (size) {
155 size_t len = (ret >= size) ? size - 1 : ret;
156 memcpy(dest, src, len);
157 dest[len] = '\0';
158 }
159 return ret;
160}
161EXPORT_SYMBOL(strlcpy);
162#endif
163
164#ifndef __HAVE_ARCH_STRCAT
165/**
166 * strcat - Append one %NUL-terminated string to another
167 * @dest: The string to be appended to
168 * @src: The string to append to it
169 */
170#undef strcat
171char *strcat(char *dest, const char *src)
172{
173 char *tmp = dest;
174
175 while (*dest)
176 dest++;
177 while ((*dest++ = *src++) != '\0')
178 ;
179 return tmp;
180}
181EXPORT_SYMBOL(strcat);
182#endif
183
184#ifndef __HAVE_ARCH_STRNCAT
185/**
186 * strncat - Append a length-limited, %NUL-terminated string to another
187 * @dest: The string to be appended to
188 * @src: The string to append to it
189 * @count: The maximum numbers of bytes to copy
190 *
191 * Note that in contrast to strncpy(), strncat() ensures the result is
192 * terminated.
193 */
194char *strncat(char *dest, const char *src, size_t count)
195{
196 char *tmp = dest;
197
198 if (count) {
199 while (*dest)
200 dest++;
201 while ((*dest++ = *src++) != 0) {
202 if (--count == 0) {
203 *dest = '\0';
204 break;
205 }
206 }
207 }
208 return tmp;
209}
210EXPORT_SYMBOL(strncat);
211#endif
212
213#ifndef __HAVE_ARCH_STRLCAT
214/**
215 * strlcat - Append a length-limited, %NUL-terminated string to another
216 * @dest: The string to be appended to
217 * @src: The string to append to it
218 * @count: The size of the destination buffer.
219 */
220size_t strlcat(char *dest, const char *src, size_t count)
221{
222 size_t dsize = strlen(dest);
223 size_t len = strlen(src);
224 size_t res = dsize + len;
225
226 /* This would be a bug */
227 BUG_ON(dsize >= count);
228
229 dest += dsize;
230 count -= dsize;
231 if (len >= count)
232 len = count-1;
233 memcpy(dest, src, len);
234 dest[len] = 0;
235 return res;
236}
237EXPORT_SYMBOL(strlcat);
238#endif
239
240#ifndef __HAVE_ARCH_STRCMP
241/**
242 * strcmp - Compare two strings
243 * @cs: One string
244 * @ct: Another string
245 */
246#undef strcmp
247int strcmp(const char *cs, const char *ct)
248{
249 signed char __res;
250
251 while (1) {
252 if ((__res = *cs - *ct++) != 0 || !*cs++)
253 break;
254 }
255 return __res;
256}
257EXPORT_SYMBOL(strcmp);
258#endif
259
260#ifndef __HAVE_ARCH_STRNCMP
261/**
262 * strncmp - Compare two length-limited strings
263 * @cs: One string
264 * @ct: Another string
265 * @count: The maximum number of bytes to compare
266 */
267int strncmp(const char *cs, const char *ct, size_t count)
268{
269 signed char __res = 0;
270
271 while (count) {
272 if ((__res = *cs - *ct++) != 0 || !*cs++)
273 break;
274 count--;
275 }
276 return __res;
277}
278EXPORT_SYMBOL(strncmp);
279#endif
280
281#ifndef __HAVE_ARCH_STRCHR
282/**
283 * strchr - Find the first occurrence of a character in a string
284 * @s: The string to be searched
285 * @c: The character to search for
286 */
287char *strchr(const char *s, int c)
288{
289 for (; *s != (char)c; ++s)
290 if (*s == '\0')
291 return NULL;
292 return (char *)s;
293}
294EXPORT_SYMBOL(strchr);
295#endif
296
297#ifndef __HAVE_ARCH_STRRCHR
298/**
299 * strrchr - Find the last occurrence of a character in a string
300 * @s: The string to be searched
301 * @c: The character to search for
302 */
303char *strrchr(const char *s, int c)
304{
305 const char *p = s + strlen(s);
306 do {
307 if (*p == (char)c)
308 return (char *)p;
309 } while (--p >= s);
310 return NULL;
311}
312EXPORT_SYMBOL(strrchr);
313#endif
314
315#ifndef __HAVE_ARCH_STRNCHR
316/**
317 * strnchr - Find a character in a length limited string
318 * @s: The string to be searched
319 * @count: The number of characters to be searched
320 * @c: The character to search for
321 */
322char *strnchr(const char *s, size_t count, int c)
323{
324 for (; count-- && *s != '\0'; ++s)
325 if (*s == (char)c)
326 return (char *)s;
327 return NULL;
328}
329EXPORT_SYMBOL(strnchr);
330#endif
331
332/**
333 * strstrip - Removes leading and trailing whitespace from @s.
334 * @s: The string to be stripped.
335 *
336 * Note that the first trailing whitespace is replaced with a %NUL-terminator
337 * in the given string @s. Returns a pointer to the first non-whitespace
338 * character in @s.
339 */
340char *strstrip(char *s)
341{
342 size_t size;
343 char *end;
344
345 size = strlen(s);
346
347 if (!size)
348 return s;
349
350 end = s + size - 1;
351 while (end >= s && isspace(*end))
352 end--;
353 *(end + 1) = '\0';
354
355 while (*s && isspace(*s))
356 s++;
357
358 return s;
359}
360EXPORT_SYMBOL(strstrip);
361
362#ifndef __HAVE_ARCH_STRLEN
363/**
364 * strlen - Find the length of a string
365 * @s: The string to be sized
366 */
367size_t strlen(const char *s)
368{
369 const char *sc;
370
371 for (sc = s; *sc != '\0'; ++sc)
372 /* nothing */;
373 return sc - s;
374}
375EXPORT_SYMBOL(strlen);
376#endif
377
378#ifndef __HAVE_ARCH_STRNLEN
379/**
380 * strnlen - Find the length of a length-limited string
381 * @s: The string to be sized
382 * @count: The maximum number of bytes to search
383 */
384size_t strnlen(const char *s, size_t count)
385{
386 const char *sc;
387
388 for (sc = s; count-- && *sc != '\0'; ++sc)
389 /* nothing */;
390 return sc - s;
391}
392EXPORT_SYMBOL(strnlen);
393#endif
394
395#ifndef __HAVE_ARCH_STRSPN
396/**
397 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
398 * @s: The string to be searched
399 * @accept: The string to search for
400 */
401size_t strspn(const char *s, const char *accept)
402{
403 const char *p;
404 const char *a;
405 size_t count = 0;
406
407 for (p = s; *p != '\0'; ++p) {
408 for (a = accept; *a != '\0'; ++a) {
409 if (*p == *a)
410 break;
411 }
412 if (*a == '\0')
413 return count;
414 ++count;
415 }
416 return count;
417}
418
419EXPORT_SYMBOL(strspn);
420#endif
421
422#ifndef __HAVE_ARCH_STRCSPN
423/**
424 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
425 * @s: The string to be searched
426 * @reject: The string to avoid
427 */
428size_t strcspn(const char *s, const char *reject)
429{
430 const char *p;
431 const char *r;
432 size_t count = 0;
433
434 for (p = s; *p != '\0'; ++p) {
435 for (r = reject; *r != '\0'; ++r) {
436 if (*p == *r)
437 return count;
438 }
439 ++count;
440 }
441 return count;
442}
443EXPORT_SYMBOL(strcspn);
444#endif
445
446#ifndef __HAVE_ARCH_STRPBRK
447/**
448 * strpbrk - Find the first occurrence of a set of characters
449 * @cs: The string to be searched
450 * @ct: The characters to search for
451 */
452char *strpbrk(const char *cs, const char *ct)
453{
454 const char *sc1, *sc2;
455
456 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
457 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
458 if (*sc1 == *sc2)
459 return (char *)sc1;
460 }
461 }
462 return NULL;
463}
464EXPORT_SYMBOL(strpbrk);
465#endif
466
467#ifndef __HAVE_ARCH_STRSEP
468/**
469 * strsep - Split a string into tokens
470 * @s: The string to be searched
471 * @ct: The characters to search for
472 *
473 * strsep() updates @s to point after the token, ready for the next call.
474 *
475 * It returns empty tokens, too, behaving exactly like the libc function
476 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
477 * Same semantics, slimmer shape. ;)
478 */
479char *strsep(char **s, const char *ct)
480{
481 char *sbegin = *s;
482 char *end;
483
484 if (sbegin == NULL)
485 return NULL;
486
487 end = strpbrk(sbegin, ct);
488 if (end)
489 *end++ = '\0';
490 *s = end;
491 return sbegin;
492}
493EXPORT_SYMBOL(strsep);
494#endif
495
496/**
497 * sysfs_streq - return true if strings are equal, modulo trailing newline
498 * @s1: one string
499 * @s2: another string
500 *
501 * This routine returns true iff two strings are equal, treating both
502 * NUL and newline-then-NUL as equivalent string terminations. It's
503 * geared for use with sysfs input strings, which generally terminate
504 * with newlines but are compared against values without newlines.
505 */
506bool sysfs_streq(const char *s1, const char *s2)
507{
508 while (*s1 && *s1 == *s2) {
509 s1++;
510 s2++;
511 }
512
513 if (*s1 == *s2)
514 return true;
515 if (!*s1 && *s2 == '\n' && !s2[1])
516 return true;
517 if (*s1 == '\n' && !s1[1] && !*s2)
518 return true;
519 return false;
520}
521EXPORT_SYMBOL(sysfs_streq);
522
523#ifndef __HAVE_ARCH_MEMSET
524/**
525 * memset - Fill a region of memory with the given value
526 * @s: Pointer to the start of the area.
527 * @c: The byte to fill the area with
528 * @count: The size of the area.
529 *
530 * Do not use memset() to access IO space, use memset_io() instead.
531 */
532void *memset(void *s, int c, size_t count)
533{
534 char *xs = s;
535
536 while (count--)
537 *xs++ = c;
538 return s;
539}
540EXPORT_SYMBOL(memset);
541#endif
542
543#ifndef __HAVE_ARCH_MEMCPY
544/**
545 * memcpy - Copy one area of memory to another
546 * @dest: Where to copy to
547 * @src: Where to copy from
548 * @count: The size of the area.
549 *
550 * You should not use this function to access IO space, use memcpy_toio()
551 * or memcpy_fromio() instead.
552 */
553void *memcpy(void *dest, const void *src, size_t count)
554{
555 char *tmp = dest;
556 const char *s = src;
557
558 while (count--)
559 *tmp++ = *s++;
560 return dest;
561}
562EXPORT_SYMBOL(memcpy);
563#endif
564
565#ifndef __HAVE_ARCH_MEMMOVE
566/**
567 * memmove - Copy one area of memory to another
568 * @dest: Where to copy to
569 * @src: Where to copy from
570 * @count: The size of the area.
571 *
572 * Unlike memcpy(), memmove() copes with overlapping areas.
573 */
574void *memmove(void *dest, const void *src, size_t count)
575{
576 char *tmp;
577 const char *s;
578
579 if (dest <= src) {
580 tmp = dest;
581 s = src;
582 while (count--)
583 *tmp++ = *s++;
584 } else {
585 tmp = dest;
586 tmp += count;
587 s = src;
588 s += count;
589 while (count--)
590 *--tmp = *--s;
591 }
592 return dest;
593}
594EXPORT_SYMBOL(memmove);
595#endif
596
597#ifndef __HAVE_ARCH_MEMCMP
598/**
599 * memcmp - Compare two areas of memory
600 * @cs: One area of memory
601 * @ct: Another area of memory
602 * @count: The size of the area.
603 */
604#undef memcmp
605int memcmp(const void *cs, const void *ct, size_t count)
606{
607 const unsigned char *su1, *su2;
608 int res = 0;
609
610 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
611 if ((res = *su1 - *su2) != 0)
612 break;
613 return res;
614}
615EXPORT_SYMBOL(memcmp);
616#endif
617
618#ifndef __HAVE_ARCH_MEMSCAN
619/**
620 * memscan - Find a character in an area of memory.
621 * @addr: The memory area
622 * @c: The byte to search for
623 * @size: The size of the area.
624 *
625 * returns the address of the first occurrence of @c, or 1 byte past
626 * the area if @c is not found
627 */
628void *memscan(void *addr, int c, size_t size)
629{
630 unsigned char *p = addr;
631
632 while (size) {
633 if (*p == c)
634 return (void *)p;
635 p++;
636 size--;
637 }
638 return (void *)p;
639}
640EXPORT_SYMBOL(memscan);
641#endif
642
643#ifndef __HAVE_ARCH_STRSTR
644/**
645 * strstr - Find the first substring in a %NUL terminated string
646 * @s1: The string to be searched
647 * @s2: The string to search for
648 */
649char *strstr(const char *s1, const char *s2)
650{
651 int l1, l2;
652
653 l2 = strlen(s2);
654 if (!l2)
655 return (char *)s1;
656 l1 = strlen(s1);
657 while (l1 >= l2) {
658 l1--;
659 if (!memcmp(s1, s2, l2))
660 return (char *)s1;
661 s1++;
662 }
663 return NULL;
664}
665EXPORT_SYMBOL(strstr);
666#endif
667
668#ifndef __HAVE_ARCH_MEMCHR
669/**
670 * memchr - Find a character in an area of memory.
671 * @s: The memory area
672 * @c: The byte to search for
673 * @n: The size of the area.
674 *
675 * returns the address of the first occurrence of @c, or %NULL
676 * if @c is not found
677 */
678void *memchr(const void *s, int c, size_t n)
679{
680 const unsigned char *p = s;
681 while (n-- != 0) {
682 if ((unsigned char)c == *p++) {
683 return (void *)(p - 1);
684 }
685 }
686 return NULL;
687}
688EXPORT_SYMBOL(memchr);
689#endif