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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 <ioe@informatik.tu-chemnitz.de>
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 <jason@topic.com.au>,
18 * Matthew Hawkins <matt@mh.dropbear.id.au>
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 = 0; c2 = 0;
40 if (len) {
41 do {
42 c1 = *s1; c2 = *s2;
43 s1++; s2++;
44 if (!c1)
45 break;
46 if (!c2)
47 break;
48 if (c1 == c2)
49 continue;
50 c1 = tolower(c1);
51 c2 = tolower(c2);
52 if (c1 != c2)
53 break;
54 } while (--len);
55 }
56 return (int)c1 - (int)c2;
57}
58
59EXPORT_SYMBOL(strnicmp);
60#endif
61
62#ifndef __HAVE_ARCH_STRCPY
63/**
64 * strcpy - Copy a %NUL terminated string
65 * @dest: Where to copy the string to
66 * @src: Where to copy the string from
67 */
68char * strcpy(char * dest,const char *src)
69{
70 char *tmp = dest;
71
72 while ((*dest++ = *src++) != '\0')
73 /* nothing */;
74 return tmp;
75}
76EXPORT_SYMBOL(strcpy);
77#endif
78
79#ifndef __HAVE_ARCH_STRNCPY
80/**
81 * strncpy - Copy a length-limited, %NUL-terminated string
82 * @dest: Where to copy the string to
83 * @src: Where to copy the string from
84 * @count: The maximum number of bytes to copy
85 *
86 * The result is not %NUL-terminated if the source exceeds
87 * @count bytes.
88 */
89char * strncpy(char * dest,const char *src,size_t count)
90{
91 char *tmp = dest;
92
93 while (count) {
94 if ((*tmp = *src) != 0) src++;
95 tmp++;
96 count--;
97 }
98 return dest;
99}
100EXPORT_SYMBOL(strncpy);
101#endif
102
103#ifndef __HAVE_ARCH_STRLCPY
104/**
105 * strlcpy - Copy a %NUL terminated string into a sized buffer
106 * @dest: Where to copy the string to
107 * @src: Where to copy the string from
108 * @size: size of destination buffer
109 *
110 * Compatible with *BSD: the result is always a valid
111 * NUL-terminated string that fits in the buffer (unless,
112 * of course, the buffer size is zero). It does not pad
113 * out the result like strncpy() does.
114 */
115size_t strlcpy(char *dest, const char *src, size_t size)
116{
117 size_t ret = strlen(src);
118
119 if (size) {
120 size_t len = (ret >= size) ? size-1 : ret;
121 memcpy(dest, src, len);
122 dest[len] = '\0';
123 }
124 return ret;
125}
126EXPORT_SYMBOL(strlcpy);
127#endif
128
129#ifndef __HAVE_ARCH_STRCAT
130/**
131 * strcat - Append one %NUL-terminated string to another
132 * @dest: The string to be appended to
133 * @src: The string to append to it
134 */
135char * strcat(char * dest, const char * src)
136{
137 char *tmp = dest;
138
139 while (*dest)
140 dest++;
141 while ((*dest++ = *src++) != '\0')
142 ;
143
144 return tmp;
145}
146EXPORT_SYMBOL(strcat);
147#endif
148
149#ifndef __HAVE_ARCH_STRNCAT
150/**
151 * strncat - Append a length-limited, %NUL-terminated string to another
152 * @dest: The string to be appended to
153 * @src: The string to append to it
154 * @count: The maximum numbers of bytes to copy
155 *
156 * Note that in contrast to strncpy, strncat ensures the result is
157 * terminated.
158 */
159char * strncat(char *dest, const char *src, size_t count)
160{
161 char *tmp = dest;
162
163 if (count) {
164 while (*dest)
165 dest++;
166 while ((*dest++ = *src++) != 0) {
167 if (--count == 0) {
168 *dest = '\0';
169 break;
170 }
171 }
172 }
173
174 return tmp;
175}
176EXPORT_SYMBOL(strncat);
177#endif
178
179#ifndef __HAVE_ARCH_STRLCAT
180/**
181 * strlcat - Append a length-limited, %NUL-terminated string to another
182 * @dest: The string to be appended to
183 * @src: The string to append to it
184 * @count: The size of the destination buffer.
185 */
186size_t strlcat(char *dest, const char *src, size_t count)
187{
188 size_t dsize = strlen(dest);
189 size_t len = strlen(src);
190 size_t res = dsize + len;
191
192 /* This would be a bug */
193 BUG_ON(dsize >= count);
194
195 dest += dsize;
196 count -= dsize;
197 if (len >= count)
198 len = count-1;
199 memcpy(dest, src, len);
200 dest[len] = 0;
201 return res;
202}
203EXPORT_SYMBOL(strlcat);
204#endif
205
206#ifndef __HAVE_ARCH_STRCMP
207/**
208 * strcmp - Compare two strings
209 * @cs: One string
210 * @ct: Another string
211 */
212int strcmp(const char * cs,const char * ct)
213{
214 register signed char __res;
215
216 while (1) {
217 if ((__res = *cs - *ct++) != 0 || !*cs++)
218 break;
219 }
220
221 return __res;
222}
223EXPORT_SYMBOL(strcmp);
224#endif
225
226#ifndef __HAVE_ARCH_STRNCMP
227/**
228 * strncmp - Compare two length-limited strings
229 * @cs: One string
230 * @ct: Another string
231 * @count: The maximum number of bytes to compare
232 */
233int strncmp(const char * cs,const char * ct,size_t count)
234{
235 register signed char __res = 0;
236
237 while (count) {
238 if ((__res = *cs - *ct++) != 0 || !*cs++)
239 break;
240 count--;
241 }
242
243 return __res;
244}
245EXPORT_SYMBOL(strncmp);
246#endif
247
248#ifndef __HAVE_ARCH_STRCHR
249/**
250 * strchr - Find the first occurrence of a character in a string
251 * @s: The string to be searched
252 * @c: The character to search for
253 */
254char * strchr(const char * s, int c)
255{
256 for(; *s != (char) c; ++s)
257 if (*s == '\0')
258 return NULL;
259 return (char *) s;
260}
261EXPORT_SYMBOL(strchr);
262#endif
263
264#ifndef __HAVE_ARCH_STRRCHR
265/**
266 * strrchr - Find the last occurrence of a character in a string
267 * @s: The string to be searched
268 * @c: The character to search for
269 */
270char * strrchr(const char * s, int c)
271{
272 const char *p = s + strlen(s);
273 do {
274 if (*p == (char)c)
275 return (char *)p;
276 } while (--p >= s);
277 return NULL;
278}
279EXPORT_SYMBOL(strrchr);
280#endif
281
282#ifndef __HAVE_ARCH_STRNCHR
283/**
284 * strnchr - Find a character in a length limited string
285 * @s: The string to be searched
286 * @count: The number of characters to be searched
287 * @c: The character to search for
288 */
289char *strnchr(const char *s, size_t count, int c)
290{
291 for (; count-- && *s != '\0'; ++s)
292 if (*s == (char) c)
293 return (char *) s;
294 return NULL;
295}
296EXPORT_SYMBOL(strnchr);
297#endif
298
299#ifndef __HAVE_ARCH_STRLEN
300/**
301 * strlen - Find the length of a string
302 * @s: The string to be sized
303 */
304size_t strlen(const char * s)
305{
306 const char *sc;
307
308 for (sc = s; *sc != '\0'; ++sc)
309 /* nothing */;
310 return sc - s;
311}
312EXPORT_SYMBOL(strlen);
313#endif
314
315#ifndef __HAVE_ARCH_STRNLEN
316/**
317 * strnlen - Find the length of a length-limited string
318 * @s: The string to be sized
319 * @count: The maximum number of bytes to search
320 */
321size_t strnlen(const char * s, size_t count)
322{
323 const char *sc;
324
325 for (sc = s; count-- && *sc != '\0'; ++sc)
326 /* nothing */;
327 return sc - s;
328}
329EXPORT_SYMBOL(strnlen);
330#endif
331
332#ifndef __HAVE_ARCH_STRSPN
333/**
334 * strspn - Calculate the length of the initial substring of @s which only
335 * contain letters in @accept
336 * @s: The string to be searched
337 * @accept: The string to search for
338 */
339size_t strspn(const char *s, const char *accept)
340{
341 const char *p;
342 const char *a;
343 size_t count = 0;
344
345 for (p = s; *p != '\0'; ++p) {
346 for (a = accept; *a != '\0'; ++a) {
347 if (*p == *a)
348 break;
349 }
350 if (*a == '\0')
351 return count;
352 ++count;
353 }
354
355 return count;
356}
357
358EXPORT_SYMBOL(strspn);
359#endif
360
361/**
362 * strcspn - Calculate the length of the initial substring of @s which does
363 * not contain letters in @reject
364 * @s: The string to be searched
365 * @reject: The string to avoid
366 */
367size_t strcspn(const char *s, const char *reject)
368{
369 const char *p;
370 const char *r;
371 size_t count = 0;
372
373 for (p = s; *p != '\0'; ++p) {
374 for (r = reject; *r != '\0'; ++r) {
375 if (*p == *r)
376 return count;
377 }
378 ++count;
379 }
380
381 return count;
382}
383EXPORT_SYMBOL(strcspn);
384
385#ifndef __HAVE_ARCH_STRPBRK
386/**
387 * strpbrk - Find the first occurrence of a set of characters
388 * @cs: The string to be searched
389 * @ct: The characters to search for
390 */
391char * strpbrk(const char * cs,const char * ct)
392{
393 const char *sc1,*sc2;
394
395 for( sc1 = cs; *sc1 != '\0'; ++sc1) {
396 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
397 if (*sc1 == *sc2)
398 return (char *) sc1;
399 }
400 }
401 return NULL;
402}
403EXPORT_SYMBOL(strpbrk);
404#endif
405
406#ifndef __HAVE_ARCH_STRSEP
407/**
408 * strsep - Split a string into tokens
409 * @s: The string to be searched
410 * @ct: The characters to search for
411 *
412 * strsep() updates @s to point after the token, ready for the next call.
413 *
414 * It returns empty tokens, too, behaving exactly like the libc function
415 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
416 * Same semantics, slimmer shape. ;)
417 */
418char * strsep(char **s, const char *ct)
419{
420 char *sbegin = *s, *end;
421
422 if (sbegin == NULL)
423 return NULL;
424
425 end = strpbrk(sbegin, ct);
426 if (end)
427 *end++ = '\0';
428 *s = end;
429
430 return sbegin;
431}
432
433EXPORT_SYMBOL(strsep);
434#endif
435
436#ifndef __HAVE_ARCH_MEMSET
437/**
438 * memset - Fill a region of memory with the given value
439 * @s: Pointer to the start of the area.
440 * @c: The byte to fill the area with
441 * @count: The size of the area.
442 *
443 * Do not use memset() to access IO space, use memset_io() instead.
444 */
445void * memset(void * s,int c,size_t count)
446{
447 char *xs = (char *) s;
448
449 while (count--)
450 *xs++ = c;
451
452 return s;
453}
454EXPORT_SYMBOL(memset);
455#endif
456
457#ifndef __HAVE_ARCH_MEMCPY
458/**
459 * memcpy - Copy one area of memory to another
460 * @dest: Where to copy to
461 * @src: Where to copy from
462 * @count: The size of the area.
463 *
464 * You should not use this function to access IO space, use memcpy_toio()
465 * or memcpy_fromio() instead.
466 */
467void * memcpy(void * dest,const void *src,size_t count)
468{
469 char *tmp = (char *) dest, *s = (char *) src;
470
471 while (count--)
472 *tmp++ = *s++;
473
474 return dest;
475}
476EXPORT_SYMBOL(memcpy);
477#endif
478
479#ifndef __HAVE_ARCH_MEMMOVE
480/**
481 * memmove - Copy one area of memory to another
482 * @dest: Where to copy to
483 * @src: Where to copy from
484 * @count: The size of the area.
485 *
486 * Unlike memcpy(), memmove() copes with overlapping areas.
487 */
488void * memmove(void * dest,const void *src,size_t count)
489{
490 char *tmp, *s;
491
492 if (dest <= src) {
493 tmp = (char *) dest;
494 s = (char *) src;
495 while (count--)
496 *tmp++ = *s++;
497 }
498 else {
499 tmp = (char *) dest + count;
500 s = (char *) src + count;
501 while (count--)
502 *--tmp = *--s;
503 }
504
505 return dest;
506}
507EXPORT_SYMBOL(memmove);
508#endif
509
510#ifndef __HAVE_ARCH_MEMCMP
511/**
512 * memcmp - Compare two areas of memory
513 * @cs: One area of memory
514 * @ct: Another area of memory
515 * @count: The size of the area.
516 */
517int memcmp(const void * cs,const void * ct,size_t count)
518{
519 const unsigned char *su1, *su2;
520 int res = 0;
521
522 for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
523 if ((res = *su1 - *su2) != 0)
524 break;
525 return res;
526}
527EXPORT_SYMBOL(memcmp);
528#endif
529
530#ifndef __HAVE_ARCH_MEMSCAN
531/**
532 * memscan - Find a character in an area of memory.
533 * @addr: The memory area
534 * @c: The byte to search for
535 * @size: The size of the area.
536 *
537 * returns the address of the first occurrence of @c, or 1 byte past
538 * the area if @c is not found
539 */
540void * memscan(void * addr, int c, size_t size)
541{
542 unsigned char * p = (unsigned char *) addr;
543
544 while (size) {
545 if (*p == c)
546 return (void *) p;
547 p++;
548 size--;
549 }
550 return (void *) p;
551}
552EXPORT_SYMBOL(memscan);
553#endif
554
555#ifndef __HAVE_ARCH_STRSTR
556/**
557 * strstr - Find the first substring in a %NUL terminated string
558 * @s1: The string to be searched
559 * @s2: The string to search for
560 */
561char * strstr(const char * s1,const char * s2)
562{
563 int l1, l2;
564
565 l2 = strlen(s2);
566 if (!l2)
567 return (char *) s1;
568 l1 = strlen(s1);
569 while (l1 >= l2) {
570 l1--;
571 if (!memcmp(s1,s2,l2))
572 return (char *) s1;
573 s1++;
574 }
575 return NULL;
576}
577EXPORT_SYMBOL(strstr);
578#endif
579
580#ifndef __HAVE_ARCH_MEMCHR
581/**
582 * memchr - Find a character in an area of memory.
583 * @s: The memory area
584 * @c: The byte to search for
585 * @n: The size of the area.
586 *
587 * returns the address of the first occurrence of @c, or %NULL
588 * if @c is not found
589 */
590void *memchr(const void *s, int c, size_t n)
591{
592 const unsigned char *p = s;
593 while (n-- != 0) {
594 if ((unsigned char)c == *p++) {
595 return (void *)(p-1);
596 }
597 }
598 return NULL;
599}
600EXPORT_SYMBOL(memchr);
601#endif