projects/linux·blob v4.3-rc5 · refs

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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/kernel.h>
26#include <linux/export.h>
27#include <linux/bug.h>
28#include <linux/errno.h>
29
30#include <asm/byteorder.h>
31#include <asm/word-at-a-time.h>
32#include <asm/page.h>
33
34#ifndef __HAVE_ARCH_STRNCASECMP
35/**
36 * strncasecmp - Case insensitive, length-limited string comparison
37 * @s1: One string
38 * @s2: The other string
39 * @len: the maximum number of characters to compare
40 */
41int strncasecmp(const char *s1, const char *s2, size_t len)
42{
43 /* Yes, Virginia, it had better be unsigned */
44 unsigned char c1, c2;
45
46 if (!len)
47 return 0;
48
49 do {
50 c1 = *s1++;
51 c2 = *s2++;
52 if (!c1 || !c2)
53 break;
54 if (c1 == c2)
55 continue;
56 c1 = tolower(c1);
57 c2 = tolower(c2);
58 if (c1 != c2)
59 break;
60 } while (--len);
61 return (int)c1 - (int)c2;
62}
63EXPORT_SYMBOL(strncasecmp);
64#endif
65
66#ifndef __HAVE_ARCH_STRCASECMP
67int strcasecmp(const char *s1, const char *s2)
68{
69 int c1, c2;
70
71 do {
72 c1 = tolower(*s1++);
73 c2 = tolower(*s2++);
74 } while (c1 == c2 && c1 != 0);
75 return c1 - c2;
76}
77EXPORT_SYMBOL(strcasecmp);
78#endif
79
80#ifndef __HAVE_ARCH_STRCPY
81/**
82 * strcpy - Copy a %NUL terminated string
83 * @dest: Where to copy the string to
84 * @src: Where to copy the string from
85 */
86#undef strcpy
87char *strcpy(char *dest, const char *src)
88{
89 char *tmp = dest;
90
91 while ((*dest++ = *src++) != '\0')
92 /* nothing */;
93 return tmp;
94}
95EXPORT_SYMBOL(strcpy);
96#endif
97
98#ifndef __HAVE_ARCH_STRNCPY
99/**
100 * strncpy - Copy a length-limited, C-string
101 * @dest: Where to copy the string to
102 * @src: Where to copy the string from
103 * @count: The maximum number of bytes to copy
104 *
105 * The result is not %NUL-terminated if the source exceeds
106 * @count bytes.
107 *
108 * In the case where the length of @src is less than that of
109 * count, the remainder of @dest will be padded with %NUL.
110 *
111 */
112char *strncpy(char *dest, const char *src, size_t count)
113{
114 char *tmp = dest;
115
116 while (count) {
117 if ((*tmp = *src) != 0)
118 src++;
119 tmp++;
120 count--;
121 }
122 return dest;
123}
124EXPORT_SYMBOL(strncpy);
125#endif
126
127#ifndef __HAVE_ARCH_STRLCPY
128/**
129 * strlcpy - Copy a C-string into a sized buffer
130 * @dest: Where to copy the string to
131 * @src: Where to copy the string from
132 * @size: size of destination buffer
133 *
134 * Compatible with *BSD: the result is always a valid
135 * NUL-terminated string that fits in the buffer (unless,
136 * of course, the buffer size is zero). It does not pad
137 * out the result like strncpy() does.
138 */
139size_t strlcpy(char *dest, const char *src, size_t size)
140{
141 size_t ret = strlen(src);
142
143 if (size) {
144 size_t len = (ret >= size) ? size - 1 : ret;
145 memcpy(dest, src, len);
146 dest[len] = '\0';
147 }
148 return ret;
149}
150EXPORT_SYMBOL(strlcpy);
151#endif
152
153#ifndef __HAVE_ARCH_STRSCPY
154/**
155 * strscpy - Copy a C-string into a sized buffer
156 * @dest: Where to copy the string to
157 * @src: Where to copy the string from
158 * @count: Size of destination buffer
159 *
160 * Copy the string, or as much of it as fits, into the dest buffer.
161 * The routine returns the number of characters copied (not including
162 * the trailing NUL) or -E2BIG if the destination buffer wasn't big enough.
163 * The behavior is undefined if the string buffers overlap.
164 * The destination buffer is always NUL terminated, unless it's zero-sized.
165 *
166 * Preferred to strlcpy() since the API doesn't require reading memory
167 * from the src string beyond the specified "count" bytes, and since
168 * the return value is easier to error-check than strlcpy()'s.
169 * In addition, the implementation is robust to the string changing out
170 * from underneath it, unlike the current strlcpy() implementation.
171 *
172 * Preferred to strncpy() since it always returns a valid string, and
173 * doesn't unnecessarily force the tail of the destination buffer to be
174 * zeroed. If the zeroing is desired, it's likely cleaner to use strscpy()
175 * with an overflow test, then just memset() the tail of the dest buffer.
176 */
177ssize_t strscpy(char *dest, const char *src, size_t count)
178{
179 const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
180 size_t max = count;
181 long res = 0;
182
183 if (count == 0)
184 return -E2BIG;
185
186#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
187 /*
188 * If src is unaligned, don't cross a page boundary,
189 * since we don't know if the next page is mapped.
190 */
191 if ((long)src & (sizeof(long) - 1)) {
192 size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
193 if (limit < max)
194 max = limit;
195 }
196#else
197 /* If src or dest is unaligned, don't do word-at-a-time. */
198 if (((long) dest | (long) src) & (sizeof(long) - 1))
199 max = 0;
200#endif
201
202 while (max >= sizeof(unsigned long)) {
203 unsigned long c, data;
204
205 c = *(unsigned long *)(src+res);
206 if (has_zero(c, &data, &constants)) {
207 data = prep_zero_mask(c, data, &constants);
208 data = create_zero_mask(data);
209 *(unsigned long *)(dest+res) = c & zero_bytemask(data);
210 return res + find_zero(data);
211 }
212 *(unsigned long *)(dest+res) = c;
213 res += sizeof(unsigned long);
214 count -= sizeof(unsigned long);
215 max -= sizeof(unsigned long);
216 }
217
218 while (count) {
219 char c;
220
221 c = src[res];
222 dest[res] = c;
223 if (!c)
224 return res;
225 res++;
226 count--;
227 }
228
229 /* Hit buffer length without finding a NUL; force NUL-termination. */
230 if (res)
231 dest[res-1] = '\0';
232
233 return -E2BIG;
234}
235EXPORT_SYMBOL(strscpy);
236#endif
237
238#ifndef __HAVE_ARCH_STRCAT
239/**
240 * strcat - Append one %NUL-terminated string to another
241 * @dest: The string to be appended to
242 * @src: The string to append to it
243 */
244#undef strcat
245char *strcat(char *dest, const char *src)
246{
247 char *tmp = dest;
248
249 while (*dest)
250 dest++;
251 while ((*dest++ = *src++) != '\0')
252 ;
253 return tmp;
254}
255EXPORT_SYMBOL(strcat);
256#endif
257
258#ifndef __HAVE_ARCH_STRNCAT
259/**
260 * strncat - Append a length-limited, C-string to another
261 * @dest: The string to be appended to
262 * @src: The string to append to it
263 * @count: The maximum numbers of bytes to copy
264 *
265 * Note that in contrast to strncpy(), strncat() ensures the result is
266 * terminated.
267 */
268char *strncat(char *dest, const char *src, size_t count)
269{
270 char *tmp = dest;
271
272 if (count) {
273 while (*dest)
274 dest++;
275 while ((*dest++ = *src++) != 0) {
276 if (--count == 0) {
277 *dest = '\0';
278 break;
279 }
280 }
281 }
282 return tmp;
283}
284EXPORT_SYMBOL(strncat);
285#endif
286
287#ifndef __HAVE_ARCH_STRLCAT
288/**
289 * strlcat - Append a length-limited, C-string to another
290 * @dest: The string to be appended to
291 * @src: The string to append to it
292 * @count: The size of the destination buffer.
293 */
294size_t strlcat(char *dest, const char *src, size_t count)
295{
296 size_t dsize = strlen(dest);
297 size_t len = strlen(src);
298 size_t res = dsize + len;
299
300 /* This would be a bug */
301 BUG_ON(dsize >= count);
302
303 dest += dsize;
304 count -= dsize;
305 if (len >= count)
306 len = count-1;
307 memcpy(dest, src, len);
308 dest[len] = 0;
309 return res;
310}
311EXPORT_SYMBOL(strlcat);
312#endif
313
314#ifndef __HAVE_ARCH_STRCMP
315/**
316 * strcmp - Compare two strings
317 * @cs: One string
318 * @ct: Another string
319 */
320#undef strcmp
321int strcmp(const char *cs, const char *ct)
322{
323 unsigned char c1, c2;
324
325 while (1) {
326 c1 = *cs++;
327 c2 = *ct++;
328 if (c1 != c2)
329 return c1 < c2 ? -1 : 1;
330 if (!c1)
331 break;
332 }
333 return 0;
334}
335EXPORT_SYMBOL(strcmp);
336#endif
337
338#ifndef __HAVE_ARCH_STRNCMP
339/**
340 * strncmp - Compare two length-limited strings
341 * @cs: One string
342 * @ct: Another string
343 * @count: The maximum number of bytes to compare
344 */
345int strncmp(const char *cs, const char *ct, size_t count)
346{
347 unsigned char c1, c2;
348
349 while (count) {
350 c1 = *cs++;
351 c2 = *ct++;
352 if (c1 != c2)
353 return c1 < c2 ? -1 : 1;
354 if (!c1)
355 break;
356 count--;
357 }
358 return 0;
359}
360EXPORT_SYMBOL(strncmp);
361#endif
362
363#ifndef __HAVE_ARCH_STRCHR
364/**
365 * strchr - Find the first occurrence of a character in a string
366 * @s: The string to be searched
367 * @c: The character to search for
368 */
369char *strchr(const char *s, int c)
370{
371 for (; *s != (char)c; ++s)
372 if (*s == '\0')
373 return NULL;
374 return (char *)s;
375}
376EXPORT_SYMBOL(strchr);
377#endif
378
379#ifndef __HAVE_ARCH_STRCHRNUL
380/**
381 * strchrnul - Find and return a character in a string, or end of string
382 * @s: The string to be searched
383 * @c: The character to search for
384 *
385 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
386 * return a pointer to the null byte at the end of s.
387 */
388char *strchrnul(const char *s, int c)
389{
390 while (*s && *s != (char)c)
391 s++;
392 return (char *)s;
393}
394EXPORT_SYMBOL(strchrnul);
395#endif
396
397#ifndef __HAVE_ARCH_STRRCHR
398/**
399 * strrchr - Find the last occurrence of a character in a string
400 * @s: The string to be searched
401 * @c: The character to search for
402 */
403char *strrchr(const char *s, int c)
404{
405 const char *last = NULL;
406 do {
407 if (*s == (char)c)
408 last = s;
409 } while (*s++);
410 return (char *)last;
411}
412EXPORT_SYMBOL(strrchr);
413#endif
414
415#ifndef __HAVE_ARCH_STRNCHR
416/**
417 * strnchr - Find a character in a length limited string
418 * @s: The string to be searched
419 * @count: The number of characters to be searched
420 * @c: The character to search for
421 */
422char *strnchr(const char *s, size_t count, int c)
423{
424 for (; count-- && *s != '\0'; ++s)
425 if (*s == (char)c)
426 return (char *)s;
427 return NULL;
428}
429EXPORT_SYMBOL(strnchr);
430#endif
431
432/**
433 * skip_spaces - Removes leading whitespace from @str.
434 * @str: The string to be stripped.
435 *
436 * Returns a pointer to the first non-whitespace character in @str.
437 */
438char *skip_spaces(const char *str)
439{
440 while (isspace(*str))
441 ++str;
442 return (char *)str;
443}
444EXPORT_SYMBOL(skip_spaces);
445
446/**
447 * strim - Removes leading and trailing whitespace from @s.
448 * @s: The string to be stripped.
449 *
450 * Note that the first trailing whitespace is replaced with a %NUL-terminator
451 * in the given string @s. Returns a pointer to the first non-whitespace
452 * character in @s.
453 */
454char *strim(char *s)
455{
456 size_t size;
457 char *end;
458
459 size = strlen(s);
460 if (!size)
461 return s;
462
463 end = s + size - 1;
464 while (end >= s && isspace(*end))
465 end--;
466 *(end + 1) = '\0';
467
468 return skip_spaces(s);
469}
470EXPORT_SYMBOL(strim);
471
472#ifndef __HAVE_ARCH_STRLEN
473/**
474 * strlen - Find the length of a string
475 * @s: The string to be sized
476 */
477size_t strlen(const char *s)
478{
479 const char *sc;
480
481 for (sc = s; *sc != '\0'; ++sc)
482 /* nothing */;
483 return sc - s;
484}
485EXPORT_SYMBOL(strlen);
486#endif
487
488#ifndef __HAVE_ARCH_STRNLEN
489/**
490 * strnlen - Find the length of a length-limited string
491 * @s: The string to be sized
492 * @count: The maximum number of bytes to search
493 */
494size_t strnlen(const char *s, size_t count)
495{
496 const char *sc;
497
498 for (sc = s; count-- && *sc != '\0'; ++sc)
499 /* nothing */;
500 return sc - s;
501}
502EXPORT_SYMBOL(strnlen);
503#endif
504
505#ifndef __HAVE_ARCH_STRSPN
506/**
507 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
508 * @s: The string to be searched
509 * @accept: The string to search for
510 */
511size_t strspn(const char *s, const char *accept)
512{
513 const char *p;
514 const char *a;
515 size_t count = 0;
516
517 for (p = s; *p != '\0'; ++p) {
518 for (a = accept; *a != '\0'; ++a) {
519 if (*p == *a)
520 break;
521 }
522 if (*a == '\0')
523 return count;
524 ++count;
525 }
526 return count;
527}
528
529EXPORT_SYMBOL(strspn);
530#endif
531
532#ifndef __HAVE_ARCH_STRCSPN
533/**
534 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
535 * @s: The string to be searched
536 * @reject: The string to avoid
537 */
538size_t strcspn(const char *s, const char *reject)
539{
540 const char *p;
541 const char *r;
542 size_t count = 0;
543
544 for (p = s; *p != '\0'; ++p) {
545 for (r = reject; *r != '\0'; ++r) {
546 if (*p == *r)
547 return count;
548 }
549 ++count;
550 }
551 return count;
552}
553EXPORT_SYMBOL(strcspn);
554#endif
555
556#ifndef __HAVE_ARCH_STRPBRK
557/**
558 * strpbrk - Find the first occurrence of a set of characters
559 * @cs: The string to be searched
560 * @ct: The characters to search for
561 */
562char *strpbrk(const char *cs, const char *ct)
563{
564 const char *sc1, *sc2;
565
566 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
567 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
568 if (*sc1 == *sc2)
569 return (char *)sc1;
570 }
571 }
572 return NULL;
573}
574EXPORT_SYMBOL(strpbrk);
575#endif
576
577#ifndef __HAVE_ARCH_STRSEP
578/**
579 * strsep - Split a string into tokens
580 * @s: The string to be searched
581 * @ct: The characters to search for
582 *
583 * strsep() updates @s to point after the token, ready for the next call.
584 *
585 * It returns empty tokens, too, behaving exactly like the libc function
586 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
587 * Same semantics, slimmer shape. ;)
588 */
589char *strsep(char **s, const char *ct)
590{
591 char *sbegin = *s;
592 char *end;
593
594 if (sbegin == NULL)
595 return NULL;
596
597 end = strpbrk(sbegin, ct);
598 if (end)
599 *end++ = '\0';
600 *s = end;
601 return sbegin;
602}
603EXPORT_SYMBOL(strsep);
604#endif
605
606/**
607 * sysfs_streq - return true if strings are equal, modulo trailing newline
608 * @s1: one string
609 * @s2: another string
610 *
611 * This routine returns true iff two strings are equal, treating both
612 * NUL and newline-then-NUL as equivalent string terminations. It's
613 * geared for use with sysfs input strings, which generally terminate
614 * with newlines but are compared against values without newlines.
615 */
616bool sysfs_streq(const char *s1, const char *s2)
617{
618 while (*s1 && *s1 == *s2) {
619 s1++;
620 s2++;
621 }
622
623 if (*s1 == *s2)
624 return true;
625 if (!*s1 && *s2 == '\n' && !s2[1])
626 return true;
627 if (*s1 == '\n' && !s1[1] && !*s2)
628 return true;
629 return false;
630}
631EXPORT_SYMBOL(sysfs_streq);
632
633/**
634 * strtobool - convert common user inputs into boolean values
635 * @s: input string
636 * @res: result
637 *
638 * This routine returns 0 iff the first character is one of 'Yy1Nn0'.
639 * Otherwise it will return -EINVAL. Value pointed to by res is
640 * updated upon finding a match.
641 */
642int strtobool(const char *s, bool *res)
643{
644 switch (s[0]) {
645 case 'y':
646 case 'Y':
647 case '1':
648 *res = true;
649 break;
650 case 'n':
651 case 'N':
652 case '0':
653 *res = false;
654 break;
655 default:
656 return -EINVAL;
657 }
658 return 0;
659}
660EXPORT_SYMBOL(strtobool);
661
662#ifndef __HAVE_ARCH_MEMSET
663/**
664 * memset - Fill a region of memory with the given value
665 * @s: Pointer to the start of the area.
666 * @c: The byte to fill the area with
667 * @count: The size of the area.
668 *
669 * Do not use memset() to access IO space, use memset_io() instead.
670 */
671void *memset(void *s, int c, size_t count)
672{
673 char *xs = s;
674
675 while (count--)
676 *xs++ = c;
677 return s;
678}
679EXPORT_SYMBOL(memset);
680#endif
681
682/**
683 * memzero_explicit - Fill a region of memory (e.g. sensitive
684 * keying data) with 0s.
685 * @s: Pointer to the start of the area.
686 * @count: The size of the area.
687 *
688 * Note: usually using memset() is just fine (!), but in cases
689 * where clearing out _local_ data at the end of a scope is
690 * necessary, memzero_explicit() should be used instead in
691 * order to prevent the compiler from optimising away zeroing.
692 *
693 * memzero_explicit() doesn't need an arch-specific version as
694 * it just invokes the one of memset() implicitly.
695 */
696void memzero_explicit(void *s, size_t count)
697{
698 memset(s, 0, count);
699 barrier_data(s);
700}
701EXPORT_SYMBOL(memzero_explicit);
702
703#ifndef __HAVE_ARCH_MEMCPY
704/**
705 * memcpy - Copy one area of memory to another
706 * @dest: Where to copy to
707 * @src: Where to copy from
708 * @count: The size of the area.
709 *
710 * You should not use this function to access IO space, use memcpy_toio()
711 * or memcpy_fromio() instead.
712 */
713void *memcpy(void *dest, const void *src, size_t count)
714{
715 char *tmp = dest;
716 const char *s = src;
717
718 while (count--)
719 *tmp++ = *s++;
720 return dest;
721}
722EXPORT_SYMBOL(memcpy);
723#endif
724
725#ifndef __HAVE_ARCH_MEMMOVE
726/**
727 * memmove - Copy one area of memory to another
728 * @dest: Where to copy to
729 * @src: Where to copy from
730 * @count: The size of the area.
731 *
732 * Unlike memcpy(), memmove() copes with overlapping areas.
733 */
734void *memmove(void *dest, const void *src, size_t count)
735{
736 char *tmp;
737 const char *s;
738
739 if (dest <= src) {
740 tmp = dest;
741 s = src;
742 while (count--)
743 *tmp++ = *s++;
744 } else {
745 tmp = dest;
746 tmp += count;
747 s = src;
748 s += count;
749 while (count--)
750 *--tmp = *--s;
751 }
752 return dest;
753}
754EXPORT_SYMBOL(memmove);
755#endif
756
757#ifndef __HAVE_ARCH_MEMCMP
758/**
759 * memcmp - Compare two areas of memory
760 * @cs: One area of memory
761 * @ct: Another area of memory
762 * @count: The size of the area.
763 */
764#undef memcmp
765__visible int memcmp(const void *cs, const void *ct, size_t count)
766{
767 const unsigned char *su1, *su2;
768 int res = 0;
769
770 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
771 if ((res = *su1 - *su2) != 0)
772 break;
773 return res;
774}
775EXPORT_SYMBOL(memcmp);
776#endif
777
778#ifndef __HAVE_ARCH_MEMSCAN
779/**
780 * memscan - Find a character in an area of memory.
781 * @addr: The memory area
782 * @c: The byte to search for
783 * @size: The size of the area.
784 *
785 * returns the address of the first occurrence of @c, or 1 byte past
786 * the area if @c is not found
787 */
788void *memscan(void *addr, int c, size_t size)
789{
790 unsigned char *p = addr;
791
792 while (size) {
793 if (*p == c)
794 return (void *)p;
795 p++;
796 size--;
797 }
798 return (void *)p;
799}
800EXPORT_SYMBOL(memscan);
801#endif
802
803#ifndef __HAVE_ARCH_STRSTR
804/**
805 * strstr - Find the first substring in a %NUL terminated string
806 * @s1: The string to be searched
807 * @s2: The string to search for
808 */
809char *strstr(const char *s1, const char *s2)
810{
811 size_t l1, l2;
812
813 l2 = strlen(s2);
814 if (!l2)
815 return (char *)s1;
816 l1 = strlen(s1);
817 while (l1 >= l2) {
818 l1--;
819 if (!memcmp(s1, s2, l2))
820 return (char *)s1;
821 s1++;
822 }
823 return NULL;
824}
825EXPORT_SYMBOL(strstr);
826#endif
827
828#ifndef __HAVE_ARCH_STRNSTR
829/**
830 * strnstr - Find the first substring in a length-limited string
831 * @s1: The string to be searched
832 * @s2: The string to search for
833 * @len: the maximum number of characters to search
834 */
835char *strnstr(const char *s1, const char *s2, size_t len)
836{
837 size_t l2;
838
839 l2 = strlen(s2);
840 if (!l2)
841 return (char *)s1;
842 while (len >= l2) {
843 len--;
844 if (!memcmp(s1, s2, l2))
845 return (char *)s1;
846 s1++;
847 }
848 return NULL;
849}
850EXPORT_SYMBOL(strnstr);
851#endif
852
853#ifndef __HAVE_ARCH_MEMCHR
854/**
855 * memchr - Find a character in an area of memory.
856 * @s: The memory area
857 * @c: The byte to search for
858 * @n: The size of the area.
859 *
860 * returns the address of the first occurrence of @c, or %NULL
861 * if @c is not found
862 */
863void *memchr(const void *s, int c, size_t n)
864{
865 const unsigned char *p = s;
866 while (n-- != 0) {
867 if ((unsigned char)c == *p++) {
868 return (void *)(p - 1);
869 }
870 }
871 return NULL;
872}
873EXPORT_SYMBOL(memchr);
874#endif
875
876static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
877{
878 while (bytes) {
879 if (*start != value)
880 return (void *)start;
881 start++;
882 bytes--;
883 }
884 return NULL;
885}
886
887/**
888 * memchr_inv - Find an unmatching character in an area of memory.
889 * @start: The memory area
890 * @c: Find a character other than c
891 * @bytes: The size of the area.
892 *
893 * returns the address of the first character other than @c, or %NULL
894 * if the whole buffer contains just @c.
895 */
896void *memchr_inv(const void *start, int c, size_t bytes)
897{
898 u8 value = c;
899 u64 value64;
900 unsigned int words, prefix;
901
902 if (bytes <= 16)
903 return check_bytes8(start, value, bytes);
904
905 value64 = value;
906#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
907 value64 *= 0x0101010101010101;
908#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
909 value64 *= 0x01010101;
910 value64 |= value64 << 32;
911#else
912 value64 |= value64 << 8;
913 value64 |= value64 << 16;
914 value64 |= value64 << 32;
915#endif
916
917 prefix = (unsigned long)start % 8;
918 if (prefix) {
919 u8 *r;
920
921 prefix = 8 - prefix;
922 r = check_bytes8(start, value, prefix);
923 if (r)
924 return r;
925 start += prefix;
926 bytes -= prefix;
927 }
928
929 words = bytes / 8;
930
931 while (words) {
932 if (*(u64 *)start != value64)
933 return check_bytes8(start, value, 8);
934 start += 8;
935 words--;
936 }
937
938 return check_bytes8(start, value, bytes % 8);
939}
940EXPORT_SYMBOL(memchr_inv);
941
942/**
943 * strreplace - Replace all occurrences of character in string.
944 * @s: The string to operate on.
945 * @old: The character being replaced.
946 * @new: The character @old is replaced with.
947 *
948 * Returns pointer to the nul byte at the end of @s.
949 */
950char *strreplace(char *s, char old, char new)
951{
952 for (; *s; ++s)
953 if (*s == old)
954 *s = new;
955 return s;
956}
957EXPORT_SYMBOL(strreplace);