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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 <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/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 * match_string - matches given string in an array
635 * @array: array of strings
636 * @n: number of strings in the array or -1 for NULL terminated arrays
637 * @string: string to match with
638 *
639 * Return:
640 * index of a @string in the @array if matches, or %-EINVAL otherwise.
641 */
642int match_string(const char * const *array, size_t n, const char *string)
643{
644 int index;
645 const char *item;
646
647 for (index = 0; index < n; index++) {
648 item = array[index];
649 if (!item)
650 break;
651 if (!strcmp(item, string))
652 return index;
653 }
654
655 return -EINVAL;
656}
657EXPORT_SYMBOL(match_string);
658
659#ifndef __HAVE_ARCH_MEMSET
660/**
661 * memset - Fill a region of memory with the given value
662 * @s: Pointer to the start of the area.
663 * @c: The byte to fill the area with
664 * @count: The size of the area.
665 *
666 * Do not use memset() to access IO space, use memset_io() instead.
667 */
668void *memset(void *s, int c, size_t count)
669{
670 char *xs = s;
671
672 while (count--)
673 *xs++ = c;
674 return s;
675}
676EXPORT_SYMBOL(memset);
677#endif
678
679/**
680 * memzero_explicit - Fill a region of memory (e.g. sensitive
681 * keying data) with 0s.
682 * @s: Pointer to the start of the area.
683 * @count: The size of the area.
684 *
685 * Note: usually using memset() is just fine (!), but in cases
686 * where clearing out _local_ data at the end of a scope is
687 * necessary, memzero_explicit() should be used instead in
688 * order to prevent the compiler from optimising away zeroing.
689 *
690 * memzero_explicit() doesn't need an arch-specific version as
691 * it just invokes the one of memset() implicitly.
692 */
693void memzero_explicit(void *s, size_t count)
694{
695 memset(s, 0, count);
696 barrier_data(s);
697}
698EXPORT_SYMBOL(memzero_explicit);
699
700#ifndef __HAVE_ARCH_MEMCPY
701/**
702 * memcpy - Copy one area of memory to another
703 * @dest: Where to copy to
704 * @src: Where to copy from
705 * @count: The size of the area.
706 *
707 * You should not use this function to access IO space, use memcpy_toio()
708 * or memcpy_fromio() instead.
709 */
710void *memcpy(void *dest, const void *src, size_t count)
711{
712 char *tmp = dest;
713 const char *s = src;
714
715 while (count--)
716 *tmp++ = *s++;
717 return dest;
718}
719EXPORT_SYMBOL(memcpy);
720#endif
721
722#ifndef __HAVE_ARCH_MEMMOVE
723/**
724 * memmove - Copy one area of memory to another
725 * @dest: Where to copy to
726 * @src: Where to copy from
727 * @count: The size of the area.
728 *
729 * Unlike memcpy(), memmove() copes with overlapping areas.
730 */
731void *memmove(void *dest, const void *src, size_t count)
732{
733 char *tmp;
734 const char *s;
735
736 if (dest <= src) {
737 tmp = dest;
738 s = src;
739 while (count--)
740 *tmp++ = *s++;
741 } else {
742 tmp = dest;
743 tmp += count;
744 s = src;
745 s += count;
746 while (count--)
747 *--tmp = *--s;
748 }
749 return dest;
750}
751EXPORT_SYMBOL(memmove);
752#endif
753
754#ifndef __HAVE_ARCH_MEMCMP
755/**
756 * memcmp - Compare two areas of memory
757 * @cs: One area of memory
758 * @ct: Another area of memory
759 * @count: The size of the area.
760 */
761#undef memcmp
762__visible int memcmp(const void *cs, const void *ct, size_t count)
763{
764 const unsigned char *su1, *su2;
765 int res = 0;
766
767 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
768 if ((res = *su1 - *su2) != 0)
769 break;
770 return res;
771}
772EXPORT_SYMBOL(memcmp);
773#endif
774
775#ifndef __HAVE_ARCH_MEMSCAN
776/**
777 * memscan - Find a character in an area of memory.
778 * @addr: The memory area
779 * @c: The byte to search for
780 * @size: The size of the area.
781 *
782 * returns the address of the first occurrence of @c, or 1 byte past
783 * the area if @c is not found
784 */
785void *memscan(void *addr, int c, size_t size)
786{
787 unsigned char *p = addr;
788
789 while (size) {
790 if (*p == c)
791 return (void *)p;
792 p++;
793 size--;
794 }
795 return (void *)p;
796}
797EXPORT_SYMBOL(memscan);
798#endif
799
800#ifndef __HAVE_ARCH_STRSTR
801/**
802 * strstr - Find the first substring in a %NUL terminated string
803 * @s1: The string to be searched
804 * @s2: The string to search for
805 */
806char *strstr(const char *s1, const char *s2)
807{
808 size_t l1, l2;
809
810 l2 = strlen(s2);
811 if (!l2)
812 return (char *)s1;
813 l1 = strlen(s1);
814 while (l1 >= l2) {
815 l1--;
816 if (!memcmp(s1, s2, l2))
817 return (char *)s1;
818 s1++;
819 }
820 return NULL;
821}
822EXPORT_SYMBOL(strstr);
823#endif
824
825#ifndef __HAVE_ARCH_STRNSTR
826/**
827 * strnstr - Find the first substring in a length-limited string
828 * @s1: The string to be searched
829 * @s2: The string to search for
830 * @len: the maximum number of characters to search
831 */
832char *strnstr(const char *s1, const char *s2, size_t len)
833{
834 size_t l2;
835
836 l2 = strlen(s2);
837 if (!l2)
838 return (char *)s1;
839 while (len >= l2) {
840 len--;
841 if (!memcmp(s1, s2, l2))
842 return (char *)s1;
843 s1++;
844 }
845 return NULL;
846}
847EXPORT_SYMBOL(strnstr);
848#endif
849
850#ifndef __HAVE_ARCH_MEMCHR
851/**
852 * memchr - Find a character in an area of memory.
853 * @s: The memory area
854 * @c: The byte to search for
855 * @n: The size of the area.
856 *
857 * returns the address of the first occurrence of @c, or %NULL
858 * if @c is not found
859 */
860void *memchr(const void *s, int c, size_t n)
861{
862 const unsigned char *p = s;
863 while (n-- != 0) {
864 if ((unsigned char)c == *p++) {
865 return (void *)(p - 1);
866 }
867 }
868 return NULL;
869}
870EXPORT_SYMBOL(memchr);
871#endif
872
873static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
874{
875 while (bytes) {
876 if (*start != value)
877 return (void *)start;
878 start++;
879 bytes--;
880 }
881 return NULL;
882}
883
884/**
885 * memchr_inv - Find an unmatching character in an area of memory.
886 * @start: The memory area
887 * @c: Find a character other than c
888 * @bytes: The size of the area.
889 *
890 * returns the address of the first character other than @c, or %NULL
891 * if the whole buffer contains just @c.
892 */
893void *memchr_inv(const void *start, int c, size_t bytes)
894{
895 u8 value = c;
896 u64 value64;
897 unsigned int words, prefix;
898
899 if (bytes <= 16)
900 return check_bytes8(start, value, bytes);
901
902 value64 = value;
903#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
904 value64 *= 0x0101010101010101ULL;
905#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
906 value64 *= 0x01010101;
907 value64 |= value64 << 32;
908#else
909 value64 |= value64 << 8;
910 value64 |= value64 << 16;
911 value64 |= value64 << 32;
912#endif
913
914 prefix = (unsigned long)start % 8;
915 if (prefix) {
916 u8 *r;
917
918 prefix = 8 - prefix;
919 r = check_bytes8(start, value, prefix);
920 if (r)
921 return r;
922 start += prefix;
923 bytes -= prefix;
924 }
925
926 words = bytes / 8;
927
928 while (words) {
929 if (*(u64 *)start != value64)
930 return check_bytes8(start, value, 8);
931 start += 8;
932 words--;
933 }
934
935 return check_bytes8(start, value, bytes % 8);
936}
937EXPORT_SYMBOL(memchr_inv);
938
939/**
940 * strreplace - Replace all occurrences of character in string.
941 * @s: The string to operate on.
942 * @old: The character being replaced.
943 * @new: The character @old is replaced with.
944 *
945 * Returns pointer to the nul byte at the end of @s.
946 */
947char *strreplace(char *s, char old, char new)
948{
949 for (; *s; ++s)
950 if (*s == old)
951 *s = new;
952 return s;
953}
954EXPORT_SYMBOL(strreplace);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/lib/string.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8/*
9 * This file should be used only for "library" routines that may have
10 * alternative implementations on specific architectures (generally
11 * found in <asm-xx/string.h>), or get overloaded by FORTIFY_SOURCE.
12 * (Specifically, this file is built with __NO_FORTIFY.)
13 *
14 * Other helper functions should live in string_helpers.c.
15 */
16
17#define __NO_FORTIFY
18#include <linux/bits.h>
19#include <linux/bug.h>
20#include <linux/ctype.h>
21#include <linux/errno.h>
22#include <linux/limits.h>
23#include <linux/linkage.h>
24#include <linux/stddef.h>
25#include <linux/string.h>
26#include <linux/types.h>
27
28#include <asm/page.h>
29#include <asm/rwonce.h>
30#include <asm/unaligned.h>
31#include <asm/word-at-a-time.h>
32
33#ifndef __HAVE_ARCH_STRNCASECMP
34/**
35 * strncasecmp - Case insensitive, length-limited string comparison
36 * @s1: One string
37 * @s2: The other string
38 * @len: the maximum number of characters to compare
39 */
40int strncasecmp(const char *s1, const char *s2, size_t len)
41{
42 /* Yes, Virginia, it had better be unsigned */
43 unsigned char c1, c2;
44
45 if (!len)
46 return 0;
47
48 do {
49 c1 = *s1++;
50 c2 = *s2++;
51 if (!c1 || !c2)
52 break;
53 if (c1 == c2)
54 continue;
55 c1 = tolower(c1);
56 c2 = tolower(c2);
57 if (c1 != c2)
58 break;
59 } while (--len);
60 return (int)c1 - (int)c2;
61}
62EXPORT_SYMBOL(strncasecmp);
63#endif
64
65#ifndef __HAVE_ARCH_STRCASECMP
66int strcasecmp(const char *s1, const char *s2)
67{
68 int c1, c2;
69
70 do {
71 c1 = tolower(*s1++);
72 c2 = tolower(*s2++);
73 } while (c1 == c2 && c1 != 0);
74 return c1 - c2;
75}
76EXPORT_SYMBOL(strcasecmp);
77#endif
78
79#ifndef __HAVE_ARCH_STRCPY
80char *strcpy(char *dest, const char *src)
81{
82 char *tmp = dest;
83
84 while ((*dest++ = *src++) != '\0')
85 /* nothing */;
86 return tmp;
87}
88EXPORT_SYMBOL(strcpy);
89#endif
90
91#ifndef __HAVE_ARCH_STRNCPY
92char *strncpy(char *dest, const char *src, size_t count)
93{
94 char *tmp = dest;
95
96 while (count) {
97 if ((*tmp = *src) != 0)
98 src++;
99 tmp++;
100 count--;
101 }
102 return dest;
103}
104EXPORT_SYMBOL(strncpy);
105#endif
106
107ssize_t sized_strscpy(char *dest, const char *src, size_t count)
108{
109 const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
110 size_t max = count;
111 long res = 0;
112
113 if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
114 return -E2BIG;
115
116#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
117 /*
118 * If src is unaligned, don't cross a page boundary,
119 * since we don't know if the next page is mapped.
120 */
121 if ((long)src & (sizeof(long) - 1)) {
122 size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
123 if (limit < max)
124 max = limit;
125 }
126#else
127 /* If src or dest is unaligned, don't do word-at-a-time. */
128 if (((long) dest | (long) src) & (sizeof(long) - 1))
129 max = 0;
130#endif
131
132 /*
133 * read_word_at_a_time() below may read uninitialized bytes after the
134 * trailing zero and use them in comparisons. Disable this optimization
135 * under KMSAN to prevent false positive reports.
136 */
137 if (IS_ENABLED(CONFIG_KMSAN))
138 max = 0;
139
140 while (max >= sizeof(unsigned long)) {
141 unsigned long c, data;
142
143 c = read_word_at_a_time(src+res);
144 if (has_zero(c, &data, &constants)) {
145 data = prep_zero_mask(c, data, &constants);
146 data = create_zero_mask(data);
147 *(unsigned long *)(dest+res) = c & zero_bytemask(data);
148 return res + find_zero(data);
149 }
150 *(unsigned long *)(dest+res) = c;
151 res += sizeof(unsigned long);
152 count -= sizeof(unsigned long);
153 max -= sizeof(unsigned long);
154 }
155
156 while (count) {
157 char c;
158
159 c = src[res];
160 dest[res] = c;
161 if (!c)
162 return res;
163 res++;
164 count--;
165 }
166
167 /* Hit buffer length without finding a NUL; force NUL-termination. */
168 if (res)
169 dest[res-1] = '\0';
170
171 return -E2BIG;
172}
173EXPORT_SYMBOL(sized_strscpy);
174
175/**
176 * stpcpy - copy a string from src to dest returning a pointer to the new end
177 * of dest, including src's %NUL-terminator. May overrun dest.
178 * @dest: pointer to end of string being copied into. Must be large enough
179 * to receive copy.
180 * @src: pointer to the beginning of string being copied from. Must not overlap
181 * dest.
182 *
183 * stpcpy differs from strcpy in a key way: the return value is a pointer
184 * to the new %NUL-terminating character in @dest. (For strcpy, the return
185 * value is a pointer to the start of @dest). This interface is considered
186 * unsafe as it doesn't perform bounds checking of the inputs. As such it's
187 * not recommended for usage. Instead, its definition is provided in case
188 * the compiler lowers other libcalls to stpcpy.
189 */
190char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
191char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
192{
193 while ((*dest++ = *src++) != '\0')
194 /* nothing */;
195 return --dest;
196}
197EXPORT_SYMBOL(stpcpy);
198
199#ifndef __HAVE_ARCH_STRCAT
200char *strcat(char *dest, const char *src)
201{
202 char *tmp = dest;
203
204 while (*dest)
205 dest++;
206 while ((*dest++ = *src++) != '\0')
207 ;
208 return tmp;
209}
210EXPORT_SYMBOL(strcat);
211#endif
212
213#ifndef __HAVE_ARCH_STRNCAT
214char *strncat(char *dest, const char *src, size_t count)
215{
216 char *tmp = dest;
217
218 if (count) {
219 while (*dest)
220 dest++;
221 while ((*dest++ = *src++) != 0) {
222 if (--count == 0) {
223 *dest = '\0';
224 break;
225 }
226 }
227 }
228 return tmp;
229}
230EXPORT_SYMBOL(strncat);
231#endif
232
233#ifndef __HAVE_ARCH_STRLCAT
234size_t strlcat(char *dest, const char *src, size_t count)
235{
236 size_t dsize = strlen(dest);
237 size_t len = strlen(src);
238 size_t res = dsize + len;
239
240 /* This would be a bug */
241 BUG_ON(dsize >= count);
242
243 dest += dsize;
244 count -= dsize;
245 if (len >= count)
246 len = count-1;
247 __builtin_memcpy(dest, src, len);
248 dest[len] = 0;
249 return res;
250}
251EXPORT_SYMBOL(strlcat);
252#endif
253
254#ifndef __HAVE_ARCH_STRCMP
255/**
256 * strcmp - Compare two strings
257 * @cs: One string
258 * @ct: Another string
259 */
260int strcmp(const char *cs, const char *ct)
261{
262 unsigned char c1, c2;
263
264 while (1) {
265 c1 = *cs++;
266 c2 = *ct++;
267 if (c1 != c2)
268 return c1 < c2 ? -1 : 1;
269 if (!c1)
270 break;
271 }
272 return 0;
273}
274EXPORT_SYMBOL(strcmp);
275#endif
276
277#ifndef __HAVE_ARCH_STRNCMP
278/**
279 * strncmp - Compare two length-limited strings
280 * @cs: One string
281 * @ct: Another string
282 * @count: The maximum number of bytes to compare
283 */
284int strncmp(const char *cs, const char *ct, size_t count)
285{
286 unsigned char c1, c2;
287
288 while (count) {
289 c1 = *cs++;
290 c2 = *ct++;
291 if (c1 != c2)
292 return c1 < c2 ? -1 : 1;
293 if (!c1)
294 break;
295 count--;
296 }
297 return 0;
298}
299EXPORT_SYMBOL(strncmp);
300#endif
301
302#ifndef __HAVE_ARCH_STRCHR
303/**
304 * strchr - Find the first occurrence of a character in a string
305 * @s: The string to be searched
306 * @c: The character to search for
307 *
308 * Note that the %NUL-terminator is considered part of the string, and can
309 * be searched for.
310 */
311char *strchr(const char *s, int c)
312{
313 for (; *s != (char)c; ++s)
314 if (*s == '\0')
315 return NULL;
316 return (char *)s;
317}
318EXPORT_SYMBOL(strchr);
319#endif
320
321#ifndef __HAVE_ARCH_STRCHRNUL
322/**
323 * strchrnul - Find and return a character in a string, or end of string
324 * @s: The string to be searched
325 * @c: The character to search for
326 *
327 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
328 * return a pointer to the null byte at the end of s.
329 */
330char *strchrnul(const char *s, int c)
331{
332 while (*s && *s != (char)c)
333 s++;
334 return (char *)s;
335}
336EXPORT_SYMBOL(strchrnul);
337#endif
338
339/**
340 * strnchrnul - Find and return a character in a length limited string,
341 * or end of string
342 * @s: The string to be searched
343 * @count: The number of characters to be searched
344 * @c: The character to search for
345 *
346 * Returns pointer to the first occurrence of 'c' in s. If c is not found,
347 * then return a pointer to the last character of the string.
348 */
349char *strnchrnul(const char *s, size_t count, int c)
350{
351 while (count-- && *s && *s != (char)c)
352 s++;
353 return (char *)s;
354}
355
356#ifndef __HAVE_ARCH_STRRCHR
357/**
358 * strrchr - Find the last occurrence of a character in a string
359 * @s: The string to be searched
360 * @c: The character to search for
361 */
362char *strrchr(const char *s, int c)
363{
364 const char *last = NULL;
365 do {
366 if (*s == (char)c)
367 last = s;
368 } while (*s++);
369 return (char *)last;
370}
371EXPORT_SYMBOL(strrchr);
372#endif
373
374#ifndef __HAVE_ARCH_STRNCHR
375/**
376 * strnchr - Find a character in a length limited string
377 * @s: The string to be searched
378 * @count: The number of characters to be searched
379 * @c: The character to search for
380 *
381 * Note that the %NUL-terminator is considered part of the string, and can
382 * be searched for.
383 */
384char *strnchr(const char *s, size_t count, int c)
385{
386 while (count--) {
387 if (*s == (char)c)
388 return (char *)s;
389 if (*s++ == '\0')
390 break;
391 }
392 return NULL;
393}
394EXPORT_SYMBOL(strnchr);
395#endif
396
397#ifndef __HAVE_ARCH_STRLEN
398size_t strlen(const char *s)
399{
400 const char *sc;
401
402 for (sc = s; *sc != '\0'; ++sc)
403 /* nothing */;
404 return sc - s;
405}
406EXPORT_SYMBOL(strlen);
407#endif
408
409#ifndef __HAVE_ARCH_STRNLEN
410size_t strnlen(const char *s, size_t count)
411{
412 const char *sc;
413
414 for (sc = s; count-- && *sc != '\0'; ++sc)
415 /* nothing */;
416 return sc - s;
417}
418EXPORT_SYMBOL(strnlen);
419#endif
420
421#ifndef __HAVE_ARCH_STRSPN
422/**
423 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
424 * @s: The string to be searched
425 * @accept: The string to search for
426 */
427size_t strspn(const char *s, const char *accept)
428{
429 const char *p;
430
431 for (p = s; *p != '\0'; ++p) {
432 if (!strchr(accept, *p))
433 break;
434 }
435 return p - s;
436}
437EXPORT_SYMBOL(strspn);
438#endif
439
440#ifndef __HAVE_ARCH_STRCSPN
441/**
442 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
443 * @s: The string to be searched
444 * @reject: The string to avoid
445 */
446size_t strcspn(const char *s, const char *reject)
447{
448 const char *p;
449
450 for (p = s; *p != '\0'; ++p) {
451 if (strchr(reject, *p))
452 break;
453 }
454 return p - s;
455}
456EXPORT_SYMBOL(strcspn);
457#endif
458
459#ifndef __HAVE_ARCH_STRPBRK
460/**
461 * strpbrk - Find the first occurrence of a set of characters
462 * @cs: The string to be searched
463 * @ct: The characters to search for
464 */
465char *strpbrk(const char *cs, const char *ct)
466{
467 const char *sc;
468
469 for (sc = cs; *sc != '\0'; ++sc) {
470 if (strchr(ct, *sc))
471 return (char *)sc;
472 }
473 return NULL;
474}
475EXPORT_SYMBOL(strpbrk);
476#endif
477
478#ifndef __HAVE_ARCH_STRSEP
479/**
480 * strsep - Split a string into tokens
481 * @s: The string to be searched
482 * @ct: The characters to search for
483 *
484 * strsep() updates @s to point after the token, ready for the next call.
485 *
486 * It returns empty tokens, too, behaving exactly like the libc function
487 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
488 * Same semantics, slimmer shape. ;)
489 */
490char *strsep(char **s, const char *ct)
491{
492 char *sbegin = *s;
493 char *end;
494
495 if (sbegin == NULL)
496 return NULL;
497
498 end = strpbrk(sbegin, ct);
499 if (end)
500 *end++ = '\0';
501 *s = end;
502 return sbegin;
503}
504EXPORT_SYMBOL(strsep);
505#endif
506
507#ifndef __HAVE_ARCH_MEMSET
508/**
509 * memset - Fill a region of memory with the given value
510 * @s: Pointer to the start of the area.
511 * @c: The byte to fill the area with
512 * @count: The size of the area.
513 *
514 * Do not use memset() to access IO space, use memset_io() instead.
515 */
516void *memset(void *s, int c, size_t count)
517{
518 char *xs = s;
519
520 while (count--)
521 *xs++ = c;
522 return s;
523}
524EXPORT_SYMBOL(memset);
525#endif
526
527#ifndef __HAVE_ARCH_MEMSET16
528/**
529 * memset16() - Fill a memory area with a uint16_t
530 * @s: Pointer to the start of the area.
531 * @v: The value to fill the area with
532 * @count: The number of values to store
533 *
534 * Differs from memset() in that it fills with a uint16_t instead
535 * of a byte. Remember that @count is the number of uint16_ts to
536 * store, not the number of bytes.
537 */
538void *memset16(uint16_t *s, uint16_t v, size_t count)
539{
540 uint16_t *xs = s;
541
542 while (count--)
543 *xs++ = v;
544 return s;
545}
546EXPORT_SYMBOL(memset16);
547#endif
548
549#ifndef __HAVE_ARCH_MEMSET32
550/**
551 * memset32() - Fill a memory area with a uint32_t
552 * @s: Pointer to the start of the area.
553 * @v: The value to fill the area with
554 * @count: The number of values to store
555 *
556 * Differs from memset() in that it fills with a uint32_t instead
557 * of a byte. Remember that @count is the number of uint32_ts to
558 * store, not the number of bytes.
559 */
560void *memset32(uint32_t *s, uint32_t v, size_t count)
561{
562 uint32_t *xs = s;
563
564 while (count--)
565 *xs++ = v;
566 return s;
567}
568EXPORT_SYMBOL(memset32);
569#endif
570
571#ifndef __HAVE_ARCH_MEMSET64
572/**
573 * memset64() - Fill a memory area with a uint64_t
574 * @s: Pointer to the start of the area.
575 * @v: The value to fill the area with
576 * @count: The number of values to store
577 *
578 * Differs from memset() in that it fills with a uint64_t instead
579 * of a byte. Remember that @count is the number of uint64_ts to
580 * store, not the number of bytes.
581 */
582void *memset64(uint64_t *s, uint64_t v, size_t count)
583{
584 uint64_t *xs = s;
585
586 while (count--)
587 *xs++ = v;
588 return s;
589}
590EXPORT_SYMBOL(memset64);
591#endif
592
593#ifndef __HAVE_ARCH_MEMCPY
594/**
595 * memcpy - Copy one area of memory to another
596 * @dest: Where to copy to
597 * @src: Where to copy from
598 * @count: The size of the area.
599 *
600 * You should not use this function to access IO space, use memcpy_toio()
601 * or memcpy_fromio() instead.
602 */
603void *memcpy(void *dest, const void *src, size_t count)
604{
605 char *tmp = dest;
606 const char *s = src;
607
608 while (count--)
609 *tmp++ = *s++;
610 return dest;
611}
612EXPORT_SYMBOL(memcpy);
613#endif
614
615#ifndef __HAVE_ARCH_MEMMOVE
616/**
617 * memmove - Copy one area of memory to another
618 * @dest: Where to copy to
619 * @src: Where to copy from
620 * @count: The size of the area.
621 *
622 * Unlike memcpy(), memmove() copes with overlapping areas.
623 */
624void *memmove(void *dest, const void *src, size_t count)
625{
626 char *tmp;
627 const char *s;
628
629 if (dest <= src) {
630 tmp = dest;
631 s = src;
632 while (count--)
633 *tmp++ = *s++;
634 } else {
635 tmp = dest;
636 tmp += count;
637 s = src;
638 s += count;
639 while (count--)
640 *--tmp = *--s;
641 }
642 return dest;
643}
644EXPORT_SYMBOL(memmove);
645#endif
646
647#ifndef __HAVE_ARCH_MEMCMP
648/**
649 * memcmp - Compare two areas of memory
650 * @cs: One area of memory
651 * @ct: Another area of memory
652 * @count: The size of the area.
653 */
654#undef memcmp
655__visible int memcmp(const void *cs, const void *ct, size_t count)
656{
657 const unsigned char *su1, *su2;
658 int res = 0;
659
660#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
661 if (count >= sizeof(unsigned long)) {
662 const unsigned long *u1 = cs;
663 const unsigned long *u2 = ct;
664 do {
665 if (get_unaligned(u1) != get_unaligned(u2))
666 break;
667 u1++;
668 u2++;
669 count -= sizeof(unsigned long);
670 } while (count >= sizeof(unsigned long));
671 cs = u1;
672 ct = u2;
673 }
674#endif
675 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
676 if ((res = *su1 - *su2) != 0)
677 break;
678 return res;
679}
680EXPORT_SYMBOL(memcmp);
681#endif
682
683#ifndef __HAVE_ARCH_BCMP
684/**
685 * bcmp - returns 0 if and only if the buffers have identical contents.
686 * @a: pointer to first buffer.
687 * @b: pointer to second buffer.
688 * @len: size of buffers.
689 *
690 * The sign or magnitude of a non-zero return value has no particular
691 * meaning, and architectures may implement their own more efficient bcmp(). So
692 * while this particular implementation is a simple (tail) call to memcmp, do
693 * not rely on anything but whether the return value is zero or non-zero.
694 */
695int bcmp(const void *a, const void *b, size_t len)
696{
697 return memcmp(a, b, len);
698}
699EXPORT_SYMBOL(bcmp);
700#endif
701
702#ifndef __HAVE_ARCH_MEMSCAN
703/**
704 * memscan - Find a character in an area of memory.
705 * @addr: The memory area
706 * @c: The byte to search for
707 * @size: The size of the area.
708 *
709 * returns the address of the first occurrence of @c, or 1 byte past
710 * the area if @c is not found
711 */
712void *memscan(void *addr, int c, size_t size)
713{
714 unsigned char *p = addr;
715
716 while (size) {
717 if (*p == (unsigned char)c)
718 return (void *)p;
719 p++;
720 size--;
721 }
722 return (void *)p;
723}
724EXPORT_SYMBOL(memscan);
725#endif
726
727#ifndef __HAVE_ARCH_STRSTR
728/**
729 * strstr - Find the first substring in a %NUL terminated string
730 * @s1: The string to be searched
731 * @s2: The string to search for
732 */
733char *strstr(const char *s1, const char *s2)
734{
735 size_t l1, l2;
736
737 l2 = strlen(s2);
738 if (!l2)
739 return (char *)s1;
740 l1 = strlen(s1);
741 while (l1 >= l2) {
742 l1--;
743 if (!memcmp(s1, s2, l2))
744 return (char *)s1;
745 s1++;
746 }
747 return NULL;
748}
749EXPORT_SYMBOL(strstr);
750#endif
751
752#ifndef __HAVE_ARCH_STRNSTR
753/**
754 * strnstr - Find the first substring in a length-limited string
755 * @s1: The string to be searched
756 * @s2: The string to search for
757 * @len: the maximum number of characters to search
758 */
759char *strnstr(const char *s1, const char *s2, size_t len)
760{
761 size_t l2;
762
763 l2 = strlen(s2);
764 if (!l2)
765 return (char *)s1;
766 while (len >= l2) {
767 len--;
768 if (!memcmp(s1, s2, l2))
769 return (char *)s1;
770 s1++;
771 }
772 return NULL;
773}
774EXPORT_SYMBOL(strnstr);
775#endif
776
777#ifndef __HAVE_ARCH_MEMCHR
778/**
779 * memchr - Find a character in an area of memory.
780 * @s: The memory area
781 * @c: The byte to search for
782 * @n: The size of the area.
783 *
784 * returns the address of the first occurrence of @c, or %NULL
785 * if @c is not found
786 */
787void *memchr(const void *s, int c, size_t n)
788{
789 const unsigned char *p = s;
790 while (n-- != 0) {
791 if ((unsigned char)c == *p++) {
792 return (void *)(p - 1);
793 }
794 }
795 return NULL;
796}
797EXPORT_SYMBOL(memchr);
798#endif
799
800static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
801{
802 while (bytes) {
803 if (*start != value)
804 return (void *)start;
805 start++;
806 bytes--;
807 }
808 return NULL;
809}
810
811/**
812 * memchr_inv - Find an unmatching character in an area of memory.
813 * @start: The memory area
814 * @c: Find a character other than c
815 * @bytes: The size of the area.
816 *
817 * returns the address of the first character other than @c, or %NULL
818 * if the whole buffer contains just @c.
819 */
820void *memchr_inv(const void *start, int c, size_t bytes)
821{
822 u8 value = c;
823 u64 value64;
824 unsigned int words, prefix;
825
826 if (bytes <= 16)
827 return check_bytes8(start, value, bytes);
828
829 value64 = value;
830#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
831 value64 *= 0x0101010101010101ULL;
832#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
833 value64 *= 0x01010101;
834 value64 |= value64 << 32;
835#else
836 value64 |= value64 << 8;
837 value64 |= value64 << 16;
838 value64 |= value64 << 32;
839#endif
840
841 prefix = (unsigned long)start % 8;
842 if (prefix) {
843 u8 *r;
844
845 prefix = 8 - prefix;
846 r = check_bytes8(start, value, prefix);
847 if (r)
848 return r;
849 start += prefix;
850 bytes -= prefix;
851 }
852
853 words = bytes / 8;
854
855 while (words) {
856 if (*(u64 *)start != value64)
857 return check_bytes8(start, value, 8);
858 start += 8;
859 words--;
860 }
861
862 return check_bytes8(start, value, bytes % 8);
863}
864EXPORT_SYMBOL(memchr_inv);