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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 * stupid library routines.. The optimized versions should generally be found
10 * as inline code in <asm-xx/string.h>
11 *
12 * These are buggy as well..
13 *
14 * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de>
15 * - Added strsep() which will replace strtok() soon (because strsep() is
16 * reentrant and should be faster). Use only strsep() in new code, please.
17 *
18 * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>,
19 * Matthew Hawkins <matt@mh.dropbear.id.au>
20 * - Kissed strtok() goodbye
21 */
22
23#include <linux/types.h>
24#include <linux/string.h>
25#include <linux/ctype.h>
26#include <linux/kernel.h>
27#include <linux/export.h>
28#include <linux/bug.h>
29#include <linux/errno.h>
30#include <linux/slab.h>
31
32#include <asm/byteorder.h>
33#include <asm/word-at-a-time.h>
34#include <asm/page.h>
35
36#ifndef __HAVE_ARCH_STRNCASECMP
37/**
38 * strncasecmp - Case insensitive, length-limited string comparison
39 * @s1: One string
40 * @s2: The other string
41 * @len: the maximum number of characters to compare
42 */
43int strncasecmp(const char *s1, const char *s2, size_t len)
44{
45 /* Yes, Virginia, it had better be unsigned */
46 unsigned char c1, c2;
47
48 if (!len)
49 return 0;
50
51 do {
52 c1 = *s1++;
53 c2 = *s2++;
54 if (!c1 || !c2)
55 break;
56 if (c1 == c2)
57 continue;
58 c1 = tolower(c1);
59 c2 = tolower(c2);
60 if (c1 != c2)
61 break;
62 } while (--len);
63 return (int)c1 - (int)c2;
64}
65EXPORT_SYMBOL(strncasecmp);
66#endif
67
68#ifndef __HAVE_ARCH_STRCASECMP
69int strcasecmp(const char *s1, const char *s2)
70{
71 int c1, c2;
72
73 do {
74 c1 = tolower(*s1++);
75 c2 = tolower(*s2++);
76 } while (c1 == c2 && c1 != 0);
77 return c1 - c2;
78}
79EXPORT_SYMBOL(strcasecmp);
80#endif
81
82#ifndef __HAVE_ARCH_STRCPY
83/**
84 * strcpy - Copy a %NUL terminated string
85 * @dest: Where to copy the string to
86 * @src: Where to copy the string from
87 */
88#undef strcpy
89char *strcpy(char *dest, const char *src)
90{
91 char *tmp = dest;
92
93 while ((*dest++ = *src++) != '\0')
94 /* nothing */;
95 return tmp;
96}
97EXPORT_SYMBOL(strcpy);
98#endif
99
100#ifndef __HAVE_ARCH_STRNCPY
101/**
102 * strncpy - Copy a length-limited, C-string
103 * @dest: Where to copy the string to
104 * @src: Where to copy the string from
105 * @count: The maximum number of bytes to copy
106 *
107 * The result is not %NUL-terminated if the source exceeds
108 * @count bytes.
109 *
110 * In the case where the length of @src is less than that of
111 * count, the remainder of @dest will be padded with %NUL.
112 *
113 */
114char *strncpy(char *dest, const char *src, size_t count)
115{
116 char *tmp = dest;
117
118 while (count) {
119 if ((*tmp = *src) != 0)
120 src++;
121 tmp++;
122 count--;
123 }
124 return dest;
125}
126EXPORT_SYMBOL(strncpy);
127#endif
128
129#ifndef __HAVE_ARCH_STRLCPY
130/**
131 * strlcpy - Copy a C-string into a sized buffer
132 * @dest: Where to copy the string to
133 * @src: Where to copy the string from
134 * @size: size of destination buffer
135 *
136 * Compatible with ``*BSD``: the result is always a valid
137 * NUL-terminated string that fits in the buffer (unless,
138 * of course, the buffer size is zero). It does not pad
139 * out the result like strncpy() does.
140 */
141size_t strlcpy(char *dest, const char *src, size_t size)
142{
143 size_t ret = strlen(src);
144
145 if (size) {
146 size_t len = (ret >= size) ? size - 1 : ret;
147 memcpy(dest, src, len);
148 dest[len] = '\0';
149 }
150 return ret;
151}
152EXPORT_SYMBOL(strlcpy);
153#endif
154
155#ifndef __HAVE_ARCH_STRSCPY
156/**
157 * strscpy - Copy a C-string into a sized buffer
158 * @dest: Where to copy the string to
159 * @src: Where to copy the string from
160 * @count: Size of destination buffer
161 *
162 * Copy the string, or as much of it as fits, into the dest buffer. The
163 * behavior is undefined if the string buffers overlap. The destination
164 * 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 zeroing is desired please use strscpy_pad().
175 *
176 * Returns:
177 * * The number of characters copied (not including the trailing %NUL)
178 * * -E2BIG if count is 0 or @src was truncated.
179 */
180ssize_t strscpy(char *dest, const char *src, size_t count)
181{
182 const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
183 size_t max = count;
184 long res = 0;
185
186 if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
187 return -E2BIG;
188
189#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
190 /*
191 * If src is unaligned, don't cross a page boundary,
192 * since we don't know if the next page is mapped.
193 */
194 if ((long)src & (sizeof(long) - 1)) {
195 size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
196 if (limit < max)
197 max = limit;
198 }
199#else
200 /* If src or dest is unaligned, don't do word-at-a-time. */
201 if (((long) dest | (long) src) & (sizeof(long) - 1))
202 max = 0;
203#endif
204
205 while (max >= sizeof(unsigned long)) {
206 unsigned long c, data;
207
208 c = read_word_at_a_time(src+res);
209 if (has_zero(c, &data, &constants)) {
210 data = prep_zero_mask(c, data, &constants);
211 data = create_zero_mask(data);
212 *(unsigned long *)(dest+res) = c & zero_bytemask(data);
213 return res + find_zero(data);
214 }
215 *(unsigned long *)(dest+res) = c;
216 res += sizeof(unsigned long);
217 count -= sizeof(unsigned long);
218 max -= sizeof(unsigned long);
219 }
220
221 while (count) {
222 char c;
223
224 c = src[res];
225 dest[res] = c;
226 if (!c)
227 return res;
228 res++;
229 count--;
230 }
231
232 /* Hit buffer length without finding a NUL; force NUL-termination. */
233 if (res)
234 dest[res-1] = '\0';
235
236 return -E2BIG;
237}
238EXPORT_SYMBOL(strscpy);
239#endif
240
241/**
242 * strscpy_pad() - Copy a C-string into a sized buffer
243 * @dest: Where to copy the string to
244 * @src: Where to copy the string from
245 * @count: Size of destination buffer
246 *
247 * Copy the string, or as much of it as fits, into the dest buffer. The
248 * behavior is undefined if the string buffers overlap. The destination
249 * buffer is always %NUL terminated, unless it's zero-sized.
250 *
251 * If the source string is shorter than the destination buffer, zeros
252 * the tail of the destination buffer.
253 *
254 * For full explanation of why you may want to consider using the
255 * 'strscpy' functions please see the function docstring for strscpy().
256 *
257 * Returns:
258 * * The number of characters copied (not including the trailing %NUL)
259 * * -E2BIG if count is 0 or @src was truncated.
260 */
261ssize_t strscpy_pad(char *dest, const char *src, size_t count)
262{
263 ssize_t written;
264
265 written = strscpy(dest, src, count);
266 if (written < 0 || written == count - 1)
267 return written;
268
269 memset(dest + written + 1, 0, count - written - 1);
270
271 return written;
272}
273EXPORT_SYMBOL(strscpy_pad);
274
275/**
276 * stpcpy - copy a string from src to dest returning a pointer to the new end
277 * of dest, including src's %NUL-terminator. May overrun dest.
278 * @dest: pointer to end of string being copied into. Must be large enough
279 * to receive copy.
280 * @src: pointer to the beginning of string being copied from. Must not overlap
281 * dest.
282 *
283 * stpcpy differs from strcpy in a key way: the return value is a pointer
284 * to the new %NUL-terminating character in @dest. (For strcpy, the return
285 * value is a pointer to the start of @dest). This interface is considered
286 * unsafe as it doesn't perform bounds checking of the inputs. As such it's
287 * not recommended for usage. Instead, its definition is provided in case
288 * the compiler lowers other libcalls to stpcpy.
289 */
290char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
291char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
292{
293 while ((*dest++ = *src++) != '\0')
294 /* nothing */;
295 return --dest;
296}
297EXPORT_SYMBOL(stpcpy);
298
299#ifndef __HAVE_ARCH_STRCAT
300/**
301 * strcat - Append one %NUL-terminated string to another
302 * @dest: The string to be appended to
303 * @src: The string to append to it
304 */
305#undef strcat
306char *strcat(char *dest, const char *src)
307{
308 char *tmp = dest;
309
310 while (*dest)
311 dest++;
312 while ((*dest++ = *src++) != '\0')
313 ;
314 return tmp;
315}
316EXPORT_SYMBOL(strcat);
317#endif
318
319#ifndef __HAVE_ARCH_STRNCAT
320/**
321 * strncat - Append a length-limited, C-string to another
322 * @dest: The string to be appended to
323 * @src: The string to append to it
324 * @count: The maximum numbers of bytes to copy
325 *
326 * Note that in contrast to strncpy(), strncat() ensures the result is
327 * terminated.
328 */
329char *strncat(char *dest, const char *src, size_t count)
330{
331 char *tmp = dest;
332
333 if (count) {
334 while (*dest)
335 dest++;
336 while ((*dest++ = *src++) != 0) {
337 if (--count == 0) {
338 *dest = '\0';
339 break;
340 }
341 }
342 }
343 return tmp;
344}
345EXPORT_SYMBOL(strncat);
346#endif
347
348#ifndef __HAVE_ARCH_STRLCAT
349/**
350 * strlcat - Append a length-limited, C-string to another
351 * @dest: The string to be appended to
352 * @src: The string to append to it
353 * @count: The size of the destination buffer.
354 */
355size_t strlcat(char *dest, const char *src, size_t count)
356{
357 size_t dsize = strlen(dest);
358 size_t len = strlen(src);
359 size_t res = dsize + len;
360
361 /* This would be a bug */
362 BUG_ON(dsize >= count);
363
364 dest += dsize;
365 count -= dsize;
366 if (len >= count)
367 len = count-1;
368 memcpy(dest, src, len);
369 dest[len] = 0;
370 return res;
371}
372EXPORT_SYMBOL(strlcat);
373#endif
374
375#ifndef __HAVE_ARCH_STRCMP
376/**
377 * strcmp - Compare two strings
378 * @cs: One string
379 * @ct: Another string
380 */
381#undef strcmp
382int strcmp(const char *cs, const char *ct)
383{
384 unsigned char c1, c2;
385
386 while (1) {
387 c1 = *cs++;
388 c2 = *ct++;
389 if (c1 != c2)
390 return c1 < c2 ? -1 : 1;
391 if (!c1)
392 break;
393 }
394 return 0;
395}
396EXPORT_SYMBOL(strcmp);
397#endif
398
399#ifndef __HAVE_ARCH_STRNCMP
400/**
401 * strncmp - Compare two length-limited strings
402 * @cs: One string
403 * @ct: Another string
404 * @count: The maximum number of bytes to compare
405 */
406int strncmp(const char *cs, const char *ct, size_t count)
407{
408 unsigned char c1, c2;
409
410 while (count) {
411 c1 = *cs++;
412 c2 = *ct++;
413 if (c1 != c2)
414 return c1 < c2 ? -1 : 1;
415 if (!c1)
416 break;
417 count--;
418 }
419 return 0;
420}
421EXPORT_SYMBOL(strncmp);
422#endif
423
424#ifndef __HAVE_ARCH_STRCHR
425/**
426 * strchr - Find the first occurrence of a character in a string
427 * @s: The string to be searched
428 * @c: The character to search for
429 *
430 * Note that the %NUL-terminator is considered part of the string, and can
431 * be searched for.
432 */
433char *strchr(const char *s, int c)
434{
435 for (; *s != (char)c; ++s)
436 if (*s == '\0')
437 return NULL;
438 return (char *)s;
439}
440EXPORT_SYMBOL(strchr);
441#endif
442
443#ifndef __HAVE_ARCH_STRCHRNUL
444/**
445 * strchrnul - Find and return a character in a string, or end of string
446 * @s: The string to be searched
447 * @c: The character to search for
448 *
449 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
450 * return a pointer to the null byte at the end of s.
451 */
452char *strchrnul(const char *s, int c)
453{
454 while (*s && *s != (char)c)
455 s++;
456 return (char *)s;
457}
458EXPORT_SYMBOL(strchrnul);
459#endif
460
461/**
462 * strnchrnul - Find and return a character in a length limited string,
463 * or end of string
464 * @s: The string to be searched
465 * @count: The number of characters to be searched
466 * @c: The character to search for
467 *
468 * Returns pointer to the first occurrence of 'c' in s. If c is not found,
469 * then return a pointer to the last character of the string.
470 */
471char *strnchrnul(const char *s, size_t count, int c)
472{
473 while (count-- && *s && *s != (char)c)
474 s++;
475 return (char *)s;
476}
477
478#ifndef __HAVE_ARCH_STRRCHR
479/**
480 * strrchr - Find the last occurrence of a character in a string
481 * @s: The string to be searched
482 * @c: The character to search for
483 */
484char *strrchr(const char *s, int c)
485{
486 const char *last = NULL;
487 do {
488 if (*s == (char)c)
489 last = s;
490 } while (*s++);
491 return (char *)last;
492}
493EXPORT_SYMBOL(strrchr);
494#endif
495
496#ifndef __HAVE_ARCH_STRNCHR
497/**
498 * strnchr - Find a character in a length limited string
499 * @s: The string to be searched
500 * @count: The number of characters to be searched
501 * @c: The character to search for
502 *
503 * Note that the %NUL-terminator is considered part of the string, and can
504 * be searched for.
505 */
506char *strnchr(const char *s, size_t count, int c)
507{
508 while (count--) {
509 if (*s == (char)c)
510 return (char *)s;
511 if (*s++ == '\0')
512 break;
513 }
514 return NULL;
515}
516EXPORT_SYMBOL(strnchr);
517#endif
518
519/**
520 * skip_spaces - Removes leading whitespace from @str.
521 * @str: The string to be stripped.
522 *
523 * Returns a pointer to the first non-whitespace character in @str.
524 */
525char *skip_spaces(const char *str)
526{
527 while (isspace(*str))
528 ++str;
529 return (char *)str;
530}
531EXPORT_SYMBOL(skip_spaces);
532
533/**
534 * strim - Removes leading and trailing whitespace from @s.
535 * @s: The string to be stripped.
536 *
537 * Note that the first trailing whitespace is replaced with a %NUL-terminator
538 * in the given string @s. Returns a pointer to the first non-whitespace
539 * character in @s.
540 */
541char *strim(char *s)
542{
543 size_t size;
544 char *end;
545
546 size = strlen(s);
547 if (!size)
548 return s;
549
550 end = s + size - 1;
551 while (end >= s && isspace(*end))
552 end--;
553 *(end + 1) = '\0';
554
555 return skip_spaces(s);
556}
557EXPORT_SYMBOL(strim);
558
559#ifndef __HAVE_ARCH_STRLEN
560/**
561 * strlen - Find the length of a string
562 * @s: The string to be sized
563 */
564size_t strlen(const char *s)
565{
566 const char *sc;
567
568 for (sc = s; *sc != '\0'; ++sc)
569 /* nothing */;
570 return sc - s;
571}
572EXPORT_SYMBOL(strlen);
573#endif
574
575#ifndef __HAVE_ARCH_STRNLEN
576/**
577 * strnlen - Find the length of a length-limited string
578 * @s: The string to be sized
579 * @count: The maximum number of bytes to search
580 */
581size_t strnlen(const char *s, size_t count)
582{
583 const char *sc;
584
585 for (sc = s; count-- && *sc != '\0'; ++sc)
586 /* nothing */;
587 return sc - s;
588}
589EXPORT_SYMBOL(strnlen);
590#endif
591
592#ifndef __HAVE_ARCH_STRSPN
593/**
594 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
595 * @s: The string to be searched
596 * @accept: The string to search for
597 */
598size_t strspn(const char *s, const char *accept)
599{
600 const char *p;
601 const char *a;
602 size_t count = 0;
603
604 for (p = s; *p != '\0'; ++p) {
605 for (a = accept; *a != '\0'; ++a) {
606 if (*p == *a)
607 break;
608 }
609 if (*a == '\0')
610 return count;
611 ++count;
612 }
613 return count;
614}
615
616EXPORT_SYMBOL(strspn);
617#endif
618
619#ifndef __HAVE_ARCH_STRCSPN
620/**
621 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
622 * @s: The string to be searched
623 * @reject: The string to avoid
624 */
625size_t strcspn(const char *s, const char *reject)
626{
627 const char *p;
628 const char *r;
629 size_t count = 0;
630
631 for (p = s; *p != '\0'; ++p) {
632 for (r = reject; *r != '\0'; ++r) {
633 if (*p == *r)
634 return count;
635 }
636 ++count;
637 }
638 return count;
639}
640EXPORT_SYMBOL(strcspn);
641#endif
642
643#ifndef __HAVE_ARCH_STRPBRK
644/**
645 * strpbrk - Find the first occurrence of a set of characters
646 * @cs: The string to be searched
647 * @ct: The characters to search for
648 */
649char *strpbrk(const char *cs, const char *ct)
650{
651 const char *sc1, *sc2;
652
653 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
654 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
655 if (*sc1 == *sc2)
656 return (char *)sc1;
657 }
658 }
659 return NULL;
660}
661EXPORT_SYMBOL(strpbrk);
662#endif
663
664#ifndef __HAVE_ARCH_STRSEP
665/**
666 * strsep - Split a string into tokens
667 * @s: The string to be searched
668 * @ct: The characters to search for
669 *
670 * strsep() updates @s to point after the token, ready for the next call.
671 *
672 * It returns empty tokens, too, behaving exactly like the libc function
673 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
674 * Same semantics, slimmer shape. ;)
675 */
676char *strsep(char **s, const char *ct)
677{
678 char *sbegin = *s;
679 char *end;
680
681 if (sbegin == NULL)
682 return NULL;
683
684 end = strpbrk(sbegin, ct);
685 if (end)
686 *end++ = '\0';
687 *s = end;
688 return sbegin;
689}
690EXPORT_SYMBOL(strsep);
691#endif
692
693/**
694 * sysfs_streq - return true if strings are equal, modulo trailing newline
695 * @s1: one string
696 * @s2: another string
697 *
698 * This routine returns true iff two strings are equal, treating both
699 * NUL and newline-then-NUL as equivalent string terminations. It's
700 * geared for use with sysfs input strings, which generally terminate
701 * with newlines but are compared against values without newlines.
702 */
703bool sysfs_streq(const char *s1, const char *s2)
704{
705 while (*s1 && *s1 == *s2) {
706 s1++;
707 s2++;
708 }
709
710 if (*s1 == *s2)
711 return true;
712 if (!*s1 && *s2 == '\n' && !s2[1])
713 return true;
714 if (*s1 == '\n' && !s1[1] && !*s2)
715 return true;
716 return false;
717}
718EXPORT_SYMBOL(sysfs_streq);
719
720/**
721 * match_string - matches given string in an array
722 * @array: array of strings
723 * @n: number of strings in the array or -1 for NULL terminated arrays
724 * @string: string to match with
725 *
726 * This routine will look for a string in an array of strings up to the
727 * n-th element in the array or until the first NULL element.
728 *
729 * Historically the value of -1 for @n, was used to search in arrays that
730 * are NULL terminated. However, the function does not make a distinction
731 * when finishing the search: either @n elements have been compared OR
732 * the first NULL element was found.
733 *
734 * Return:
735 * index of a @string in the @array if matches, or %-EINVAL otherwise.
736 */
737int match_string(const char * const *array, size_t n, const char *string)
738{
739 int index;
740 const char *item;
741
742 for (index = 0; index < n; index++) {
743 item = array[index];
744 if (!item)
745 break;
746 if (!strcmp(item, string))
747 return index;
748 }
749
750 return -EINVAL;
751}
752EXPORT_SYMBOL(match_string);
753
754/**
755 * __sysfs_match_string - matches given string in an array
756 * @array: array of strings
757 * @n: number of strings in the array or -1 for NULL terminated arrays
758 * @str: string to match with
759 *
760 * Returns index of @str in the @array or -EINVAL, just like match_string().
761 * Uses sysfs_streq instead of strcmp for matching.
762 *
763 * This routine will look for a string in an array of strings up to the
764 * n-th element in the array or until the first NULL element.
765 *
766 * Historically the value of -1 for @n, was used to search in arrays that
767 * are NULL terminated. However, the function does not make a distinction
768 * when finishing the search: either @n elements have been compared OR
769 * the first NULL element was found.
770 */
771int __sysfs_match_string(const char * const *array, size_t n, const char *str)
772{
773 const char *item;
774 int index;
775
776 for (index = 0; index < n; index++) {
777 item = array[index];
778 if (!item)
779 break;
780 if (sysfs_streq(item, str))
781 return index;
782 }
783
784 return -EINVAL;
785}
786EXPORT_SYMBOL(__sysfs_match_string);
787
788#ifndef __HAVE_ARCH_MEMSET
789/**
790 * memset - Fill a region of memory with the given value
791 * @s: Pointer to the start of the area.
792 * @c: The byte to fill the area with
793 * @count: The size of the area.
794 *
795 * Do not use memset() to access IO space, use memset_io() instead.
796 */
797void *memset(void *s, int c, size_t count)
798{
799 char *xs = s;
800
801 while (count--)
802 *xs++ = c;
803 return s;
804}
805EXPORT_SYMBOL(memset);
806#endif
807
808#ifndef __HAVE_ARCH_MEMSET16
809/**
810 * memset16() - Fill a memory area with a uint16_t
811 * @s: Pointer to the start of the area.
812 * @v: The value to fill the area with
813 * @count: The number of values to store
814 *
815 * Differs from memset() in that it fills with a uint16_t instead
816 * of a byte. Remember that @count is the number of uint16_ts to
817 * store, not the number of bytes.
818 */
819void *memset16(uint16_t *s, uint16_t v, size_t count)
820{
821 uint16_t *xs = s;
822
823 while (count--)
824 *xs++ = v;
825 return s;
826}
827EXPORT_SYMBOL(memset16);
828#endif
829
830#ifndef __HAVE_ARCH_MEMSET32
831/**
832 * memset32() - Fill a memory area with a uint32_t
833 * @s: Pointer to the start of the area.
834 * @v: The value to fill the area with
835 * @count: The number of values to store
836 *
837 * Differs from memset() in that it fills with a uint32_t instead
838 * of a byte. Remember that @count is the number of uint32_ts to
839 * store, not the number of bytes.
840 */
841void *memset32(uint32_t *s, uint32_t v, size_t count)
842{
843 uint32_t *xs = s;
844
845 while (count--)
846 *xs++ = v;
847 return s;
848}
849EXPORT_SYMBOL(memset32);
850#endif
851
852#ifndef __HAVE_ARCH_MEMSET64
853/**
854 * memset64() - Fill a memory area with a uint64_t
855 * @s: Pointer to the start of the area.
856 * @v: The value to fill the area with
857 * @count: The number of values to store
858 *
859 * Differs from memset() in that it fills with a uint64_t instead
860 * of a byte. Remember that @count is the number of uint64_ts to
861 * store, not the number of bytes.
862 */
863void *memset64(uint64_t *s, uint64_t v, size_t count)
864{
865 uint64_t *xs = s;
866
867 while (count--)
868 *xs++ = v;
869 return s;
870}
871EXPORT_SYMBOL(memset64);
872#endif
873
874#ifndef __HAVE_ARCH_MEMCPY
875/**
876 * memcpy - Copy one area of memory to another
877 * @dest: Where to copy to
878 * @src: Where to copy from
879 * @count: The size of the area.
880 *
881 * You should not use this function to access IO space, use memcpy_toio()
882 * or memcpy_fromio() instead.
883 */
884void *memcpy(void *dest, const void *src, size_t count)
885{
886 char *tmp = dest;
887 const char *s = src;
888
889 while (count--)
890 *tmp++ = *s++;
891 return dest;
892}
893EXPORT_SYMBOL(memcpy);
894#endif
895
896#ifndef __HAVE_ARCH_MEMMOVE
897/**
898 * memmove - Copy one area of memory to another
899 * @dest: Where to copy to
900 * @src: Where to copy from
901 * @count: The size of the area.
902 *
903 * Unlike memcpy(), memmove() copes with overlapping areas.
904 */
905void *memmove(void *dest, const void *src, size_t count)
906{
907 char *tmp;
908 const char *s;
909
910 if (dest <= src) {
911 tmp = dest;
912 s = src;
913 while (count--)
914 *tmp++ = *s++;
915 } else {
916 tmp = dest;
917 tmp += count;
918 s = src;
919 s += count;
920 while (count--)
921 *--tmp = *--s;
922 }
923 return dest;
924}
925EXPORT_SYMBOL(memmove);
926#endif
927
928#ifndef __HAVE_ARCH_MEMCMP
929/**
930 * memcmp - Compare two areas of memory
931 * @cs: One area of memory
932 * @ct: Another area of memory
933 * @count: The size of the area.
934 */
935#undef memcmp
936__visible int memcmp(const void *cs, const void *ct, size_t count)
937{
938 const unsigned char *su1, *su2;
939 int res = 0;
940
941 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
942 if ((res = *su1 - *su2) != 0)
943 break;
944 return res;
945}
946EXPORT_SYMBOL(memcmp);
947#endif
948
949#ifndef __HAVE_ARCH_BCMP
950/**
951 * bcmp - returns 0 if and only if the buffers have identical contents.
952 * @a: pointer to first buffer.
953 * @b: pointer to second buffer.
954 * @len: size of buffers.
955 *
956 * The sign or magnitude of a non-zero return value has no particular
957 * meaning, and architectures may implement their own more efficient bcmp(). So
958 * while this particular implementation is a simple (tail) call to memcmp, do
959 * not rely on anything but whether the return value is zero or non-zero.
960 */
961#undef bcmp
962int bcmp(const void *a, const void *b, size_t len)
963{
964 return memcmp(a, b, len);
965}
966EXPORT_SYMBOL(bcmp);
967#endif
968
969#ifndef __HAVE_ARCH_MEMSCAN
970/**
971 * memscan - Find a character in an area of memory.
972 * @addr: The memory area
973 * @c: The byte to search for
974 * @size: The size of the area.
975 *
976 * returns the address of the first occurrence of @c, or 1 byte past
977 * the area if @c is not found
978 */
979void *memscan(void *addr, int c, size_t size)
980{
981 unsigned char *p = addr;
982
983 while (size) {
984 if (*p == c)
985 return (void *)p;
986 p++;
987 size--;
988 }
989 return (void *)p;
990}
991EXPORT_SYMBOL(memscan);
992#endif
993
994#ifndef __HAVE_ARCH_STRSTR
995/**
996 * strstr - Find the first substring in a %NUL terminated string
997 * @s1: The string to be searched
998 * @s2: The string to search for
999 */
1000char *strstr(const char *s1, const char *s2)
1001{
1002 size_t l1, l2;
1003
1004 l2 = strlen(s2);
1005 if (!l2)
1006 return (char *)s1;
1007 l1 = strlen(s1);
1008 while (l1 >= l2) {
1009 l1--;
1010 if (!memcmp(s1, s2, l2))
1011 return (char *)s1;
1012 s1++;
1013 }
1014 return NULL;
1015}
1016EXPORT_SYMBOL(strstr);
1017#endif
1018
1019#ifndef __HAVE_ARCH_STRNSTR
1020/**
1021 * strnstr - Find the first substring in a length-limited string
1022 * @s1: The string to be searched
1023 * @s2: The string to search for
1024 * @len: the maximum number of characters to search
1025 */
1026char *strnstr(const char *s1, const char *s2, size_t len)
1027{
1028 size_t l2;
1029
1030 l2 = strlen(s2);
1031 if (!l2)
1032 return (char *)s1;
1033 while (len >= l2) {
1034 len--;
1035 if (!memcmp(s1, s2, l2))
1036 return (char *)s1;
1037 s1++;
1038 }
1039 return NULL;
1040}
1041EXPORT_SYMBOL(strnstr);
1042#endif
1043
1044#ifndef __HAVE_ARCH_MEMCHR
1045/**
1046 * memchr - Find a character in an area of memory.
1047 * @s: The memory area
1048 * @c: The byte to search for
1049 * @n: The size of the area.
1050 *
1051 * returns the address of the first occurrence of @c, or %NULL
1052 * if @c is not found
1053 */
1054void *memchr(const void *s, int c, size_t n)
1055{
1056 const unsigned char *p = s;
1057 while (n-- != 0) {
1058 if ((unsigned char)c == *p++) {
1059 return (void *)(p - 1);
1060 }
1061 }
1062 return NULL;
1063}
1064EXPORT_SYMBOL(memchr);
1065#endif
1066
1067static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
1068{
1069 while (bytes) {
1070 if (*start != value)
1071 return (void *)start;
1072 start++;
1073 bytes--;
1074 }
1075 return NULL;
1076}
1077
1078/**
1079 * memchr_inv - Find an unmatching character in an area of memory.
1080 * @start: The memory area
1081 * @c: Find a character other than c
1082 * @bytes: The size of the area.
1083 *
1084 * returns the address of the first character other than @c, or %NULL
1085 * if the whole buffer contains just @c.
1086 */
1087void *memchr_inv(const void *start, int c, size_t bytes)
1088{
1089 u8 value = c;
1090 u64 value64;
1091 unsigned int words, prefix;
1092
1093 if (bytes <= 16)
1094 return check_bytes8(start, value, bytes);
1095
1096 value64 = value;
1097#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
1098 value64 *= 0x0101010101010101ULL;
1099#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
1100 value64 *= 0x01010101;
1101 value64 |= value64 << 32;
1102#else
1103 value64 |= value64 << 8;
1104 value64 |= value64 << 16;
1105 value64 |= value64 << 32;
1106#endif
1107
1108 prefix = (unsigned long)start % 8;
1109 if (prefix) {
1110 u8 *r;
1111
1112 prefix = 8 - prefix;
1113 r = check_bytes8(start, value, prefix);
1114 if (r)
1115 return r;
1116 start += prefix;
1117 bytes -= prefix;
1118 }
1119
1120 words = bytes / 8;
1121
1122 while (words) {
1123 if (*(u64 *)start != value64)
1124 return check_bytes8(start, value, 8);
1125 start += 8;
1126 words--;
1127 }
1128
1129 return check_bytes8(start, value, bytes % 8);
1130}
1131EXPORT_SYMBOL(memchr_inv);
1132
1133/**
1134 * strreplace - Replace all occurrences of character in string.
1135 * @s: The string to operate on.
1136 * @old: The character being replaced.
1137 * @new: The character @old is replaced with.
1138 *
1139 * Returns pointer to the nul byte at the end of @s.
1140 */
1141char *strreplace(char *s, char old, char new)
1142{
1143 for (; *s; ++s)
1144 if (*s == old)
1145 *s = new;
1146 return s;
1147}
1148EXPORT_SYMBOL(strreplace);
1149
1150void fortify_panic(const char *name)
1151{
1152 pr_emerg("detected buffer overflow in %s\n", name);
1153 BUG();
1154}
1155EXPORT_SYMBOL(fortify_panic);