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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#ifndef __HAVE_ARCH_STRCAT
276/**
277 * strcat - Append one %NUL-terminated string to another
278 * @dest: The string to be appended to
279 * @src: The string to append to it
280 */
281#undef strcat
282char *strcat(char *dest, const char *src)
283{
284 char *tmp = dest;
285
286 while (*dest)
287 dest++;
288 while ((*dest++ = *src++) != '\0')
289 ;
290 return tmp;
291}
292EXPORT_SYMBOL(strcat);
293#endif
294
295#ifndef __HAVE_ARCH_STRNCAT
296/**
297 * strncat - Append a length-limited, C-string to another
298 * @dest: The string to be appended to
299 * @src: The string to append to it
300 * @count: The maximum numbers of bytes to copy
301 *
302 * Note that in contrast to strncpy(), strncat() ensures the result is
303 * terminated.
304 */
305char *strncat(char *dest, const char *src, size_t count)
306{
307 char *tmp = dest;
308
309 if (count) {
310 while (*dest)
311 dest++;
312 while ((*dest++ = *src++) != 0) {
313 if (--count == 0) {
314 *dest = '\0';
315 break;
316 }
317 }
318 }
319 return tmp;
320}
321EXPORT_SYMBOL(strncat);
322#endif
323
324#ifndef __HAVE_ARCH_STRLCAT
325/**
326 * strlcat - Append a length-limited, C-string to another
327 * @dest: The string to be appended to
328 * @src: The string to append to it
329 * @count: The size of the destination buffer.
330 */
331size_t strlcat(char *dest, const char *src, size_t count)
332{
333 size_t dsize = strlen(dest);
334 size_t len = strlen(src);
335 size_t res = dsize + len;
336
337 /* This would be a bug */
338 BUG_ON(dsize >= count);
339
340 dest += dsize;
341 count -= dsize;
342 if (len >= count)
343 len = count-1;
344 memcpy(dest, src, len);
345 dest[len] = 0;
346 return res;
347}
348EXPORT_SYMBOL(strlcat);
349#endif
350
351#ifndef __HAVE_ARCH_STRCMP
352/**
353 * strcmp - Compare two strings
354 * @cs: One string
355 * @ct: Another string
356 */
357#undef strcmp
358int strcmp(const char *cs, const char *ct)
359{
360 unsigned char c1, c2;
361
362 while (1) {
363 c1 = *cs++;
364 c2 = *ct++;
365 if (c1 != c2)
366 return c1 < c2 ? -1 : 1;
367 if (!c1)
368 break;
369 }
370 return 0;
371}
372EXPORT_SYMBOL(strcmp);
373#endif
374
375#ifndef __HAVE_ARCH_STRNCMP
376/**
377 * strncmp - Compare two length-limited strings
378 * @cs: One string
379 * @ct: Another string
380 * @count: The maximum number of bytes to compare
381 */
382int strncmp(const char *cs, const char *ct, size_t count)
383{
384 unsigned char c1, c2;
385
386 while (count) {
387 c1 = *cs++;
388 c2 = *ct++;
389 if (c1 != c2)
390 return c1 < c2 ? -1 : 1;
391 if (!c1)
392 break;
393 count--;
394 }
395 return 0;
396}
397EXPORT_SYMBOL(strncmp);
398#endif
399
400#ifndef __HAVE_ARCH_STRCHR
401/**
402 * strchr - Find the first occurrence of a character in a string
403 * @s: The string to be searched
404 * @c: The character to search for
405 *
406 * Note that the %NUL-terminator is considered part of the string, and can
407 * be searched for.
408 */
409char *strchr(const char *s, int c)
410{
411 for (; *s != (char)c; ++s)
412 if (*s == '\0')
413 return NULL;
414 return (char *)s;
415}
416EXPORT_SYMBOL(strchr);
417#endif
418
419#ifndef __HAVE_ARCH_STRCHRNUL
420/**
421 * strchrnul - Find and return a character in a string, or end of string
422 * @s: The string to be searched
423 * @c: The character to search for
424 *
425 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
426 * return a pointer to the null byte at the end of s.
427 */
428char *strchrnul(const char *s, int c)
429{
430 while (*s && *s != (char)c)
431 s++;
432 return (char *)s;
433}
434EXPORT_SYMBOL(strchrnul);
435#endif
436
437#ifndef __HAVE_ARCH_STRRCHR
438/**
439 * strrchr - Find the last occurrence of a character in a string
440 * @s: The string to be searched
441 * @c: The character to search for
442 */
443char *strrchr(const char *s, int c)
444{
445 const char *last = NULL;
446 do {
447 if (*s == (char)c)
448 last = s;
449 } while (*s++);
450 return (char *)last;
451}
452EXPORT_SYMBOL(strrchr);
453#endif
454
455#ifndef __HAVE_ARCH_STRNCHR
456/**
457 * strnchr - Find a character in a length limited string
458 * @s: The string to be searched
459 * @count: The number of characters to be searched
460 * @c: The character to search for
461 *
462 * Note that the %NUL-terminator is considered part of the string, and can
463 * be searched for.
464 */
465char *strnchr(const char *s, size_t count, int c)
466{
467 while (count--) {
468 if (*s == (char)c)
469 return (char *)s;
470 if (*s++ == '\0')
471 break;
472 }
473 return NULL;
474}
475EXPORT_SYMBOL(strnchr);
476#endif
477
478/**
479 * skip_spaces - Removes leading whitespace from @str.
480 * @str: The string to be stripped.
481 *
482 * Returns a pointer to the first non-whitespace character in @str.
483 */
484char *skip_spaces(const char *str)
485{
486 while (isspace(*str))
487 ++str;
488 return (char *)str;
489}
490EXPORT_SYMBOL(skip_spaces);
491
492/**
493 * strim - Removes leading and trailing whitespace from @s.
494 * @s: The string to be stripped.
495 *
496 * Note that the first trailing whitespace is replaced with a %NUL-terminator
497 * in the given string @s. Returns a pointer to the first non-whitespace
498 * character in @s.
499 */
500char *strim(char *s)
501{
502 size_t size;
503 char *end;
504
505 size = strlen(s);
506 if (!size)
507 return s;
508
509 end = s + size - 1;
510 while (end >= s && isspace(*end))
511 end--;
512 *(end + 1) = '\0';
513
514 return skip_spaces(s);
515}
516EXPORT_SYMBOL(strim);
517
518#ifndef __HAVE_ARCH_STRLEN
519/**
520 * strlen - Find the length of a string
521 * @s: The string to be sized
522 */
523size_t strlen(const char *s)
524{
525 const char *sc;
526
527 for (sc = s; *sc != '\0'; ++sc)
528 /* nothing */;
529 return sc - s;
530}
531EXPORT_SYMBOL(strlen);
532#endif
533
534#ifndef __HAVE_ARCH_STRNLEN
535/**
536 * strnlen - Find the length of a length-limited string
537 * @s: The string to be sized
538 * @count: The maximum number of bytes to search
539 */
540size_t strnlen(const char *s, size_t count)
541{
542 const char *sc;
543
544 for (sc = s; count-- && *sc != '\0'; ++sc)
545 /* nothing */;
546 return sc - s;
547}
548EXPORT_SYMBOL(strnlen);
549#endif
550
551#ifndef __HAVE_ARCH_STRSPN
552/**
553 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
554 * @s: The string to be searched
555 * @accept: The string to search for
556 */
557size_t strspn(const char *s, const char *accept)
558{
559 const char *p;
560 const char *a;
561 size_t count = 0;
562
563 for (p = s; *p != '\0'; ++p) {
564 for (a = accept; *a != '\0'; ++a) {
565 if (*p == *a)
566 break;
567 }
568 if (*a == '\0')
569 return count;
570 ++count;
571 }
572 return count;
573}
574
575EXPORT_SYMBOL(strspn);
576#endif
577
578#ifndef __HAVE_ARCH_STRCSPN
579/**
580 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
581 * @s: The string to be searched
582 * @reject: The string to avoid
583 */
584size_t strcspn(const char *s, const char *reject)
585{
586 const char *p;
587 const char *r;
588 size_t count = 0;
589
590 for (p = s; *p != '\0'; ++p) {
591 for (r = reject; *r != '\0'; ++r) {
592 if (*p == *r)
593 return count;
594 }
595 ++count;
596 }
597 return count;
598}
599EXPORT_SYMBOL(strcspn);
600#endif
601
602#ifndef __HAVE_ARCH_STRPBRK
603/**
604 * strpbrk - Find the first occurrence of a set of characters
605 * @cs: The string to be searched
606 * @ct: The characters to search for
607 */
608char *strpbrk(const char *cs, const char *ct)
609{
610 const char *sc1, *sc2;
611
612 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
613 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
614 if (*sc1 == *sc2)
615 return (char *)sc1;
616 }
617 }
618 return NULL;
619}
620EXPORT_SYMBOL(strpbrk);
621#endif
622
623#ifndef __HAVE_ARCH_STRSEP
624/**
625 * strsep - Split a string into tokens
626 * @s: The string to be searched
627 * @ct: The characters to search for
628 *
629 * strsep() updates @s to point after the token, ready for the next call.
630 *
631 * It returns empty tokens, too, behaving exactly like the libc function
632 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
633 * Same semantics, slimmer shape. ;)
634 */
635char *strsep(char **s, const char *ct)
636{
637 char *sbegin = *s;
638 char *end;
639
640 if (sbegin == NULL)
641 return NULL;
642
643 end = strpbrk(sbegin, ct);
644 if (end)
645 *end++ = '\0';
646 *s = end;
647 return sbegin;
648}
649EXPORT_SYMBOL(strsep);
650#endif
651
652/**
653 * sysfs_streq - return true if strings are equal, modulo trailing newline
654 * @s1: one string
655 * @s2: another string
656 *
657 * This routine returns true iff two strings are equal, treating both
658 * NUL and newline-then-NUL as equivalent string terminations. It's
659 * geared for use with sysfs input strings, which generally terminate
660 * with newlines but are compared against values without newlines.
661 */
662bool sysfs_streq(const char *s1, const char *s2)
663{
664 while (*s1 && *s1 == *s2) {
665 s1++;
666 s2++;
667 }
668
669 if (*s1 == *s2)
670 return true;
671 if (!*s1 && *s2 == '\n' && !s2[1])
672 return true;
673 if (*s1 == '\n' && !s1[1] && !*s2)
674 return true;
675 return false;
676}
677EXPORT_SYMBOL(sysfs_streq);
678
679/**
680 * match_string - matches given string in an array
681 * @array: array of strings
682 * @n: number of strings in the array or -1 for NULL terminated arrays
683 * @string: string to match with
684 *
685 * Return:
686 * index of a @string in the @array if matches, or %-EINVAL otherwise.
687 */
688int match_string(const char * const *array, size_t n, const char *string)
689{
690 int index;
691 const char *item;
692
693 for (index = 0; index < n; index++) {
694 item = array[index];
695 if (!item)
696 break;
697 if (!strcmp(item, string))
698 return index;
699 }
700
701 return -EINVAL;
702}
703EXPORT_SYMBOL(match_string);
704
705/**
706 * __sysfs_match_string - matches given string in an array
707 * @array: array of strings
708 * @n: number of strings in the array or -1 for NULL terminated arrays
709 * @str: string to match with
710 *
711 * Returns index of @str in the @array or -EINVAL, just like match_string().
712 * Uses sysfs_streq instead of strcmp for matching.
713 */
714int __sysfs_match_string(const char * const *array, size_t n, const char *str)
715{
716 const char *item;
717 int index;
718
719 for (index = 0; index < n; index++) {
720 item = array[index];
721 if (!item)
722 break;
723 if (sysfs_streq(item, str))
724 return index;
725 }
726
727 return -EINVAL;
728}
729EXPORT_SYMBOL(__sysfs_match_string);
730
731#ifndef __HAVE_ARCH_MEMSET
732/**
733 * memset - Fill a region of memory with the given value
734 * @s: Pointer to the start of the area.
735 * @c: The byte to fill the area with
736 * @count: The size of the area.
737 *
738 * Do not use memset() to access IO space, use memset_io() instead.
739 */
740void *memset(void *s, int c, size_t count)
741{
742 char *xs = s;
743
744 while (count--)
745 *xs++ = c;
746 return s;
747}
748EXPORT_SYMBOL(memset);
749#endif
750
751#ifndef __HAVE_ARCH_MEMSET16
752/**
753 * memset16() - Fill a memory area with a uint16_t
754 * @s: Pointer to the start of the area.
755 * @v: The value to fill the area with
756 * @count: The number of values to store
757 *
758 * Differs from memset() in that it fills with a uint16_t instead
759 * of a byte. Remember that @count is the number of uint16_ts to
760 * store, not the number of bytes.
761 */
762void *memset16(uint16_t *s, uint16_t v, size_t count)
763{
764 uint16_t *xs = s;
765
766 while (count--)
767 *xs++ = v;
768 return s;
769}
770EXPORT_SYMBOL(memset16);
771#endif
772
773#ifndef __HAVE_ARCH_MEMSET32
774/**
775 * memset32() - Fill a memory area with a uint32_t
776 * @s: Pointer to the start of the area.
777 * @v: The value to fill the area with
778 * @count: The number of values to store
779 *
780 * Differs from memset() in that it fills with a uint32_t instead
781 * of a byte. Remember that @count is the number of uint32_ts to
782 * store, not the number of bytes.
783 */
784void *memset32(uint32_t *s, uint32_t v, size_t count)
785{
786 uint32_t *xs = s;
787
788 while (count--)
789 *xs++ = v;
790 return s;
791}
792EXPORT_SYMBOL(memset32);
793#endif
794
795#ifndef __HAVE_ARCH_MEMSET64
796/**
797 * memset64() - Fill a memory area with a uint64_t
798 * @s: Pointer to the start of the area.
799 * @v: The value to fill the area with
800 * @count: The number of values to store
801 *
802 * Differs from memset() in that it fills with a uint64_t instead
803 * of a byte. Remember that @count is the number of uint64_ts to
804 * store, not the number of bytes.
805 */
806void *memset64(uint64_t *s, uint64_t v, size_t count)
807{
808 uint64_t *xs = s;
809
810 while (count--)
811 *xs++ = v;
812 return s;
813}
814EXPORT_SYMBOL(memset64);
815#endif
816
817#ifndef __HAVE_ARCH_MEMCPY
818/**
819 * memcpy - Copy one area of memory to another
820 * @dest: Where to copy to
821 * @src: Where to copy from
822 * @count: The size of the area.
823 *
824 * You should not use this function to access IO space, use memcpy_toio()
825 * or memcpy_fromio() instead.
826 */
827void *memcpy(void *dest, const void *src, size_t count)
828{
829 char *tmp = dest;
830 const char *s = src;
831
832 while (count--)
833 *tmp++ = *s++;
834 return dest;
835}
836EXPORT_SYMBOL(memcpy);
837#endif
838
839#ifndef __HAVE_ARCH_MEMMOVE
840/**
841 * memmove - Copy one area of memory to another
842 * @dest: Where to copy to
843 * @src: Where to copy from
844 * @count: The size of the area.
845 *
846 * Unlike memcpy(), memmove() copes with overlapping areas.
847 */
848void *memmove(void *dest, const void *src, size_t count)
849{
850 char *tmp;
851 const char *s;
852
853 if (dest <= src) {
854 tmp = dest;
855 s = src;
856 while (count--)
857 *tmp++ = *s++;
858 } else {
859 tmp = dest;
860 tmp += count;
861 s = src;
862 s += count;
863 while (count--)
864 *--tmp = *--s;
865 }
866 return dest;
867}
868EXPORT_SYMBOL(memmove);
869#endif
870
871#ifndef __HAVE_ARCH_MEMCMP
872/**
873 * memcmp - Compare two areas of memory
874 * @cs: One area of memory
875 * @ct: Another area of memory
876 * @count: The size of the area.
877 */
878#undef memcmp
879__visible int memcmp(const void *cs, const void *ct, size_t count)
880{
881 const unsigned char *su1, *su2;
882 int res = 0;
883
884 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
885 if ((res = *su1 - *su2) != 0)
886 break;
887 return res;
888}
889EXPORT_SYMBOL(memcmp);
890#endif
891
892#ifndef __HAVE_ARCH_BCMP
893/**
894 * bcmp - returns 0 if and only if the buffers have identical contents.
895 * @a: pointer to first buffer.
896 * @b: pointer to second buffer.
897 * @len: size of buffers.
898 *
899 * The sign or magnitude of a non-zero return value has no particular
900 * meaning, and architectures may implement their own more efficient bcmp(). So
901 * while this particular implementation is a simple (tail) call to memcmp, do
902 * not rely on anything but whether the return value is zero or non-zero.
903 */
904#undef bcmp
905int bcmp(const void *a, const void *b, size_t len)
906{
907 return memcmp(a, b, len);
908}
909EXPORT_SYMBOL(bcmp);
910#endif
911
912#ifndef __HAVE_ARCH_MEMSCAN
913/**
914 * memscan - Find a character in an area of memory.
915 * @addr: The memory area
916 * @c: The byte to search for
917 * @size: The size of the area.
918 *
919 * returns the address of the first occurrence of @c, or 1 byte past
920 * the area if @c is not found
921 */
922void *memscan(void *addr, int c, size_t size)
923{
924 unsigned char *p = addr;
925
926 while (size) {
927 if (*p == c)
928 return (void *)p;
929 p++;
930 size--;
931 }
932 return (void *)p;
933}
934EXPORT_SYMBOL(memscan);
935#endif
936
937#ifndef __HAVE_ARCH_STRSTR
938/**
939 * strstr - Find the first substring in a %NUL terminated string
940 * @s1: The string to be searched
941 * @s2: The string to search for
942 */
943char *strstr(const char *s1, const char *s2)
944{
945 size_t l1, l2;
946
947 l2 = strlen(s2);
948 if (!l2)
949 return (char *)s1;
950 l1 = strlen(s1);
951 while (l1 >= l2) {
952 l1--;
953 if (!memcmp(s1, s2, l2))
954 return (char *)s1;
955 s1++;
956 }
957 return NULL;
958}
959EXPORT_SYMBOL(strstr);
960#endif
961
962#ifndef __HAVE_ARCH_STRNSTR
963/**
964 * strnstr - Find the first substring in a length-limited string
965 * @s1: The string to be searched
966 * @s2: The string to search for
967 * @len: the maximum number of characters to search
968 */
969char *strnstr(const char *s1, const char *s2, size_t len)
970{
971 size_t l2;
972
973 l2 = strlen(s2);
974 if (!l2)
975 return (char *)s1;
976 while (len >= l2) {
977 len--;
978 if (!memcmp(s1, s2, l2))
979 return (char *)s1;
980 s1++;
981 }
982 return NULL;
983}
984EXPORT_SYMBOL(strnstr);
985#endif
986
987#ifndef __HAVE_ARCH_MEMCHR
988/**
989 * memchr - Find a character in an area of memory.
990 * @s: The memory area
991 * @c: The byte to search for
992 * @n: The size of the area.
993 *
994 * returns the address of the first occurrence of @c, or %NULL
995 * if @c is not found
996 */
997void *memchr(const void *s, int c, size_t n)
998{
999 const unsigned char *p = s;
1000 while (n-- != 0) {
1001 if ((unsigned char)c == *p++) {
1002 return (void *)(p - 1);
1003 }
1004 }
1005 return NULL;
1006}
1007EXPORT_SYMBOL(memchr);
1008#endif
1009
1010static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
1011{
1012 while (bytes) {
1013 if (*start != value)
1014 return (void *)start;
1015 start++;
1016 bytes--;
1017 }
1018 return NULL;
1019}
1020
1021/**
1022 * memchr_inv - Find an unmatching character in an area of memory.
1023 * @start: The memory area
1024 * @c: Find a character other than c
1025 * @bytes: The size of the area.
1026 *
1027 * returns the address of the first character other than @c, or %NULL
1028 * if the whole buffer contains just @c.
1029 */
1030void *memchr_inv(const void *start, int c, size_t bytes)
1031{
1032 u8 value = c;
1033 u64 value64;
1034 unsigned int words, prefix;
1035
1036 if (bytes <= 16)
1037 return check_bytes8(start, value, bytes);
1038
1039 value64 = value;
1040#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
1041 value64 *= 0x0101010101010101ULL;
1042#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
1043 value64 *= 0x01010101;
1044 value64 |= value64 << 32;
1045#else
1046 value64 |= value64 << 8;
1047 value64 |= value64 << 16;
1048 value64 |= value64 << 32;
1049#endif
1050
1051 prefix = (unsigned long)start % 8;
1052 if (prefix) {
1053 u8 *r;
1054
1055 prefix = 8 - prefix;
1056 r = check_bytes8(start, value, prefix);
1057 if (r)
1058 return r;
1059 start += prefix;
1060 bytes -= prefix;
1061 }
1062
1063 words = bytes / 8;
1064
1065 while (words) {
1066 if (*(u64 *)start != value64)
1067 return check_bytes8(start, value, 8);
1068 start += 8;
1069 words--;
1070 }
1071
1072 return check_bytes8(start, value, bytes % 8);
1073}
1074EXPORT_SYMBOL(memchr_inv);
1075
1076/**
1077 * strreplace - Replace all occurrences of character in string.
1078 * @s: The string to operate on.
1079 * @old: The character being replaced.
1080 * @new: The character @old is replaced with.
1081 *
1082 * Returns pointer to the nul byte at the end of @s.
1083 */
1084char *strreplace(char *s, char old, char new)
1085{
1086 for (; *s; ++s)
1087 if (*s == old)
1088 *s = new;
1089 return s;
1090}
1091EXPORT_SYMBOL(strreplace);
1092
1093void fortify_panic(const char *name)
1094{
1095 pr_emerg("detected buffer overflow in %s\n", name);
1096 BUG();
1097}
1098EXPORT_SYMBOL(fortify_panic);