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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
31#include <asm/byteorder.h>
32#include <asm/word-at-a-time.h>
33#include <asm/page.h>
34
35#ifndef __HAVE_ARCH_STRNCASECMP
36/**
37 * strncasecmp - Case insensitive, length-limited string comparison
38 * @s1: One string
39 * @s2: The other string
40 * @len: the maximum number of characters to compare
41 */
42int strncasecmp(const char *s1, const char *s2, size_t len)
43{
44 /* Yes, Virginia, it had better be unsigned */
45 unsigned char c1, c2;
46
47 if (!len)
48 return 0;
49
50 do {
51 c1 = *s1++;
52 c2 = *s2++;
53 if (!c1 || !c2)
54 break;
55 if (c1 == c2)
56 continue;
57 c1 = tolower(c1);
58 c2 = tolower(c2);
59 if (c1 != c2)
60 break;
61 } while (--len);
62 return (int)c1 - (int)c2;
63}
64EXPORT_SYMBOL(strncasecmp);
65#endif
66
67#ifndef __HAVE_ARCH_STRCASECMP
68int strcasecmp(const char *s1, const char *s2)
69{
70 int c1, c2;
71
72 do {
73 c1 = tolower(*s1++);
74 c2 = tolower(*s2++);
75 } while (c1 == c2 && c1 != 0);
76 return c1 - c2;
77}
78EXPORT_SYMBOL(strcasecmp);
79#endif
80
81#ifndef __HAVE_ARCH_STRCPY
82/**
83 * strcpy - Copy a %NUL terminated string
84 * @dest: Where to copy the string to
85 * @src: Where to copy the string from
86 */
87#undef strcpy
88char *strcpy(char *dest, const char *src)
89{
90 char *tmp = dest;
91
92 while ((*dest++ = *src++) != '\0')
93 /* nothing */;
94 return tmp;
95}
96EXPORT_SYMBOL(strcpy);
97#endif
98
99#ifndef __HAVE_ARCH_STRNCPY
100/**
101 * strncpy - Copy a length-limited, C-string
102 * @dest: Where to copy the string to
103 * @src: Where to copy the string from
104 * @count: The maximum number of bytes to copy
105 *
106 * The result is not %NUL-terminated if the source exceeds
107 * @count bytes.
108 *
109 * In the case where the length of @src is less than that of
110 * count, the remainder of @dest will be padded with %NUL.
111 *
112 */
113char *strncpy(char *dest, const char *src, size_t count)
114{
115 char *tmp = dest;
116
117 while (count) {
118 if ((*tmp = *src) != 0)
119 src++;
120 tmp++;
121 count--;
122 }
123 return dest;
124}
125EXPORT_SYMBOL(strncpy);
126#endif
127
128#ifndef __HAVE_ARCH_STRLCPY
129/**
130 * strlcpy - Copy a C-string into a sized buffer
131 * @dest: Where to copy the string to
132 * @src: Where to copy the string from
133 * @size: size of destination buffer
134 *
135 * Compatible with ``*BSD``: the result is always a valid
136 * NUL-terminated string that fits in the buffer (unless,
137 * of course, the buffer size is zero). It does not pad
138 * out the result like strncpy() does.
139 */
140size_t strlcpy(char *dest, const char *src, size_t size)
141{
142 size_t ret = strlen(src);
143
144 if (size) {
145 size_t len = (ret >= size) ? size - 1 : ret;
146 memcpy(dest, src, len);
147 dest[len] = '\0';
148 }
149 return ret;
150}
151EXPORT_SYMBOL(strlcpy);
152#endif
153
154#ifndef __HAVE_ARCH_STRSCPY
155/**
156 * strscpy - Copy a C-string into a sized buffer
157 * @dest: Where to copy the string to
158 * @src: Where to copy the string from
159 * @count: Size of destination buffer
160 *
161 * Copy the string, or as much of it as fits, into the dest buffer.
162 * The routine returns the number of characters copied (not including
163 * the trailing NUL) or -E2BIG if the destination buffer wasn't big enough.
164 * The behavior is undefined if the string buffers overlap.
165 * The destination buffer is always NUL terminated, unless it's zero-sized.
166 *
167 * Preferred to strlcpy() since the API doesn't require reading memory
168 * from the src string beyond the specified "count" bytes, and since
169 * the return value is easier to error-check than strlcpy()'s.
170 * In addition, the implementation is robust to the string changing out
171 * from underneath it, unlike the current strlcpy() implementation.
172 *
173 * Preferred to strncpy() since it always returns a valid string, and
174 * doesn't unnecessarily force the tail of the destination buffer to be
175 * zeroed. If the zeroing is desired, it's likely cleaner to use strscpy()
176 * with an overflow test, then just memset() the tail of the dest buffer.
177 */
178ssize_t strscpy(char *dest, const char *src, size_t count)
179{
180 const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
181 size_t max = count;
182 long res = 0;
183
184 if (count == 0)
185 return -E2BIG;
186
187#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
188 /*
189 * If src is unaligned, don't cross a page boundary,
190 * since we don't know if the next page is mapped.
191 */
192 if ((long)src & (sizeof(long) - 1)) {
193 size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
194 if (limit < max)
195 max = limit;
196 }
197#else
198 /* If src or dest is unaligned, don't do word-at-a-time. */
199 if (((long) dest | (long) src) & (sizeof(long) - 1))
200 max = 0;
201#endif
202
203 while (max >= sizeof(unsigned long)) {
204 unsigned long c, data;
205
206 c = read_word_at_a_time(src+res);
207 if (has_zero(c, &data, &constants)) {
208 data = prep_zero_mask(c, data, &constants);
209 data = create_zero_mask(data);
210 *(unsigned long *)(dest+res) = c & zero_bytemask(data);
211 return res + find_zero(data);
212 }
213 *(unsigned long *)(dest+res) = c;
214 res += sizeof(unsigned long);
215 count -= sizeof(unsigned long);
216 max -= sizeof(unsigned long);
217 }
218
219 while (count) {
220 char c;
221
222 c = src[res];
223 dest[res] = c;
224 if (!c)
225 return res;
226 res++;
227 count--;
228 }
229
230 /* Hit buffer length without finding a NUL; force NUL-termination. */
231 if (res)
232 dest[res-1] = '\0';
233
234 return -E2BIG;
235}
236EXPORT_SYMBOL(strscpy);
237#endif
238
239#ifndef __HAVE_ARCH_STRCAT
240/**
241 * strcat - Append one %NUL-terminated string to another
242 * @dest: The string to be appended to
243 * @src: The string to append to it
244 */
245#undef strcat
246char *strcat(char *dest, const char *src)
247{
248 char *tmp = dest;
249
250 while (*dest)
251 dest++;
252 while ((*dest++ = *src++) != '\0')
253 ;
254 return tmp;
255}
256EXPORT_SYMBOL(strcat);
257#endif
258
259#ifndef __HAVE_ARCH_STRNCAT
260/**
261 * strncat - Append a length-limited, C-string to another
262 * @dest: The string to be appended to
263 * @src: The string to append to it
264 * @count: The maximum numbers of bytes to copy
265 *
266 * Note that in contrast to strncpy(), strncat() ensures the result is
267 * terminated.
268 */
269char *strncat(char *dest, const char *src, size_t count)
270{
271 char *tmp = dest;
272
273 if (count) {
274 while (*dest)
275 dest++;
276 while ((*dest++ = *src++) != 0) {
277 if (--count == 0) {
278 *dest = '\0';
279 break;
280 }
281 }
282 }
283 return tmp;
284}
285EXPORT_SYMBOL(strncat);
286#endif
287
288#ifndef __HAVE_ARCH_STRLCAT
289/**
290 * strlcat - Append a length-limited, C-string to another
291 * @dest: The string to be appended to
292 * @src: The string to append to it
293 * @count: The size of the destination buffer.
294 */
295size_t strlcat(char *dest, const char *src, size_t count)
296{
297 size_t dsize = strlen(dest);
298 size_t len = strlen(src);
299 size_t res = dsize + len;
300
301 /* This would be a bug */
302 BUG_ON(dsize >= count);
303
304 dest += dsize;
305 count -= dsize;
306 if (len >= count)
307 len = count-1;
308 memcpy(dest, src, len);
309 dest[len] = 0;
310 return res;
311}
312EXPORT_SYMBOL(strlcat);
313#endif
314
315#ifndef __HAVE_ARCH_STRCMP
316/**
317 * strcmp - Compare two strings
318 * @cs: One string
319 * @ct: Another string
320 */
321#undef strcmp
322int strcmp(const char *cs, const char *ct)
323{
324 unsigned char c1, c2;
325
326 while (1) {
327 c1 = *cs++;
328 c2 = *ct++;
329 if (c1 != c2)
330 return c1 < c2 ? -1 : 1;
331 if (!c1)
332 break;
333 }
334 return 0;
335}
336EXPORT_SYMBOL(strcmp);
337#endif
338
339#ifndef __HAVE_ARCH_STRNCMP
340/**
341 * strncmp - Compare two length-limited strings
342 * @cs: One string
343 * @ct: Another string
344 * @count: The maximum number of bytes to compare
345 */
346int strncmp(const char *cs, const char *ct, size_t count)
347{
348 unsigned char c1, c2;
349
350 while (count) {
351 c1 = *cs++;
352 c2 = *ct++;
353 if (c1 != c2)
354 return c1 < c2 ? -1 : 1;
355 if (!c1)
356 break;
357 count--;
358 }
359 return 0;
360}
361EXPORT_SYMBOL(strncmp);
362#endif
363
364#ifndef __HAVE_ARCH_STRCHR
365/**
366 * strchr - Find the first occurrence of a character in a string
367 * @s: The string to be searched
368 * @c: The character to search for
369 */
370char *strchr(const char *s, int c)
371{
372 for (; *s != (char)c; ++s)
373 if (*s == '\0')
374 return NULL;
375 return (char *)s;
376}
377EXPORT_SYMBOL(strchr);
378#endif
379
380#ifndef __HAVE_ARCH_STRCHRNUL
381/**
382 * strchrnul - Find and return a character in a string, or end of string
383 * @s: The string to be searched
384 * @c: The character to search for
385 *
386 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
387 * return a pointer to the null byte at the end of s.
388 */
389char *strchrnul(const char *s, int c)
390{
391 while (*s && *s != (char)c)
392 s++;
393 return (char *)s;
394}
395EXPORT_SYMBOL(strchrnul);
396#endif
397
398#ifndef __HAVE_ARCH_STRRCHR
399/**
400 * strrchr - Find the last occurrence of a character in a string
401 * @s: The string to be searched
402 * @c: The character to search for
403 */
404char *strrchr(const char *s, int c)
405{
406 const char *last = NULL;
407 do {
408 if (*s == (char)c)
409 last = s;
410 } while (*s++);
411 return (char *)last;
412}
413EXPORT_SYMBOL(strrchr);
414#endif
415
416#ifndef __HAVE_ARCH_STRNCHR
417/**
418 * strnchr - Find a character in a length limited string
419 * @s: The string to be searched
420 * @count: The number of characters to be searched
421 * @c: The character to search for
422 */
423char *strnchr(const char *s, size_t count, int c)
424{
425 for (; count-- && *s != '\0'; ++s)
426 if (*s == (char)c)
427 return (char *)s;
428 return NULL;
429}
430EXPORT_SYMBOL(strnchr);
431#endif
432
433/**
434 * skip_spaces - Removes leading whitespace from @str.
435 * @str: The string to be stripped.
436 *
437 * Returns a pointer to the first non-whitespace character in @str.
438 */
439char *skip_spaces(const char *str)
440{
441 while (isspace(*str))
442 ++str;
443 return (char *)str;
444}
445EXPORT_SYMBOL(skip_spaces);
446
447/**
448 * strim - Removes leading and trailing whitespace from @s.
449 * @s: The string to be stripped.
450 *
451 * Note that the first trailing whitespace is replaced with a %NUL-terminator
452 * in the given string @s. Returns a pointer to the first non-whitespace
453 * character in @s.
454 */
455char *strim(char *s)
456{
457 size_t size;
458 char *end;
459
460 size = strlen(s);
461 if (!size)
462 return s;
463
464 end = s + size - 1;
465 while (end >= s && isspace(*end))
466 end--;
467 *(end + 1) = '\0';
468
469 return skip_spaces(s);
470}
471EXPORT_SYMBOL(strim);
472
473#ifndef __HAVE_ARCH_STRLEN
474/**
475 * strlen - Find the length of a string
476 * @s: The string to be sized
477 */
478size_t strlen(const char *s)
479{
480 const char *sc;
481
482 for (sc = s; *sc != '\0'; ++sc)
483 /* nothing */;
484 return sc - s;
485}
486EXPORT_SYMBOL(strlen);
487#endif
488
489#ifndef __HAVE_ARCH_STRNLEN
490/**
491 * strnlen - Find the length of a length-limited string
492 * @s: The string to be sized
493 * @count: The maximum number of bytes to search
494 */
495size_t strnlen(const char *s, size_t count)
496{
497 const char *sc;
498
499 for (sc = s; count-- && *sc != '\0'; ++sc)
500 /* nothing */;
501 return sc - s;
502}
503EXPORT_SYMBOL(strnlen);
504#endif
505
506#ifndef __HAVE_ARCH_STRSPN
507/**
508 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
509 * @s: The string to be searched
510 * @accept: The string to search for
511 */
512size_t strspn(const char *s, const char *accept)
513{
514 const char *p;
515 const char *a;
516 size_t count = 0;
517
518 for (p = s; *p != '\0'; ++p) {
519 for (a = accept; *a != '\0'; ++a) {
520 if (*p == *a)
521 break;
522 }
523 if (*a == '\0')
524 return count;
525 ++count;
526 }
527 return count;
528}
529
530EXPORT_SYMBOL(strspn);
531#endif
532
533#ifndef __HAVE_ARCH_STRCSPN
534/**
535 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
536 * @s: The string to be searched
537 * @reject: The string to avoid
538 */
539size_t strcspn(const char *s, const char *reject)
540{
541 const char *p;
542 const char *r;
543 size_t count = 0;
544
545 for (p = s; *p != '\0'; ++p) {
546 for (r = reject; *r != '\0'; ++r) {
547 if (*p == *r)
548 return count;
549 }
550 ++count;
551 }
552 return count;
553}
554EXPORT_SYMBOL(strcspn);
555#endif
556
557#ifndef __HAVE_ARCH_STRPBRK
558/**
559 * strpbrk - Find the first occurrence of a set of characters
560 * @cs: The string to be searched
561 * @ct: The characters to search for
562 */
563char *strpbrk(const char *cs, const char *ct)
564{
565 const char *sc1, *sc2;
566
567 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
568 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
569 if (*sc1 == *sc2)
570 return (char *)sc1;
571 }
572 }
573 return NULL;
574}
575EXPORT_SYMBOL(strpbrk);
576#endif
577
578#ifndef __HAVE_ARCH_STRSEP
579/**
580 * strsep - Split a string into tokens
581 * @s: The string to be searched
582 * @ct: The characters to search for
583 *
584 * strsep() updates @s to point after the token, ready for the next call.
585 *
586 * It returns empty tokens, too, behaving exactly like the libc function
587 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
588 * Same semantics, slimmer shape. ;)
589 */
590char *strsep(char **s, const char *ct)
591{
592 char *sbegin = *s;
593 char *end;
594
595 if (sbegin == NULL)
596 return NULL;
597
598 end = strpbrk(sbegin, ct);
599 if (end)
600 *end++ = '\0';
601 *s = end;
602 return sbegin;
603}
604EXPORT_SYMBOL(strsep);
605#endif
606
607/**
608 * sysfs_streq - return true if strings are equal, modulo trailing newline
609 * @s1: one string
610 * @s2: another string
611 *
612 * This routine returns true iff two strings are equal, treating both
613 * NUL and newline-then-NUL as equivalent string terminations. It's
614 * geared for use with sysfs input strings, which generally terminate
615 * with newlines but are compared against values without newlines.
616 */
617bool sysfs_streq(const char *s1, const char *s2)
618{
619 while (*s1 && *s1 == *s2) {
620 s1++;
621 s2++;
622 }
623
624 if (*s1 == *s2)
625 return true;
626 if (!*s1 && *s2 == '\n' && !s2[1])
627 return true;
628 if (*s1 == '\n' && !s1[1] && !*s2)
629 return true;
630 return false;
631}
632EXPORT_SYMBOL(sysfs_streq);
633
634/**
635 * match_string - matches given string in an array
636 * @array: array of strings
637 * @n: number of strings in the array or -1 for NULL terminated arrays
638 * @string: string to match with
639 *
640 * Return:
641 * index of a @string in the @array if matches, or %-EINVAL otherwise.
642 */
643int match_string(const char * const *array, size_t n, const char *string)
644{
645 int index;
646 const char *item;
647
648 for (index = 0; index < n; index++) {
649 item = array[index];
650 if (!item)
651 break;
652 if (!strcmp(item, string))
653 return index;
654 }
655
656 return -EINVAL;
657}
658EXPORT_SYMBOL(match_string);
659
660/**
661 * __sysfs_match_string - matches given string in an array
662 * @array: array of strings
663 * @n: number of strings in the array or -1 for NULL terminated arrays
664 * @str: string to match with
665 *
666 * Returns index of @str in the @array or -EINVAL, just like match_string().
667 * Uses sysfs_streq instead of strcmp for matching.
668 */
669int __sysfs_match_string(const char * const *array, size_t n, const char *str)
670{
671 const char *item;
672 int index;
673
674 for (index = 0; index < n; index++) {
675 item = array[index];
676 if (!item)
677 break;
678 if (sysfs_streq(item, str))
679 return index;
680 }
681
682 return -EINVAL;
683}
684EXPORT_SYMBOL(__sysfs_match_string);
685
686#ifndef __HAVE_ARCH_MEMSET
687/**
688 * memset - Fill a region of memory with the given value
689 * @s: Pointer to the start of the area.
690 * @c: The byte to fill the area with
691 * @count: The size of the area.
692 *
693 * Do not use memset() to access IO space, use memset_io() instead.
694 */
695void *memset(void *s, int c, size_t count)
696{
697 char *xs = s;
698
699 while (count--)
700 *xs++ = c;
701 return s;
702}
703EXPORT_SYMBOL(memset);
704#endif
705
706/**
707 * memzero_explicit - Fill a region of memory (e.g. sensitive
708 * keying data) with 0s.
709 * @s: Pointer to the start of the area.
710 * @count: The size of the area.
711 *
712 * Note: usually using memset() is just fine (!), but in cases
713 * where clearing out _local_ data at the end of a scope is
714 * necessary, memzero_explicit() should be used instead in
715 * order to prevent the compiler from optimising away zeroing.
716 *
717 * memzero_explicit() doesn't need an arch-specific version as
718 * it just invokes the one of memset() implicitly.
719 */
720void memzero_explicit(void *s, size_t count)
721{
722 memset(s, 0, count);
723 barrier_data(s);
724}
725EXPORT_SYMBOL(memzero_explicit);
726
727#ifndef __HAVE_ARCH_MEMSET16
728/**
729 * memset16() - Fill a memory area with a uint16_t
730 * @s: Pointer to the start of the area.
731 * @v: The value to fill the area with
732 * @count: The number of values to store
733 *
734 * Differs from memset() in that it fills with a uint16_t instead
735 * of a byte. Remember that @count is the number of uint16_ts to
736 * store, not the number of bytes.
737 */
738void *memset16(uint16_t *s, uint16_t v, size_t count)
739{
740 uint16_t *xs = s;
741
742 while (count--)
743 *xs++ = v;
744 return s;
745}
746EXPORT_SYMBOL(memset16);
747#endif
748
749#ifndef __HAVE_ARCH_MEMSET32
750/**
751 * memset32() - Fill a memory area with a uint32_t
752 * @s: Pointer to the start of the area.
753 * @v: The value to fill the area with
754 * @count: The number of values to store
755 *
756 * Differs from memset() in that it fills with a uint32_t instead
757 * of a byte. Remember that @count is the number of uint32_ts to
758 * store, not the number of bytes.
759 */
760void *memset32(uint32_t *s, uint32_t v, size_t count)
761{
762 uint32_t *xs = s;
763
764 while (count--)
765 *xs++ = v;
766 return s;
767}
768EXPORT_SYMBOL(memset32);
769#endif
770
771#ifndef __HAVE_ARCH_MEMSET64
772/**
773 * memset64() - Fill a memory area with a uint64_t
774 * @s: Pointer to the start of the area.
775 * @v: The value to fill the area with
776 * @count: The number of values to store
777 *
778 * Differs from memset() in that it fills with a uint64_t instead
779 * of a byte. Remember that @count is the number of uint64_ts to
780 * store, not the number of bytes.
781 */
782void *memset64(uint64_t *s, uint64_t v, size_t count)
783{
784 uint64_t *xs = s;
785
786 while (count--)
787 *xs++ = v;
788 return s;
789}
790EXPORT_SYMBOL(memset64);
791#endif
792
793#ifndef __HAVE_ARCH_MEMCPY
794/**
795 * memcpy - Copy one area of memory to another
796 * @dest: Where to copy to
797 * @src: Where to copy from
798 * @count: The size of the area.
799 *
800 * You should not use this function to access IO space, use memcpy_toio()
801 * or memcpy_fromio() instead.
802 */
803void *memcpy(void *dest, const void *src, size_t count)
804{
805 char *tmp = dest;
806 const char *s = src;
807
808 while (count--)
809 *tmp++ = *s++;
810 return dest;
811}
812EXPORT_SYMBOL(memcpy);
813#endif
814
815#ifndef __HAVE_ARCH_MEMMOVE
816/**
817 * memmove - Copy one area of memory to another
818 * @dest: Where to copy to
819 * @src: Where to copy from
820 * @count: The size of the area.
821 *
822 * Unlike memcpy(), memmove() copes with overlapping areas.
823 */
824void *memmove(void *dest, const void *src, size_t count)
825{
826 char *tmp;
827 const char *s;
828
829 if (dest <= src) {
830 tmp = dest;
831 s = src;
832 while (count--)
833 *tmp++ = *s++;
834 } else {
835 tmp = dest;
836 tmp += count;
837 s = src;
838 s += count;
839 while (count--)
840 *--tmp = *--s;
841 }
842 return dest;
843}
844EXPORT_SYMBOL(memmove);
845#endif
846
847#ifndef __HAVE_ARCH_MEMCMP
848/**
849 * memcmp - Compare two areas of memory
850 * @cs: One area of memory
851 * @ct: Another area of memory
852 * @count: The size of the area.
853 */
854#undef memcmp
855__visible int memcmp(const void *cs, const void *ct, size_t count)
856{
857 const unsigned char *su1, *su2;
858 int res = 0;
859
860 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
861 if ((res = *su1 - *su2) != 0)
862 break;
863 return res;
864}
865EXPORT_SYMBOL(memcmp);
866#endif
867
868#ifndef __HAVE_ARCH_MEMSCAN
869/**
870 * memscan - Find a character in an area of memory.
871 * @addr: The memory area
872 * @c: The byte to search for
873 * @size: The size of the area.
874 *
875 * returns the address of the first occurrence of @c, or 1 byte past
876 * the area if @c is not found
877 */
878void *memscan(void *addr, int c, size_t size)
879{
880 unsigned char *p = addr;
881
882 while (size) {
883 if (*p == c)
884 return (void *)p;
885 p++;
886 size--;
887 }
888 return (void *)p;
889}
890EXPORT_SYMBOL(memscan);
891#endif
892
893#ifndef __HAVE_ARCH_STRSTR
894/**
895 * strstr - Find the first substring in a %NUL terminated string
896 * @s1: The string to be searched
897 * @s2: The string to search for
898 */
899char *strstr(const char *s1, const char *s2)
900{
901 size_t l1, l2;
902
903 l2 = strlen(s2);
904 if (!l2)
905 return (char *)s1;
906 l1 = strlen(s1);
907 while (l1 >= l2) {
908 l1--;
909 if (!memcmp(s1, s2, l2))
910 return (char *)s1;
911 s1++;
912 }
913 return NULL;
914}
915EXPORT_SYMBOL(strstr);
916#endif
917
918#ifndef __HAVE_ARCH_STRNSTR
919/**
920 * strnstr - Find the first substring in a length-limited string
921 * @s1: The string to be searched
922 * @s2: The string to search for
923 * @len: the maximum number of characters to search
924 */
925char *strnstr(const char *s1, const char *s2, size_t len)
926{
927 size_t l2;
928
929 l2 = strlen(s2);
930 if (!l2)
931 return (char *)s1;
932 while (len >= l2) {
933 len--;
934 if (!memcmp(s1, s2, l2))
935 return (char *)s1;
936 s1++;
937 }
938 return NULL;
939}
940EXPORT_SYMBOL(strnstr);
941#endif
942
943#ifndef __HAVE_ARCH_MEMCHR
944/**
945 * memchr - Find a character in an area of memory.
946 * @s: The memory area
947 * @c: The byte to search for
948 * @n: The size of the area.
949 *
950 * returns the address of the first occurrence of @c, or %NULL
951 * if @c is not found
952 */
953void *memchr(const void *s, int c, size_t n)
954{
955 const unsigned char *p = s;
956 while (n-- != 0) {
957 if ((unsigned char)c == *p++) {
958 return (void *)(p - 1);
959 }
960 }
961 return NULL;
962}
963EXPORT_SYMBOL(memchr);
964#endif
965
966static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
967{
968 while (bytes) {
969 if (*start != value)
970 return (void *)start;
971 start++;
972 bytes--;
973 }
974 return NULL;
975}
976
977/**
978 * memchr_inv - Find an unmatching character in an area of memory.
979 * @start: The memory area
980 * @c: Find a character other than c
981 * @bytes: The size of the area.
982 *
983 * returns the address of the first character other than @c, or %NULL
984 * if the whole buffer contains just @c.
985 */
986void *memchr_inv(const void *start, int c, size_t bytes)
987{
988 u8 value = c;
989 u64 value64;
990 unsigned int words, prefix;
991
992 if (bytes <= 16)
993 return check_bytes8(start, value, bytes);
994
995 value64 = value;
996#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
997 value64 *= 0x0101010101010101ULL;
998#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
999 value64 *= 0x01010101;
1000 value64 |= value64 << 32;
1001#else
1002 value64 |= value64 << 8;
1003 value64 |= value64 << 16;
1004 value64 |= value64 << 32;
1005#endif
1006
1007 prefix = (unsigned long)start % 8;
1008 if (prefix) {
1009 u8 *r;
1010
1011 prefix = 8 - prefix;
1012 r = check_bytes8(start, value, prefix);
1013 if (r)
1014 return r;
1015 start += prefix;
1016 bytes -= prefix;
1017 }
1018
1019 words = bytes / 8;
1020
1021 while (words) {
1022 if (*(u64 *)start != value64)
1023 return check_bytes8(start, value, 8);
1024 start += 8;
1025 words--;
1026 }
1027
1028 return check_bytes8(start, value, bytes % 8);
1029}
1030EXPORT_SYMBOL(memchr_inv);
1031
1032/**
1033 * strreplace - Replace all occurrences of character in string.
1034 * @s: The string to operate on.
1035 * @old: The character being replaced.
1036 * @new: The character @old is replaced with.
1037 *
1038 * Returns pointer to the nul byte at the end of @s.
1039 */
1040char *strreplace(char *s, char old, char new)
1041{
1042 for (; *s; ++s)
1043 if (*s == old)
1044 *s = new;
1045 return s;
1046}
1047EXPORT_SYMBOL(strreplace);
1048
1049void fortify_panic(const char *name)
1050{
1051 pr_emerg("detected buffer overflow in %s\n", name);
1052 BUG();
1053}
1054EXPORT_SYMBOL(fortify_panic);