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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#ifndef __HAVE_ARCH_STRNICMP
31/**
32 * strnicmp - Case insensitive, length-limited string comparison
33 * @s1: One string
34 * @s2: The other string
35 * @len: the maximum number of characters to compare
36 */
37int strnicmp(const char *s1, const char *s2, size_t len)
38{
39 /* Yes, Virginia, it had better be unsigned */
40 unsigned char c1, c2;
41
42 if (!len)
43 return 0;
44
45 do {
46 c1 = *s1++;
47 c2 = *s2++;
48 if (!c1 || !c2)
49 break;
50 if (c1 == c2)
51 continue;
52 c1 = tolower(c1);
53 c2 = tolower(c2);
54 if (c1 != c2)
55 break;
56 } while (--len);
57 return (int)c1 - (int)c2;
58}
59EXPORT_SYMBOL(strnicmp);
60#endif
61
62#ifndef __HAVE_ARCH_STRCASECMP
63int strcasecmp(const char *s1, const char *s2)
64{
65 int c1, c2;
66
67 do {
68 c1 = tolower(*s1++);
69 c2 = tolower(*s2++);
70 } while (c1 == c2 && c1 != 0);
71 return c1 - c2;
72}
73EXPORT_SYMBOL(strcasecmp);
74#endif
75
76#ifndef __HAVE_ARCH_STRNCASECMP
77int strncasecmp(const char *s1, const char *s2, size_t n)
78{
79 int c1, c2;
80
81 do {
82 c1 = tolower(*s1++);
83 c2 = tolower(*s2++);
84 } while ((--n > 0) && c1 == c2 && c1 != 0);
85 return c1 - c2;
86}
87EXPORT_SYMBOL(strncasecmp);
88#endif
89
90#ifndef __HAVE_ARCH_STRCPY
91/**
92 * strcpy - Copy a %NUL terminated string
93 * @dest: Where to copy the string to
94 * @src: Where to copy the string from
95 */
96#undef strcpy
97char *strcpy(char *dest, const char *src)
98{
99 char *tmp = dest;
100
101 while ((*dest++ = *src++) != '\0')
102 /* nothing */;
103 return tmp;
104}
105EXPORT_SYMBOL(strcpy);
106#endif
107
108#ifndef __HAVE_ARCH_STRNCPY
109/**
110 * strncpy - Copy a length-limited, %NUL-terminated string
111 * @dest: Where to copy the string to
112 * @src: Where to copy the string from
113 * @count: The maximum number of bytes to copy
114 *
115 * The result is not %NUL-terminated if the source exceeds
116 * @count bytes.
117 *
118 * In the case where the length of @src is less than that of
119 * count, the remainder of @dest will be padded with %NUL.
120 *
121 */
122char *strncpy(char *dest, const char *src, size_t count)
123{
124 char *tmp = dest;
125
126 while (count) {
127 if ((*tmp = *src) != 0)
128 src++;
129 tmp++;
130 count--;
131 }
132 return dest;
133}
134EXPORT_SYMBOL(strncpy);
135#endif
136
137#ifndef __HAVE_ARCH_STRLCPY
138/**
139 * strlcpy - Copy a %NUL terminated string into a sized buffer
140 * @dest: Where to copy the string to
141 * @src: Where to copy the string from
142 * @size: size of destination buffer
143 *
144 * Compatible with *BSD: the result is always a valid
145 * NUL-terminated string that fits in the buffer (unless,
146 * of course, the buffer size is zero). It does not pad
147 * out the result like strncpy() does.
148 */
149size_t strlcpy(char *dest, const char *src, size_t size)
150{
151 size_t ret = strlen(src);
152
153 if (size) {
154 size_t len = (ret >= size) ? size - 1 : ret;
155 memcpy(dest, src, len);
156 dest[len] = '\0';
157 }
158 return ret;
159}
160EXPORT_SYMBOL(strlcpy);
161#endif
162
163#ifndef __HAVE_ARCH_STRCAT
164/**
165 * strcat - Append one %NUL-terminated string to another
166 * @dest: The string to be appended to
167 * @src: The string to append to it
168 */
169#undef strcat
170char *strcat(char *dest, const char *src)
171{
172 char *tmp = dest;
173
174 while (*dest)
175 dest++;
176 while ((*dest++ = *src++) != '\0')
177 ;
178 return tmp;
179}
180EXPORT_SYMBOL(strcat);
181#endif
182
183#ifndef __HAVE_ARCH_STRNCAT
184/**
185 * strncat - Append a length-limited, %NUL-terminated string to another
186 * @dest: The string to be appended to
187 * @src: The string to append to it
188 * @count: The maximum numbers of bytes to copy
189 *
190 * Note that in contrast to strncpy(), strncat() ensures the result is
191 * terminated.
192 */
193char *strncat(char *dest, const char *src, size_t count)
194{
195 char *tmp = dest;
196
197 if (count) {
198 while (*dest)
199 dest++;
200 while ((*dest++ = *src++) != 0) {
201 if (--count == 0) {
202 *dest = '\0';
203 break;
204 }
205 }
206 }
207 return tmp;
208}
209EXPORT_SYMBOL(strncat);
210#endif
211
212#ifndef __HAVE_ARCH_STRLCAT
213/**
214 * strlcat - Append a length-limited, %NUL-terminated string to another
215 * @dest: The string to be appended to
216 * @src: The string to append to it
217 * @count: The size of the destination buffer.
218 */
219size_t strlcat(char *dest, const char *src, size_t count)
220{
221 size_t dsize = strlen(dest);
222 size_t len = strlen(src);
223 size_t res = dsize + len;
224
225 /* This would be a bug */
226 BUG_ON(dsize >= count);
227
228 dest += dsize;
229 count -= dsize;
230 if (len >= count)
231 len = count-1;
232 memcpy(dest, src, len);
233 dest[len] = 0;
234 return res;
235}
236EXPORT_SYMBOL(strlcat);
237#endif
238
239#ifndef __HAVE_ARCH_STRCMP
240/**
241 * strcmp - Compare two strings
242 * @cs: One string
243 * @ct: Another string
244 */
245#undef strcmp
246int strcmp(const char *cs, const char *ct)
247{
248 unsigned char c1, c2;
249
250 while (1) {
251 c1 = *cs++;
252 c2 = *ct++;
253 if (c1 != c2)
254 return c1 < c2 ? -1 : 1;
255 if (!c1)
256 break;
257 }
258 return 0;
259}
260EXPORT_SYMBOL(strcmp);
261#endif
262
263#ifndef __HAVE_ARCH_STRNCMP
264/**
265 * strncmp - Compare two length-limited strings
266 * @cs: One string
267 * @ct: Another string
268 * @count: The maximum number of bytes to compare
269 */
270int strncmp(const char *cs, const char *ct, size_t count)
271{
272 unsigned char c1, c2;
273
274 while (count) {
275 c1 = *cs++;
276 c2 = *ct++;
277 if (c1 != c2)
278 return c1 < c2 ? -1 : 1;
279 if (!c1)
280 break;
281 count--;
282 }
283 return 0;
284}
285EXPORT_SYMBOL(strncmp);
286#endif
287
288#ifndef __HAVE_ARCH_STRCHR
289/**
290 * strchr - Find the first occurrence of a character in a string
291 * @s: The string to be searched
292 * @c: The character to search for
293 */
294char *strchr(const char *s, int c)
295{
296 for (; *s != (char)c; ++s)
297 if (*s == '\0')
298 return NULL;
299 return (char *)s;
300}
301EXPORT_SYMBOL(strchr);
302#endif
303
304#ifndef __HAVE_ARCH_STRRCHR
305/**
306 * strrchr - Find the last occurrence of a character in a string
307 * @s: The string to be searched
308 * @c: The character to search for
309 */
310char *strrchr(const char *s, int c)
311{
312 const char *p = s + strlen(s);
313 do {
314 if (*p == (char)c)
315 return (char *)p;
316 } while (--p >= s);
317 return NULL;
318}
319EXPORT_SYMBOL(strrchr);
320#endif
321
322#ifndef __HAVE_ARCH_STRNCHR
323/**
324 * strnchr - Find a character in a length limited string
325 * @s: The string to be searched
326 * @count: The number of characters to be searched
327 * @c: The character to search for
328 */
329char *strnchr(const char *s, size_t count, int c)
330{
331 for (; count-- && *s != '\0'; ++s)
332 if (*s == (char)c)
333 return (char *)s;
334 return NULL;
335}
336EXPORT_SYMBOL(strnchr);
337#endif
338
339/**
340 * skip_spaces - Removes leading whitespace from @str.
341 * @str: The string to be stripped.
342 *
343 * Returns a pointer to the first non-whitespace character in @str.
344 */
345char *skip_spaces(const char *str)
346{
347 while (isspace(*str))
348 ++str;
349 return (char *)str;
350}
351EXPORT_SYMBOL(skip_spaces);
352
353/**
354 * strim - Removes leading and trailing whitespace from @s.
355 * @s: The string to be stripped.
356 *
357 * Note that the first trailing whitespace is replaced with a %NUL-terminator
358 * in the given string @s. Returns a pointer to the first non-whitespace
359 * character in @s.
360 */
361char *strim(char *s)
362{
363 size_t size;
364 char *end;
365
366 size = strlen(s);
367 if (!size)
368 return s;
369
370 end = s + size - 1;
371 while (end >= s && isspace(*end))
372 end--;
373 *(end + 1) = '\0';
374
375 return skip_spaces(s);
376}
377EXPORT_SYMBOL(strim);
378
379#ifndef __HAVE_ARCH_STRLEN
380/**
381 * strlen - Find the length of a string
382 * @s: The string to be sized
383 */
384size_t strlen(const char *s)
385{
386 const char *sc;
387
388 for (sc = s; *sc != '\0'; ++sc)
389 /* nothing */;
390 return sc - s;
391}
392EXPORT_SYMBOL(strlen);
393#endif
394
395#ifndef __HAVE_ARCH_STRNLEN
396/**
397 * strnlen - Find the length of a length-limited string
398 * @s: The string to be sized
399 * @count: The maximum number of bytes to search
400 */
401size_t strnlen(const char *s, size_t count)
402{
403 const char *sc;
404
405 for (sc = s; count-- && *sc != '\0'; ++sc)
406 /* nothing */;
407 return sc - s;
408}
409EXPORT_SYMBOL(strnlen);
410#endif
411
412#ifndef __HAVE_ARCH_STRSPN
413/**
414 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
415 * @s: The string to be searched
416 * @accept: The string to search for
417 */
418size_t strspn(const char *s, const char *accept)
419{
420 const char *p;
421 const char *a;
422 size_t count = 0;
423
424 for (p = s; *p != '\0'; ++p) {
425 for (a = accept; *a != '\0'; ++a) {
426 if (*p == *a)
427 break;
428 }
429 if (*a == '\0')
430 return count;
431 ++count;
432 }
433 return count;
434}
435
436EXPORT_SYMBOL(strspn);
437#endif
438
439#ifndef __HAVE_ARCH_STRCSPN
440/**
441 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
442 * @s: The string to be searched
443 * @reject: The string to avoid
444 */
445size_t strcspn(const char *s, const char *reject)
446{
447 const char *p;
448 const char *r;
449 size_t count = 0;
450
451 for (p = s; *p != '\0'; ++p) {
452 for (r = reject; *r != '\0'; ++r) {
453 if (*p == *r)
454 return count;
455 }
456 ++count;
457 }
458 return count;
459}
460EXPORT_SYMBOL(strcspn);
461#endif
462
463#ifndef __HAVE_ARCH_STRPBRK
464/**
465 * strpbrk - Find the first occurrence of a set of characters
466 * @cs: The string to be searched
467 * @ct: The characters to search for
468 */
469char *strpbrk(const char *cs, const char *ct)
470{
471 const char *sc1, *sc2;
472
473 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
474 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
475 if (*sc1 == *sc2)
476 return (char *)sc1;
477 }
478 }
479 return NULL;
480}
481EXPORT_SYMBOL(strpbrk);
482#endif
483
484#ifndef __HAVE_ARCH_STRSEP
485/**
486 * strsep - Split a string into tokens
487 * @s: The string to be searched
488 * @ct: The characters to search for
489 *
490 * strsep() updates @s to point after the token, ready for the next call.
491 *
492 * It returns empty tokens, too, behaving exactly like the libc function
493 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
494 * Same semantics, slimmer shape. ;)
495 */
496char *strsep(char **s, const char *ct)
497{
498 char *sbegin = *s;
499 char *end;
500
501 if (sbegin == NULL)
502 return NULL;
503
504 end = strpbrk(sbegin, ct);
505 if (end)
506 *end++ = '\0';
507 *s = end;
508 return sbegin;
509}
510EXPORT_SYMBOL(strsep);
511#endif
512
513/**
514 * sysfs_streq - return true if strings are equal, modulo trailing newline
515 * @s1: one string
516 * @s2: another string
517 *
518 * This routine returns true iff two strings are equal, treating both
519 * NUL and newline-then-NUL as equivalent string terminations. It's
520 * geared for use with sysfs input strings, which generally terminate
521 * with newlines but are compared against values without newlines.
522 */
523bool sysfs_streq(const char *s1, const char *s2)
524{
525 while (*s1 && *s1 == *s2) {
526 s1++;
527 s2++;
528 }
529
530 if (*s1 == *s2)
531 return true;
532 if (!*s1 && *s2 == '\n' && !s2[1])
533 return true;
534 if (*s1 == '\n' && !s1[1] && !*s2)
535 return true;
536 return false;
537}
538EXPORT_SYMBOL(sysfs_streq);
539
540/**
541 * strtobool - convert common user inputs into boolean values
542 * @s: input string
543 * @res: result
544 *
545 * This routine returns 0 iff the first character is one of 'Yy1Nn0'.
546 * Otherwise it will return -EINVAL. Value pointed to by res is
547 * updated upon finding a match.
548 */
549int strtobool(const char *s, bool *res)
550{
551 switch (s[0]) {
552 case 'y':
553 case 'Y':
554 case '1':
555 *res = true;
556 break;
557 case 'n':
558 case 'N':
559 case '0':
560 *res = false;
561 break;
562 default:
563 return -EINVAL;
564 }
565 return 0;
566}
567EXPORT_SYMBOL(strtobool);
568
569#ifndef __HAVE_ARCH_MEMSET
570/**
571 * memset - Fill a region of memory with the given value
572 * @s: Pointer to the start of the area.
573 * @c: The byte to fill the area with
574 * @count: The size of the area.
575 *
576 * Do not use memset() to access IO space, use memset_io() instead.
577 */
578void *memset(void *s, int c, size_t count)
579{
580 char *xs = s;
581
582 while (count--)
583 *xs++ = c;
584 return s;
585}
586EXPORT_SYMBOL(memset);
587#endif
588
589#ifndef __HAVE_ARCH_MEMCPY
590/**
591 * memcpy - Copy one area of memory to another
592 * @dest: Where to copy to
593 * @src: Where to copy from
594 * @count: The size of the area.
595 *
596 * You should not use this function to access IO space, use memcpy_toio()
597 * or memcpy_fromio() instead.
598 */
599void *memcpy(void *dest, const void *src, size_t count)
600{
601 char *tmp = dest;
602 const char *s = src;
603
604 while (count--)
605 *tmp++ = *s++;
606 return dest;
607}
608EXPORT_SYMBOL(memcpy);
609#endif
610
611#ifndef __HAVE_ARCH_MEMMOVE
612/**
613 * memmove - Copy one area of memory to another
614 * @dest: Where to copy to
615 * @src: Where to copy from
616 * @count: The size of the area.
617 *
618 * Unlike memcpy(), memmove() copes with overlapping areas.
619 */
620void *memmove(void *dest, const void *src, size_t count)
621{
622 char *tmp;
623 const char *s;
624
625 if (dest <= src) {
626 tmp = dest;
627 s = src;
628 while (count--)
629 *tmp++ = *s++;
630 } else {
631 tmp = dest;
632 tmp += count;
633 s = src;
634 s += count;
635 while (count--)
636 *--tmp = *--s;
637 }
638 return dest;
639}
640EXPORT_SYMBOL(memmove);
641#endif
642
643#ifndef __HAVE_ARCH_MEMCMP
644/**
645 * memcmp - Compare two areas of memory
646 * @cs: One area of memory
647 * @ct: Another area of memory
648 * @count: The size of the area.
649 */
650#undef memcmp
651__visible int memcmp(const void *cs, const void *ct, size_t count)
652{
653 const unsigned char *su1, *su2;
654 int res = 0;
655
656 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
657 if ((res = *su1 - *su2) != 0)
658 break;
659 return res;
660}
661EXPORT_SYMBOL(memcmp);
662#endif
663
664#ifndef __HAVE_ARCH_MEMSCAN
665/**
666 * memscan - Find a character in an area of memory.
667 * @addr: The memory area
668 * @c: The byte to search for
669 * @size: The size of the area.
670 *
671 * returns the address of the first occurrence of @c, or 1 byte past
672 * the area if @c is not found
673 */
674void *memscan(void *addr, int c, size_t size)
675{
676 unsigned char *p = addr;
677
678 while (size) {
679 if (*p == c)
680 return (void *)p;
681 p++;
682 size--;
683 }
684 return (void *)p;
685}
686EXPORT_SYMBOL(memscan);
687#endif
688
689#ifndef __HAVE_ARCH_STRSTR
690/**
691 * strstr - Find the first substring in a %NUL terminated string
692 * @s1: The string to be searched
693 * @s2: The string to search for
694 */
695char *strstr(const char *s1, const char *s2)
696{
697 size_t l1, l2;
698
699 l2 = strlen(s2);
700 if (!l2)
701 return (char *)s1;
702 l1 = strlen(s1);
703 while (l1 >= l2) {
704 l1--;
705 if (!memcmp(s1, s2, l2))
706 return (char *)s1;
707 s1++;
708 }
709 return NULL;
710}
711EXPORT_SYMBOL(strstr);
712#endif
713
714#ifndef __HAVE_ARCH_STRNSTR
715/**
716 * strnstr - Find the first substring in a length-limited string
717 * @s1: The string to be searched
718 * @s2: The string to search for
719 * @len: the maximum number of characters to search
720 */
721char *strnstr(const char *s1, const char *s2, size_t len)
722{
723 size_t l2;
724
725 l2 = strlen(s2);
726 if (!l2)
727 return (char *)s1;
728 while (len >= l2) {
729 len--;
730 if (!memcmp(s1, s2, l2))
731 return (char *)s1;
732 s1++;
733 }
734 return NULL;
735}
736EXPORT_SYMBOL(strnstr);
737#endif
738
739#ifndef __HAVE_ARCH_MEMCHR
740/**
741 * memchr - Find a character in an area of memory.
742 * @s: The memory area
743 * @c: The byte to search for
744 * @n: The size of the area.
745 *
746 * returns the address of the first occurrence of @c, or %NULL
747 * if @c is not found
748 */
749void *memchr(const void *s, int c, size_t n)
750{
751 const unsigned char *p = s;
752 while (n-- != 0) {
753 if ((unsigned char)c == *p++) {
754 return (void *)(p - 1);
755 }
756 }
757 return NULL;
758}
759EXPORT_SYMBOL(memchr);
760#endif
761
762static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
763{
764 while (bytes) {
765 if (*start != value)
766 return (void *)start;
767 start++;
768 bytes--;
769 }
770 return NULL;
771}
772
773/**
774 * memchr_inv - Find an unmatching character in an area of memory.
775 * @start: The memory area
776 * @c: Find a character other than c
777 * @bytes: The size of the area.
778 *
779 * returns the address of the first character other than @c, or %NULL
780 * if the whole buffer contains just @c.
781 */
782void *memchr_inv(const void *start, int c, size_t bytes)
783{
784 u8 value = c;
785 u64 value64;
786 unsigned int words, prefix;
787
788 if (bytes <= 16)
789 return check_bytes8(start, value, bytes);
790
791 value64 = value;
792#if defined(ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
793 value64 *= 0x0101010101010101;
794#elif defined(ARCH_HAS_FAST_MULTIPLIER)
795 value64 *= 0x01010101;
796 value64 |= value64 << 32;
797#else
798 value64 |= value64 << 8;
799 value64 |= value64 << 16;
800 value64 |= value64 << 32;
801#endif
802
803 prefix = (unsigned long)start % 8;
804 if (prefix) {
805 u8 *r;
806
807 prefix = 8 - prefix;
808 r = check_bytes8(start, value, prefix);
809 if (r)
810 return r;
811 start += prefix;
812 bytes -= prefix;
813 }
814
815 words = bytes / 8;
816
817 while (words) {
818 if (*(u64 *)start != value64)
819 return check_bytes8(start, value, 8);
820 start += 8;
821 words--;
822 }
823
824 return check_bytes8(start, value, bytes % 8);
825}
826EXPORT_SYMBOL(memchr_inv);
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 */
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. The
162 * behavior is undefined if the string buffers overlap. The destination
163 * buffer is always NUL terminated, unless it's zero-sized.
164 *
165 * Preferred to strlcpy() since the API doesn't require reading memory
166 * from the src string beyond the specified "count" bytes, and since
167 * the return value is easier to error-check than strlcpy()'s.
168 * In addition, the implementation is robust to the string changing out
169 * from underneath it, unlike the current strlcpy() implementation.
170 *
171 * Preferred to strncpy() since it always returns a valid string, and
172 * doesn't unnecessarily force the tail of the destination buffer to be
173 * zeroed. If zeroing is desired please use strscpy_pad().
174 *
175 * Returns:
176 * * The number of characters copied (not including the trailing %NUL)
177 * * -E2BIG if count is 0 or @src was truncated.
178 */
179ssize_t strscpy(char *dest, const char *src, size_t count)
180{
181 const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
182 size_t max = count;
183 long res = 0;
184
185 if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
186 return -E2BIG;
187
188#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
189 /*
190 * If src is unaligned, don't cross a page boundary,
191 * since we don't know if the next page is mapped.
192 */
193 if ((long)src & (sizeof(long) - 1)) {
194 size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
195 if (limit < max)
196 max = limit;
197 }
198#else
199 /* If src or dest is unaligned, don't do word-at-a-time. */
200 if (((long) dest | (long) src) & (sizeof(long) - 1))
201 max = 0;
202#endif
203
204 while (max >= sizeof(unsigned long)) {
205 unsigned long c, data;
206
207 c = read_word_at_a_time(src+res);
208 if (has_zero(c, &data, &constants)) {
209 data = prep_zero_mask(c, data, &constants);
210 data = create_zero_mask(data);
211 *(unsigned long *)(dest+res) = c & zero_bytemask(data);
212 return res + find_zero(data);
213 }
214 *(unsigned long *)(dest+res) = c;
215 res += sizeof(unsigned long);
216 count -= sizeof(unsigned long);
217 max -= sizeof(unsigned long);
218 }
219
220 while (count) {
221 char c;
222
223 c = src[res];
224 dest[res] = c;
225 if (!c)
226 return res;
227 res++;
228 count--;
229 }
230
231 /* Hit buffer length without finding a NUL; force NUL-termination. */
232 if (res)
233 dest[res-1] = '\0';
234
235 return -E2BIG;
236}
237EXPORT_SYMBOL(strscpy);
238#endif
239
240/**
241 * strscpy_pad() - Copy a C-string into a sized buffer
242 * @dest: Where to copy the string to
243 * @src: Where to copy the string from
244 * @count: Size of destination buffer
245 *
246 * Copy the string, or as much of it as fits, into the dest buffer. The
247 * behavior is undefined if the string buffers overlap. The destination
248 * buffer is always %NUL terminated, unless it's zero-sized.
249 *
250 * If the source string is shorter than the destination buffer, zeros
251 * the tail of the destination buffer.
252 *
253 * For full explanation of why you may want to consider using the
254 * 'strscpy' functions please see the function docstring for strscpy().
255 *
256 * Returns:
257 * * The number of characters copied (not including the trailing %NUL)
258 * * -E2BIG if count is 0 or @src was truncated.
259 */
260ssize_t strscpy_pad(char *dest, const char *src, size_t count)
261{
262 ssize_t written;
263
264 written = strscpy(dest, src, count);
265 if (written < 0 || written == count - 1)
266 return written;
267
268 memset(dest + written + 1, 0, count - written - 1);
269
270 return written;
271}
272EXPORT_SYMBOL(strscpy_pad);
273
274/**
275 * stpcpy - copy a string from src to dest returning a pointer to the new end
276 * of dest, including src's %NUL-terminator. May overrun dest.
277 * @dest: pointer to end of string being copied into. Must be large enough
278 * to receive copy.
279 * @src: pointer to the beginning of string being copied from. Must not overlap
280 * dest.
281 *
282 * stpcpy differs from strcpy in a key way: the return value is a pointer
283 * to the new %NUL-terminating character in @dest. (For strcpy, the return
284 * value is a pointer to the start of @dest). This interface is considered
285 * unsafe as it doesn't perform bounds checking of the inputs. As such it's
286 * not recommended for usage. Instead, its definition is provided in case
287 * the compiler lowers other libcalls to stpcpy.
288 */
289char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
290char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
291{
292 while ((*dest++ = *src++) != '\0')
293 /* nothing */;
294 return --dest;
295}
296EXPORT_SYMBOL(stpcpy);
297
298#ifndef __HAVE_ARCH_STRCAT
299/**
300 * strcat - Append one %NUL-terminated string to another
301 * @dest: The string to be appended to
302 * @src: The string to append to it
303 */
304char *strcat(char *dest, const char *src)
305{
306 char *tmp = dest;
307
308 while (*dest)
309 dest++;
310 while ((*dest++ = *src++) != '\0')
311 ;
312 return tmp;
313}
314EXPORT_SYMBOL(strcat);
315#endif
316
317#ifndef __HAVE_ARCH_STRNCAT
318/**
319 * strncat - Append a length-limited, C-string to another
320 * @dest: The string to be appended to
321 * @src: The string to append to it
322 * @count: The maximum numbers of bytes to copy
323 *
324 * Note that in contrast to strncpy(), strncat() ensures the result is
325 * terminated.
326 */
327char *strncat(char *dest, const char *src, size_t count)
328{
329 char *tmp = dest;
330
331 if (count) {
332 while (*dest)
333 dest++;
334 while ((*dest++ = *src++) != 0) {
335 if (--count == 0) {
336 *dest = '\0';
337 break;
338 }
339 }
340 }
341 return tmp;
342}
343EXPORT_SYMBOL(strncat);
344#endif
345
346#ifndef __HAVE_ARCH_STRLCAT
347/**
348 * strlcat - Append a length-limited, C-string to another
349 * @dest: The string to be appended to
350 * @src: The string to append to it
351 * @count: The size of the destination buffer.
352 */
353size_t strlcat(char *dest, const char *src, size_t count)
354{
355 size_t dsize = strlen(dest);
356 size_t len = strlen(src);
357 size_t res = dsize + len;
358
359 /* This would be a bug */
360 BUG_ON(dsize >= count);
361
362 dest += dsize;
363 count -= dsize;
364 if (len >= count)
365 len = count-1;
366 memcpy(dest, src, len);
367 dest[len] = 0;
368 return res;
369}
370EXPORT_SYMBOL(strlcat);
371#endif
372
373#ifndef __HAVE_ARCH_STRCMP
374/**
375 * strcmp - Compare two strings
376 * @cs: One string
377 * @ct: Another string
378 */
379int strcmp(const char *cs, const char *ct)
380{
381 unsigned char c1, c2;
382
383 while (1) {
384 c1 = *cs++;
385 c2 = *ct++;
386 if (c1 != c2)
387 return c1 < c2 ? -1 : 1;
388 if (!c1)
389 break;
390 }
391 return 0;
392}
393EXPORT_SYMBOL(strcmp);
394#endif
395
396#ifndef __HAVE_ARCH_STRNCMP
397/**
398 * strncmp - Compare two length-limited strings
399 * @cs: One string
400 * @ct: Another string
401 * @count: The maximum number of bytes to compare
402 */
403int strncmp(const char *cs, const char *ct, size_t count)
404{
405 unsigned char c1, c2;
406
407 while (count) {
408 c1 = *cs++;
409 c2 = *ct++;
410 if (c1 != c2)
411 return c1 < c2 ? -1 : 1;
412 if (!c1)
413 break;
414 count--;
415 }
416 return 0;
417}
418EXPORT_SYMBOL(strncmp);
419#endif
420
421#ifndef __HAVE_ARCH_STRCHR
422/**
423 * strchr - Find the first occurrence of a character in a string
424 * @s: The string to be searched
425 * @c: The character to search for
426 *
427 * Note that the %NUL-terminator is considered part of the string, and can
428 * be searched for.
429 */
430char *strchr(const char *s, int c)
431{
432 for (; *s != (char)c; ++s)
433 if (*s == '\0')
434 return NULL;
435 return (char *)s;
436}
437EXPORT_SYMBOL(strchr);
438#endif
439
440#ifndef __HAVE_ARCH_STRCHRNUL
441/**
442 * strchrnul - Find and return a character in a string, or end of string
443 * @s: The string to be searched
444 * @c: The character to search for
445 *
446 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
447 * return a pointer to the null byte at the end of s.
448 */
449char *strchrnul(const char *s, int c)
450{
451 while (*s && *s != (char)c)
452 s++;
453 return (char *)s;
454}
455EXPORT_SYMBOL(strchrnul);
456#endif
457
458/**
459 * strnchrnul - Find and return a character in a length limited string,
460 * or end of string
461 * @s: The string to be searched
462 * @count: The number of characters to be searched
463 * @c: The character to search for
464 *
465 * Returns pointer to the first occurrence of 'c' in s. If c is not found,
466 * then return a pointer to the last character of the string.
467 */
468char *strnchrnul(const char *s, size_t count, int c)
469{
470 while (count-- && *s && *s != (char)c)
471 s++;
472 return (char *)s;
473}
474
475#ifndef __HAVE_ARCH_STRRCHR
476/**
477 * strrchr - Find the last occurrence of a character in a string
478 * @s: The string to be searched
479 * @c: The character to search for
480 */
481char *strrchr(const char *s, int c)
482{
483 const char *last = NULL;
484 do {
485 if (*s == (char)c)
486 last = s;
487 } while (*s++);
488 return (char *)last;
489}
490EXPORT_SYMBOL(strrchr);
491#endif
492
493#ifndef __HAVE_ARCH_STRNCHR
494/**
495 * strnchr - Find a character in a length limited string
496 * @s: The string to be searched
497 * @count: The number of characters to be searched
498 * @c: The character to search for
499 *
500 * Note that the %NUL-terminator is considered part of the string, and can
501 * be searched for.
502 */
503char *strnchr(const char *s, size_t count, int c)
504{
505 while (count--) {
506 if (*s == (char)c)
507 return (char *)s;
508 if (*s++ == '\0')
509 break;
510 }
511 return NULL;
512}
513EXPORT_SYMBOL(strnchr);
514#endif
515
516/**
517 * skip_spaces - Removes leading whitespace from @str.
518 * @str: The string to be stripped.
519 *
520 * Returns a pointer to the first non-whitespace character in @str.
521 */
522char *skip_spaces(const char *str)
523{
524 while (isspace(*str))
525 ++str;
526 return (char *)str;
527}
528EXPORT_SYMBOL(skip_spaces);
529
530/**
531 * strim - Removes leading and trailing whitespace from @s.
532 * @s: The string to be stripped.
533 *
534 * Note that the first trailing whitespace is replaced with a %NUL-terminator
535 * in the given string @s. Returns a pointer to the first non-whitespace
536 * character in @s.
537 */
538char *strim(char *s)
539{
540 size_t size;
541 char *end;
542
543 size = strlen(s);
544 if (!size)
545 return s;
546
547 end = s + size - 1;
548 while (end >= s && isspace(*end))
549 end--;
550 *(end + 1) = '\0';
551
552 return skip_spaces(s);
553}
554EXPORT_SYMBOL(strim);
555
556#ifndef __HAVE_ARCH_STRLEN
557/**
558 * strlen - Find the length of a string
559 * @s: The string to be sized
560 */
561size_t strlen(const char *s)
562{
563 const char *sc;
564
565 for (sc = s; *sc != '\0'; ++sc)
566 /* nothing */;
567 return sc - s;
568}
569EXPORT_SYMBOL(strlen);
570#endif
571
572#ifndef __HAVE_ARCH_STRNLEN
573/**
574 * strnlen - Find the length of a length-limited string
575 * @s: The string to be sized
576 * @count: The maximum number of bytes to search
577 */
578size_t strnlen(const char *s, size_t count)
579{
580 const char *sc;
581
582 for (sc = s; count-- && *sc != '\0'; ++sc)
583 /* nothing */;
584 return sc - s;
585}
586EXPORT_SYMBOL(strnlen);
587#endif
588
589#ifndef __HAVE_ARCH_STRSPN
590/**
591 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
592 * @s: The string to be searched
593 * @accept: The string to search for
594 */
595size_t strspn(const char *s, const char *accept)
596{
597 const char *p;
598 const char *a;
599 size_t count = 0;
600
601 for (p = s; *p != '\0'; ++p) {
602 for (a = accept; *a != '\0'; ++a) {
603 if (*p == *a)
604 break;
605 }
606 if (*a == '\0')
607 return count;
608 ++count;
609 }
610 return count;
611}
612
613EXPORT_SYMBOL(strspn);
614#endif
615
616#ifndef __HAVE_ARCH_STRCSPN
617/**
618 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
619 * @s: The string to be searched
620 * @reject: The string to avoid
621 */
622size_t strcspn(const char *s, const char *reject)
623{
624 const char *p;
625 const char *r;
626 size_t count = 0;
627
628 for (p = s; *p != '\0'; ++p) {
629 for (r = reject; *r != '\0'; ++r) {
630 if (*p == *r)
631 return count;
632 }
633 ++count;
634 }
635 return count;
636}
637EXPORT_SYMBOL(strcspn);
638#endif
639
640#ifndef __HAVE_ARCH_STRPBRK
641/**
642 * strpbrk - Find the first occurrence of a set of characters
643 * @cs: The string to be searched
644 * @ct: The characters to search for
645 */
646char *strpbrk(const char *cs, const char *ct)
647{
648 const char *sc1, *sc2;
649
650 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
651 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
652 if (*sc1 == *sc2)
653 return (char *)sc1;
654 }
655 }
656 return NULL;
657}
658EXPORT_SYMBOL(strpbrk);
659#endif
660
661#ifndef __HAVE_ARCH_STRSEP
662/**
663 * strsep - Split a string into tokens
664 * @s: The string to be searched
665 * @ct: The characters to search for
666 *
667 * strsep() updates @s to point after the token, ready for the next call.
668 *
669 * It returns empty tokens, too, behaving exactly like the libc function
670 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
671 * Same semantics, slimmer shape. ;)
672 */
673char *strsep(char **s, const char *ct)
674{
675 char *sbegin = *s;
676 char *end;
677
678 if (sbegin == NULL)
679 return NULL;
680
681 end = strpbrk(sbegin, ct);
682 if (end)
683 *end++ = '\0';
684 *s = end;
685 return sbegin;
686}
687EXPORT_SYMBOL(strsep);
688#endif
689
690/**
691 * sysfs_streq - return true if strings are equal, modulo trailing newline
692 * @s1: one string
693 * @s2: another string
694 *
695 * This routine returns true iff two strings are equal, treating both
696 * NUL and newline-then-NUL as equivalent string terminations. It's
697 * geared for use with sysfs input strings, which generally terminate
698 * with newlines but are compared against values without newlines.
699 */
700bool sysfs_streq(const char *s1, const char *s2)
701{
702 while (*s1 && *s1 == *s2) {
703 s1++;
704 s2++;
705 }
706
707 if (*s1 == *s2)
708 return true;
709 if (!*s1 && *s2 == '\n' && !s2[1])
710 return true;
711 if (*s1 == '\n' && !s1[1] && !*s2)
712 return true;
713 return false;
714}
715EXPORT_SYMBOL(sysfs_streq);
716
717/**
718 * match_string - matches given string in an array
719 * @array: array of strings
720 * @n: number of strings in the array or -1 for NULL terminated arrays
721 * @string: string to match with
722 *
723 * This routine will look for a string in an array of strings up to the
724 * n-th element in the array or until the first NULL element.
725 *
726 * Historically the value of -1 for @n, was used to search in arrays that
727 * are NULL terminated. However, the function does not make a distinction
728 * when finishing the search: either @n elements have been compared OR
729 * the first NULL element was found.
730 *
731 * Return:
732 * index of a @string in the @array if matches, or %-EINVAL otherwise.
733 */
734int match_string(const char * const *array, size_t n, const char *string)
735{
736 int index;
737 const char *item;
738
739 for (index = 0; index < n; index++) {
740 item = array[index];
741 if (!item)
742 break;
743 if (!strcmp(item, string))
744 return index;
745 }
746
747 return -EINVAL;
748}
749EXPORT_SYMBOL(match_string);
750
751/**
752 * __sysfs_match_string - matches given string in an array
753 * @array: array of strings
754 * @n: number of strings in the array or -1 for NULL terminated arrays
755 * @str: string to match with
756 *
757 * Returns index of @str in the @array or -EINVAL, just like match_string().
758 * Uses sysfs_streq instead of strcmp for matching.
759 *
760 * This routine will look for a string in an array of strings up to the
761 * n-th element in the array or until the first NULL element.
762 *
763 * Historically the value of -1 for @n, was used to search in arrays that
764 * are NULL terminated. However, the function does not make a distinction
765 * when finishing the search: either @n elements have been compared OR
766 * the first NULL element was found.
767 */
768int __sysfs_match_string(const char * const *array, size_t n, const char *str)
769{
770 const char *item;
771 int index;
772
773 for (index = 0; index < n; index++) {
774 item = array[index];
775 if (!item)
776 break;
777 if (sysfs_streq(item, str))
778 return index;
779 }
780
781 return -EINVAL;
782}
783EXPORT_SYMBOL(__sysfs_match_string);
784
785#ifndef __HAVE_ARCH_MEMSET
786/**
787 * memset - Fill a region of memory with the given value
788 * @s: Pointer to the start of the area.
789 * @c: The byte to fill the area with
790 * @count: The size of the area.
791 *
792 * Do not use memset() to access IO space, use memset_io() instead.
793 */
794void *memset(void *s, int c, size_t count)
795{
796 char *xs = s;
797
798 while (count--)
799 *xs++ = c;
800 return s;
801}
802EXPORT_SYMBOL(memset);
803#endif
804
805#ifndef __HAVE_ARCH_MEMSET16
806/**
807 * memset16() - Fill a memory area with a uint16_t
808 * @s: Pointer to the start of the area.
809 * @v: The value to fill the area with
810 * @count: The number of values to store
811 *
812 * Differs from memset() in that it fills with a uint16_t instead
813 * of a byte. Remember that @count is the number of uint16_ts to
814 * store, not the number of bytes.
815 */
816void *memset16(uint16_t *s, uint16_t v, size_t count)
817{
818 uint16_t *xs = s;
819
820 while (count--)
821 *xs++ = v;
822 return s;
823}
824EXPORT_SYMBOL(memset16);
825#endif
826
827#ifndef __HAVE_ARCH_MEMSET32
828/**
829 * memset32() - Fill a memory area with a uint32_t
830 * @s: Pointer to the start of the area.
831 * @v: The value to fill the area with
832 * @count: The number of values to store
833 *
834 * Differs from memset() in that it fills with a uint32_t instead
835 * of a byte. Remember that @count is the number of uint32_ts to
836 * store, not the number of bytes.
837 */
838void *memset32(uint32_t *s, uint32_t v, size_t count)
839{
840 uint32_t *xs = s;
841
842 while (count--)
843 *xs++ = v;
844 return s;
845}
846EXPORT_SYMBOL(memset32);
847#endif
848
849#ifndef __HAVE_ARCH_MEMSET64
850/**
851 * memset64() - Fill a memory area with a uint64_t
852 * @s: Pointer to the start of the area.
853 * @v: The value to fill the area with
854 * @count: The number of values to store
855 *
856 * Differs from memset() in that it fills with a uint64_t instead
857 * of a byte. Remember that @count is the number of uint64_ts to
858 * store, not the number of bytes.
859 */
860void *memset64(uint64_t *s, uint64_t v, size_t count)
861{
862 uint64_t *xs = s;
863
864 while (count--)
865 *xs++ = v;
866 return s;
867}
868EXPORT_SYMBOL(memset64);
869#endif
870
871#ifndef __HAVE_ARCH_MEMCPY
872/**
873 * memcpy - Copy one area of memory to another
874 * @dest: Where to copy to
875 * @src: Where to copy from
876 * @count: The size of the area.
877 *
878 * You should not use this function to access IO space, use memcpy_toio()
879 * or memcpy_fromio() instead.
880 */
881void *memcpy(void *dest, const void *src, size_t count)
882{
883 char *tmp = dest;
884 const char *s = src;
885
886 while (count--)
887 *tmp++ = *s++;
888 return dest;
889}
890EXPORT_SYMBOL(memcpy);
891#endif
892
893#ifndef __HAVE_ARCH_MEMMOVE
894/**
895 * memmove - Copy one area of memory to another
896 * @dest: Where to copy to
897 * @src: Where to copy from
898 * @count: The size of the area.
899 *
900 * Unlike memcpy(), memmove() copes with overlapping areas.
901 */
902void *memmove(void *dest, const void *src, size_t count)
903{
904 char *tmp;
905 const char *s;
906
907 if (dest <= src) {
908 tmp = dest;
909 s = src;
910 while (count--)
911 *tmp++ = *s++;
912 } else {
913 tmp = dest;
914 tmp += count;
915 s = src;
916 s += count;
917 while (count--)
918 *--tmp = *--s;
919 }
920 return dest;
921}
922EXPORT_SYMBOL(memmove);
923#endif
924
925#ifndef __HAVE_ARCH_MEMCMP
926/**
927 * memcmp - Compare two areas of memory
928 * @cs: One area of memory
929 * @ct: Another area of memory
930 * @count: The size of the area.
931 */
932#undef memcmp
933__visible int memcmp(const void *cs, const void *ct, size_t count)
934{
935 const unsigned char *su1, *su2;
936 int res = 0;
937
938 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
939 if ((res = *su1 - *su2) != 0)
940 break;
941 return res;
942}
943EXPORT_SYMBOL(memcmp);
944#endif
945
946#ifndef __HAVE_ARCH_BCMP
947/**
948 * bcmp - returns 0 if and only if the buffers have identical contents.
949 * @a: pointer to first buffer.
950 * @b: pointer to second buffer.
951 * @len: size of buffers.
952 *
953 * The sign or magnitude of a non-zero return value has no particular
954 * meaning, and architectures may implement their own more efficient bcmp(). So
955 * while this particular implementation is a simple (tail) call to memcmp, do
956 * not rely on anything but whether the return value is zero or non-zero.
957 */
958int bcmp(const void *a, const void *b, size_t len)
959{
960 return memcmp(a, b, len);
961}
962EXPORT_SYMBOL(bcmp);
963#endif
964
965#ifndef __HAVE_ARCH_MEMSCAN
966/**
967 * memscan - Find a character in an area of memory.
968 * @addr: The memory area
969 * @c: The byte to search for
970 * @size: The size of the area.
971 *
972 * returns the address of the first occurrence of @c, or 1 byte past
973 * the area if @c is not found
974 */
975void *memscan(void *addr, int c, size_t size)
976{
977 unsigned char *p = addr;
978
979 while (size) {
980 if (*p == (unsigned char)c)
981 return (void *)p;
982 p++;
983 size--;
984 }
985 return (void *)p;
986}
987EXPORT_SYMBOL(memscan);
988#endif
989
990#ifndef __HAVE_ARCH_STRSTR
991/**
992 * strstr - Find the first substring in a %NUL terminated string
993 * @s1: The string to be searched
994 * @s2: The string to search for
995 */
996char *strstr(const char *s1, const char *s2)
997{
998 size_t l1, l2;
999
1000 l2 = strlen(s2);
1001 if (!l2)
1002 return (char *)s1;
1003 l1 = strlen(s1);
1004 while (l1 >= l2) {
1005 l1--;
1006 if (!memcmp(s1, s2, l2))
1007 return (char *)s1;
1008 s1++;
1009 }
1010 return NULL;
1011}
1012EXPORT_SYMBOL(strstr);
1013#endif
1014
1015#ifndef __HAVE_ARCH_STRNSTR
1016/**
1017 * strnstr - Find the first substring in a length-limited string
1018 * @s1: The string to be searched
1019 * @s2: The string to search for
1020 * @len: the maximum number of characters to search
1021 */
1022char *strnstr(const char *s1, const char *s2, size_t len)
1023{
1024 size_t l2;
1025
1026 l2 = strlen(s2);
1027 if (!l2)
1028 return (char *)s1;
1029 while (len >= l2) {
1030 len--;
1031 if (!memcmp(s1, s2, l2))
1032 return (char *)s1;
1033 s1++;
1034 }
1035 return NULL;
1036}
1037EXPORT_SYMBOL(strnstr);
1038#endif
1039
1040#ifndef __HAVE_ARCH_MEMCHR
1041/**
1042 * memchr - Find a character in an area of memory.
1043 * @s: The memory area
1044 * @c: The byte to search for
1045 * @n: The size of the area.
1046 *
1047 * returns the address of the first occurrence of @c, or %NULL
1048 * if @c is not found
1049 */
1050void *memchr(const void *s, int c, size_t n)
1051{
1052 const unsigned char *p = s;
1053 while (n-- != 0) {
1054 if ((unsigned char)c == *p++) {
1055 return (void *)(p - 1);
1056 }
1057 }
1058 return NULL;
1059}
1060EXPORT_SYMBOL(memchr);
1061#endif
1062
1063static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
1064{
1065 while (bytes) {
1066 if (*start != value)
1067 return (void *)start;
1068 start++;
1069 bytes--;
1070 }
1071 return NULL;
1072}
1073
1074/**
1075 * memchr_inv - Find an unmatching character in an area of memory.
1076 * @start: The memory area
1077 * @c: Find a character other than c
1078 * @bytes: The size of the area.
1079 *
1080 * returns the address of the first character other than @c, or %NULL
1081 * if the whole buffer contains just @c.
1082 */
1083void *memchr_inv(const void *start, int c, size_t bytes)
1084{
1085 u8 value = c;
1086 u64 value64;
1087 unsigned int words, prefix;
1088
1089 if (bytes <= 16)
1090 return check_bytes8(start, value, bytes);
1091
1092 value64 = value;
1093#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
1094 value64 *= 0x0101010101010101ULL;
1095#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
1096 value64 *= 0x01010101;
1097 value64 |= value64 << 32;
1098#else
1099 value64 |= value64 << 8;
1100 value64 |= value64 << 16;
1101 value64 |= value64 << 32;
1102#endif
1103
1104 prefix = (unsigned long)start % 8;
1105 if (prefix) {
1106 u8 *r;
1107
1108 prefix = 8 - prefix;
1109 r = check_bytes8(start, value, prefix);
1110 if (r)
1111 return r;
1112 start += prefix;
1113 bytes -= prefix;
1114 }
1115
1116 words = bytes / 8;
1117
1118 while (words) {
1119 if (*(u64 *)start != value64)
1120 return check_bytes8(start, value, 8);
1121 start += 8;
1122 words--;
1123 }
1124
1125 return check_bytes8(start, value, bytes % 8);
1126}
1127EXPORT_SYMBOL(memchr_inv);
1128
1129/**
1130 * strreplace - Replace all occurrences of character in string.
1131 * @s: The string to operate on.
1132 * @old: The character being replaced.
1133 * @new: The character @old is replaced with.
1134 *
1135 * Returns pointer to the nul byte at the end of @s.
1136 */
1137char *strreplace(char *s, char old, char new)
1138{
1139 for (; *s; ++s)
1140 if (*s == old)
1141 *s = new;
1142 return s;
1143}
1144EXPORT_SYMBOL(strreplace);
1145
1146void fortify_panic(const char *name)
1147{
1148 pr_emerg("detected buffer overflow in %s\n", name);
1149 BUG();
1150}
1151EXPORT_SYMBOL(fortify_panic);