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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/lib/string.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8/*
9 * This file should be used only for "library" routines that may have
10 * alternative implementations on specific architectures (generally
11 * found in <asm-xx/string.h>), or get overloaded by FORTIFY_SOURCE.
12 * (Specifically, this file is built with __NO_FORTIFY.)
13 *
14 * Other helper functions should live in string_helpers.c.
15 */
16
17#define __NO_FORTIFY
18#include <linux/types.h>
19#include <linux/string.h>
20#include <linux/ctype.h>
21#include <linux/kernel.h>
22#include <linux/export.h>
23#include <linux/bug.h>
24#include <linux/errno.h>
25#include <linux/slab.h>
26
27#include <asm/unaligned.h>
28#include <asm/byteorder.h>
29#include <asm/word-at-a-time.h>
30#include <asm/page.h>
31
32#ifndef __HAVE_ARCH_STRNCASECMP
33/**
34 * strncasecmp - Case insensitive, length-limited string comparison
35 * @s1: One string
36 * @s2: The other string
37 * @len: the maximum number of characters to compare
38 */
39int strncasecmp(const char *s1, const char *s2, size_t len)
40{
41 /* Yes, Virginia, it had better be unsigned */
42 unsigned char c1, c2;
43
44 if (!len)
45 return 0;
46
47 do {
48 c1 = *s1++;
49 c2 = *s2++;
50 if (!c1 || !c2)
51 break;
52 if (c1 == c2)
53 continue;
54 c1 = tolower(c1);
55 c2 = tolower(c2);
56 if (c1 != c2)
57 break;
58 } while (--len);
59 return (int)c1 - (int)c2;
60}
61EXPORT_SYMBOL(strncasecmp);
62#endif
63
64#ifndef __HAVE_ARCH_STRCASECMP
65int strcasecmp(const char *s1, const char *s2)
66{
67 int c1, c2;
68
69 do {
70 c1 = tolower(*s1++);
71 c2 = tolower(*s2++);
72 } while (c1 == c2 && c1 != 0);
73 return c1 - c2;
74}
75EXPORT_SYMBOL(strcasecmp);
76#endif
77
78#ifndef __HAVE_ARCH_STRCPY
79char *strcpy(char *dest, const char *src)
80{
81 char *tmp = dest;
82
83 while ((*dest++ = *src++) != '\0')
84 /* nothing */;
85 return tmp;
86}
87EXPORT_SYMBOL(strcpy);
88#endif
89
90#ifndef __HAVE_ARCH_STRNCPY
91char *strncpy(char *dest, const char *src, size_t count)
92{
93 char *tmp = dest;
94
95 while (count) {
96 if ((*tmp = *src) != 0)
97 src++;
98 tmp++;
99 count--;
100 }
101 return dest;
102}
103EXPORT_SYMBOL(strncpy);
104#endif
105
106#ifndef __HAVE_ARCH_STRSCPY
107ssize_t strscpy(char *dest, const char *src, size_t count)
108{
109 const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
110 size_t max = count;
111 long res = 0;
112
113 if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
114 return -E2BIG;
115
116#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
117 /*
118 * If src is unaligned, don't cross a page boundary,
119 * since we don't know if the next page is mapped.
120 */
121 if ((long)src & (sizeof(long) - 1)) {
122 size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
123 if (limit < max)
124 max = limit;
125 }
126#else
127 /* If src or dest is unaligned, don't do word-at-a-time. */
128 if (((long) dest | (long) src) & (sizeof(long) - 1))
129 max = 0;
130#endif
131
132 /*
133 * read_word_at_a_time() below may read uninitialized bytes after the
134 * trailing zero and use them in comparisons. Disable this optimization
135 * under KMSAN to prevent false positive reports.
136 */
137 if (IS_ENABLED(CONFIG_KMSAN))
138 max = 0;
139
140 while (max >= sizeof(unsigned long)) {
141 unsigned long c, data;
142
143 c = read_word_at_a_time(src+res);
144 if (has_zero(c, &data, &constants)) {
145 data = prep_zero_mask(c, data, &constants);
146 data = create_zero_mask(data);
147 *(unsigned long *)(dest+res) = c & zero_bytemask(data);
148 return res + find_zero(data);
149 }
150 *(unsigned long *)(dest+res) = c;
151 res += sizeof(unsigned long);
152 count -= sizeof(unsigned long);
153 max -= sizeof(unsigned long);
154 }
155
156 while (count) {
157 char c;
158
159 c = src[res];
160 dest[res] = c;
161 if (!c)
162 return res;
163 res++;
164 count--;
165 }
166
167 /* Hit buffer length without finding a NUL; force NUL-termination. */
168 if (res)
169 dest[res-1] = '\0';
170
171 return -E2BIG;
172}
173EXPORT_SYMBOL(strscpy);
174#endif
175
176/**
177 * stpcpy - copy a string from src to dest returning a pointer to the new end
178 * of dest, including src's %NUL-terminator. May overrun dest.
179 * @dest: pointer to end of string being copied into. Must be large enough
180 * to receive copy.
181 * @src: pointer to the beginning of string being copied from. Must not overlap
182 * dest.
183 *
184 * stpcpy differs from strcpy in a key way: the return value is a pointer
185 * to the new %NUL-terminating character in @dest. (For strcpy, the return
186 * value is a pointer to the start of @dest). This interface is considered
187 * unsafe as it doesn't perform bounds checking of the inputs. As such it's
188 * not recommended for usage. Instead, its definition is provided in case
189 * the compiler lowers other libcalls to stpcpy.
190 */
191char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
192char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
193{
194 while ((*dest++ = *src++) != '\0')
195 /* nothing */;
196 return --dest;
197}
198EXPORT_SYMBOL(stpcpy);
199
200#ifndef __HAVE_ARCH_STRCAT
201char *strcat(char *dest, const char *src)
202{
203 char *tmp = dest;
204
205 while (*dest)
206 dest++;
207 while ((*dest++ = *src++) != '\0')
208 ;
209 return tmp;
210}
211EXPORT_SYMBOL(strcat);
212#endif
213
214#ifndef __HAVE_ARCH_STRNCAT
215char *strncat(char *dest, const char *src, size_t count)
216{
217 char *tmp = dest;
218
219 if (count) {
220 while (*dest)
221 dest++;
222 while ((*dest++ = *src++) != 0) {
223 if (--count == 0) {
224 *dest = '\0';
225 break;
226 }
227 }
228 }
229 return tmp;
230}
231EXPORT_SYMBOL(strncat);
232#endif
233
234#ifndef __HAVE_ARCH_STRLCAT
235size_t strlcat(char *dest, const char *src, size_t count)
236{
237 size_t dsize = strlen(dest);
238 size_t len = strlen(src);
239 size_t res = dsize + len;
240
241 /* This would be a bug */
242 BUG_ON(dsize >= count);
243
244 dest += dsize;
245 count -= dsize;
246 if (len >= count)
247 len = count-1;
248 __builtin_memcpy(dest, src, len);
249 dest[len] = 0;
250 return res;
251}
252EXPORT_SYMBOL(strlcat);
253#endif
254
255#ifndef __HAVE_ARCH_STRCMP
256/**
257 * strcmp - Compare two strings
258 * @cs: One string
259 * @ct: Another string
260 */
261int strcmp(const char *cs, const char *ct)
262{
263 unsigned char c1, c2;
264
265 while (1) {
266 c1 = *cs++;
267 c2 = *ct++;
268 if (c1 != c2)
269 return c1 < c2 ? -1 : 1;
270 if (!c1)
271 break;
272 }
273 return 0;
274}
275EXPORT_SYMBOL(strcmp);
276#endif
277
278#ifndef __HAVE_ARCH_STRNCMP
279/**
280 * strncmp - Compare two length-limited strings
281 * @cs: One string
282 * @ct: Another string
283 * @count: The maximum number of bytes to compare
284 */
285int strncmp(const char *cs, const char *ct, size_t count)
286{
287 unsigned char c1, c2;
288
289 while (count) {
290 c1 = *cs++;
291 c2 = *ct++;
292 if (c1 != c2)
293 return c1 < c2 ? -1 : 1;
294 if (!c1)
295 break;
296 count--;
297 }
298 return 0;
299}
300EXPORT_SYMBOL(strncmp);
301#endif
302
303#ifndef __HAVE_ARCH_STRCHR
304/**
305 * strchr - Find the first occurrence of a character in a string
306 * @s: The string to be searched
307 * @c: The character to search for
308 *
309 * Note that the %NUL-terminator is considered part of the string, and can
310 * be searched for.
311 */
312char *strchr(const char *s, int c)
313{
314 for (; *s != (char)c; ++s)
315 if (*s == '\0')
316 return NULL;
317 return (char *)s;
318}
319EXPORT_SYMBOL(strchr);
320#endif
321
322#ifndef __HAVE_ARCH_STRCHRNUL
323/**
324 * strchrnul - Find and return a character in a string, or end of string
325 * @s: The string to be searched
326 * @c: The character to search for
327 *
328 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
329 * return a pointer to the null byte at the end of s.
330 */
331char *strchrnul(const char *s, int c)
332{
333 while (*s && *s != (char)c)
334 s++;
335 return (char *)s;
336}
337EXPORT_SYMBOL(strchrnul);
338#endif
339
340/**
341 * strnchrnul - Find and return a character in a length limited string,
342 * or end of string
343 * @s: The string to be searched
344 * @count: The number of characters to be searched
345 * @c: The character to search for
346 *
347 * Returns pointer to the first occurrence of 'c' in s. If c is not found,
348 * then return a pointer to the last character of the string.
349 */
350char *strnchrnul(const char *s, size_t count, int c)
351{
352 while (count-- && *s && *s != (char)c)
353 s++;
354 return (char *)s;
355}
356
357#ifndef __HAVE_ARCH_STRRCHR
358/**
359 * strrchr - Find the last occurrence of a character in a string
360 * @s: The string to be searched
361 * @c: The character to search for
362 */
363char *strrchr(const char *s, int c)
364{
365 const char *last = NULL;
366 do {
367 if (*s == (char)c)
368 last = s;
369 } while (*s++);
370 return (char *)last;
371}
372EXPORT_SYMBOL(strrchr);
373#endif
374
375#ifndef __HAVE_ARCH_STRNCHR
376/**
377 * strnchr - Find a character in a length limited string
378 * @s: The string to be searched
379 * @count: The number of characters to be searched
380 * @c: The character to search for
381 *
382 * Note that the %NUL-terminator is considered part of the string, and can
383 * be searched for.
384 */
385char *strnchr(const char *s, size_t count, int c)
386{
387 while (count--) {
388 if (*s == (char)c)
389 return (char *)s;
390 if (*s++ == '\0')
391 break;
392 }
393 return NULL;
394}
395EXPORT_SYMBOL(strnchr);
396#endif
397
398#ifndef __HAVE_ARCH_STRLEN
399size_t strlen(const char *s)
400{
401 const char *sc;
402
403 for (sc = s; *sc != '\0'; ++sc)
404 /* nothing */;
405 return sc - s;
406}
407EXPORT_SYMBOL(strlen);
408#endif
409
410#ifndef __HAVE_ARCH_STRNLEN
411size_t strnlen(const char *s, size_t count)
412{
413 const char *sc;
414
415 for (sc = s; count-- && *sc != '\0'; ++sc)
416 /* nothing */;
417 return sc - s;
418}
419EXPORT_SYMBOL(strnlen);
420#endif
421
422#ifndef __HAVE_ARCH_STRSPN
423/**
424 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
425 * @s: The string to be searched
426 * @accept: The string to search for
427 */
428size_t strspn(const char *s, const char *accept)
429{
430 const char *p;
431
432 for (p = s; *p != '\0'; ++p) {
433 if (!strchr(accept, *p))
434 break;
435 }
436 return p - s;
437}
438EXPORT_SYMBOL(strspn);
439#endif
440
441#ifndef __HAVE_ARCH_STRCSPN
442/**
443 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
444 * @s: The string to be searched
445 * @reject: The string to avoid
446 */
447size_t strcspn(const char *s, const char *reject)
448{
449 const char *p;
450
451 for (p = s; *p != '\0'; ++p) {
452 if (strchr(reject, *p))
453 break;
454 }
455 return p - s;
456}
457EXPORT_SYMBOL(strcspn);
458#endif
459
460#ifndef __HAVE_ARCH_STRPBRK
461/**
462 * strpbrk - Find the first occurrence of a set of characters
463 * @cs: The string to be searched
464 * @ct: The characters to search for
465 */
466char *strpbrk(const char *cs, const char *ct)
467{
468 const char *sc;
469
470 for (sc = cs; *sc != '\0'; ++sc) {
471 if (strchr(ct, *sc))
472 return (char *)sc;
473 }
474 return NULL;
475}
476EXPORT_SYMBOL(strpbrk);
477#endif
478
479#ifndef __HAVE_ARCH_STRSEP
480/**
481 * strsep - Split a string into tokens
482 * @s: The string to be searched
483 * @ct: The characters to search for
484 *
485 * strsep() updates @s to point after the token, ready for the next call.
486 *
487 * It returns empty tokens, too, behaving exactly like the libc function
488 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
489 * Same semantics, slimmer shape. ;)
490 */
491char *strsep(char **s, const char *ct)
492{
493 char *sbegin = *s;
494 char *end;
495
496 if (sbegin == NULL)
497 return NULL;
498
499 end = strpbrk(sbegin, ct);
500 if (end)
501 *end++ = '\0';
502 *s = end;
503 return sbegin;
504}
505EXPORT_SYMBOL(strsep);
506#endif
507
508#ifndef __HAVE_ARCH_MEMSET
509/**
510 * memset - Fill a region of memory with the given value
511 * @s: Pointer to the start of the area.
512 * @c: The byte to fill the area with
513 * @count: The size of the area.
514 *
515 * Do not use memset() to access IO space, use memset_io() instead.
516 */
517void *memset(void *s, int c, size_t count)
518{
519 char *xs = s;
520
521 while (count--)
522 *xs++ = c;
523 return s;
524}
525EXPORT_SYMBOL(memset);
526#endif
527
528#ifndef __HAVE_ARCH_MEMSET16
529/**
530 * memset16() - Fill a memory area with a uint16_t
531 * @s: Pointer to the start of the area.
532 * @v: The value to fill the area with
533 * @count: The number of values to store
534 *
535 * Differs from memset() in that it fills with a uint16_t instead
536 * of a byte. Remember that @count is the number of uint16_ts to
537 * store, not the number of bytes.
538 */
539void *memset16(uint16_t *s, uint16_t v, size_t count)
540{
541 uint16_t *xs = s;
542
543 while (count--)
544 *xs++ = v;
545 return s;
546}
547EXPORT_SYMBOL(memset16);
548#endif
549
550#ifndef __HAVE_ARCH_MEMSET32
551/**
552 * memset32() - Fill a memory area with a uint32_t
553 * @s: Pointer to the start of the area.
554 * @v: The value to fill the area with
555 * @count: The number of values to store
556 *
557 * Differs from memset() in that it fills with a uint32_t instead
558 * of a byte. Remember that @count is the number of uint32_ts to
559 * store, not the number of bytes.
560 */
561void *memset32(uint32_t *s, uint32_t v, size_t count)
562{
563 uint32_t *xs = s;
564
565 while (count--)
566 *xs++ = v;
567 return s;
568}
569EXPORT_SYMBOL(memset32);
570#endif
571
572#ifndef __HAVE_ARCH_MEMSET64
573/**
574 * memset64() - Fill a memory area with a uint64_t
575 * @s: Pointer to the start of the area.
576 * @v: The value to fill the area with
577 * @count: The number of values to store
578 *
579 * Differs from memset() in that it fills with a uint64_t instead
580 * of a byte. Remember that @count is the number of uint64_ts to
581 * store, not the number of bytes.
582 */
583void *memset64(uint64_t *s, uint64_t v, size_t count)
584{
585 uint64_t *xs = s;
586
587 while (count--)
588 *xs++ = v;
589 return s;
590}
591EXPORT_SYMBOL(memset64);
592#endif
593
594#ifndef __HAVE_ARCH_MEMCPY
595/**
596 * memcpy - Copy one area of memory to another
597 * @dest: Where to copy to
598 * @src: Where to copy from
599 * @count: The size of the area.
600 *
601 * You should not use this function to access IO space, use memcpy_toio()
602 * or memcpy_fromio() instead.
603 */
604void *memcpy(void *dest, const void *src, size_t count)
605{
606 char *tmp = dest;
607 const char *s = src;
608
609 while (count--)
610 *tmp++ = *s++;
611 return dest;
612}
613EXPORT_SYMBOL(memcpy);
614#endif
615
616#ifndef __HAVE_ARCH_MEMMOVE
617/**
618 * memmove - Copy one area of memory to another
619 * @dest: Where to copy to
620 * @src: Where to copy from
621 * @count: The size of the area.
622 *
623 * Unlike memcpy(), memmove() copes with overlapping areas.
624 */
625void *memmove(void *dest, const void *src, size_t count)
626{
627 char *tmp;
628 const char *s;
629
630 if (dest <= src) {
631 tmp = dest;
632 s = src;
633 while (count--)
634 *tmp++ = *s++;
635 } else {
636 tmp = dest;
637 tmp += count;
638 s = src;
639 s += count;
640 while (count--)
641 *--tmp = *--s;
642 }
643 return dest;
644}
645EXPORT_SYMBOL(memmove);
646#endif
647
648#ifndef __HAVE_ARCH_MEMCMP
649/**
650 * memcmp - Compare two areas of memory
651 * @cs: One area of memory
652 * @ct: Another area of memory
653 * @count: The size of the area.
654 */
655#undef memcmp
656__visible int memcmp(const void *cs, const void *ct, size_t count)
657{
658 const unsigned char *su1, *su2;
659 int res = 0;
660
661#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
662 if (count >= sizeof(unsigned long)) {
663 const unsigned long *u1 = cs;
664 const unsigned long *u2 = ct;
665 do {
666 if (get_unaligned(u1) != get_unaligned(u2))
667 break;
668 u1++;
669 u2++;
670 count -= sizeof(unsigned long);
671 } while (count >= sizeof(unsigned long));
672 cs = u1;
673 ct = u2;
674 }
675#endif
676 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
677 if ((res = *su1 - *su2) != 0)
678 break;
679 return res;
680}
681EXPORT_SYMBOL(memcmp);
682#endif
683
684#ifndef __HAVE_ARCH_BCMP
685/**
686 * bcmp - returns 0 if and only if the buffers have identical contents.
687 * @a: pointer to first buffer.
688 * @b: pointer to second buffer.
689 * @len: size of buffers.
690 *
691 * The sign or magnitude of a non-zero return value has no particular
692 * meaning, and architectures may implement their own more efficient bcmp(). So
693 * while this particular implementation is a simple (tail) call to memcmp, do
694 * not rely on anything but whether the return value is zero or non-zero.
695 */
696int bcmp(const void *a, const void *b, size_t len)
697{
698 return memcmp(a, b, len);
699}
700EXPORT_SYMBOL(bcmp);
701#endif
702
703#ifndef __HAVE_ARCH_MEMSCAN
704/**
705 * memscan - Find a character in an area of memory.
706 * @addr: The memory area
707 * @c: The byte to search for
708 * @size: The size of the area.
709 *
710 * returns the address of the first occurrence of @c, or 1 byte past
711 * the area if @c is not found
712 */
713void *memscan(void *addr, int c, size_t size)
714{
715 unsigned char *p = addr;
716
717 while (size) {
718 if (*p == (unsigned char)c)
719 return (void *)p;
720 p++;
721 size--;
722 }
723 return (void *)p;
724}
725EXPORT_SYMBOL(memscan);
726#endif
727
728#ifndef __HAVE_ARCH_STRSTR
729/**
730 * strstr - Find the first substring in a %NUL terminated string
731 * @s1: The string to be searched
732 * @s2: The string to search for
733 */
734char *strstr(const char *s1, const char *s2)
735{
736 size_t l1, l2;
737
738 l2 = strlen(s2);
739 if (!l2)
740 return (char *)s1;
741 l1 = strlen(s1);
742 while (l1 >= l2) {
743 l1--;
744 if (!memcmp(s1, s2, l2))
745 return (char *)s1;
746 s1++;
747 }
748 return NULL;
749}
750EXPORT_SYMBOL(strstr);
751#endif
752
753#ifndef __HAVE_ARCH_STRNSTR
754/**
755 * strnstr - Find the first substring in a length-limited string
756 * @s1: The string to be searched
757 * @s2: The string to search for
758 * @len: the maximum number of characters to search
759 */
760char *strnstr(const char *s1, const char *s2, size_t len)
761{
762 size_t l2;
763
764 l2 = strlen(s2);
765 if (!l2)
766 return (char *)s1;
767 while (len >= l2) {
768 len--;
769 if (!memcmp(s1, s2, l2))
770 return (char *)s1;
771 s1++;
772 }
773 return NULL;
774}
775EXPORT_SYMBOL(strnstr);
776#endif
777
778#ifndef __HAVE_ARCH_MEMCHR
779/**
780 * memchr - Find a character in an area of memory.
781 * @s: The memory area
782 * @c: The byte to search for
783 * @n: The size of the area.
784 *
785 * returns the address of the first occurrence of @c, or %NULL
786 * if @c is not found
787 */
788void *memchr(const void *s, int c, size_t n)
789{
790 const unsigned char *p = s;
791 while (n-- != 0) {
792 if ((unsigned char)c == *p++) {
793 return (void *)(p - 1);
794 }
795 }
796 return NULL;
797}
798EXPORT_SYMBOL(memchr);
799#endif
800
801static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
802{
803 while (bytes) {
804 if (*start != value)
805 return (void *)start;
806 start++;
807 bytes--;
808 }
809 return NULL;
810}
811
812/**
813 * memchr_inv - Find an unmatching character in an area of memory.
814 * @start: The memory area
815 * @c: Find a character other than c
816 * @bytes: The size of the area.
817 *
818 * returns the address of the first character other than @c, or %NULL
819 * if the whole buffer contains just @c.
820 */
821void *memchr_inv(const void *start, int c, size_t bytes)
822{
823 u8 value = c;
824 u64 value64;
825 unsigned int words, prefix;
826
827 if (bytes <= 16)
828 return check_bytes8(start, value, bytes);
829
830 value64 = value;
831#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
832 value64 *= 0x0101010101010101ULL;
833#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
834 value64 *= 0x01010101;
835 value64 |= value64 << 32;
836#else
837 value64 |= value64 << 8;
838 value64 |= value64 << 16;
839 value64 |= value64 << 32;
840#endif
841
842 prefix = (unsigned long)start % 8;
843 if (prefix) {
844 u8 *r;
845
846 prefix = 8 - prefix;
847 r = check_bytes8(start, value, prefix);
848 if (r)
849 return r;
850 start += prefix;
851 bytes -= prefix;
852 }
853
854 words = bytes / 8;
855
856 while (words) {
857 if (*(u64 *)start != value64)
858 return check_bytes8(start, value, 8);
859 start += 8;
860 words--;
861 }
862
863 return check_bytes8(start, value, bytes % 8);
864}
865EXPORT_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 */
88#undef strcpy
89char *strcpy(char *dest, const char *src)
90{
91 char *tmp = dest;
92
93 while ((*dest++ = *src++) != '\0')
94 /* nothing */;
95 return tmp;
96}
97EXPORT_SYMBOL(strcpy);
98#endif
99
100#ifndef __HAVE_ARCH_STRNCPY
101/**
102 * strncpy - Copy a length-limited, C-string
103 * @dest: Where to copy the string to
104 * @src: Where to copy the string from
105 * @count: The maximum number of bytes to copy
106 *
107 * The result is not %NUL-terminated if the source exceeds
108 * @count bytes.
109 *
110 * In the case where the length of @src is less than that of
111 * count, the remainder of @dest will be padded with %NUL.
112 *
113 */
114char *strncpy(char *dest, const char *src, size_t count)
115{
116 char *tmp = dest;
117
118 while (count) {
119 if ((*tmp = *src) != 0)
120 src++;
121 tmp++;
122 count--;
123 }
124 return dest;
125}
126EXPORT_SYMBOL(strncpy);
127#endif
128
129#ifndef __HAVE_ARCH_STRLCPY
130/**
131 * strlcpy - Copy a C-string into a sized buffer
132 * @dest: Where to copy the string to
133 * @src: Where to copy the string from
134 * @size: size of destination buffer
135 *
136 * Compatible with ``*BSD``: the result is always a valid
137 * NUL-terminated string that fits in the buffer (unless,
138 * of course, the buffer size is zero). It does not pad
139 * out the result like strncpy() does.
140 */
141size_t strlcpy(char *dest, const char *src, size_t size)
142{
143 size_t ret = strlen(src);
144
145 if (size) {
146 size_t len = (ret >= size) ? size - 1 : ret;
147 memcpy(dest, src, len);
148 dest[len] = '\0';
149 }
150 return ret;
151}
152EXPORT_SYMBOL(strlcpy);
153#endif
154
155#ifndef __HAVE_ARCH_STRSCPY
156/**
157 * strscpy - Copy a C-string into a sized buffer
158 * @dest: Where to copy the string to
159 * @src: Where to copy the string from
160 * @count: Size of destination buffer
161 *
162 * Copy the string, or as much of it as fits, into the dest buffer. The
163 * behavior is undefined if the string buffers overlap. The destination
164 * buffer is always NUL terminated, unless it's zero-sized.
165 *
166 * Preferred to strlcpy() since the API doesn't require reading memory
167 * from the src string beyond the specified "count" bytes, and since
168 * the return value is easier to error-check than strlcpy()'s.
169 * In addition, the implementation is robust to the string changing out
170 * from underneath it, unlike the current strlcpy() implementation.
171 *
172 * Preferred to strncpy() since it always returns a valid string, and
173 * doesn't unnecessarily force the tail of the destination buffer to be
174 * zeroed. If zeroing is desired please use strscpy_pad().
175 *
176 * Returns:
177 * * The number of characters copied (not including the trailing %NUL)
178 * * -E2BIG if count is 0 or @src was truncated.
179 */
180ssize_t strscpy(char *dest, const char *src, size_t count)
181{
182 const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
183 size_t max = count;
184 long res = 0;
185
186 if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
187 return -E2BIG;
188
189#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
190 /*
191 * If src is unaligned, don't cross a page boundary,
192 * since we don't know if the next page is mapped.
193 */
194 if ((long)src & (sizeof(long) - 1)) {
195 size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
196 if (limit < max)
197 max = limit;
198 }
199#else
200 /* If src or dest is unaligned, don't do word-at-a-time. */
201 if (((long) dest | (long) src) & (sizeof(long) - 1))
202 max = 0;
203#endif
204
205 while (max >= sizeof(unsigned long)) {
206 unsigned long c, data;
207
208 c = read_word_at_a_time(src+res);
209 if (has_zero(c, &data, &constants)) {
210 data = prep_zero_mask(c, data, &constants);
211 data = create_zero_mask(data);
212 *(unsigned long *)(dest+res) = c & zero_bytemask(data);
213 return res + find_zero(data);
214 }
215 *(unsigned long *)(dest+res) = c;
216 res += sizeof(unsigned long);
217 count -= sizeof(unsigned long);
218 max -= sizeof(unsigned long);
219 }
220
221 while (count) {
222 char c;
223
224 c = src[res];
225 dest[res] = c;
226 if (!c)
227 return res;
228 res++;
229 count--;
230 }
231
232 /* Hit buffer length without finding a NUL; force NUL-termination. */
233 if (res)
234 dest[res-1] = '\0';
235
236 return -E2BIG;
237}
238EXPORT_SYMBOL(strscpy);
239#endif
240
241/**
242 * strscpy_pad() - Copy a C-string into a sized buffer
243 * @dest: Where to copy the string to
244 * @src: Where to copy the string from
245 * @count: Size of destination buffer
246 *
247 * Copy the string, or as much of it as fits, into the dest buffer. The
248 * behavior is undefined if the string buffers overlap. The destination
249 * buffer is always %NUL terminated, unless it's zero-sized.
250 *
251 * If the source string is shorter than the destination buffer, zeros
252 * the tail of the destination buffer.
253 *
254 * For full explanation of why you may want to consider using the
255 * 'strscpy' functions please see the function docstring for strscpy().
256 *
257 * Returns:
258 * * The number of characters copied (not including the trailing %NUL)
259 * * -E2BIG if count is 0 or @src was truncated.
260 */
261ssize_t strscpy_pad(char *dest, const char *src, size_t count)
262{
263 ssize_t written;
264
265 written = strscpy(dest, src, count);
266 if (written < 0 || written == count - 1)
267 return written;
268
269 memset(dest + written + 1, 0, count - written - 1);
270
271 return written;
272}
273EXPORT_SYMBOL(strscpy_pad);
274
275#ifndef __HAVE_ARCH_STRCAT
276/**
277 * strcat - Append one %NUL-terminated string to another
278 * @dest: The string to be appended to
279 * @src: The string to append to it
280 */
281#undef strcat
282char *strcat(char *dest, const char *src)
283{
284 char *tmp = dest;
285
286 while (*dest)
287 dest++;
288 while ((*dest++ = *src++) != '\0')
289 ;
290 return tmp;
291}
292EXPORT_SYMBOL(strcat);
293#endif
294
295#ifndef __HAVE_ARCH_STRNCAT
296/**
297 * strncat - Append a length-limited, C-string to another
298 * @dest: The string to be appended to
299 * @src: The string to append to it
300 * @count: The maximum numbers of bytes to copy
301 *
302 * Note that in contrast to strncpy(), strncat() ensures the result is
303 * terminated.
304 */
305char *strncat(char *dest, const char *src, size_t count)
306{
307 char *tmp = dest;
308
309 if (count) {
310 while (*dest)
311 dest++;
312 while ((*dest++ = *src++) != 0) {
313 if (--count == 0) {
314 *dest = '\0';
315 break;
316 }
317 }
318 }
319 return tmp;
320}
321EXPORT_SYMBOL(strncat);
322#endif
323
324#ifndef __HAVE_ARCH_STRLCAT
325/**
326 * strlcat - Append a length-limited, C-string to another
327 * @dest: The string to be appended to
328 * @src: The string to append to it
329 * @count: The size of the destination buffer.
330 */
331size_t strlcat(char *dest, const char *src, size_t count)
332{
333 size_t dsize = strlen(dest);
334 size_t len = strlen(src);
335 size_t res = dsize + len;
336
337 /* This would be a bug */
338 BUG_ON(dsize >= count);
339
340 dest += dsize;
341 count -= dsize;
342 if (len >= count)
343 len = count-1;
344 memcpy(dest, src, len);
345 dest[len] = 0;
346 return res;
347}
348EXPORT_SYMBOL(strlcat);
349#endif
350
351#ifndef __HAVE_ARCH_STRCMP
352/**
353 * strcmp - Compare two strings
354 * @cs: One string
355 * @ct: Another string
356 */
357#undef strcmp
358int strcmp(const char *cs, const char *ct)
359{
360 unsigned char c1, c2;
361
362 while (1) {
363 c1 = *cs++;
364 c2 = *ct++;
365 if (c1 != c2)
366 return c1 < c2 ? -1 : 1;
367 if (!c1)
368 break;
369 }
370 return 0;
371}
372EXPORT_SYMBOL(strcmp);
373#endif
374
375#ifndef __HAVE_ARCH_STRNCMP
376/**
377 * strncmp - Compare two length-limited strings
378 * @cs: One string
379 * @ct: Another string
380 * @count: The maximum number of bytes to compare
381 */
382int strncmp(const char *cs, const char *ct, size_t count)
383{
384 unsigned char c1, c2;
385
386 while (count) {
387 c1 = *cs++;
388 c2 = *ct++;
389 if (c1 != c2)
390 return c1 < c2 ? -1 : 1;
391 if (!c1)
392 break;
393 count--;
394 }
395 return 0;
396}
397EXPORT_SYMBOL(strncmp);
398#endif
399
400#ifndef __HAVE_ARCH_STRCHR
401/**
402 * strchr - Find the first occurrence of a character in a string
403 * @s: The string to be searched
404 * @c: The character to search for
405 *
406 * Note that the %NUL-terminator is considered part of the string, and can
407 * be searched for.
408 */
409char *strchr(const char *s, int c)
410{
411 for (; *s != (char)c; ++s)
412 if (*s == '\0')
413 return NULL;
414 return (char *)s;
415}
416EXPORT_SYMBOL(strchr);
417#endif
418
419#ifndef __HAVE_ARCH_STRCHRNUL
420/**
421 * strchrnul - Find and return a character in a string, or end of string
422 * @s: The string to be searched
423 * @c: The character to search for
424 *
425 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
426 * return a pointer to the null byte at the end of s.
427 */
428char *strchrnul(const char *s, int c)
429{
430 while (*s && *s != (char)c)
431 s++;
432 return (char *)s;
433}
434EXPORT_SYMBOL(strchrnul);
435#endif
436
437#ifndef __HAVE_ARCH_STRRCHR
438/**
439 * strrchr - Find the last occurrence of a character in a string
440 * @s: The string to be searched
441 * @c: The character to search for
442 */
443char *strrchr(const char *s, int c)
444{
445 const char *last = NULL;
446 do {
447 if (*s == (char)c)
448 last = s;
449 } while (*s++);
450 return (char *)last;
451}
452EXPORT_SYMBOL(strrchr);
453#endif
454
455#ifndef __HAVE_ARCH_STRNCHR
456/**
457 * strnchr - Find a character in a length limited string
458 * @s: The string to be searched
459 * @count: The number of characters to be searched
460 * @c: The character to search for
461 *
462 * Note that the %NUL-terminator is considered part of the string, and can
463 * be searched for.
464 */
465char *strnchr(const char *s, size_t count, int c)
466{
467 while (count--) {
468 if (*s == (char)c)
469 return (char *)s;
470 if (*s++ == '\0')
471 break;
472 }
473 return NULL;
474}
475EXPORT_SYMBOL(strnchr);
476#endif
477
478/**
479 * skip_spaces - Removes leading whitespace from @str.
480 * @str: The string to be stripped.
481 *
482 * Returns a pointer to the first non-whitespace character in @str.
483 */
484char *skip_spaces(const char *str)
485{
486 while (isspace(*str))
487 ++str;
488 return (char *)str;
489}
490EXPORT_SYMBOL(skip_spaces);
491
492/**
493 * strim - Removes leading and trailing whitespace from @s.
494 * @s: The string to be stripped.
495 *
496 * Note that the first trailing whitespace is replaced with a %NUL-terminator
497 * in the given string @s. Returns a pointer to the first non-whitespace
498 * character in @s.
499 */
500char *strim(char *s)
501{
502 size_t size;
503 char *end;
504
505 size = strlen(s);
506 if (!size)
507 return s;
508
509 end = s + size - 1;
510 while (end >= s && isspace(*end))
511 end--;
512 *(end + 1) = '\0';
513
514 return skip_spaces(s);
515}
516EXPORT_SYMBOL(strim);
517
518#ifndef __HAVE_ARCH_STRLEN
519/**
520 * strlen - Find the length of a string
521 * @s: The string to be sized
522 */
523size_t strlen(const char *s)
524{
525 const char *sc;
526
527 for (sc = s; *sc != '\0'; ++sc)
528 /* nothing */;
529 return sc - s;
530}
531EXPORT_SYMBOL(strlen);
532#endif
533
534#ifndef __HAVE_ARCH_STRNLEN
535/**
536 * strnlen - Find the length of a length-limited string
537 * @s: The string to be sized
538 * @count: The maximum number of bytes to search
539 */
540size_t strnlen(const char *s, size_t count)
541{
542 const char *sc;
543
544 for (sc = s; count-- && *sc != '\0'; ++sc)
545 /* nothing */;
546 return sc - s;
547}
548EXPORT_SYMBOL(strnlen);
549#endif
550
551#ifndef __HAVE_ARCH_STRSPN
552/**
553 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
554 * @s: The string to be searched
555 * @accept: The string to search for
556 */
557size_t strspn(const char *s, const char *accept)
558{
559 const char *p;
560 const char *a;
561 size_t count = 0;
562
563 for (p = s; *p != '\0'; ++p) {
564 for (a = accept; *a != '\0'; ++a) {
565 if (*p == *a)
566 break;
567 }
568 if (*a == '\0')
569 return count;
570 ++count;
571 }
572 return count;
573}
574
575EXPORT_SYMBOL(strspn);
576#endif
577
578#ifndef __HAVE_ARCH_STRCSPN
579/**
580 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
581 * @s: The string to be searched
582 * @reject: The string to avoid
583 */
584size_t strcspn(const char *s, const char *reject)
585{
586 const char *p;
587 const char *r;
588 size_t count = 0;
589
590 for (p = s; *p != '\0'; ++p) {
591 for (r = reject; *r != '\0'; ++r) {
592 if (*p == *r)
593 return count;
594 }
595 ++count;
596 }
597 return count;
598}
599EXPORT_SYMBOL(strcspn);
600#endif
601
602#ifndef __HAVE_ARCH_STRPBRK
603/**
604 * strpbrk - Find the first occurrence of a set of characters
605 * @cs: The string to be searched
606 * @ct: The characters to search for
607 */
608char *strpbrk(const char *cs, const char *ct)
609{
610 const char *sc1, *sc2;
611
612 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
613 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
614 if (*sc1 == *sc2)
615 return (char *)sc1;
616 }
617 }
618 return NULL;
619}
620EXPORT_SYMBOL(strpbrk);
621#endif
622
623#ifndef __HAVE_ARCH_STRSEP
624/**
625 * strsep - Split a string into tokens
626 * @s: The string to be searched
627 * @ct: The characters to search for
628 *
629 * strsep() updates @s to point after the token, ready for the next call.
630 *
631 * It returns empty tokens, too, behaving exactly like the libc function
632 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
633 * Same semantics, slimmer shape. ;)
634 */
635char *strsep(char **s, const char *ct)
636{
637 char *sbegin = *s;
638 char *end;
639
640 if (sbegin == NULL)
641 return NULL;
642
643 end = strpbrk(sbegin, ct);
644 if (end)
645 *end++ = '\0';
646 *s = end;
647 return sbegin;
648}
649EXPORT_SYMBOL(strsep);
650#endif
651
652/**
653 * sysfs_streq - return true if strings are equal, modulo trailing newline
654 * @s1: one string
655 * @s2: another string
656 *
657 * This routine returns true iff two strings are equal, treating both
658 * NUL and newline-then-NUL as equivalent string terminations. It's
659 * geared for use with sysfs input strings, which generally terminate
660 * with newlines but are compared against values without newlines.
661 */
662bool sysfs_streq(const char *s1, const char *s2)
663{
664 while (*s1 && *s1 == *s2) {
665 s1++;
666 s2++;
667 }
668
669 if (*s1 == *s2)
670 return true;
671 if (!*s1 && *s2 == '\n' && !s2[1])
672 return true;
673 if (*s1 == '\n' && !s1[1] && !*s2)
674 return true;
675 return false;
676}
677EXPORT_SYMBOL(sysfs_streq);
678
679/**
680 * match_string - matches given string in an array
681 * @array: array of strings
682 * @n: number of strings in the array or -1 for NULL terminated arrays
683 * @string: string to match with
684 *
685 * Return:
686 * index of a @string in the @array if matches, or %-EINVAL otherwise.
687 */
688int match_string(const char * const *array, size_t n, const char *string)
689{
690 int index;
691 const char *item;
692
693 for (index = 0; index < n; index++) {
694 item = array[index];
695 if (!item)
696 break;
697 if (!strcmp(item, string))
698 return index;
699 }
700
701 return -EINVAL;
702}
703EXPORT_SYMBOL(match_string);
704
705/**
706 * __sysfs_match_string - matches given string in an array
707 * @array: array of strings
708 * @n: number of strings in the array or -1 for NULL terminated arrays
709 * @str: string to match with
710 *
711 * Returns index of @str in the @array or -EINVAL, just like match_string().
712 * Uses sysfs_streq instead of strcmp for matching.
713 */
714int __sysfs_match_string(const char * const *array, size_t n, const char *str)
715{
716 const char *item;
717 int index;
718
719 for (index = 0; index < n; index++) {
720 item = array[index];
721 if (!item)
722 break;
723 if (sysfs_streq(item, str))
724 return index;
725 }
726
727 return -EINVAL;
728}
729EXPORT_SYMBOL(__sysfs_match_string);
730
731#ifndef __HAVE_ARCH_MEMSET
732/**
733 * memset - Fill a region of memory with the given value
734 * @s: Pointer to the start of the area.
735 * @c: The byte to fill the area with
736 * @count: The size of the area.
737 *
738 * Do not use memset() to access IO space, use memset_io() instead.
739 */
740void *memset(void *s, int c, size_t count)
741{
742 char *xs = s;
743
744 while (count--)
745 *xs++ = c;
746 return s;
747}
748EXPORT_SYMBOL(memset);
749#endif
750
751#ifndef __HAVE_ARCH_MEMSET16
752/**
753 * memset16() - Fill a memory area with a uint16_t
754 * @s: Pointer to the start of the area.
755 * @v: The value to fill the area with
756 * @count: The number of values to store
757 *
758 * Differs from memset() in that it fills with a uint16_t instead
759 * of a byte. Remember that @count is the number of uint16_ts to
760 * store, not the number of bytes.
761 */
762void *memset16(uint16_t *s, uint16_t v, size_t count)
763{
764 uint16_t *xs = s;
765
766 while (count--)
767 *xs++ = v;
768 return s;
769}
770EXPORT_SYMBOL(memset16);
771#endif
772
773#ifndef __HAVE_ARCH_MEMSET32
774/**
775 * memset32() - Fill a memory area with a uint32_t
776 * @s: Pointer to the start of the area.
777 * @v: The value to fill the area with
778 * @count: The number of values to store
779 *
780 * Differs from memset() in that it fills with a uint32_t instead
781 * of a byte. Remember that @count is the number of uint32_ts to
782 * store, not the number of bytes.
783 */
784void *memset32(uint32_t *s, uint32_t v, size_t count)
785{
786 uint32_t *xs = s;
787
788 while (count--)
789 *xs++ = v;
790 return s;
791}
792EXPORT_SYMBOL(memset32);
793#endif
794
795#ifndef __HAVE_ARCH_MEMSET64
796/**
797 * memset64() - Fill a memory area with a uint64_t
798 * @s: Pointer to the start of the area.
799 * @v: The value to fill the area with
800 * @count: The number of values to store
801 *
802 * Differs from memset() in that it fills with a uint64_t instead
803 * of a byte. Remember that @count is the number of uint64_ts to
804 * store, not the number of bytes.
805 */
806void *memset64(uint64_t *s, uint64_t v, size_t count)
807{
808 uint64_t *xs = s;
809
810 while (count--)
811 *xs++ = v;
812 return s;
813}
814EXPORT_SYMBOL(memset64);
815#endif
816
817#ifndef __HAVE_ARCH_MEMCPY
818/**
819 * memcpy - Copy one area of memory to another
820 * @dest: Where to copy to
821 * @src: Where to copy from
822 * @count: The size of the area.
823 *
824 * You should not use this function to access IO space, use memcpy_toio()
825 * or memcpy_fromio() instead.
826 */
827void *memcpy(void *dest, const void *src, size_t count)
828{
829 char *tmp = dest;
830 const char *s = src;
831
832 while (count--)
833 *tmp++ = *s++;
834 return dest;
835}
836EXPORT_SYMBOL(memcpy);
837#endif
838
839#ifndef __HAVE_ARCH_MEMMOVE
840/**
841 * memmove - Copy one area of memory to another
842 * @dest: Where to copy to
843 * @src: Where to copy from
844 * @count: The size of the area.
845 *
846 * Unlike memcpy(), memmove() copes with overlapping areas.
847 */
848void *memmove(void *dest, const void *src, size_t count)
849{
850 char *tmp;
851 const char *s;
852
853 if (dest <= src) {
854 tmp = dest;
855 s = src;
856 while (count--)
857 *tmp++ = *s++;
858 } else {
859 tmp = dest;
860 tmp += count;
861 s = src;
862 s += count;
863 while (count--)
864 *--tmp = *--s;
865 }
866 return dest;
867}
868EXPORT_SYMBOL(memmove);
869#endif
870
871#ifndef __HAVE_ARCH_MEMCMP
872/**
873 * memcmp - Compare two areas of memory
874 * @cs: One area of memory
875 * @ct: Another area of memory
876 * @count: The size of the area.
877 */
878#undef memcmp
879__visible int memcmp(const void *cs, const void *ct, size_t count)
880{
881 const unsigned char *su1, *su2;
882 int res = 0;
883
884 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
885 if ((res = *su1 - *su2) != 0)
886 break;
887 return res;
888}
889EXPORT_SYMBOL(memcmp);
890#endif
891
892#ifndef __HAVE_ARCH_BCMP
893/**
894 * bcmp - returns 0 if and only if the buffers have identical contents.
895 * @a: pointer to first buffer.
896 * @b: pointer to second buffer.
897 * @len: size of buffers.
898 *
899 * The sign or magnitude of a non-zero return value has no particular
900 * meaning, and architectures may implement their own more efficient bcmp(). So
901 * while this particular implementation is a simple (tail) call to memcmp, do
902 * not rely on anything but whether the return value is zero or non-zero.
903 */
904#undef bcmp
905int bcmp(const void *a, const void *b, size_t len)
906{
907 return memcmp(a, b, len);
908}
909EXPORT_SYMBOL(bcmp);
910#endif
911
912#ifndef __HAVE_ARCH_MEMSCAN
913/**
914 * memscan - Find a character in an area of memory.
915 * @addr: The memory area
916 * @c: The byte to search for
917 * @size: The size of the area.
918 *
919 * returns the address of the first occurrence of @c, or 1 byte past
920 * the area if @c is not found
921 */
922void *memscan(void *addr, int c, size_t size)
923{
924 unsigned char *p = addr;
925
926 while (size) {
927 if (*p == c)
928 return (void *)p;
929 p++;
930 size--;
931 }
932 return (void *)p;
933}
934EXPORT_SYMBOL(memscan);
935#endif
936
937#ifndef __HAVE_ARCH_STRSTR
938/**
939 * strstr - Find the first substring in a %NUL terminated string
940 * @s1: The string to be searched
941 * @s2: The string to search for
942 */
943char *strstr(const char *s1, const char *s2)
944{
945 size_t l1, l2;
946
947 l2 = strlen(s2);
948 if (!l2)
949 return (char *)s1;
950 l1 = strlen(s1);
951 while (l1 >= l2) {
952 l1--;
953 if (!memcmp(s1, s2, l2))
954 return (char *)s1;
955 s1++;
956 }
957 return NULL;
958}
959EXPORT_SYMBOL(strstr);
960#endif
961
962#ifndef __HAVE_ARCH_STRNSTR
963/**
964 * strnstr - Find the first substring in a length-limited string
965 * @s1: The string to be searched
966 * @s2: The string to search for
967 * @len: the maximum number of characters to search
968 */
969char *strnstr(const char *s1, const char *s2, size_t len)
970{
971 size_t l2;
972
973 l2 = strlen(s2);
974 if (!l2)
975 return (char *)s1;
976 while (len >= l2) {
977 len--;
978 if (!memcmp(s1, s2, l2))
979 return (char *)s1;
980 s1++;
981 }
982 return NULL;
983}
984EXPORT_SYMBOL(strnstr);
985#endif
986
987#ifndef __HAVE_ARCH_MEMCHR
988/**
989 * memchr - Find a character in an area of memory.
990 * @s: The memory area
991 * @c: The byte to search for
992 * @n: The size of the area.
993 *
994 * returns the address of the first occurrence of @c, or %NULL
995 * if @c is not found
996 */
997void *memchr(const void *s, int c, size_t n)
998{
999 const unsigned char *p = s;
1000 while (n-- != 0) {
1001 if ((unsigned char)c == *p++) {
1002 return (void *)(p - 1);
1003 }
1004 }
1005 return NULL;
1006}
1007EXPORT_SYMBOL(memchr);
1008#endif
1009
1010static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
1011{
1012 while (bytes) {
1013 if (*start != value)
1014 return (void *)start;
1015 start++;
1016 bytes--;
1017 }
1018 return NULL;
1019}
1020
1021/**
1022 * memchr_inv - Find an unmatching character in an area of memory.
1023 * @start: The memory area
1024 * @c: Find a character other than c
1025 * @bytes: The size of the area.
1026 *
1027 * returns the address of the first character other than @c, or %NULL
1028 * if the whole buffer contains just @c.
1029 */
1030void *memchr_inv(const void *start, int c, size_t bytes)
1031{
1032 u8 value = c;
1033 u64 value64;
1034 unsigned int words, prefix;
1035
1036 if (bytes <= 16)
1037 return check_bytes8(start, value, bytes);
1038
1039 value64 = value;
1040#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
1041 value64 *= 0x0101010101010101ULL;
1042#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
1043 value64 *= 0x01010101;
1044 value64 |= value64 << 32;
1045#else
1046 value64 |= value64 << 8;
1047 value64 |= value64 << 16;
1048 value64 |= value64 << 32;
1049#endif
1050
1051 prefix = (unsigned long)start % 8;
1052 if (prefix) {
1053 u8 *r;
1054
1055 prefix = 8 - prefix;
1056 r = check_bytes8(start, value, prefix);
1057 if (r)
1058 return r;
1059 start += prefix;
1060 bytes -= prefix;
1061 }
1062
1063 words = bytes / 8;
1064
1065 while (words) {
1066 if (*(u64 *)start != value64)
1067 return check_bytes8(start, value, 8);
1068 start += 8;
1069 words--;
1070 }
1071
1072 return check_bytes8(start, value, bytes % 8);
1073}
1074EXPORT_SYMBOL(memchr_inv);
1075
1076/**
1077 * strreplace - Replace all occurrences of character in string.
1078 * @s: The string to operate on.
1079 * @old: The character being replaced.
1080 * @new: The character @old is replaced with.
1081 *
1082 * Returns pointer to the nul byte at the end of @s.
1083 */
1084char *strreplace(char *s, char old, char new)
1085{
1086 for (; *s; ++s)
1087 if (*s == old)
1088 *s = new;
1089 return s;
1090}
1091EXPORT_SYMBOL(strreplace);
1092
1093void fortify_panic(const char *name)
1094{
1095 pr_emerg("detected buffer overflow in %s\n", name);
1096 BUG();
1097}
1098EXPORT_SYMBOL(fortify_panic);