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