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.
163 * The routine returns the number of characters copied (not including
164 * the trailing NUL) or -E2BIG if the destination buffer wasn't big enough.
165 * The behavior is undefined if the string buffers overlap.
166 * The destination buffer is always NUL terminated, unless it's zero-sized.
167 *
168 * Preferred to strlcpy() since the API doesn't require reading memory
169 * from the src string beyond the specified "count" bytes, and since
170 * the return value is easier to error-check than strlcpy()'s.
171 * In addition, the implementation is robust to the string changing out
172 * from underneath it, unlike the current strlcpy() implementation.
173 *
174 * Preferred to strncpy() since it always returns a valid string, and
175 * doesn't unnecessarily force the tail of the destination buffer to be
176 * zeroed. If the zeroing is desired, it's likely cleaner to use strscpy()
177 * with an overflow test, then just memset() the tail of the dest buffer.
178 */
179ssize_t strscpy(char *dest, const char *src, size_t count)
180{
181 const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
182 size_t max = count;
183 long res = 0;
184
185 if (count == 0)
186 return -E2BIG;
187
188#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
189 /*
190 * If src is unaligned, don't cross a page boundary,
191 * since we don't know if the next page is mapped.
192 */
193 if ((long)src & (sizeof(long) - 1)) {
194 size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
195 if (limit < max)
196 max = limit;
197 }
198#else
199 /* If src or dest is unaligned, don't do word-at-a-time. */
200 if (((long) dest | (long) src) & (sizeof(long) - 1))
201 max = 0;
202#endif
203
204 while (max >= sizeof(unsigned long)) {
205 unsigned long c, data;
206
207 c = read_word_at_a_time(src+res);
208 if (has_zero(c, &data, &constants)) {
209 data = prep_zero_mask(c, data, &constants);
210 data = create_zero_mask(data);
211 *(unsigned long *)(dest+res) = c & zero_bytemask(data);
212 return res + find_zero(data);
213 }
214 *(unsigned long *)(dest+res) = c;
215 res += sizeof(unsigned long);
216 count -= sizeof(unsigned long);
217 max -= sizeof(unsigned long);
218 }
219
220 while (count) {
221 char c;
222
223 c = src[res];
224 dest[res] = c;
225 if (!c)
226 return res;
227 res++;
228 count--;
229 }
230
231 /* Hit buffer length without finding a NUL; force NUL-termination. */
232 if (res)
233 dest[res-1] = '\0';
234
235 return -E2BIG;
236}
237EXPORT_SYMBOL(strscpy);
238#endif
239
240#ifndef __HAVE_ARCH_STRCAT
241/**
242 * strcat - Append one %NUL-terminated string to another
243 * @dest: The string to be appended to
244 * @src: The string to append to it
245 */
246#undef strcat
247char *strcat(char *dest, const char *src)
248{
249 char *tmp = dest;
250
251 while (*dest)
252 dest++;
253 while ((*dest++ = *src++) != '\0')
254 ;
255 return tmp;
256}
257EXPORT_SYMBOL(strcat);
258#endif
259
260#ifndef __HAVE_ARCH_STRNCAT
261/**
262 * strncat - Append a length-limited, C-string to another
263 * @dest: The string to be appended to
264 * @src: The string to append to it
265 * @count: The maximum numbers of bytes to copy
266 *
267 * Note that in contrast to strncpy(), strncat() ensures the result is
268 * terminated.
269 */
270char *strncat(char *dest, const char *src, size_t count)
271{
272 char *tmp = dest;
273
274 if (count) {
275 while (*dest)
276 dest++;
277 while ((*dest++ = *src++) != 0) {
278 if (--count == 0) {
279 *dest = '\0';
280 break;
281 }
282 }
283 }
284 return tmp;
285}
286EXPORT_SYMBOL(strncat);
287#endif
288
289#ifndef __HAVE_ARCH_STRLCAT
290/**
291 * strlcat - Append a length-limited, C-string to another
292 * @dest: The string to be appended to
293 * @src: The string to append to it
294 * @count: The size of the destination buffer.
295 */
296size_t strlcat(char *dest, const char *src, size_t count)
297{
298 size_t dsize = strlen(dest);
299 size_t len = strlen(src);
300 size_t res = dsize + len;
301
302 /* This would be a bug */
303 BUG_ON(dsize >= count);
304
305 dest += dsize;
306 count -= dsize;
307 if (len >= count)
308 len = count-1;
309 memcpy(dest, src, len);
310 dest[len] = 0;
311 return res;
312}
313EXPORT_SYMBOL(strlcat);
314#endif
315
316#ifndef __HAVE_ARCH_STRCMP
317/**
318 * strcmp - Compare two strings
319 * @cs: One string
320 * @ct: Another string
321 */
322#undef strcmp
323int strcmp(const char *cs, const char *ct)
324{
325 unsigned char c1, c2;
326
327 while (1) {
328 c1 = *cs++;
329 c2 = *ct++;
330 if (c1 != c2)
331 return c1 < c2 ? -1 : 1;
332 if (!c1)
333 break;
334 }
335 return 0;
336}
337EXPORT_SYMBOL(strcmp);
338#endif
339
340#ifndef __HAVE_ARCH_STRNCMP
341/**
342 * strncmp - Compare two length-limited strings
343 * @cs: One string
344 * @ct: Another string
345 * @count: The maximum number of bytes to compare
346 */
347int strncmp(const char *cs, const char *ct, size_t count)
348{
349 unsigned char c1, c2;
350
351 while (count) {
352 c1 = *cs++;
353 c2 = *ct++;
354 if (c1 != c2)
355 return c1 < c2 ? -1 : 1;
356 if (!c1)
357 break;
358 count--;
359 }
360 return 0;
361}
362EXPORT_SYMBOL(strncmp);
363#endif
364
365#ifndef __HAVE_ARCH_STRCHR
366/**
367 * strchr - Find the first occurrence of a character in a string
368 * @s: The string to be searched
369 * @c: The character to search for
370 */
371char *strchr(const char *s, int c)
372{
373 for (; *s != (char)c; ++s)
374 if (*s == '\0')
375 return NULL;
376 return (char *)s;
377}
378EXPORT_SYMBOL(strchr);
379#endif
380
381#ifndef __HAVE_ARCH_STRCHRNUL
382/**
383 * strchrnul - Find and return a character in a string, or end of string
384 * @s: The string to be searched
385 * @c: The character to search for
386 *
387 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
388 * return a pointer to the null byte at the end of s.
389 */
390char *strchrnul(const char *s, int c)
391{
392 while (*s && *s != (char)c)
393 s++;
394 return (char *)s;
395}
396EXPORT_SYMBOL(strchrnul);
397#endif
398
399#ifndef __HAVE_ARCH_STRRCHR
400/**
401 * strrchr - Find the last occurrence of a character in a string
402 * @s: The string to be searched
403 * @c: The character to search for
404 */
405char *strrchr(const char *s, int c)
406{
407 const char *last = NULL;
408 do {
409 if (*s == (char)c)
410 last = s;
411 } while (*s++);
412 return (char *)last;
413}
414EXPORT_SYMBOL(strrchr);
415#endif
416
417#ifndef __HAVE_ARCH_STRNCHR
418/**
419 * strnchr - Find a character in a length limited string
420 * @s: The string to be searched
421 * @count: The number of characters to be searched
422 * @c: The character to search for
423 */
424char *strnchr(const char *s, size_t count, int c)
425{
426 for (; count-- && *s != '\0'; ++s)
427 if (*s == (char)c)
428 return (char *)s;
429 return NULL;
430}
431EXPORT_SYMBOL(strnchr);
432#endif
433
434/**
435 * skip_spaces - Removes leading whitespace from @str.
436 * @str: The string to be stripped.
437 *
438 * Returns a pointer to the first non-whitespace character in @str.
439 */
440char *skip_spaces(const char *str)
441{
442 while (isspace(*str))
443 ++str;
444 return (char *)str;
445}
446EXPORT_SYMBOL(skip_spaces);
447
448/**
449 * strim - Removes leading and trailing whitespace from @s.
450 * @s: The string to be stripped.
451 *
452 * Note that the first trailing whitespace is replaced with a %NUL-terminator
453 * in the given string @s. Returns a pointer to the first non-whitespace
454 * character in @s.
455 */
456char *strim(char *s)
457{
458 size_t size;
459 char *end;
460
461 size = strlen(s);
462 if (!size)
463 return s;
464
465 end = s + size - 1;
466 while (end >= s && isspace(*end))
467 end--;
468 *(end + 1) = '\0';
469
470 return skip_spaces(s);
471}
472EXPORT_SYMBOL(strim);
473
474#ifndef __HAVE_ARCH_STRLEN
475/**
476 * strlen - Find the length of a string
477 * @s: The string to be sized
478 */
479size_t strlen(const char *s)
480{
481 const char *sc;
482
483 for (sc = s; *sc != '\0'; ++sc)
484 /* nothing */;
485 return sc - s;
486}
487EXPORT_SYMBOL(strlen);
488#endif
489
490#ifndef __HAVE_ARCH_STRNLEN
491/**
492 * strnlen - Find the length of a length-limited string
493 * @s: The string to be sized
494 * @count: The maximum number of bytes to search
495 */
496size_t strnlen(const char *s, size_t count)
497{
498 const char *sc;
499
500 for (sc = s; count-- && *sc != '\0'; ++sc)
501 /* nothing */;
502 return sc - s;
503}
504EXPORT_SYMBOL(strnlen);
505#endif
506
507#ifndef __HAVE_ARCH_STRSPN
508/**
509 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
510 * @s: The string to be searched
511 * @accept: The string to search for
512 */
513size_t strspn(const char *s, const char *accept)
514{
515 const char *p;
516 const char *a;
517 size_t count = 0;
518
519 for (p = s; *p != '\0'; ++p) {
520 for (a = accept; *a != '\0'; ++a) {
521 if (*p == *a)
522 break;
523 }
524 if (*a == '\0')
525 return count;
526 ++count;
527 }
528 return count;
529}
530
531EXPORT_SYMBOL(strspn);
532#endif
533
534#ifndef __HAVE_ARCH_STRCSPN
535/**
536 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
537 * @s: The string to be searched
538 * @reject: The string to avoid
539 */
540size_t strcspn(const char *s, const char *reject)
541{
542 const char *p;
543 const char *r;
544 size_t count = 0;
545
546 for (p = s; *p != '\0'; ++p) {
547 for (r = reject; *r != '\0'; ++r) {
548 if (*p == *r)
549 return count;
550 }
551 ++count;
552 }
553 return count;
554}
555EXPORT_SYMBOL(strcspn);
556#endif
557
558#ifndef __HAVE_ARCH_STRPBRK
559/**
560 * strpbrk - Find the first occurrence of a set of characters
561 * @cs: The string to be searched
562 * @ct: The characters to search for
563 */
564char *strpbrk(const char *cs, const char *ct)
565{
566 const char *sc1, *sc2;
567
568 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
569 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
570 if (*sc1 == *sc2)
571 return (char *)sc1;
572 }
573 }
574 return NULL;
575}
576EXPORT_SYMBOL(strpbrk);
577#endif
578
579#ifndef __HAVE_ARCH_STRSEP
580/**
581 * strsep - Split a string into tokens
582 * @s: The string to be searched
583 * @ct: The characters to search for
584 *
585 * strsep() updates @s to point after the token, ready for the next call.
586 *
587 * It returns empty tokens, too, behaving exactly like the libc function
588 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
589 * Same semantics, slimmer shape. ;)
590 */
591char *strsep(char **s, const char *ct)
592{
593 char *sbegin = *s;
594 char *end;
595
596 if (sbegin == NULL)
597 return NULL;
598
599 end = strpbrk(sbegin, ct);
600 if (end)
601 *end++ = '\0';
602 *s = end;
603 return sbegin;
604}
605EXPORT_SYMBOL(strsep);
606#endif
607
608/**
609 * sysfs_streq - return true if strings are equal, modulo trailing newline
610 * @s1: one string
611 * @s2: another string
612 *
613 * This routine returns true iff two strings are equal, treating both
614 * NUL and newline-then-NUL as equivalent string terminations. It's
615 * geared for use with sysfs input strings, which generally terminate
616 * with newlines but are compared against values without newlines.
617 */
618bool sysfs_streq(const char *s1, const char *s2)
619{
620 while (*s1 && *s1 == *s2) {
621 s1++;
622 s2++;
623 }
624
625 if (*s1 == *s2)
626 return true;
627 if (!*s1 && *s2 == '\n' && !s2[1])
628 return true;
629 if (*s1 == '\n' && !s1[1] && !*s2)
630 return true;
631 return false;
632}
633EXPORT_SYMBOL(sysfs_streq);
634
635/**
636 * match_string - matches given string in an array
637 * @array: array of strings
638 * @n: number of strings in the array or -1 for NULL terminated arrays
639 * @string: string to match with
640 *
641 * Return:
642 * index of a @string in the @array if matches, or %-EINVAL otherwise.
643 */
644int match_string(const char * const *array, size_t n, const char *string)
645{
646 int index;
647 const char *item;
648
649 for (index = 0; index < n; index++) {
650 item = array[index];
651 if (!item)
652 break;
653 if (!strcmp(item, string))
654 return index;
655 }
656
657 return -EINVAL;
658}
659EXPORT_SYMBOL(match_string);
660
661/**
662 * __sysfs_match_string - matches given string in an array
663 * @array: array of strings
664 * @n: number of strings in the array or -1 for NULL terminated arrays
665 * @str: string to match with
666 *
667 * Returns index of @str in the @array or -EINVAL, just like match_string().
668 * Uses sysfs_streq instead of strcmp for matching.
669 */
670int __sysfs_match_string(const char * const *array, size_t n, const char *str)
671{
672 const char *item;
673 int index;
674
675 for (index = 0; index < n; index++) {
676 item = array[index];
677 if (!item)
678 break;
679 if (sysfs_streq(item, str))
680 return index;
681 }
682
683 return -EINVAL;
684}
685EXPORT_SYMBOL(__sysfs_match_string);
686
687#ifndef __HAVE_ARCH_MEMSET
688/**
689 * memset - Fill a region of memory with the given value
690 * @s: Pointer to the start of the area.
691 * @c: The byte to fill the area with
692 * @count: The size of the area.
693 *
694 * Do not use memset() to access IO space, use memset_io() instead.
695 */
696void *memset(void *s, int c, size_t count)
697{
698 char *xs = s;
699
700 while (count--)
701 *xs++ = c;
702 return s;
703}
704EXPORT_SYMBOL(memset);
705#endif
706
707/**
708 * memzero_explicit - Fill a region of memory (e.g. sensitive
709 * keying data) with 0s.
710 * @s: Pointer to the start of the area.
711 * @count: The size of the area.
712 *
713 * Note: usually using memset() is just fine (!), but in cases
714 * where clearing out _local_ data at the end of a scope is
715 * necessary, memzero_explicit() should be used instead in
716 * order to prevent the compiler from optimising away zeroing.
717 *
718 * memzero_explicit() doesn't need an arch-specific version as
719 * it just invokes the one of memset() implicitly.
720 */
721void memzero_explicit(void *s, size_t count)
722{
723 memset(s, 0, count);
724 barrier_data(s);
725}
726EXPORT_SYMBOL(memzero_explicit);
727
728#ifndef __HAVE_ARCH_MEMSET16
729/**
730 * memset16() - Fill a memory area with a uint16_t
731 * @s: Pointer to the start of the area.
732 * @v: The value to fill the area with
733 * @count: The number of values to store
734 *
735 * Differs from memset() in that it fills with a uint16_t instead
736 * of a byte. Remember that @count is the number of uint16_ts to
737 * store, not the number of bytes.
738 */
739void *memset16(uint16_t *s, uint16_t v, size_t count)
740{
741 uint16_t *xs = s;
742
743 while (count--)
744 *xs++ = v;
745 return s;
746}
747EXPORT_SYMBOL(memset16);
748#endif
749
750#ifndef __HAVE_ARCH_MEMSET32
751/**
752 * memset32() - Fill a memory area with a uint32_t
753 * @s: Pointer to the start of the area.
754 * @v: The value to fill the area with
755 * @count: The number of values to store
756 *
757 * Differs from memset() in that it fills with a uint32_t instead
758 * of a byte. Remember that @count is the number of uint32_ts to
759 * store, not the number of bytes.
760 */
761void *memset32(uint32_t *s, uint32_t v, size_t count)
762{
763 uint32_t *xs = s;
764
765 while (count--)
766 *xs++ = v;
767 return s;
768}
769EXPORT_SYMBOL(memset32);
770#endif
771
772#ifndef __HAVE_ARCH_MEMSET64
773/**
774 * memset64() - Fill a memory area with a uint64_t
775 * @s: Pointer to the start of the area.
776 * @v: The value to fill the area with
777 * @count: The number of values to store
778 *
779 * Differs from memset() in that it fills with a uint64_t instead
780 * of a byte. Remember that @count is the number of uint64_ts to
781 * store, not the number of bytes.
782 */
783void *memset64(uint64_t *s, uint64_t v, size_t count)
784{
785 uint64_t *xs = s;
786
787 while (count--)
788 *xs++ = v;
789 return s;
790}
791EXPORT_SYMBOL(memset64);
792#endif
793
794#ifndef __HAVE_ARCH_MEMCPY
795/**
796 * memcpy - Copy one area of memory to another
797 * @dest: Where to copy to
798 * @src: Where to copy from
799 * @count: The size of the area.
800 *
801 * You should not use this function to access IO space, use memcpy_toio()
802 * or memcpy_fromio() instead.
803 */
804void *memcpy(void *dest, const void *src, size_t count)
805{
806 char *tmp = dest;
807 const char *s = src;
808
809 while (count--)
810 *tmp++ = *s++;
811 return dest;
812}
813EXPORT_SYMBOL(memcpy);
814#endif
815
816#ifndef __HAVE_ARCH_MEMMOVE
817/**
818 * memmove - Copy one area of memory to another
819 * @dest: Where to copy to
820 * @src: Where to copy from
821 * @count: The size of the area.
822 *
823 * Unlike memcpy(), memmove() copes with overlapping areas.
824 */
825void *memmove(void *dest, const void *src, size_t count)
826{
827 char *tmp;
828 const char *s;
829
830 if (dest <= src) {
831 tmp = dest;
832 s = src;
833 while (count--)
834 *tmp++ = *s++;
835 } else {
836 tmp = dest;
837 tmp += count;
838 s = src;
839 s += count;
840 while (count--)
841 *--tmp = *--s;
842 }
843 return dest;
844}
845EXPORT_SYMBOL(memmove);
846#endif
847
848#ifndef __HAVE_ARCH_MEMCMP
849/**
850 * memcmp - Compare two areas of memory
851 * @cs: One area of memory
852 * @ct: Another area of memory
853 * @count: The size of the area.
854 */
855#undef memcmp
856__visible int memcmp(const void *cs, const void *ct, size_t count)
857{
858 const unsigned char *su1, *su2;
859 int res = 0;
860
861 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
862 if ((res = *su1 - *su2) != 0)
863 break;
864 return res;
865}
866EXPORT_SYMBOL(memcmp);
867#endif
868
869#ifndef __HAVE_ARCH_MEMSCAN
870/**
871 * memscan - Find a character in an area of memory.
872 * @addr: The memory area
873 * @c: The byte to search for
874 * @size: The size of the area.
875 *
876 * returns the address of the first occurrence of @c, or 1 byte past
877 * the area if @c is not found
878 */
879void *memscan(void *addr, int c, size_t size)
880{
881 unsigned char *p = addr;
882
883 while (size) {
884 if (*p == c)
885 return (void *)p;
886 p++;
887 size--;
888 }
889 return (void *)p;
890}
891EXPORT_SYMBOL(memscan);
892#endif
893
894#ifndef __HAVE_ARCH_STRSTR
895/**
896 * strstr - Find the first substring in a %NUL terminated string
897 * @s1: The string to be searched
898 * @s2: The string to search for
899 */
900char *strstr(const char *s1, const char *s2)
901{
902 size_t l1, l2;
903
904 l2 = strlen(s2);
905 if (!l2)
906 return (char *)s1;
907 l1 = strlen(s1);
908 while (l1 >= l2) {
909 l1--;
910 if (!memcmp(s1, s2, l2))
911 return (char *)s1;
912 s1++;
913 }
914 return NULL;
915}
916EXPORT_SYMBOL(strstr);
917#endif
918
919#ifndef __HAVE_ARCH_STRNSTR
920/**
921 * strnstr - Find the first substring in a length-limited string
922 * @s1: The string to be searched
923 * @s2: The string to search for
924 * @len: the maximum number of characters to search
925 */
926char *strnstr(const char *s1, const char *s2, size_t len)
927{
928 size_t l2;
929
930 l2 = strlen(s2);
931 if (!l2)
932 return (char *)s1;
933 while (len >= l2) {
934 len--;
935 if (!memcmp(s1, s2, l2))
936 return (char *)s1;
937 s1++;
938 }
939 return NULL;
940}
941EXPORT_SYMBOL(strnstr);
942#endif
943
944#ifndef __HAVE_ARCH_MEMCHR
945/**
946 * memchr - Find a character in an area of memory.
947 * @s: The memory area
948 * @c: The byte to search for
949 * @n: The size of the area.
950 *
951 * returns the address of the first occurrence of @c, or %NULL
952 * if @c is not found
953 */
954void *memchr(const void *s, int c, size_t n)
955{
956 const unsigned char *p = s;
957 while (n-- != 0) {
958 if ((unsigned char)c == *p++) {
959 return (void *)(p - 1);
960 }
961 }
962 return NULL;
963}
964EXPORT_SYMBOL(memchr);
965#endif
966
967static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
968{
969 while (bytes) {
970 if (*start != value)
971 return (void *)start;
972 start++;
973 bytes--;
974 }
975 return NULL;
976}
977
978/**
979 * memchr_inv - Find an unmatching character in an area of memory.
980 * @start: The memory area
981 * @c: Find a character other than c
982 * @bytes: The size of the area.
983 *
984 * returns the address of the first character other than @c, or %NULL
985 * if the whole buffer contains just @c.
986 */
987void *memchr_inv(const void *start, int c, size_t bytes)
988{
989 u8 value = c;
990 u64 value64;
991 unsigned int words, prefix;
992
993 if (bytes <= 16)
994 return check_bytes8(start, value, bytes);
995
996 value64 = value;
997#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
998 value64 *= 0x0101010101010101ULL;
999#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
1000 value64 *= 0x01010101;
1001 value64 |= value64 << 32;
1002#else
1003 value64 |= value64 << 8;
1004 value64 |= value64 << 16;
1005 value64 |= value64 << 32;
1006#endif
1007
1008 prefix = (unsigned long)start % 8;
1009 if (prefix) {
1010 u8 *r;
1011
1012 prefix = 8 - prefix;
1013 r = check_bytes8(start, value, prefix);
1014 if (r)
1015 return r;
1016 start += prefix;
1017 bytes -= prefix;
1018 }
1019
1020 words = bytes / 8;
1021
1022 while (words) {
1023 if (*(u64 *)start != value64)
1024 return check_bytes8(start, value, 8);
1025 start += 8;
1026 words--;
1027 }
1028
1029 return check_bytes8(start, value, bytes % 8);
1030}
1031EXPORT_SYMBOL(memchr_inv);
1032
1033/**
1034 * strreplace - Replace all occurrences of character in string.
1035 * @s: The string to operate on.
1036 * @old: The character being replaced.
1037 * @new: The character @old is replaced with.
1038 *
1039 * Returns pointer to the nul byte at the end of @s.
1040 */
1041char *strreplace(char *s, char old, char new)
1042{
1043 for (; *s; ++s)
1044 if (*s == old)
1045 *s = new;
1046 return s;
1047}
1048EXPORT_SYMBOL(strreplace);
1049
1050void fortify_panic(const char *name)
1051{
1052 pr_emerg("detected buffer overflow in %s\n", name);
1053 BUG();
1054}
1055EXPORT_SYMBOL(fortify_panic);
1056