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b2441318 1// SPDX-License-Identifier: GPL-2.0
1da177e4
LT
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>
8bc3bcc9
PG
26#include <linux/kernel.h>
27#include <linux/export.h>
50af5ead 28#include <linux/bug.h>
8bc3bcc9 29#include <linux/errno.h>
ce76d938 30#include <linux/slab.h>
1da177e4 31
30035e45
CM
32#include <asm/byteorder.h>
33#include <asm/word-at-a-time.h>
34#include <asm/page.h>
35
cd514e72 36#ifndef __HAVE_ARCH_STRNCASECMP
1da177e4 37/**
cd514e72 38 * strncasecmp - Case insensitive, length-limited string comparison
1da177e4
LT
39 * @s1: One string
40 * @s2: The other string
41 * @len: the maximum number of characters to compare
42 */
cd514e72 43int strncasecmp(const char *s1, const char *s2, size_t len)
1da177e4
LT
44{
45 /* Yes, Virginia, it had better be unsigned */
46 unsigned char c1, c2;
47
a11d2b64
AGR
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);
1da177e4
LT
63 return (int)c1 - (int)c2;
64}
cd514e72
RV
65EXPORT_SYMBOL(strncasecmp);
66#endif
1da177e4 67
ded220bd
DM
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
1da177e4
LT
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 */
0c28130b 88#undef strcpy
51a0f0f6 89char *strcpy(char *dest, const char *src)
1da177e4
LT
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/**
0046dd9f 102 * strncpy - Copy a length-limited, C-string
1da177e4
LT
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.
25279526 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 *
1da177e4 113 */
51a0f0f6 114char *strncpy(char *dest, const char *src, size_t count)
1da177e4
LT
115{
116 char *tmp = dest;
117
118 while (count) {
51a0f0f6
JJ
119 if ((*tmp = *src) != 0)
120 src++;
1da177e4
LT
121 tmp++;
122 count--;
123 }
124 return dest;
125}
126EXPORT_SYMBOL(strncpy);
127#endif
128
129#ifndef __HAVE_ARCH_STRLCPY
130/**
0046dd9f 131 * strlcpy - Copy a C-string into a sized buffer
1da177e4
LT
132 * @dest: Where to copy the string to
133 * @src: Where to copy the string from
134 * @size: size of destination buffer
135 *
0e056eb5 136 * Compatible with ``*BSD``: the result is always a valid
1da177e4
LT
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) {
51a0f0f6 146 size_t len = (ret >= size) ? size - 1 : ret;
1da177e4
LT
147 memcpy(dest, src, len);
148 dest[len] = '\0';
149 }
150 return ret;
151}
152EXPORT_SYMBOL(strlcpy);
153#endif
154
30035e45
CM
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 *
458a3bf8
TH
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.
30035e45
CM
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
458a3bf8
TH
174 * zeroed. If zeroing is desired please use strscpy_pad().
175 *
917cda27
JP
176 * Returns:
177 * * The number of characters copied (not including the trailing %NUL)
178 * * -E2BIG if count is 0 or @src was truncated.
30035e45
CM
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
9a156466 186 if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
30035e45
CM
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
1a3241ff 208 c = read_word_at_a_time(src+res);
30035e45
CM
209 if (has_zero(c, &data, &constants)) {
210 data = prep_zero_mask(c, data, &constants);
211 data = create_zero_mask(data);
990486c8 212 *(unsigned long *)(dest+res) = c & zero_bytemask(data);
30035e45
CM
213 return res + find_zero(data);
214 }
990486c8 215 *(unsigned long *)(dest+res) = c;
30035e45
CM
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
458a3bf8
TH
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 *
917cda27
JP
257 * Returns:
258 * * The number of characters copied (not including the trailing %NUL)
259 * * -E2BIG if count is 0 or @src was truncated.
458a3bf8
TH
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
1da177e4
LT
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 */
0c28130b 281#undef strcat
51a0f0f6 282char *strcat(char *dest, const char *src)
1da177e4
LT
283{
284 char *tmp = dest;
285
286 while (*dest)
287 dest++;
288 while ((*dest++ = *src++) != '\0')
289 ;
1da177e4
LT
290 return tmp;
291}
292EXPORT_SYMBOL(strcat);
293#endif
294
295#ifndef __HAVE_ARCH_STRNCAT
296/**
0046dd9f 297 * strncat - Append a length-limited, C-string to another
1da177e4
LT
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 *
72fd4a35 302 * Note that in contrast to strncpy(), strncat() ensures the result is
1da177e4
LT
303 * terminated.
304 */
51a0f0f6 305char *strncat(char *dest, const char *src, size_t count)
1da177e4
LT
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 }
1da177e4
LT
319 return tmp;
320}
321EXPORT_SYMBOL(strncat);
322#endif
323
324#ifndef __HAVE_ARCH_STRLCAT
325/**
0046dd9f 326 * strlcat - Append a length-limited, C-string to another
1da177e4
LT
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 */
0c28130b 357#undef strcmp
51a0f0f6 358int strcmp(const char *cs, const char *ct)
1da177e4 359{
a414f01a 360 unsigned char c1, c2;
1da177e4
LT
361
362 while (1) {
a414f01a
LT
363 c1 = *cs++;
364 c2 = *ct++;
365 if (c1 != c2)
366 return c1 < c2 ? -1 : 1;
367 if (!c1)
1da177e4
LT
368 break;
369 }
a414f01a 370 return 0;
1da177e4
LT
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 */
51a0f0f6 382int strncmp(const char *cs, const char *ct, size_t count)
1da177e4 383{
a414f01a 384 unsigned char c1, c2;
1da177e4
LT
385
386 while (count) {
a414f01a
LT
387 c1 = *cs++;
388 c2 = *ct++;
389 if (c1 != c2)
390 return c1 < c2 ? -1 : 1;
391 if (!c1)
1da177e4
LT
392 break;
393 count--;
394 }
a414f01a 395 return 0;
1da177e4
LT
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
b0975710
PR
405 *
406 * Note that the %NUL-terminator is considered part of the string, and can
407 * be searched for.
1da177e4 408 */
51a0f0f6 409char *strchr(const char *s, int c)
1da177e4 410{
51a0f0f6 411 for (; *s != (char)c; ++s)
1da177e4
LT
412 if (*s == '\0')
413 return NULL;
51a0f0f6 414 return (char *)s;
1da177e4
LT
415}
416EXPORT_SYMBOL(strchr);
417#endif
418
11d200e9
GL
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
1da177e4
LT
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 */
51a0f0f6 443char *strrchr(const char *s, int c)
1da177e4 444{
8da53d45
RV
445 const char *last = NULL;
446 do {
447 if (*s == (char)c)
448 last = s;
449 } while (*s++);
450 return (char *)last;
1da177e4
LT
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
b0975710
PR
461 *
462 * Note that the %NUL-terminator is considered part of the string, and can
463 * be searched for.
1da177e4
LT
464 */
465char *strnchr(const char *s, size_t count, int c)
466{
b0975710 467 while (count--) {
51a0f0f6
JJ
468 if (*s == (char)c)
469 return (char *)s;
b0975710
PR
470 if (*s++ == '\0')
471 break;
472 }
1da177e4
LT
473 return NULL;
474}
475EXPORT_SYMBOL(strnchr);
476#endif
477
f653398c 478/**
a6cd13f3
RD
479 * skip_spaces - Removes leading whitespace from @str.
480 * @str: The string to be stripped.
f653398c 481 *
a6cd13f3 482 * Returns a pointer to the first non-whitespace character in @str.
f653398c
AGR
483 */
484char *skip_spaces(const char *str)
485{
486 while (isspace(*str))
487 ++str;
488 return (char *)str;
489}
490EXPORT_SYMBOL(skip_spaces);
491
481fad48 492/**
ca54cb8c 493 * strim - Removes leading and trailing whitespace from @s.
481fad48
PE
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 */
ca54cb8c 500char *strim(char *s)
481fad48
PE
501{
502 size_t size;
503 char *end;
504
505 size = strlen(s);
481fad48
PE
506 if (!size)
507 return s;
508
509 end = s + size - 1;
6e6d9fa6 510 while (end >= s && isspace(*end))
481fad48
PE
511 end--;
512 *(end + 1) = '\0';
513
66f6958e 514 return skip_spaces(s);
481fad48 515}
ca54cb8c 516EXPORT_SYMBOL(strim);
481fad48 517
1da177e4
LT
518#ifndef __HAVE_ARCH_STRLEN
519/**
520 * strlen - Find the length of a string
521 * @s: The string to be sized
522 */
51a0f0f6 523size_t strlen(const char *s)
1da177e4
LT
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 */
51a0f0f6 540size_t strnlen(const char *s, size_t count)
1da177e4
LT
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/**
72fd4a35 553 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
1da177e4
LT
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 }
1da177e4
LT
572 return count;
573}
574
575EXPORT_SYMBOL(strspn);
576#endif
577
8833d328 578#ifndef __HAVE_ARCH_STRCSPN
1da177e4 579/**
72fd4a35 580 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
1da177e4
LT
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 }
1da177e4 597 return count;
51a0f0f6 598}
1da177e4 599EXPORT_SYMBOL(strcspn);
8833d328 600#endif
1da177e4
LT
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 */
51a0f0f6 608char *strpbrk(const char *cs, const char *ct)
1da177e4 609{
51a0f0f6 610 const char *sc1, *sc2;
1da177e4 611
51a0f0f6
JJ
612 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
613 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
1da177e4 614 if (*sc1 == *sc2)
51a0f0f6 615 return (char *)sc1;
1da177e4
LT
616 }
617 }
618 return NULL;
619}
894b5779 620EXPORT_SYMBOL(strpbrk);
1da177e4
LT
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 */
51a0f0f6 635char *strsep(char **s, const char *ct)
1da177e4 636{
51a0f0f6
JJ
637 char *sbegin = *s;
638 char *end;
1da177e4
LT
639
640 if (sbegin == NULL)
641 return NULL;
642
643 end = strpbrk(sbegin, ct);
644 if (end)
645 *end++ = '\0';
646 *s = end;
1da177e4
LT
647 return sbegin;
648}
1da177e4
LT
649EXPORT_SYMBOL(strsep);
650#endif
651
34990cf7
DB
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
56b06081
AS
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
e1fe7b6a
HK
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
1da177e4
LT
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 */
51a0f0f6 740void *memset(void *s, int c, size_t count)
1da177e4 741{
850b9247 742 char *xs = s;
1da177e4
LT
743
744 while (count--)
745 *xs++ = c;
1da177e4
LT
746 return s;
747}
748EXPORT_SYMBOL(memset);
749#endif
750
d4c5efdb
DB
751/**
752 * memzero_explicit - Fill a region of memory (e.g. sensitive
753 * keying data) with 0s.
754 * @s: Pointer to the start of the area.
755 * @count: The size of the area.
756 *
8155330a
DB
757 * Note: usually using memset() is just fine (!), but in cases
758 * where clearing out _local_ data at the end of a scope is
759 * necessary, memzero_explicit() should be used instead in
760 * order to prevent the compiler from optimising away zeroing.
761 *
d4c5efdb
DB
762 * memzero_explicit() doesn't need an arch-specific version as
763 * it just invokes the one of memset() implicitly.
764 */
765void memzero_explicit(void *s, size_t count)
766{
767 memset(s, 0, count);
7829fb09 768 barrier_data(s);
d4c5efdb
DB
769}
770EXPORT_SYMBOL(memzero_explicit);
771
3b3c4bab
MW
772#ifndef __HAVE_ARCH_MEMSET16
773/**
774 * memset16() - Fill a memory area with a uint16_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 uint16_t instead
780 * of a byte. Remember that @count is the number of uint16_ts to
781 * store, not the number of bytes.
782 */
783void *memset16(uint16_t *s, uint16_t v, size_t count)
784{
785 uint16_t *xs = s;
786
787 while (count--)
788 *xs++ = v;
789 return s;
790}
791EXPORT_SYMBOL(memset16);
792#endif
793
794#ifndef __HAVE_ARCH_MEMSET32
795/**
796 * memset32() - Fill a memory area with a uint32_t
797 * @s: Pointer to the start of the area.
798 * @v: The value to fill the area with
799 * @count: The number of values to store
800 *
801 * Differs from memset() in that it fills with a uint32_t instead
802 * of a byte. Remember that @count is the number of uint32_ts to
803 * store, not the number of bytes.
804 */
805void *memset32(uint32_t *s, uint32_t v, size_t count)
806{
807 uint32_t *xs = s;
808
809 while (count--)
810 *xs++ = v;
811 return s;
812}
813EXPORT_SYMBOL(memset32);
814#endif
815
816#ifndef __HAVE_ARCH_MEMSET64
817/**
818 * memset64() - Fill a memory area with a uint64_t
819 * @s: Pointer to the start of the area.
820 * @v: The value to fill the area with
821 * @count: The number of values to store
822 *
823 * Differs from memset() in that it fills with a uint64_t instead
824 * of a byte. Remember that @count is the number of uint64_ts to
825 * store, not the number of bytes.
826 */
827void *memset64(uint64_t *s, uint64_t v, size_t count)
828{
829 uint64_t *xs = s;
830
831 while (count--)
832 *xs++ = v;
833 return s;
834}
835EXPORT_SYMBOL(memset64);
836#endif
837
1da177e4
LT
838#ifndef __HAVE_ARCH_MEMCPY
839/**
840 * memcpy - Copy one area of memory to another
841 * @dest: Where to copy to
842 * @src: Where to copy from
843 * @count: The size of the area.
844 *
845 * You should not use this function to access IO space, use memcpy_toio()
846 * or memcpy_fromio() instead.
847 */
51a0f0f6 848void *memcpy(void *dest, const void *src, size_t count)
1da177e4 849{
850b9247 850 char *tmp = dest;
4c416ab7 851 const char *s = src;
1da177e4
LT
852
853 while (count--)
854 *tmp++ = *s++;
1da177e4
LT
855 return dest;
856}
857EXPORT_SYMBOL(memcpy);
858#endif
859
860#ifndef __HAVE_ARCH_MEMMOVE
861/**
862 * memmove - Copy one area of memory to another
863 * @dest: Where to copy to
864 * @src: Where to copy from
865 * @count: The size of the area.
866 *
867 * Unlike memcpy(), memmove() copes with overlapping areas.
868 */
51a0f0f6 869void *memmove(void *dest, const void *src, size_t count)
1da177e4 870{
82da2c37
PJ
871 char *tmp;
872 const char *s;
1da177e4
LT
873
874 if (dest <= src) {
850b9247
JJ
875 tmp = dest;
876 s = src;
1da177e4
LT
877 while (count--)
878 *tmp++ = *s++;
51a0f0f6 879 } else {
850b9247
JJ
880 tmp = dest;
881 tmp += count;
882 s = src;
883 s += count;
1da177e4
LT
884 while (count--)
885 *--tmp = *--s;
51a0f0f6 886 }
1da177e4
LT
887 return dest;
888}
889EXPORT_SYMBOL(memmove);
890#endif
891
892#ifndef __HAVE_ARCH_MEMCMP
893/**
894 * memcmp - Compare two areas of memory
895 * @cs: One area of memory
896 * @ct: Another area of memory
897 * @count: The size of the area.
898 */
0c28130b 899#undef memcmp
a7330c99 900__visible int memcmp(const void *cs, const void *ct, size_t count)
1da177e4
LT
901{
902 const unsigned char *su1, *su2;
903 int res = 0;
904
51a0f0f6 905 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
1da177e4
LT
906 if ((res = *su1 - *su2) != 0)
907 break;
908 return res;
909}
910EXPORT_SYMBOL(memcmp);
911#endif
912
5f074f3e
ND
913#ifndef __HAVE_ARCH_BCMP
914/**
915 * bcmp - returns 0 if and only if the buffers have identical contents.
916 * @a: pointer to first buffer.
917 * @b: pointer to second buffer.
918 * @len: size of buffers.
919 *
920 * The sign or magnitude of a non-zero return value has no particular
921 * meaning, and architectures may implement their own more efficient bcmp(). So
922 * while this particular implementation is a simple (tail) call to memcmp, do
923 * not rely on anything but whether the return value is zero or non-zero.
924 */
925#undef bcmp
926int bcmp(const void *a, const void *b, size_t len)
927{
928 return memcmp(a, b, len);
929}
930EXPORT_SYMBOL(bcmp);
931#endif
932
1da177e4
LT
933#ifndef __HAVE_ARCH_MEMSCAN
934/**
935 * memscan - Find a character in an area of memory.
936 * @addr: The memory area
937 * @c: The byte to search for
938 * @size: The size of the area.
939 *
940 * returns the address of the first occurrence of @c, or 1 byte past
941 * the area if @c is not found
942 */
51a0f0f6 943void *memscan(void *addr, int c, size_t size)
1da177e4 944{
850b9247 945 unsigned char *p = addr;
1da177e4
LT
946
947 while (size) {
948 if (*p == c)
51a0f0f6 949 return (void *)p;
1da177e4
LT
950 p++;
951 size--;
952 }
51a0f0f6 953 return (void *)p;
1da177e4
LT
954}
955EXPORT_SYMBOL(memscan);
956#endif
957
958#ifndef __HAVE_ARCH_STRSTR
959/**
960 * strstr - Find the first substring in a %NUL terminated string
961 * @s1: The string to be searched
962 * @s2: The string to search for
963 */
51a0f0f6 964char *strstr(const char *s1, const char *s2)
1da177e4 965{
d5f1fb53 966 size_t l1, l2;
1da177e4
LT
967
968 l2 = strlen(s2);
969 if (!l2)
51a0f0f6 970 return (char *)s1;
1da177e4
LT
971 l1 = strlen(s1);
972 while (l1 >= l2) {
973 l1--;
51a0f0f6
JJ
974 if (!memcmp(s1, s2, l2))
975 return (char *)s1;
1da177e4
LT
976 s1++;
977 }
978 return NULL;
979}
980EXPORT_SYMBOL(strstr);
981#endif
982
d5f1fb53
LZ
983#ifndef __HAVE_ARCH_STRNSTR
984/**
985 * strnstr - Find the first substring in a length-limited string
986 * @s1: The string to be searched
987 * @s2: The string to search for
988 * @len: the maximum number of characters to search
989 */
990char *strnstr(const char *s1, const char *s2, size_t len)
991{
d6a2eedf 992 size_t l2;
d5f1fb53
LZ
993
994 l2 = strlen(s2);
995 if (!l2)
996 return (char *)s1;
d6a2eedf
AGR
997 while (len >= l2) {
998 len--;
d5f1fb53
LZ
999 if (!memcmp(s1, s2, l2))
1000 return (char *)s1;
1001 s1++;
1002 }
1003 return NULL;
1004}
1005EXPORT_SYMBOL(strnstr);
1006#endif
1007
1da177e4
LT
1008#ifndef __HAVE_ARCH_MEMCHR
1009/**
1010 * memchr - Find a character in an area of memory.
1011 * @s: The memory area
1012 * @c: The byte to search for
1013 * @n: The size of the area.
1014 *
1015 * returns the address of the first occurrence of @c, or %NULL
1016 * if @c is not found
1017 */
1018void *memchr(const void *s, int c, size_t n)
1019{
1020 const unsigned char *p = s;
1021 while (n-- != 0) {
1022 if ((unsigned char)c == *p++) {
51a0f0f6 1023 return (void *)(p - 1);
1da177e4
LT
1024 }
1025 }
1026 return NULL;
1027}
1028EXPORT_SYMBOL(memchr);
1029#endif
79824820
AM
1030
1031static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
1032{
1033 while (bytes) {
1034 if (*start != value)
1035 return (void *)start;
1036 start++;
1037 bytes--;
1038 }
1039 return NULL;
1040}
1041
1042/**
1043 * memchr_inv - Find an unmatching character in an area of memory.
1044 * @start: The memory area
1045 * @c: Find a character other than c
1046 * @bytes: The size of the area.
1047 *
1048 * returns the address of the first character other than @c, or %NULL
1049 * if the whole buffer contains just @c.
1050 */
1051void *memchr_inv(const void *start, int c, size_t bytes)
1052{
1053 u8 value = c;
1054 u64 value64;
1055 unsigned int words, prefix;
1056
1057 if (bytes <= 16)
1058 return check_bytes8(start, value, bytes);
1059
f43804bf 1060 value64 = value;
72d93104 1061#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
3368e8fb 1062 value64 *= 0x0101010101010101ULL;
72d93104 1063#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
f43804bf
AM
1064 value64 *= 0x01010101;
1065 value64 |= value64 << 32;
1066#else
1067 value64 |= value64 << 8;
1068 value64 |= value64 << 16;
1069 value64 |= value64 << 32;
1070#endif
79824820 1071
f43804bf 1072 prefix = (unsigned long)start % 8;
79824820 1073 if (prefix) {
f43804bf
AM
1074 u8 *r;
1075
1076 prefix = 8 - prefix;
1077 r = check_bytes8(start, value, prefix);
79824820
AM
1078 if (r)
1079 return r;
1080 start += prefix;
1081 bytes -= prefix;
1082 }
1083
1084 words = bytes / 8;
1085
1086 while (words) {
1087 if (*(u64 *)start != value64)
1088 return check_bytes8(start, value, 8);
1089 start += 8;
1090 words--;
1091 }
1092
1093 return check_bytes8(start, value, bytes % 8);
1094}
1095EXPORT_SYMBOL(memchr_inv);
94df2904
RV
1096
1097/**
1098 * strreplace - Replace all occurrences of character in string.
1099 * @s: The string to operate on.
1100 * @old: The character being replaced.
1101 * @new: The character @old is replaced with.
1102 *
1103 * Returns pointer to the nul byte at the end of @s.
1104 */
1105char *strreplace(char *s, char old, char new)
1106{
1107 for (; *s; ++s)
1108 if (*s == old)
1109 *s = new;
1110 return s;
1111}
1112EXPORT_SYMBOL(strreplace);
6974f0c4
DM
1113
1114void fortify_panic(const char *name)
1115{
1116 pr_emerg("detected buffer overflow in %s\n", name);
1117 BUG();
1118}
1119EXPORT_SYMBOL(fortify_panic);