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 */
43 int 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 }
65 EXPORT_SYMBOL(strncasecmp);
66 #endif
67
68 #ifndef __HAVE_ARCH_STRCASECMP
69 int 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 }
79 EXPORT_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
89 char *strcpy(char *dest, const char *src)
90 {
91 char *tmp = dest;
92
93 while ((*dest++ = *src++) != '\0')
94 /* nothing */;
95 return tmp;
96 }
97 EXPORT_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 */
114 char *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 }
126 EXPORT_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 */
141 size_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 }
152 EXPORT_SYMBOL(strlcpy);
153 #endif
154
155 #ifndef __HAVE_ARCH_STRSCPY
156 /**
157 * strscpy - Copy a C-string into a sized buffer
158 * @dest: Where to copy the string to
159 * @src: Where to copy the string from
160 * @count: Size of destination buffer
161 *
162 * Copy the string, or as much of it as fits, into the dest buffer. The
163 * behavior is undefined if the string buffers overlap. The destination
164 * buffer is always NUL terminated, unless it's zero-sized.
165 *
166 * Preferred to strlcpy() since the API doesn't require reading memory
167 * from the src string beyond the specified "count" bytes, and since
168 * the return value is easier to error-check than strlcpy()'s.
169 * In addition, the implementation is robust to the string changing out
170 * from underneath it, unlike the current strlcpy() implementation.
171 *
172 * Preferred to strncpy() since it always returns a valid string, and
173 * doesn't unnecessarily force the tail of the destination buffer to be
174 * zeroed. If zeroing is desired please use strscpy_pad().
175 *
176 * Returns:
177 * * The number of characters copied (not including the trailing %NUL)
178 * * -E2BIG if count is 0 or @src was truncated.
179 */
180 ssize_t strscpy(char *dest, const char *src, size_t count)
181 {
182 const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
183 size_t max = count;
184 long res = 0;
185
186 if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
187 return -E2BIG;
188
189 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
190 /*
191 * If src is unaligned, don't cross a page boundary,
192 * since we don't know if the next page is mapped.
193 */
194 if ((long)src & (sizeof(long) - 1)) {
195 size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
196 if (limit < max)
197 max = limit;
198 }
199 #else
200 /* If src or dest is unaligned, don't do word-at-a-time. */
201 if (((long) dest | (long) src) & (sizeof(long) - 1))
202 max = 0;
203 #endif
204
205 while (max >= sizeof(unsigned long)) {
206 unsigned long c, data;
207
208 c = read_word_at_a_time(src+res);
209 if (has_zero(c, &data, &constants)) {
210 data = prep_zero_mask(c, data, &constants);
211 data = create_zero_mask(data);
212 *(unsigned long *)(dest+res) = c & zero_bytemask(data);
213 return res + find_zero(data);
214 }
215 *(unsigned long *)(dest+res) = c;
216 res += sizeof(unsigned long);
217 count -= sizeof(unsigned long);
218 max -= sizeof(unsigned long);
219 }
220
221 while (count) {
222 char c;
223
224 c = src[res];
225 dest[res] = c;
226 if (!c)
227 return res;
228 res++;
229 count--;
230 }
231
232 /* Hit buffer length without finding a NUL; force NUL-termination. */
233 if (res)
234 dest[res-1] = '\0';
235
236 return -E2BIG;
237 }
238 EXPORT_SYMBOL(strscpy);
239 #endif
240
241 /**
242 * strscpy_pad() - Copy a C-string into a sized buffer
243 * @dest: Where to copy the string to
244 * @src: Where to copy the string from
245 * @count: Size of destination buffer
246 *
247 * Copy the string, or as much of it as fits, into the dest buffer. The
248 * behavior is undefined if the string buffers overlap. The destination
249 * buffer is always %NUL terminated, unless it's zero-sized.
250 *
251 * If the source string is shorter than the destination buffer, zeros
252 * the tail of the destination buffer.
253 *
254 * For full explanation of why you may want to consider using the
255 * 'strscpy' functions please see the function docstring for strscpy().
256 *
257 * Returns:
258 * * The number of characters copied (not including the trailing %NUL)
259 * * -E2BIG if count is 0 or @src was truncated.
260 */
261 ssize_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 }
273 EXPORT_SYMBOL(strscpy_pad);
274
275 #ifndef __HAVE_ARCH_STRCAT
276 /**
277 * strcat - Append one %NUL-terminated string to another
278 * @dest: The string to be appended to
279 * @src: The string to append to it
280 */
281 #undef strcat
282 char *strcat(char *dest, const char *src)
283 {
284 char *tmp = dest;
285
286 while (*dest)
287 dest++;
288 while ((*dest++ = *src++) != '\0')
289 ;
290 return tmp;
291 }
292 EXPORT_SYMBOL(strcat);
293 #endif
294
295 #ifndef __HAVE_ARCH_STRNCAT
296 /**
297 * strncat - Append a length-limited, C-string to another
298 * @dest: The string to be appended to
299 * @src: The string to append to it
300 * @count: The maximum numbers of bytes to copy
301 *
302 * Note that in contrast to strncpy(), strncat() ensures the result is
303 * terminated.
304 */
305 char *strncat(char *dest, const char *src, size_t count)
306 {
307 char *tmp = dest;
308
309 if (count) {
310 while (*dest)
311 dest++;
312 while ((*dest++ = *src++) != 0) {
313 if (--count == 0) {
314 *dest = '\0';
315 break;
316 }
317 }
318 }
319 return tmp;
320 }
321 EXPORT_SYMBOL(strncat);
322 #endif
323
324 #ifndef __HAVE_ARCH_STRLCAT
325 /**
326 * strlcat - Append a length-limited, C-string to another
327 * @dest: The string to be appended to
328 * @src: The string to append to it
329 * @count: The size of the destination buffer.
330 */
331 size_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 }
348 EXPORT_SYMBOL(strlcat);
349 #endif
350
351 #ifndef __HAVE_ARCH_STRCMP
352 /**
353 * strcmp - Compare two strings
354 * @cs: One string
355 * @ct: Another string
356 */
357 #undef strcmp
358 int strcmp(const char *cs, const char *ct)
359 {
360 unsigned char c1, c2;
361
362 while (1) {
363 c1 = *cs++;
364 c2 = *ct++;
365 if (c1 != c2)
366 return c1 < c2 ? -1 : 1;
367 if (!c1)
368 break;
369 }
370 return 0;
371 }
372 EXPORT_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 */
382 int strncmp(const char *cs, const char *ct, size_t count)
383 {
384 unsigned char c1, c2;
385
386 while (count) {
387 c1 = *cs++;
388 c2 = *ct++;
389 if (c1 != c2)
390 return c1 < c2 ? -1 : 1;
391 if (!c1)
392 break;
393 count--;
394 }
395 return 0;
396 }
397 EXPORT_SYMBOL(strncmp);
398 #endif
399
400 #ifndef __HAVE_ARCH_STRCHR
401 /**
402 * strchr - Find the first occurrence of a character in a string
403 * @s: The string to be searched
404 * @c: The character to search for
405 *
406 * Note that the %NUL-terminator is considered part of the string, and can
407 * be searched for.
408 */
409 char *strchr(const char *s, int c)
410 {
411 for (; *s != (char)c; ++s)
412 if (*s == '\0')
413 return NULL;
414 return (char *)s;
415 }
416 EXPORT_SYMBOL(strchr);
417 #endif
418
419 #ifndef __HAVE_ARCH_STRCHRNUL
420 /**
421 * strchrnul - Find and return a character in a string, or end of string
422 * @s: The string to be searched
423 * @c: The character to search for
424 *
425 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
426 * return a pointer to the null byte at the end of s.
427 */
428 char *strchrnul(const char *s, int c)
429 {
430 while (*s && *s != (char)c)
431 s++;
432 return (char *)s;
433 }
434 EXPORT_SYMBOL(strchrnul);
435 #endif
436
437 #ifndef __HAVE_ARCH_STRRCHR
438 /**
439 * strrchr - Find the last occurrence of a character in a string
440 * @s: The string to be searched
441 * @c: The character to search for
442 */
443 char *strrchr(const char *s, int c)
444 {
445 const char *last = NULL;
446 do {
447 if (*s == (char)c)
448 last = s;
449 } while (*s++);
450 return (char *)last;
451 }
452 EXPORT_SYMBOL(strrchr);
453 #endif
454
455 #ifndef __HAVE_ARCH_STRNCHR
456 /**
457 * strnchr - Find a character in a length limited string
458 * @s: The string to be searched
459 * @count: The number of characters to be searched
460 * @c: The character to search for
461 *
462 * Note that the %NUL-terminator is considered part of the string, and can
463 * be searched for.
464 */
465 char *strnchr(const char *s, size_t count, int c)
466 {
467 while (count--) {
468 if (*s == (char)c)
469 return (char *)s;
470 if (*s++ == '\0')
471 break;
472 }
473 return NULL;
474 }
475 EXPORT_SYMBOL(strnchr);
476 #endif
477
478 /**
479 * skip_spaces - Removes leading whitespace from @str.
480 * @str: The string to be stripped.
481 *
482 * Returns a pointer to the first non-whitespace character in @str.
483 */
484 char *skip_spaces(const char *str)
485 {
486 while (isspace(*str))
487 ++str;
488 return (char *)str;
489 }
490 EXPORT_SYMBOL(skip_spaces);
491
492 /**
493 * strim - Removes leading and trailing whitespace from @s.
494 * @s: The string to be stripped.
495 *
496 * Note that the first trailing whitespace is replaced with a %NUL-terminator
497 * in the given string @s. Returns a pointer to the first non-whitespace
498 * character in @s.
499 */
500 char *strim(char *s)
501 {
502 size_t size;
503 char *end;
504
505 size = strlen(s);
506 if (!size)
507 return s;
508
509 end = s + size - 1;
510 while (end >= s && isspace(*end))
511 end--;
512 *(end + 1) = '\0';
513
514 return skip_spaces(s);
515 }
516 EXPORT_SYMBOL(strim);
517
518 #ifndef __HAVE_ARCH_STRLEN
519 /**
520 * strlen - Find the length of a string
521 * @s: The string to be sized
522 */
523 size_t strlen(const char *s)
524 {
525 const char *sc;
526
527 for (sc = s; *sc != '\0'; ++sc)
528 /* nothing */;
529 return sc - s;
530 }
531 EXPORT_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 */
540 size_t strnlen(const char *s, size_t count)
541 {
542 const char *sc;
543
544 for (sc = s; count-- && *sc != '\0'; ++sc)
545 /* nothing */;
546 return sc - s;
547 }
548 EXPORT_SYMBOL(strnlen);
549 #endif
550
551 #ifndef __HAVE_ARCH_STRSPN
552 /**
553 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
554 * @s: The string to be searched
555 * @accept: The string to search for
556 */
557 size_t strspn(const char *s, const char *accept)
558 {
559 const char *p;
560 const char *a;
561 size_t count = 0;
562
563 for (p = s; *p != '\0'; ++p) {
564 for (a = accept; *a != '\0'; ++a) {
565 if (*p == *a)
566 break;
567 }
568 if (*a == '\0')
569 return count;
570 ++count;
571 }
572 return count;
573 }
574
575 EXPORT_SYMBOL(strspn);
576 #endif
577
578 #ifndef __HAVE_ARCH_STRCSPN
579 /**
580 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
581 * @s: The string to be searched
582 * @reject: The string to avoid
583 */
584 size_t strcspn(const char *s, const char *reject)
585 {
586 const char *p;
587 const char *r;
588 size_t count = 0;
589
590 for (p = s; *p != '\0'; ++p) {
591 for (r = reject; *r != '\0'; ++r) {
592 if (*p == *r)
593 return count;
594 }
595 ++count;
596 }
597 return count;
598 }
599 EXPORT_SYMBOL(strcspn);
600 #endif
601
602 #ifndef __HAVE_ARCH_STRPBRK
603 /**
604 * strpbrk - Find the first occurrence of a set of characters
605 * @cs: The string to be searched
606 * @ct: The characters to search for
607 */
608 char *strpbrk(const char *cs, const char *ct)
609 {
610 const char *sc1, *sc2;
611
612 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
613 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
614 if (*sc1 == *sc2)
615 return (char *)sc1;
616 }
617 }
618 return NULL;
619 }
620 EXPORT_SYMBOL(strpbrk);
621 #endif
622
623 #ifndef __HAVE_ARCH_STRSEP
624 /**
625 * strsep - Split a string into tokens
626 * @s: The string to be searched
627 * @ct: The characters to search for
628 *
629 * strsep() updates @s to point after the token, ready for the next call.
630 *
631 * It returns empty tokens, too, behaving exactly like the libc function
632 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
633 * Same semantics, slimmer shape. ;)
634 */
635 char *strsep(char **s, const char *ct)
636 {
637 char *sbegin = *s;
638 char *end;
639
640 if (sbegin == NULL)
641 return NULL;
642
643 end = strpbrk(sbegin, ct);
644 if (end)
645 *end++ = '\0';
646 *s = end;
647 return sbegin;
648 }
649 EXPORT_SYMBOL(strsep);
650 #endif
651
652 /**
653 * sysfs_streq - return true if strings are equal, modulo trailing newline
654 * @s1: one string
655 * @s2: another string
656 *
657 * This routine returns true iff two strings are equal, treating both
658 * NUL and newline-then-NUL as equivalent string terminations. It's
659 * geared for use with sysfs input strings, which generally terminate
660 * with newlines but are compared against values without newlines.
661 */
662 bool 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 }
677 EXPORT_SYMBOL(sysfs_streq);
678
679 /**
680 * match_string - matches given string in an array
681 * @array: array of strings
682 * @n: number of strings in the array or -1 for NULL terminated arrays
683 * @string: string to match with
684 *
685 * Return:
686 * index of a @string in the @array if matches, or %-EINVAL otherwise.
687 */
688 int 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 }
703 EXPORT_SYMBOL(match_string);
704
705 /**
706 * __sysfs_match_string - matches given string in an array
707 * @array: array of strings
708 * @n: number of strings in the array or -1 for NULL terminated arrays
709 * @str: string to match with
710 *
711 * Returns index of @str in the @array or -EINVAL, just like match_string().
712 * Uses sysfs_streq instead of strcmp for matching.
713 */
714 int __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 }
729 EXPORT_SYMBOL(__sysfs_match_string);
730
731 #ifndef __HAVE_ARCH_MEMSET
732 /**
733 * memset - Fill a region of memory with the given value
734 * @s: Pointer to the start of the area.
735 * @c: The byte to fill the area with
736 * @count: The size of the area.
737 *
738 * Do not use memset() to access IO space, use memset_io() instead.
739 */
740 void *memset(void *s, int c, size_t count)
741 {
742 char *xs = s;
743
744 while (count--)
745 *xs++ = c;
746 return s;
747 }
748 EXPORT_SYMBOL(memset);
749 #endif
750
751 #ifndef __HAVE_ARCH_MEMSET16
752 /**
753 * memset16() - Fill a memory area with a uint16_t
754 * @s: Pointer to the start of the area.
755 * @v: The value to fill the area with
756 * @count: The number of values to store
757 *
758 * Differs from memset() in that it fills with a uint16_t instead
759 * of a byte. Remember that @count is the number of uint16_ts to
760 * store, not the number of bytes.
761 */
762 void *memset16(uint16_t *s, uint16_t v, size_t count)
763 {
764 uint16_t *xs = s;
765
766 while (count--)
767 *xs++ = v;
768 return s;
769 }
770 EXPORT_SYMBOL(memset16);
771 #endif
772
773 #ifndef __HAVE_ARCH_MEMSET32
774 /**
775 * memset32() - Fill a memory area with a uint32_t
776 * @s: Pointer to the start of the area.
777 * @v: The value to fill the area with
778 * @count: The number of values to store
779 *
780 * Differs from memset() in that it fills with a uint32_t instead
781 * of a byte. Remember that @count is the number of uint32_ts to
782 * store, not the number of bytes.
783 */
784 void *memset32(uint32_t *s, uint32_t v, size_t count)
785 {
786 uint32_t *xs = s;
787
788 while (count--)
789 *xs++ = v;
790 return s;
791 }
792 EXPORT_SYMBOL(memset32);
793 #endif
794
795 #ifndef __HAVE_ARCH_MEMSET64
796 /**
797 * memset64() - Fill a memory area with a uint64_t
798 * @s: Pointer to the start of the area.
799 * @v: The value to fill the area with
800 * @count: The number of values to store
801 *
802 * Differs from memset() in that it fills with a uint64_t instead
803 * of a byte. Remember that @count is the number of uint64_ts to
804 * store, not the number of bytes.
805 */
806 void *memset64(uint64_t *s, uint64_t v, size_t count)
807 {
808 uint64_t *xs = s;
809
810 while (count--)
811 *xs++ = v;
812 return s;
813 }
814 EXPORT_SYMBOL(memset64);
815 #endif
816
817 #ifndef __HAVE_ARCH_MEMCPY
818 /**
819 * memcpy - Copy one area of memory to another
820 * @dest: Where to copy to
821 * @src: Where to copy from
822 * @count: The size of the area.
823 *
824 * You should not use this function to access IO space, use memcpy_toio()
825 * or memcpy_fromio() instead.
826 */
827 void *memcpy(void *dest, const void *src, size_t count)
828 {
829 char *tmp = dest;
830 const char *s = src;
831
832 while (count--)
833 *tmp++ = *s++;
834 return dest;
835 }
836 EXPORT_SYMBOL(memcpy);
837 #endif
838
839 #ifndef __HAVE_ARCH_MEMMOVE
840 /**
841 * memmove - Copy one area of memory to another
842 * @dest: Where to copy to
843 * @src: Where to copy from
844 * @count: The size of the area.
845 *
846 * Unlike memcpy(), memmove() copes with overlapping areas.
847 */
848 void *memmove(void *dest, const void *src, size_t count)
849 {
850 char *tmp;
851 const char *s;
852
853 if (dest <= src) {
854 tmp = dest;
855 s = src;
856 while (count--)
857 *tmp++ = *s++;
858 } else {
859 tmp = dest;
860 tmp += count;
861 s = src;
862 s += count;
863 while (count--)
864 *--tmp = *--s;
865 }
866 return dest;
867 }
868 EXPORT_SYMBOL(memmove);
869 #endif
870
871 #ifndef __HAVE_ARCH_MEMCMP
872 /**
873 * memcmp - Compare two areas of memory
874 * @cs: One area of memory
875 * @ct: Another area of memory
876 * @count: The size of the area.
877 */
878 #undef memcmp
879 __visible int memcmp(const void *cs, const void *ct, size_t count)
880 {
881 const unsigned char *su1, *su2;
882 int res = 0;
883
884 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
885 if ((res = *su1 - *su2) != 0)
886 break;
887 return res;
888 }
889 EXPORT_SYMBOL(memcmp);
890 #endif
891
892 #ifndef __HAVE_ARCH_BCMP
893 /**
894 * bcmp - returns 0 if and only if the buffers have identical contents.
895 * @a: pointer to first buffer.
896 * @b: pointer to second buffer.
897 * @len: size of buffers.
898 *
899 * The sign or magnitude of a non-zero return value has no particular
900 * meaning, and architectures may implement their own more efficient bcmp(). So
901 * while this particular implementation is a simple (tail) call to memcmp, do
902 * not rely on anything but whether the return value is zero or non-zero.
903 */
904 #undef bcmp
905 int bcmp(const void *a, const void *b, size_t len)
906 {
907 return memcmp(a, b, len);
908 }
909 EXPORT_SYMBOL(bcmp);
910 #endif
911
912 #ifndef __HAVE_ARCH_MEMSCAN
913 /**
914 * memscan - Find a character in an area of memory.
915 * @addr: The memory area
916 * @c: The byte to search for
917 * @size: The size of the area.
918 *
919 * returns the address of the first occurrence of @c, or 1 byte past
920 * the area if @c is not found
921 */
922 void *memscan(void *addr, int c, size_t size)
923 {
924 unsigned char *p = addr;
925
926 while (size) {
927 if (*p == c)
928 return (void *)p;
929 p++;
930 size--;
931 }
932 return (void *)p;
933 }
934 EXPORT_SYMBOL(memscan);
935 #endif
936
937 #ifndef __HAVE_ARCH_STRSTR
938 /**
939 * strstr - Find the first substring in a %NUL terminated string
940 * @s1: The string to be searched
941 * @s2: The string to search for
942 */
943 char *strstr(const char *s1, const char *s2)
944 {
945 size_t l1, l2;
946
947 l2 = strlen(s2);
948 if (!l2)
949 return (char *)s1;
950 l1 = strlen(s1);
951 while (l1 >= l2) {
952 l1--;
953 if (!memcmp(s1, s2, l2))
954 return (char *)s1;
955 s1++;
956 }
957 return NULL;
958 }
959 EXPORT_SYMBOL(strstr);
960 #endif
961
962 #ifndef __HAVE_ARCH_STRNSTR
963 /**
964 * strnstr - Find the first substring in a length-limited string
965 * @s1: The string to be searched
966 * @s2: The string to search for
967 * @len: the maximum number of characters to search
968 */
969 char *strnstr(const char *s1, const char *s2, size_t len)
970 {
971 size_t l2;
972
973 l2 = strlen(s2);
974 if (!l2)
975 return (char *)s1;
976 while (len >= l2) {
977 len--;
978 if (!memcmp(s1, s2, l2))
979 return (char *)s1;
980 s1++;
981 }
982 return NULL;
983 }
984 EXPORT_SYMBOL(strnstr);
985 #endif
986
987 #ifndef __HAVE_ARCH_MEMCHR
988 /**
989 * memchr - Find a character in an area of memory.
990 * @s: The memory area
991 * @c: The byte to search for
992 * @n: The size of the area.
993 *
994 * returns the address of the first occurrence of @c, or %NULL
995 * if @c is not found
996 */
997 void *memchr(const void *s, int c, size_t n)
998 {
999 const unsigned char *p = s;
1000 while (n-- != 0) {
1001 if ((unsigned char)c == *p++) {
1002 return (void *)(p - 1);
1003 }
1004 }
1005 return NULL;
1006 }
1007 EXPORT_SYMBOL(memchr);
1008 #endif
1009
1010 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
1011 {
1012 while (bytes) {
1013 if (*start != value)
1014 return (void *)start;
1015 start++;
1016 bytes--;
1017 }
1018 return NULL;
1019 }
1020
1021 /**
1022 * memchr_inv - Find an unmatching character in an area of memory.
1023 * @start: The memory area
1024 * @c: Find a character other than c
1025 * @bytes: The size of the area.
1026 *
1027 * returns the address of the first character other than @c, or %NULL
1028 * if the whole buffer contains just @c.
1029 */
1030 void *memchr_inv(const void *start, int c, size_t bytes)
1031 {
1032 u8 value = c;
1033 u64 value64;
1034 unsigned int words, prefix;
1035
1036 if (bytes <= 16)
1037 return check_bytes8(start, value, bytes);
1038
1039 value64 = value;
1040 #if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
1041 value64 *= 0x0101010101010101ULL;
1042 #elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
1043 value64 *= 0x01010101;
1044 value64 |= value64 << 32;
1045 #else
1046 value64 |= value64 << 8;
1047 value64 |= value64 << 16;
1048 value64 |= value64 << 32;
1049 #endif
1050
1051 prefix = (unsigned long)start % 8;
1052 if (prefix) {
1053 u8 *r;
1054
1055 prefix = 8 - prefix;
1056 r = check_bytes8(start, value, prefix);
1057 if (r)
1058 return r;
1059 start += prefix;
1060 bytes -= prefix;
1061 }
1062
1063 words = bytes / 8;
1064
1065 while (words) {
1066 if (*(u64 *)start != value64)
1067 return check_bytes8(start, value, 8);
1068 start += 8;
1069 words--;
1070 }
1071
1072 return check_bytes8(start, value, bytes % 8);
1073 }
1074 EXPORT_SYMBOL(memchr_inv);
1075
1076 /**
1077 * strreplace - Replace all occurrences of character in string.
1078 * @s: The string to operate on.
1079 * @old: The character being replaced.
1080 * @new: The character @old is replaced with.
1081 *
1082 * Returns pointer to the nul byte at the end of @s.
1083 */
1084 char *strreplace(char *s, char old, char new)
1085 {
1086 for (; *s; ++s)
1087 if (*s == old)
1088 *s = new;
1089 return s;
1090 }
1091 EXPORT_SYMBOL(strreplace);
1092
1093 void fortify_panic(const char *name)
1094 {
1095 pr_emerg("detected buffer overflow in %s\n", name);
1096 BUG();
1097 }
1098 EXPORT_SYMBOL(fortify_panic);