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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 * 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 */
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. The
162 * behavior is undefined if the string buffers overlap. The destination
163 * buffer is always NUL terminated, unless it's zero-sized.
164 *
165 * Preferred to strlcpy() since the API doesn't require reading memory
166 * from the src string beyond the specified "count" bytes, and since
167 * the return value is easier to error-check than strlcpy()'s.
168 * In addition, the implementation is robust to the string changing out
169 * from underneath it, unlike the current strlcpy() implementation.
170 *
171 * Preferred to strncpy() since it always returns a valid string, and
172 * doesn't unnecessarily force the tail of the destination buffer to be
173 * zeroed. If zeroing is desired please use strscpy_pad().
174 *
175 * Returns:
176 * * The number of characters copied (not including the trailing %NUL)
177 * * -E2BIG if count is 0 or @src was truncated.
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 || WARN_ON_ONCE(count > INT_MAX))
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/**
241 * strscpy_pad() - Copy a C-string into a sized buffer
242 * @dest: Where to copy the string to
243 * @src: Where to copy the string from
244 * @count: Size of destination buffer
245 *
246 * Copy the string, or as much of it as fits, into the dest buffer. The
247 * behavior is undefined if the string buffers overlap. The destination
248 * buffer is always %NUL terminated, unless it's zero-sized.
249 *
250 * If the source string is shorter than the destination buffer, zeros
251 * the tail of the destination buffer.
252 *
253 * For full explanation of why you may want to consider using the
254 * 'strscpy' functions please see the function docstring for strscpy().
255 *
256 * Returns:
257 * * The number of characters copied (not including the trailing %NUL)
258 * * -E2BIG if count is 0 or @src was truncated.
259 */
260ssize_t strscpy_pad(char *dest, const char *src, size_t count)
261{
262 ssize_t written;
263
264 written = strscpy(dest, src, count);
265 if (written < 0 || written == count - 1)
266 return written;
267
268 memset(dest + written + 1, 0, count - written - 1);
269
270 return written;
271}
272EXPORT_SYMBOL(strscpy_pad);
273
274/**
275 * stpcpy - copy a string from src to dest returning a pointer to the new end
276 * of dest, including src's %NUL-terminator. May overrun dest.
277 * @dest: pointer to end of string being copied into. Must be large enough
278 * to receive copy.
279 * @src: pointer to the beginning of string being copied from. Must not overlap
280 * dest.
281 *
282 * stpcpy differs from strcpy in a key way: the return value is a pointer
283 * to the new %NUL-terminating character in @dest. (For strcpy, the return
284 * value is a pointer to the start of @dest). This interface is considered
285 * unsafe as it doesn't perform bounds checking of the inputs. As such it's
286 * not recommended for usage. Instead, its definition is provided in case
287 * the compiler lowers other libcalls to stpcpy.
288 */
289char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
290char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
291{
292 while ((*dest++ = *src++) != '\0')
293 /* nothing */;
294 return --dest;
295}
296EXPORT_SYMBOL(stpcpy);
297
298#ifndef __HAVE_ARCH_STRCAT
299/**
300 * strcat - Append one %NUL-terminated string to another
301 * @dest: The string to be appended to
302 * @src: The string to append to it
303 */
304char *strcat(char *dest, const char *src)
305{
306 char *tmp = dest;
307
308 while (*dest)
309 dest++;
310 while ((*dest++ = *src++) != '\0')
311 ;
312 return tmp;
313}
314EXPORT_SYMBOL(strcat);
315#endif
316
317#ifndef __HAVE_ARCH_STRNCAT
318/**
319 * strncat - Append a length-limited, C-string to another
320 * @dest: The string to be appended to
321 * @src: The string to append to it
322 * @count: The maximum numbers of bytes to copy
323 *
324 * Note that in contrast to strncpy(), strncat() ensures the result is
325 * terminated.
326 */
327char *strncat(char *dest, const char *src, size_t count)
328{
329 char *tmp = dest;
330
331 if (count) {
332 while (*dest)
333 dest++;
334 while ((*dest++ = *src++) != 0) {
335 if (--count == 0) {
336 *dest = '\0';
337 break;
338 }
339 }
340 }
341 return tmp;
342}
343EXPORT_SYMBOL(strncat);
344#endif
345
346#ifndef __HAVE_ARCH_STRLCAT
347/**
348 * strlcat - Append a length-limited, C-string to another
349 * @dest: The string to be appended to
350 * @src: The string to append to it
351 * @count: The size of the destination buffer.
352 */
353size_t strlcat(char *dest, const char *src, size_t count)
354{
355 size_t dsize = strlen(dest);
356 size_t len = strlen(src);
357 size_t res = dsize + len;
358
359 /* This would be a bug */
360 BUG_ON(dsize >= count);
361
362 dest += dsize;
363 count -= dsize;
364 if (len >= count)
365 len = count-1;
366 memcpy(dest, src, len);
367 dest[len] = 0;
368 return res;
369}
370EXPORT_SYMBOL(strlcat);
371#endif
372
373#ifndef __HAVE_ARCH_STRCMP
374/**
375 * strcmp - Compare two strings
376 * @cs: One string
377 * @ct: Another string
378 */
379int strcmp(const char *cs, const char *ct)
380{
381 unsigned char c1, c2;
382
383 while (1) {
384 c1 = *cs++;
385 c2 = *ct++;
386 if (c1 != c2)
387 return c1 < c2 ? -1 : 1;
388 if (!c1)
389 break;
390 }
391 return 0;
392}
393EXPORT_SYMBOL(strcmp);
394#endif
395
396#ifndef __HAVE_ARCH_STRNCMP
397/**
398 * strncmp - Compare two length-limited strings
399 * @cs: One string
400 * @ct: Another string
401 * @count: The maximum number of bytes to compare
402 */
403int strncmp(const char *cs, const char *ct, size_t count)
404{
405 unsigned char c1, c2;
406
407 while (count) {
408 c1 = *cs++;
409 c2 = *ct++;
410 if (c1 != c2)
411 return c1 < c2 ? -1 : 1;
412 if (!c1)
413 break;
414 count--;
415 }
416 return 0;
417}
418EXPORT_SYMBOL(strncmp);
419#endif
420
421#ifndef __HAVE_ARCH_STRCHR
422/**
423 * strchr - Find the first occurrence of a character in a string
424 * @s: The string to be searched
425 * @c: The character to search for
426 *
427 * Note that the %NUL-terminator is considered part of the string, and can
428 * be searched for.
429 */
430char *strchr(const char *s, int c)
431{
432 for (; *s != (char)c; ++s)
433 if (*s == '\0')
434 return NULL;
435 return (char *)s;
436}
437EXPORT_SYMBOL(strchr);
438#endif
439
440#ifndef __HAVE_ARCH_STRCHRNUL
441/**
442 * strchrnul - Find and return a character in a string, or end of string
443 * @s: The string to be searched
444 * @c: The character to search for
445 *
446 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
447 * return a pointer to the null byte at the end of s.
448 */
449char *strchrnul(const char *s, int c)
450{
451 while (*s && *s != (char)c)
452 s++;
453 return (char *)s;
454}
455EXPORT_SYMBOL(strchrnul);
456#endif
457
458/**
459 * strnchrnul - Find and return a character in a length limited string,
460 * or end of string
461 * @s: The string to be searched
462 * @count: The number of characters to be searched
463 * @c: The character to search for
464 *
465 * Returns pointer to the first occurrence of 'c' in s. If c is not found,
466 * then return a pointer to the last character of the string.
467 */
468char *strnchrnul(const char *s, size_t count, int c)
469{
470 while (count-- && *s && *s != (char)c)
471 s++;
472 return (char *)s;
473}
474
475#ifndef __HAVE_ARCH_STRRCHR
476/**
477 * strrchr - Find the last occurrence of a character in a string
478 * @s: The string to be searched
479 * @c: The character to search for
480 */
481char *strrchr(const char *s, int c)
482{
483 const char *last = NULL;
484 do {
485 if (*s == (char)c)
486 last = s;
487 } while (*s++);
488 return (char *)last;
489}
490EXPORT_SYMBOL(strrchr);
491#endif
492
493#ifndef __HAVE_ARCH_STRNCHR
494/**
495 * strnchr - Find a character in a length limited string
496 * @s: The string to be searched
497 * @count: The number of characters to be searched
498 * @c: The character to search for
499 *
500 * Note that the %NUL-terminator is considered part of the string, and can
501 * be searched for.
502 */
503char *strnchr(const char *s, size_t count, int c)
504{
505 while (count--) {
506 if (*s == (char)c)
507 return (char *)s;
508 if (*s++ == '\0')
509 break;
510 }
511 return NULL;
512}
513EXPORT_SYMBOL(strnchr);
514#endif
515
516/**
517 * skip_spaces - Removes leading whitespace from @str.
518 * @str: The string to be stripped.
519 *
520 * Returns a pointer to the first non-whitespace character in @str.
521 */
522char *skip_spaces(const char *str)
523{
524 while (isspace(*str))
525 ++str;
526 return (char *)str;
527}
528EXPORT_SYMBOL(skip_spaces);
529
530/**
531 * strim - Removes leading and trailing whitespace from @s.
532 * @s: The string to be stripped.
533 *
534 * Note that the first trailing whitespace is replaced with a %NUL-terminator
535 * in the given string @s. Returns a pointer to the first non-whitespace
536 * character in @s.
537 */
538char *strim(char *s)
539{
540 size_t size;
541 char *end;
542
543 size = strlen(s);
544 if (!size)
545 return s;
546
547 end = s + size - 1;
548 while (end >= s && isspace(*end))
549 end--;
550 *(end + 1) = '\0';
551
552 return skip_spaces(s);
553}
554EXPORT_SYMBOL(strim);
555
556#ifndef __HAVE_ARCH_STRLEN
557/**
558 * strlen - Find the length of a string
559 * @s: The string to be sized
560 */
561size_t strlen(const char *s)
562{
563 const char *sc;
564
565 for (sc = s; *sc != '\0'; ++sc)
566 /* nothing */;
567 return sc - s;
568}
569EXPORT_SYMBOL(strlen);
570#endif
571
572#ifndef __HAVE_ARCH_STRNLEN
573/**
574 * strnlen - Find the length of a length-limited string
575 * @s: The string to be sized
576 * @count: The maximum number of bytes to search
577 */
578size_t strnlen(const char *s, size_t count)
579{
580 const char *sc;
581
582 for (sc = s; count-- && *sc != '\0'; ++sc)
583 /* nothing */;
584 return sc - s;
585}
586EXPORT_SYMBOL(strnlen);
587#endif
588
589#ifndef __HAVE_ARCH_STRSPN
590/**
591 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
592 * @s: The string to be searched
593 * @accept: The string to search for
594 */
595size_t strspn(const char *s, const char *accept)
596{
597 const char *p;
598 const char *a;
599 size_t count = 0;
600
601 for (p = s; *p != '\0'; ++p) {
602 for (a = accept; *a != '\0'; ++a) {
603 if (*p == *a)
604 break;
605 }
606 if (*a == '\0')
607 return count;
608 ++count;
609 }
610 return count;
611}
612
613EXPORT_SYMBOL(strspn);
614#endif
615
616#ifndef __HAVE_ARCH_STRCSPN
617/**
618 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
619 * @s: The string to be searched
620 * @reject: The string to avoid
621 */
622size_t strcspn(const char *s, const char *reject)
623{
624 const char *p;
625 const char *r;
626 size_t count = 0;
627
628 for (p = s; *p != '\0'; ++p) {
629 for (r = reject; *r != '\0'; ++r) {
630 if (*p == *r)
631 return count;
632 }
633 ++count;
634 }
635 return count;
636}
637EXPORT_SYMBOL(strcspn);
638#endif
639
640#ifndef __HAVE_ARCH_STRPBRK
641/**
642 * strpbrk - Find the first occurrence of a set of characters
643 * @cs: The string to be searched
644 * @ct: The characters to search for
645 */
646char *strpbrk(const char *cs, const char *ct)
647{
648 const char *sc1, *sc2;
649
650 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
651 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
652 if (*sc1 == *sc2)
653 return (char *)sc1;
654 }
655 }
656 return NULL;
657}
658EXPORT_SYMBOL(strpbrk);
659#endif
660
661#ifndef __HAVE_ARCH_STRSEP
662/**
663 * strsep - Split a string into tokens
664 * @s: The string to be searched
665 * @ct: The characters to search for
666 *
667 * strsep() updates @s to point after the token, ready for the next call.
668 *
669 * It returns empty tokens, too, behaving exactly like the libc function
670 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
671 * Same semantics, slimmer shape. ;)
672 */
673char *strsep(char **s, const char *ct)
674{
675 char *sbegin = *s;
676 char *end;
677
678 if (sbegin == NULL)
679 return NULL;
680
681 end = strpbrk(sbegin, ct);
682 if (end)
683 *end++ = '\0';
684 *s = end;
685 return sbegin;
686}
687EXPORT_SYMBOL(strsep);
688#endif
689
690/**
691 * sysfs_streq - return true if strings are equal, modulo trailing newline
692 * @s1: one string
693 * @s2: another string
694 *
695 * This routine returns true iff two strings are equal, treating both
696 * NUL and newline-then-NUL as equivalent string terminations. It's
697 * geared for use with sysfs input strings, which generally terminate
698 * with newlines but are compared against values without newlines.
699 */
700bool sysfs_streq(const char *s1, const char *s2)
701{
702 while (*s1 && *s1 == *s2) {
703 s1++;
704 s2++;
705 }
706
707 if (*s1 == *s2)
708 return true;
709 if (!*s1 && *s2 == '\n' && !s2[1])
710 return true;
711 if (*s1 == '\n' && !s1[1] && !*s2)
712 return true;
713 return false;
714}
715EXPORT_SYMBOL(sysfs_streq);
716
717/**
718 * match_string - matches given string in an array
719 * @array: array of strings
720 * @n: number of strings in the array or -1 for NULL terminated arrays
721 * @string: string to match with
722 *
723 * This routine will look for a string in an array of strings up to the
724 * n-th element in the array or until the first NULL element.
725 *
726 * Historically the value of -1 for @n, was used to search in arrays that
727 * are NULL terminated. However, the function does not make a distinction
728 * when finishing the search: either @n elements have been compared OR
729 * the first NULL element was found.
730 *
731 * Return:
732 * index of a @string in the @array if matches, or %-EINVAL otherwise.
733 */
734int match_string(const char * const *array, size_t n, const char *string)
735{
736 int index;
737 const char *item;
738
739 for (index = 0; index < n; index++) {
740 item = array[index];
741 if (!item)
742 break;
743 if (!strcmp(item, string))
744 return index;
745 }
746
747 return -EINVAL;
748}
749EXPORT_SYMBOL(match_string);
750
751/**
752 * __sysfs_match_string - matches given string in an array
753 * @array: array of strings
754 * @n: number of strings in the array or -1 for NULL terminated arrays
755 * @str: string to match with
756 *
757 * Returns index of @str in the @array or -EINVAL, just like match_string().
758 * Uses sysfs_streq instead of strcmp for matching.
759 *
760 * This routine will look for a string in an array of strings up to the
761 * n-th element in the array or until the first NULL element.
762 *
763 * Historically the value of -1 for @n, was used to search in arrays that
764 * are NULL terminated. However, the function does not make a distinction
765 * when finishing the search: either @n elements have been compared OR
766 * the first NULL element was found.
767 */
768int __sysfs_match_string(const char * const *array, size_t n, const char *str)
769{
770 const char *item;
771 int index;
772
773 for (index = 0; index < n; index++) {
774 item = array[index];
775 if (!item)
776 break;
777 if (sysfs_streq(item, str))
778 return index;
779 }
780
781 return -EINVAL;
782}
783EXPORT_SYMBOL(__sysfs_match_string);
784
785#ifndef __HAVE_ARCH_MEMSET
786/**
787 * memset - Fill a region of memory with the given value
788 * @s: Pointer to the start of the area.
789 * @c: The byte to fill the area with
790 * @count: The size of the area.
791 *
792 * Do not use memset() to access IO space, use memset_io() instead.
793 */
794void *memset(void *s, int c, size_t count)
795{
796 char *xs = s;
797
798 while (count--)
799 *xs++ = c;
800 return s;
801}
802EXPORT_SYMBOL(memset);
803#endif
804
805#ifndef __HAVE_ARCH_MEMSET16
806/**
807 * memset16() - Fill a memory area with a uint16_t
808 * @s: Pointer to the start of the area.
809 * @v: The value to fill the area with
810 * @count: The number of values to store
811 *
812 * Differs from memset() in that it fills with a uint16_t instead
813 * of a byte. Remember that @count is the number of uint16_ts to
814 * store, not the number of bytes.
815 */
816void *memset16(uint16_t *s, uint16_t v, size_t count)
817{
818 uint16_t *xs = s;
819
820 while (count--)
821 *xs++ = v;
822 return s;
823}
824EXPORT_SYMBOL(memset16);
825#endif
826
827#ifndef __HAVE_ARCH_MEMSET32
828/**
829 * memset32() - Fill a memory area with a uint32_t
830 * @s: Pointer to the start of the area.
831 * @v: The value to fill the area with
832 * @count: The number of values to store
833 *
834 * Differs from memset() in that it fills with a uint32_t instead
835 * of a byte. Remember that @count is the number of uint32_ts to
836 * store, not the number of bytes.
837 */
838void *memset32(uint32_t *s, uint32_t v, size_t count)
839{
840 uint32_t *xs = s;
841
842 while (count--)
843 *xs++ = v;
844 return s;
845}
846EXPORT_SYMBOL(memset32);
847#endif
848
849#ifndef __HAVE_ARCH_MEMSET64
850/**
851 * memset64() - Fill a memory area with a uint64_t
852 * @s: Pointer to the start of the area.
853 * @v: The value to fill the area with
854 * @count: The number of values to store
855 *
856 * Differs from memset() in that it fills with a uint64_t instead
857 * of a byte. Remember that @count is the number of uint64_ts to
858 * store, not the number of bytes.
859 */
860void *memset64(uint64_t *s, uint64_t v, size_t count)
861{
862 uint64_t *xs = s;
863
864 while (count--)
865 *xs++ = v;
866 return s;
867}
868EXPORT_SYMBOL(memset64);
869#endif
870
871#ifndef __HAVE_ARCH_MEMCPY
872/**
873 * memcpy - Copy one area of memory to another
874 * @dest: Where to copy to
875 * @src: Where to copy from
876 * @count: The size of the area.
877 *
878 * You should not use this function to access IO space, use memcpy_toio()
879 * or memcpy_fromio() instead.
880 */
881void *memcpy(void *dest, const void *src, size_t count)
882{
883 char *tmp = dest;
884 const char *s = src;
885
886 while (count--)
887 *tmp++ = *s++;
888 return dest;
889}
890EXPORT_SYMBOL(memcpy);
891#endif
892
893#ifndef __HAVE_ARCH_MEMMOVE
894/**
895 * memmove - Copy one area of memory to another
896 * @dest: Where to copy to
897 * @src: Where to copy from
898 * @count: The size of the area.
899 *
900 * Unlike memcpy(), memmove() copes with overlapping areas.
901 */
902void *memmove(void *dest, const void *src, size_t count)
903{
904 char *tmp;
905 const char *s;
906
907 if (dest <= src) {
908 tmp = dest;
909 s = src;
910 while (count--)
911 *tmp++ = *s++;
912 } else {
913 tmp = dest;
914 tmp += count;
915 s = src;
916 s += count;
917 while (count--)
918 *--tmp = *--s;
919 }
920 return dest;
921}
922EXPORT_SYMBOL(memmove);
923#endif
924
925#ifndef __HAVE_ARCH_MEMCMP
926/**
927 * memcmp - Compare two areas of memory
928 * @cs: One area of memory
929 * @ct: Another area of memory
930 * @count: The size of the area.
931 */
932#undef memcmp
933__visible int memcmp(const void *cs, const void *ct, size_t count)
934{
935 const unsigned char *su1, *su2;
936 int res = 0;
937
938 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
939 if ((res = *su1 - *su2) != 0)
940 break;
941 return res;
942}
943EXPORT_SYMBOL(memcmp);
944#endif
945
946#ifndef __HAVE_ARCH_BCMP
947/**
948 * bcmp - returns 0 if and only if the buffers have identical contents.
949 * @a: pointer to first buffer.
950 * @b: pointer to second buffer.
951 * @len: size of buffers.
952 *
953 * The sign or magnitude of a non-zero return value has no particular
954 * meaning, and architectures may implement their own more efficient bcmp(). So
955 * while this particular implementation is a simple (tail) call to memcmp, do
956 * not rely on anything but whether the return value is zero or non-zero.
957 */
958int bcmp(const void *a, const void *b, size_t len)
959{
960 return memcmp(a, b, len);
961}
962EXPORT_SYMBOL(bcmp);
963#endif
964
965#ifndef __HAVE_ARCH_MEMSCAN
966/**
967 * memscan - Find a character in an area of memory.
968 * @addr: The memory area
969 * @c: The byte to search for
970 * @size: The size of the area.
971 *
972 * returns the address of the first occurrence of @c, or 1 byte past
973 * the area if @c is not found
974 */
975void *memscan(void *addr, int c, size_t size)
976{
977 unsigned char *p = addr;
978
979 while (size) {
980 if (*p == (unsigned char)c)
981 return (void *)p;
982 p++;
983 size--;
984 }
985 return (void *)p;
986}
987EXPORT_SYMBOL(memscan);
988#endif
989
990#ifndef __HAVE_ARCH_STRSTR
991/**
992 * strstr - Find the first substring in a %NUL terminated string
993 * @s1: The string to be searched
994 * @s2: The string to search for
995 */
996char *strstr(const char *s1, const char *s2)
997{
998 size_t l1, l2;
999
1000 l2 = strlen(s2);
1001 if (!l2)
1002 return (char *)s1;
1003 l1 = strlen(s1);
1004 while (l1 >= l2) {
1005 l1--;
1006 if (!memcmp(s1, s2, l2))
1007 return (char *)s1;
1008 s1++;
1009 }
1010 return NULL;
1011}
1012EXPORT_SYMBOL(strstr);
1013#endif
1014
1015#ifndef __HAVE_ARCH_STRNSTR
1016/**
1017 * strnstr - Find the first substring in a length-limited string
1018 * @s1: The string to be searched
1019 * @s2: The string to search for
1020 * @len: the maximum number of characters to search
1021 */
1022char *strnstr(const char *s1, const char *s2, size_t len)
1023{
1024 size_t l2;
1025
1026 l2 = strlen(s2);
1027 if (!l2)
1028 return (char *)s1;
1029 while (len >= l2) {
1030 len--;
1031 if (!memcmp(s1, s2, l2))
1032 return (char *)s1;
1033 s1++;
1034 }
1035 return NULL;
1036}
1037EXPORT_SYMBOL(strnstr);
1038#endif
1039
1040#ifndef __HAVE_ARCH_MEMCHR
1041/**
1042 * memchr - Find a character in an area of memory.
1043 * @s: The memory area
1044 * @c: The byte to search for
1045 * @n: The size of the area.
1046 *
1047 * returns the address of the first occurrence of @c, or %NULL
1048 * if @c is not found
1049 */
1050void *memchr(const void *s, int c, size_t n)
1051{
1052 const unsigned char *p = s;
1053 while (n-- != 0) {
1054 if ((unsigned char)c == *p++) {
1055 return (void *)(p - 1);
1056 }
1057 }
1058 return NULL;
1059}
1060EXPORT_SYMBOL(memchr);
1061#endif
1062
1063static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
1064{
1065 while (bytes) {
1066 if (*start != value)
1067 return (void *)start;
1068 start++;
1069 bytes--;
1070 }
1071 return NULL;
1072}
1073
1074/**
1075 * memchr_inv - Find an unmatching character in an area of memory.
1076 * @start: The memory area
1077 * @c: Find a character other than c
1078 * @bytes: The size of the area.
1079 *
1080 * returns the address of the first character other than @c, or %NULL
1081 * if the whole buffer contains just @c.
1082 */
1083void *memchr_inv(const void *start, int c, size_t bytes)
1084{
1085 u8 value = c;
1086 u64 value64;
1087 unsigned int words, prefix;
1088
1089 if (bytes <= 16)
1090 return check_bytes8(start, value, bytes);
1091
1092 value64 = value;
1093#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
1094 value64 *= 0x0101010101010101ULL;
1095#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
1096 value64 *= 0x01010101;
1097 value64 |= value64 << 32;
1098#else
1099 value64 |= value64 << 8;
1100 value64 |= value64 << 16;
1101 value64 |= value64 << 32;
1102#endif
1103
1104 prefix = (unsigned long)start % 8;
1105 if (prefix) {
1106 u8 *r;
1107
1108 prefix = 8 - prefix;
1109 r = check_bytes8(start, value, prefix);
1110 if (r)
1111 return r;
1112 start += prefix;
1113 bytes -= prefix;
1114 }
1115
1116 words = bytes / 8;
1117
1118 while (words) {
1119 if (*(u64 *)start != value64)
1120 return check_bytes8(start, value, 8);
1121 start += 8;
1122 words--;
1123 }
1124
1125 return check_bytes8(start, value, bytes % 8);
1126}
1127EXPORT_SYMBOL(memchr_inv);
1128
1129/**
1130 * strreplace - Replace all occurrences of character in string.
1131 * @s: The string to operate on.
1132 * @old: The character being replaced.
1133 * @new: The character @old is replaced with.
1134 *
1135 * Returns pointer to the nul byte at the end of @s.
1136 */
1137char *strreplace(char *s, char old, char new)
1138{
1139 for (; *s; ++s)
1140 if (*s == old)
1141 *s = new;
1142 return s;
1143}
1144EXPORT_SYMBOL(strreplace);
1145
1146void fortify_panic(const char *name)
1147{
1148 pr_emerg("detected buffer overflow in %s\n", name);
1149 BUG();
1150}
1151EXPORT_SYMBOL(fortify_panic);
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_STRLCPY
107size_t strlcpy(char *dest, const char *src, size_t size)
108{
109 size_t ret = strlen(src);
110
111 if (size) {
112 size_t len = (ret >= size) ? size - 1 : ret;
113 memcpy(dest, src, len);
114 dest[len] = '\0';
115 }
116 return ret;
117}
118EXPORT_SYMBOL(strlcpy);
119#endif
120
121#ifndef __HAVE_ARCH_STRSCPY
122ssize_t strscpy(char *dest, const char *src, size_t count)
123{
124 const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
125 size_t max = count;
126 long res = 0;
127
128 if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
129 return -E2BIG;
130
131#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
132 /*
133 * If src is unaligned, don't cross a page boundary,
134 * since we don't know if the next page is mapped.
135 */
136 if ((long)src & (sizeof(long) - 1)) {
137 size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
138 if (limit < max)
139 max = limit;
140 }
141#else
142 /* If src or dest is unaligned, don't do word-at-a-time. */
143 if (((long) dest | (long) src) & (sizeof(long) - 1))
144 max = 0;
145#endif
146
147 /*
148 * read_word_at_a_time() below may read uninitialized bytes after the
149 * trailing zero and use them in comparisons. Disable this optimization
150 * under KMSAN to prevent false positive reports.
151 */
152 if (IS_ENABLED(CONFIG_KMSAN))
153 max = 0;
154
155 while (max >= sizeof(unsigned long)) {
156 unsigned long c, data;
157
158 c = read_word_at_a_time(src+res);
159 if (has_zero(c, &data, &constants)) {
160 data = prep_zero_mask(c, data, &constants);
161 data = create_zero_mask(data);
162 *(unsigned long *)(dest+res) = c & zero_bytemask(data);
163 return res + find_zero(data);
164 }
165 *(unsigned long *)(dest+res) = c;
166 res += sizeof(unsigned long);
167 count -= sizeof(unsigned long);
168 max -= sizeof(unsigned long);
169 }
170
171 while (count) {
172 char c;
173
174 c = src[res];
175 dest[res] = c;
176 if (!c)
177 return res;
178 res++;
179 count--;
180 }
181
182 /* Hit buffer length without finding a NUL; force NUL-termination. */
183 if (res)
184 dest[res-1] = '\0';
185
186 return -E2BIG;
187}
188EXPORT_SYMBOL(strscpy);
189#endif
190
191/**
192 * stpcpy - copy a string from src to dest returning a pointer to the new end
193 * of dest, including src's %NUL-terminator. May overrun dest.
194 * @dest: pointer to end of string being copied into. Must be large enough
195 * to receive copy.
196 * @src: pointer to the beginning of string being copied from. Must not overlap
197 * dest.
198 *
199 * stpcpy differs from strcpy in a key way: the return value is a pointer
200 * to the new %NUL-terminating character in @dest. (For strcpy, the return
201 * value is a pointer to the start of @dest). This interface is considered
202 * unsafe as it doesn't perform bounds checking of the inputs. As such it's
203 * not recommended for usage. Instead, its definition is provided in case
204 * the compiler lowers other libcalls to stpcpy.
205 */
206char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
207char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
208{
209 while ((*dest++ = *src++) != '\0')
210 /* nothing */;
211 return --dest;
212}
213EXPORT_SYMBOL(stpcpy);
214
215#ifndef __HAVE_ARCH_STRCAT
216char *strcat(char *dest, const char *src)
217{
218 char *tmp = dest;
219
220 while (*dest)
221 dest++;
222 while ((*dest++ = *src++) != '\0')
223 ;
224 return tmp;
225}
226EXPORT_SYMBOL(strcat);
227#endif
228
229#ifndef __HAVE_ARCH_STRNCAT
230char *strncat(char *dest, const char *src, size_t count)
231{
232 char *tmp = dest;
233
234 if (count) {
235 while (*dest)
236 dest++;
237 while ((*dest++ = *src++) != 0) {
238 if (--count == 0) {
239 *dest = '\0';
240 break;
241 }
242 }
243 }
244 return tmp;
245}
246EXPORT_SYMBOL(strncat);
247#endif
248
249#ifndef __HAVE_ARCH_STRLCAT
250size_t strlcat(char *dest, const char *src, size_t count)
251{
252 size_t dsize = strlen(dest);
253 size_t len = strlen(src);
254 size_t res = dsize + len;
255
256 /* This would be a bug */
257 BUG_ON(dsize >= count);
258
259 dest += dsize;
260 count -= dsize;
261 if (len >= count)
262 len = count-1;
263 memcpy(dest, src, len);
264 dest[len] = 0;
265 return res;
266}
267EXPORT_SYMBOL(strlcat);
268#endif
269
270#ifndef __HAVE_ARCH_STRCMP
271/**
272 * strcmp - Compare two strings
273 * @cs: One string
274 * @ct: Another string
275 */
276int strcmp(const char *cs, const char *ct)
277{
278 unsigned char c1, c2;
279
280 while (1) {
281 c1 = *cs++;
282 c2 = *ct++;
283 if (c1 != c2)
284 return c1 < c2 ? -1 : 1;
285 if (!c1)
286 break;
287 }
288 return 0;
289}
290EXPORT_SYMBOL(strcmp);
291#endif
292
293#ifndef __HAVE_ARCH_STRNCMP
294/**
295 * strncmp - Compare two length-limited strings
296 * @cs: One string
297 * @ct: Another string
298 * @count: The maximum number of bytes to compare
299 */
300int strncmp(const char *cs, const char *ct, size_t count)
301{
302 unsigned char c1, c2;
303
304 while (count) {
305 c1 = *cs++;
306 c2 = *ct++;
307 if (c1 != c2)
308 return c1 < c2 ? -1 : 1;
309 if (!c1)
310 break;
311 count--;
312 }
313 return 0;
314}
315EXPORT_SYMBOL(strncmp);
316#endif
317
318#ifndef __HAVE_ARCH_STRCHR
319/**
320 * strchr - Find the first occurrence of a character in a string
321 * @s: The string to be searched
322 * @c: The character to search for
323 *
324 * Note that the %NUL-terminator is considered part of the string, and can
325 * be searched for.
326 */
327char *strchr(const char *s, int c)
328{
329 for (; *s != (char)c; ++s)
330 if (*s == '\0')
331 return NULL;
332 return (char *)s;
333}
334EXPORT_SYMBOL(strchr);
335#endif
336
337#ifndef __HAVE_ARCH_STRCHRNUL
338/**
339 * strchrnul - Find and return a character in a string, or end of string
340 * @s: The string to be searched
341 * @c: The character to search for
342 *
343 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
344 * return a pointer to the null byte at the end of s.
345 */
346char *strchrnul(const char *s, int c)
347{
348 while (*s && *s != (char)c)
349 s++;
350 return (char *)s;
351}
352EXPORT_SYMBOL(strchrnul);
353#endif
354
355/**
356 * strnchrnul - Find and return a character in a length limited string,
357 * or end of string
358 * @s: The string to be searched
359 * @count: The number of characters to be searched
360 * @c: The character to search for
361 *
362 * Returns pointer to the first occurrence of 'c' in s. If c is not found,
363 * then return a pointer to the last character of the string.
364 */
365char *strnchrnul(const char *s, size_t count, int c)
366{
367 while (count-- && *s && *s != (char)c)
368 s++;
369 return (char *)s;
370}
371
372#ifndef __HAVE_ARCH_STRRCHR
373/**
374 * strrchr - Find the last occurrence of a character in a string
375 * @s: The string to be searched
376 * @c: The character to search for
377 */
378char *strrchr(const char *s, int c)
379{
380 const char *last = NULL;
381 do {
382 if (*s == (char)c)
383 last = s;
384 } while (*s++);
385 return (char *)last;
386}
387EXPORT_SYMBOL(strrchr);
388#endif
389
390#ifndef __HAVE_ARCH_STRNCHR
391/**
392 * strnchr - Find a character in a length limited string
393 * @s: The string to be searched
394 * @count: The number of characters to be searched
395 * @c: The character to search for
396 *
397 * Note that the %NUL-terminator is considered part of the string, and can
398 * be searched for.
399 */
400char *strnchr(const char *s, size_t count, int c)
401{
402 while (count--) {
403 if (*s == (char)c)
404 return (char *)s;
405 if (*s++ == '\0')
406 break;
407 }
408 return NULL;
409}
410EXPORT_SYMBOL(strnchr);
411#endif
412
413#ifndef __HAVE_ARCH_STRLEN
414size_t strlen(const char *s)
415{
416 const char *sc;
417
418 for (sc = s; *sc != '\0'; ++sc)
419 /* nothing */;
420 return sc - s;
421}
422EXPORT_SYMBOL(strlen);
423#endif
424
425#ifndef __HAVE_ARCH_STRNLEN
426size_t strnlen(const char *s, size_t count)
427{
428 const char *sc;
429
430 for (sc = s; count-- && *sc != '\0'; ++sc)
431 /* nothing */;
432 return sc - s;
433}
434EXPORT_SYMBOL(strnlen);
435#endif
436
437#ifndef __HAVE_ARCH_STRSPN
438/**
439 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
440 * @s: The string to be searched
441 * @accept: The string to search for
442 */
443size_t strspn(const char *s, const char *accept)
444{
445 const char *p;
446
447 for (p = s; *p != '\0'; ++p) {
448 if (!strchr(accept, *p))
449 break;
450 }
451 return p - s;
452}
453EXPORT_SYMBOL(strspn);
454#endif
455
456#ifndef __HAVE_ARCH_STRCSPN
457/**
458 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
459 * @s: The string to be searched
460 * @reject: The string to avoid
461 */
462size_t strcspn(const char *s, const char *reject)
463{
464 const char *p;
465
466 for (p = s; *p != '\0'; ++p) {
467 if (strchr(reject, *p))
468 break;
469 }
470 return p - s;
471}
472EXPORT_SYMBOL(strcspn);
473#endif
474
475#ifndef __HAVE_ARCH_STRPBRK
476/**
477 * strpbrk - Find the first occurrence of a set of characters
478 * @cs: The string to be searched
479 * @ct: The characters to search for
480 */
481char *strpbrk(const char *cs, const char *ct)
482{
483 const char *sc1, *sc2;
484
485 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
486 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
487 if (*sc1 == *sc2)
488 return (char *)sc1;
489 }
490 }
491 return NULL;
492}
493EXPORT_SYMBOL(strpbrk);
494#endif
495
496#ifndef __HAVE_ARCH_STRSEP
497/**
498 * strsep - Split a string into tokens
499 * @s: The string to be searched
500 * @ct: The characters to search for
501 *
502 * strsep() updates @s to point after the token, ready for the next call.
503 *
504 * It returns empty tokens, too, behaving exactly like the libc function
505 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
506 * Same semantics, slimmer shape. ;)
507 */
508char *strsep(char **s, const char *ct)
509{
510 char *sbegin = *s;
511 char *end;
512
513 if (sbegin == NULL)
514 return NULL;
515
516 end = strpbrk(sbegin, ct);
517 if (end)
518 *end++ = '\0';
519 *s = end;
520 return sbegin;
521}
522EXPORT_SYMBOL(strsep);
523#endif
524
525#ifndef __HAVE_ARCH_MEMSET
526/**
527 * memset - Fill a region of memory with the given value
528 * @s: Pointer to the start of the area.
529 * @c: The byte to fill the area with
530 * @count: The size of the area.
531 *
532 * Do not use memset() to access IO space, use memset_io() instead.
533 */
534void *memset(void *s, int c, size_t count)
535{
536 char *xs = s;
537
538 while (count--)
539 *xs++ = c;
540 return s;
541}
542EXPORT_SYMBOL(memset);
543#endif
544
545#ifndef __HAVE_ARCH_MEMSET16
546/**
547 * memset16() - Fill a memory area with a uint16_t
548 * @s: Pointer to the start of the area.
549 * @v: The value to fill the area with
550 * @count: The number of values to store
551 *
552 * Differs from memset() in that it fills with a uint16_t instead
553 * of a byte. Remember that @count is the number of uint16_ts to
554 * store, not the number of bytes.
555 */
556void *memset16(uint16_t *s, uint16_t v, size_t count)
557{
558 uint16_t *xs = s;
559
560 while (count--)
561 *xs++ = v;
562 return s;
563}
564EXPORT_SYMBOL(memset16);
565#endif
566
567#ifndef __HAVE_ARCH_MEMSET32
568/**
569 * memset32() - Fill a memory area with a uint32_t
570 * @s: Pointer to the start of the area.
571 * @v: The value to fill the area with
572 * @count: The number of values to store
573 *
574 * Differs from memset() in that it fills with a uint32_t instead
575 * of a byte. Remember that @count is the number of uint32_ts to
576 * store, not the number of bytes.
577 */
578void *memset32(uint32_t *s, uint32_t v, size_t count)
579{
580 uint32_t *xs = s;
581
582 while (count--)
583 *xs++ = v;
584 return s;
585}
586EXPORT_SYMBOL(memset32);
587#endif
588
589#ifndef __HAVE_ARCH_MEMSET64
590/**
591 * memset64() - Fill a memory area with a uint64_t
592 * @s: Pointer to the start of the area.
593 * @v: The value to fill the area with
594 * @count: The number of values to store
595 *
596 * Differs from memset() in that it fills with a uint64_t instead
597 * of a byte. Remember that @count is the number of uint64_ts to
598 * store, not the number of bytes.
599 */
600void *memset64(uint64_t *s, uint64_t v, size_t count)
601{
602 uint64_t *xs = s;
603
604 while (count--)
605 *xs++ = v;
606 return s;
607}
608EXPORT_SYMBOL(memset64);
609#endif
610
611#ifndef __HAVE_ARCH_MEMCPY
612/**
613 * memcpy - Copy one area of memory to another
614 * @dest: Where to copy to
615 * @src: Where to copy from
616 * @count: The size of the area.
617 *
618 * You should not use this function to access IO space, use memcpy_toio()
619 * or memcpy_fromio() instead.
620 */
621void *memcpy(void *dest, const void *src, size_t count)
622{
623 char *tmp = dest;
624 const char *s = src;
625
626 while (count--)
627 *tmp++ = *s++;
628 return dest;
629}
630EXPORT_SYMBOL(memcpy);
631#endif
632
633#ifndef __HAVE_ARCH_MEMMOVE
634/**
635 * memmove - Copy one area of memory to another
636 * @dest: Where to copy to
637 * @src: Where to copy from
638 * @count: The size of the area.
639 *
640 * Unlike memcpy(), memmove() copes with overlapping areas.
641 */
642void *memmove(void *dest, const void *src, size_t count)
643{
644 char *tmp;
645 const char *s;
646
647 if (dest <= src) {
648 tmp = dest;
649 s = src;
650 while (count--)
651 *tmp++ = *s++;
652 } else {
653 tmp = dest;
654 tmp += count;
655 s = src;
656 s += count;
657 while (count--)
658 *--tmp = *--s;
659 }
660 return dest;
661}
662EXPORT_SYMBOL(memmove);
663#endif
664
665#ifndef __HAVE_ARCH_MEMCMP
666/**
667 * memcmp - Compare two areas of memory
668 * @cs: One area of memory
669 * @ct: Another area of memory
670 * @count: The size of the area.
671 */
672#undef memcmp
673__visible int memcmp(const void *cs, const void *ct, size_t count)
674{
675 const unsigned char *su1, *su2;
676 int res = 0;
677
678#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
679 if (count >= sizeof(unsigned long)) {
680 const unsigned long *u1 = cs;
681 const unsigned long *u2 = ct;
682 do {
683 if (get_unaligned(u1) != get_unaligned(u2))
684 break;
685 u1++;
686 u2++;
687 count -= sizeof(unsigned long);
688 } while (count >= sizeof(unsigned long));
689 cs = u1;
690 ct = u2;
691 }
692#endif
693 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
694 if ((res = *su1 - *su2) != 0)
695 break;
696 return res;
697}
698EXPORT_SYMBOL(memcmp);
699#endif
700
701#ifndef __HAVE_ARCH_BCMP
702/**
703 * bcmp - returns 0 if and only if the buffers have identical contents.
704 * @a: pointer to first buffer.
705 * @b: pointer to second buffer.
706 * @len: size of buffers.
707 *
708 * The sign or magnitude of a non-zero return value has no particular
709 * meaning, and architectures may implement their own more efficient bcmp(). So
710 * while this particular implementation is a simple (tail) call to memcmp, do
711 * not rely on anything but whether the return value is zero or non-zero.
712 */
713int bcmp(const void *a, const void *b, size_t len)
714{
715 return memcmp(a, b, len);
716}
717EXPORT_SYMBOL(bcmp);
718#endif
719
720#ifndef __HAVE_ARCH_MEMSCAN
721/**
722 * memscan - Find a character in an area of memory.
723 * @addr: The memory area
724 * @c: The byte to search for
725 * @size: The size of the area.
726 *
727 * returns the address of the first occurrence of @c, or 1 byte past
728 * the area if @c is not found
729 */
730void *memscan(void *addr, int c, size_t size)
731{
732 unsigned char *p = addr;
733
734 while (size) {
735 if (*p == (unsigned char)c)
736 return (void *)p;
737 p++;
738 size--;
739 }
740 return (void *)p;
741}
742EXPORT_SYMBOL(memscan);
743#endif
744
745#ifndef __HAVE_ARCH_STRSTR
746/**
747 * strstr - Find the first substring in a %NUL terminated string
748 * @s1: The string to be searched
749 * @s2: The string to search for
750 */
751char *strstr(const char *s1, const char *s2)
752{
753 size_t l1, l2;
754
755 l2 = strlen(s2);
756 if (!l2)
757 return (char *)s1;
758 l1 = strlen(s1);
759 while (l1 >= l2) {
760 l1--;
761 if (!memcmp(s1, s2, l2))
762 return (char *)s1;
763 s1++;
764 }
765 return NULL;
766}
767EXPORT_SYMBOL(strstr);
768#endif
769
770#ifndef __HAVE_ARCH_STRNSTR
771/**
772 * strnstr - Find the first substring in a length-limited string
773 * @s1: The string to be searched
774 * @s2: The string to search for
775 * @len: the maximum number of characters to search
776 */
777char *strnstr(const char *s1, const char *s2, size_t len)
778{
779 size_t l2;
780
781 l2 = strlen(s2);
782 if (!l2)
783 return (char *)s1;
784 while (len >= l2) {
785 len--;
786 if (!memcmp(s1, s2, l2))
787 return (char *)s1;
788 s1++;
789 }
790 return NULL;
791}
792EXPORT_SYMBOL(strnstr);
793#endif
794
795#ifndef __HAVE_ARCH_MEMCHR
796/**
797 * memchr - Find a character in an area of memory.
798 * @s: The memory area
799 * @c: The byte to search for
800 * @n: The size of the area.
801 *
802 * returns the address of the first occurrence of @c, or %NULL
803 * if @c is not found
804 */
805void *memchr(const void *s, int c, size_t n)
806{
807 const unsigned char *p = s;
808 while (n-- != 0) {
809 if ((unsigned char)c == *p++) {
810 return (void *)(p - 1);
811 }
812 }
813 return NULL;
814}
815EXPORT_SYMBOL(memchr);
816#endif
817
818static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
819{
820 while (bytes) {
821 if (*start != value)
822 return (void *)start;
823 start++;
824 bytes--;
825 }
826 return NULL;
827}
828
829/**
830 * memchr_inv - Find an unmatching character in an area of memory.
831 * @start: The memory area
832 * @c: Find a character other than c
833 * @bytes: The size of the area.
834 *
835 * returns the address of the first character other than @c, or %NULL
836 * if the whole buffer contains just @c.
837 */
838void *memchr_inv(const void *start, int c, size_t bytes)
839{
840 u8 value = c;
841 u64 value64;
842 unsigned int words, prefix;
843
844 if (bytes <= 16)
845 return check_bytes8(start, value, bytes);
846
847 value64 = value;
848#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
849 value64 *= 0x0101010101010101ULL;
850#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
851 value64 *= 0x01010101;
852 value64 |= value64 << 32;
853#else
854 value64 |= value64 << 8;
855 value64 |= value64 << 16;
856 value64 |= value64 << 32;
857#endif
858
859 prefix = (unsigned long)start % 8;
860 if (prefix) {
861 u8 *r;
862
863 prefix = 8 - prefix;
864 r = check_bytes8(start, value, prefix);
865 if (r)
866 return r;
867 start += prefix;
868 bytes -= prefix;
869 }
870
871 words = bytes / 8;
872
873 while (words) {
874 if (*(u64 *)start != value64)
875 return check_bytes8(start, value, 8);
876 start += 8;
877 words--;
878 }
879
880 return check_bytes8(start, value, bytes % 8);
881}
882EXPORT_SYMBOL(memchr_inv);