1 // SPDX-License-Identifier: GPL-2.0
5 * Copyright (C) 1991, 1992 Linus Torvalds
9 * stupid library routines.. The optimized versions should generally be found
10 * as inline code in <asm-xx/string.h>
12 * These are buggy as well..
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.
18 * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>,
19 * Matthew Hawkins <matt@mh.dropbear.id.au>
20 * - Kissed strtok() goodbye
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>
32 #include <asm/byteorder.h>
33 #include <asm/word-at-a-time.h>
36 #ifndef __HAVE_ARCH_STRNCASECMP
38 * strncasecmp - Case insensitive, length-limited string comparison
40 * @s2: The other string
41 * @len: the maximum number of characters to compare
43 int strncasecmp(const char *s1, const char *s2, size_t len)
45 /* Yes, Virginia, it had better be unsigned */
63 return (int)c1 - (int)c2;
65 EXPORT_SYMBOL(strncasecmp);
68 #ifndef __HAVE_ARCH_STRCASECMP
69 int strcasecmp(const char *s1, const char *s2)
76 } while (c1 == c2 && c1 != 0);
79 EXPORT_SYMBOL(strcasecmp);
82 #ifndef __HAVE_ARCH_STRCPY
84 * strcpy - Copy a %NUL terminated string
85 * @dest: Where to copy the string to
86 * @src: Where to copy the string from
88 char *strcpy(char *dest, const char *src)
92 while ((*dest++ = *src++) != '\0')
96 EXPORT_SYMBOL(strcpy);
99 #ifndef __HAVE_ARCH_STRNCPY
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
106 * The result is not %NUL-terminated if the source exceeds
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.
113 char *strncpy(char *dest, const char *src, size_t count)
118 if ((*tmp = *src) != 0)
125 EXPORT_SYMBOL(strncpy);
128 #ifndef __HAVE_ARCH_STRLCPY
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
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.
140 size_t strlcpy(char *dest, const char *src, size_t size)
142 size_t ret = strlen(src);
145 size_t len = (ret >= size) ? size - 1 : ret;
146 memcpy(dest, src, len);
151 EXPORT_SYMBOL(strlcpy);
154 #ifndef __HAVE_ARCH_STRSCPY
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
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.
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.
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().
176 * * The number of characters copied (not including the trailing %NUL)
177 * * -E2BIG if count is 0 or @src was truncated.
179 ssize_t strscpy(char *dest, const char *src, size_t count)
181 const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
185 if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
188 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
190 * If src is unaligned, don't cross a page boundary,
191 * since we don't know if the next page is mapped.
193 if ((long)src & (sizeof(long) - 1)) {
194 size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
199 /* If src or dest is unaligned, don't do word-at-a-time. */
200 if (((long) dest | (long) src) & (sizeof(long) - 1))
204 while (max >= sizeof(unsigned long)) {
205 unsigned long c, data;
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);
214 *(unsigned long *)(dest+res) = c;
215 res += sizeof(unsigned long);
216 count -= sizeof(unsigned long);
217 max -= sizeof(unsigned long);
231 /* Hit buffer length without finding a NUL; force NUL-termination. */
237 EXPORT_SYMBOL(strscpy);
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
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.
250 * If the source string is shorter than the destination buffer, zeros
251 * the tail of the destination buffer.
253 * For full explanation of why you may want to consider using the
254 * 'strscpy' functions please see the function docstring for strscpy().
257 * * The number of characters copied (not including the trailing %NUL)
258 * * -E2BIG if count is 0 or @src was truncated.
260 ssize_t strscpy_pad(char *dest, const char *src, size_t count)
264 written = strscpy(dest, src, count);
265 if (written < 0 || written == count - 1)
268 memset(dest + written + 1, 0, count - written - 1);
272 EXPORT_SYMBOL(strscpy_pad);
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
279 * @src: pointer to the beginning of string being copied from. Must not overlap
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.
289 char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
290 char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
292 while ((*dest++ = *src++) != '\0')
296 EXPORT_SYMBOL(stpcpy);
298 #ifndef __HAVE_ARCH_STRCAT
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
304 char *strcat(char *dest, const char *src)
310 while ((*dest++ = *src++) != '\0')
314 EXPORT_SYMBOL(strcat);
317 #ifndef __HAVE_ARCH_STRNCAT
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
324 * Note that in contrast to strncpy(), strncat() ensures the result is
327 char *strncat(char *dest, const char *src, size_t count)
334 while ((*dest++ = *src++) != 0) {
343 EXPORT_SYMBOL(strncat);
346 #ifndef __HAVE_ARCH_STRLCAT
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.
353 size_t strlcat(char *dest, const char *src, size_t count)
355 size_t dsize = strlen(dest);
356 size_t len = strlen(src);
357 size_t res = dsize + len;
359 /* This would be a bug */
360 BUG_ON(dsize >= count);
366 memcpy(dest, src, len);
370 EXPORT_SYMBOL(strlcat);
373 #ifndef __HAVE_ARCH_STRCMP
375 * strcmp - Compare two strings
377 * @ct: Another string
379 int strcmp(const char *cs, const char *ct)
381 unsigned char c1, c2;
387 return c1 < c2 ? -1 : 1;
393 EXPORT_SYMBOL(strcmp);
396 #ifndef __HAVE_ARCH_STRNCMP
398 * strncmp - Compare two length-limited strings
400 * @ct: Another string
401 * @count: The maximum number of bytes to compare
403 int strncmp(const char *cs, const char *ct, size_t count)
405 unsigned char c1, c2;
411 return c1 < c2 ? -1 : 1;
418 EXPORT_SYMBOL(strncmp);
421 #ifndef __HAVE_ARCH_STRCHR
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
427 * Note that the %NUL-terminator is considered part of the string, and can
430 char *strchr(const char *s, int c)
432 for (; *s != (char)c; ++s)
437 EXPORT_SYMBOL(strchr);
440 #ifndef __HAVE_ARCH_STRCHRNUL
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
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.
449 char *strchrnul(const char *s, int c)
451 while (*s && *s != (char)c)
455 EXPORT_SYMBOL(strchrnul);
459 * strnchrnul - Find and return a character in a length limited string,
461 * @s: The string to be searched
462 * @count: The number of characters to be searched
463 * @c: The character to search for
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.
468 char *strnchrnul(const char *s, size_t count, int c)
470 while (count-- && *s && *s != (char)c)
475 #ifndef __HAVE_ARCH_STRRCHR
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
481 char *strrchr(const char *s, int c)
483 const char *last = NULL;
490 EXPORT_SYMBOL(strrchr);
493 #ifndef __HAVE_ARCH_STRNCHR
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
500 * Note that the %NUL-terminator is considered part of the string, and can
503 char *strnchr(const char *s, size_t count, int c)
513 EXPORT_SYMBOL(strnchr);
517 * skip_spaces - Removes leading whitespace from @str.
518 * @str: The string to be stripped.
520 * Returns a pointer to the first non-whitespace character in @str.
522 char *skip_spaces(const char *str)
524 while (isspace(*str))
528 EXPORT_SYMBOL(skip_spaces);
531 * strim - Removes leading and trailing whitespace from @s.
532 * @s: The string to be stripped.
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
548 while (end >= s && isspace(*end))
552 return skip_spaces(s);
554 EXPORT_SYMBOL(strim);
556 #ifndef __HAVE_ARCH_STRLEN
558 * strlen - Find the length of a string
559 * @s: The string to be sized
561 size_t strlen(const char *s)
565 for (sc = s; *sc != '\0'; ++sc)
569 EXPORT_SYMBOL(strlen);
572 #ifndef __HAVE_ARCH_STRNLEN
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
578 size_t strnlen(const char *s, size_t count)
582 for (sc = s; count-- && *sc != '\0'; ++sc)
586 EXPORT_SYMBOL(strnlen);
589 #ifndef __HAVE_ARCH_STRSPN
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
595 size_t strspn(const char *s, const char *accept)
601 for (p = s; *p != '\0'; ++p) {
602 for (a = accept; *a != '\0'; ++a) {
613 EXPORT_SYMBOL(strspn);
616 #ifndef __HAVE_ARCH_STRCSPN
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
622 size_t strcspn(const char *s, const char *reject)
628 for (p = s; *p != '\0'; ++p) {
629 for (r = reject; *r != '\0'; ++r) {
637 EXPORT_SYMBOL(strcspn);
640 #ifndef __HAVE_ARCH_STRPBRK
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
646 char *strpbrk(const char *cs, const char *ct)
648 const char *sc1, *sc2;
650 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
651 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
658 EXPORT_SYMBOL(strpbrk);
661 #ifndef __HAVE_ARCH_STRSEP
663 * strsep - Split a string into tokens
664 * @s: The string to be searched
665 * @ct: The characters to search for
667 * strsep() updates @s to point after the token, ready for the next call.
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. ;)
673 char *strsep(char **s, const char *ct)
681 end = strpbrk(sbegin, ct);
687 EXPORT_SYMBOL(strsep);
691 * sysfs_streq - return true if strings are equal, modulo trailing newline
693 * @s2: another string
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.
700 bool sysfs_streq(const char *s1, const char *s2)
702 while (*s1 && *s1 == *s2) {
709 if (!*s1 && *s2 == '\n' && !s2[1])
711 if (*s1 == '\n' && !s1[1] && !*s2)
715 EXPORT_SYMBOL(sysfs_streq);
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
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.
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.
732 * index of a @string in the @array if matches, or %-EINVAL otherwise.
734 int match_string(const char * const *array, size_t n, const char *string)
739 for (index = 0; index < n; index++) {
743 if (!strcmp(item, string))
749 EXPORT_SYMBOL(match_string);
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
757 * Returns index of @str in the @array or -EINVAL, just like match_string().
758 * Uses sysfs_streq instead of strcmp for matching.
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.
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.
768 int __sysfs_match_string(const char * const *array, size_t n, const char *str)
773 for (index = 0; index < n; index++) {
777 if (sysfs_streq(item, str))
783 EXPORT_SYMBOL(__sysfs_match_string);
785 #ifndef __HAVE_ARCH_MEMSET
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.
792 * Do not use memset() to access IO space, use memset_io() instead.
794 void *memset(void *s, int c, size_t count)
802 EXPORT_SYMBOL(memset);
805 #ifndef __HAVE_ARCH_MEMSET16
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
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.
816 void *memset16(uint16_t *s, uint16_t v, size_t count)
824 EXPORT_SYMBOL(memset16);
827 #ifndef __HAVE_ARCH_MEMSET32
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
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.
838 void *memset32(uint32_t *s, uint32_t v, size_t count)
846 EXPORT_SYMBOL(memset32);
849 #ifndef __HAVE_ARCH_MEMSET64
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
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.
860 void *memset64(uint64_t *s, uint64_t v, size_t count)
868 EXPORT_SYMBOL(memset64);
871 #ifndef __HAVE_ARCH_MEMCPY
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.
878 * You should not use this function to access IO space, use memcpy_toio()
879 * or memcpy_fromio() instead.
881 void *memcpy(void *dest, const void *src, size_t count)
890 EXPORT_SYMBOL(memcpy);
893 #ifndef __HAVE_ARCH_MEMMOVE
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.
900 * Unlike memcpy(), memmove() copes with overlapping areas.
902 void *memmove(void *dest, const void *src, size_t count)
922 EXPORT_SYMBOL(memmove);
925 #ifndef __HAVE_ARCH_MEMCMP
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.
933 __visible int memcmp(const void *cs, const void *ct, size_t count)
935 const unsigned char *su1, *su2;
938 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
939 if ((res = *su1 - *su2) != 0)
943 EXPORT_SYMBOL(memcmp);
946 #ifndef __HAVE_ARCH_BCMP
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.
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.
958 int bcmp(const void *a, const void *b, size_t len)
960 return memcmp(a, b, len);
965 #ifndef __HAVE_ARCH_MEMSCAN
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.
972 * returns the address of the first occurrence of @c, or 1 byte past
973 * the area if @c is not found
975 void *memscan(void *addr, int c, size_t size)
977 unsigned char *p = addr;
987 EXPORT_SYMBOL(memscan);
990 #ifndef __HAVE_ARCH_STRSTR
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
996 char *strstr(const char *s1, const char *s2)
1006 if (!memcmp(s1, s2, l2))
1012 EXPORT_SYMBOL(strstr);
1015 #ifndef __HAVE_ARCH_STRNSTR
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
1022 char *strnstr(const char *s1, const char *s2, size_t len)
1031 if (!memcmp(s1, s2, l2))
1037 EXPORT_SYMBOL(strnstr);
1040 #ifndef __HAVE_ARCH_MEMCHR
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.
1047 * returns the address of the first occurrence of @c, or %NULL
1048 * if @c is not found
1050 void *memchr(const void *s, int c, size_t n)
1052 const unsigned char *p = s;
1054 if ((unsigned char)c == *p++) {
1055 return (void *)(p - 1);
1060 EXPORT_SYMBOL(memchr);
1063 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
1066 if (*start != value)
1067 return (void *)start;
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.
1080 * returns the address of the first character other than @c, or %NULL
1081 * if the whole buffer contains just @c.
1083 void *memchr_inv(const void *start, int c, size_t bytes)
1087 unsigned int words, prefix;
1090 return check_bytes8(start, value, bytes);
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;
1099 value64 |= value64 << 8;
1100 value64 |= value64 << 16;
1101 value64 |= value64 << 32;
1104 prefix = (unsigned long)start % 8;
1108 prefix = 8 - prefix;
1109 r = check_bytes8(start, value, prefix);
1119 if (*(u64 *)start != value64)
1120 return check_bytes8(start, value, 8);
1125 return check_bytes8(start, value, bytes % 8);
1127 EXPORT_SYMBOL(memchr_inv);
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.
1135 * Returns pointer to the nul byte at the end of @s.
1137 char *strreplace(char *s, char old, char new)
1144 EXPORT_SYMBOL(strreplace);
1146 void fortify_panic(const char *name)
1148 pr_emerg("detected buffer overflow in %s\n", name);
1151 EXPORT_SYMBOL(fortify_panic);