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git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - lib/string.c
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
89 char *strcpy(char *dest
, const char *src
)
93 while ((*dest
++ = *src
++) != '\0')
97 EXPORT_SYMBOL(strcpy
);
100 #ifndef __HAVE_ARCH_STRNCPY
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
107 * The result is not %NUL-terminated if the source exceeds
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.
114 char *strncpy(char *dest
, const char *src
, size_t count
)
119 if ((*tmp
= *src
) != 0)
126 EXPORT_SYMBOL(strncpy
);
129 #ifndef __HAVE_ARCH_STRLCPY
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
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.
141 size_t strlcpy(char *dest
, const char *src
, size_t size
)
143 size_t ret
= strlen(src
);
146 size_t len
= (ret
>= size
) ? size
- 1 : ret
;
147 memcpy(dest
, src
, len
);
152 EXPORT_SYMBOL(strlcpy
);
155 #ifndef __HAVE_ARCH_STRSCPY
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
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.
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.
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().
177 * * The number of characters copied (not including the trailing %NUL)
178 * * -E2BIG if count is 0 or @src was truncated.
180 ssize_t
strscpy(char *dest
, const char *src
, size_t count
)
182 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
186 if (count
== 0 || WARN_ON_ONCE(count
> INT_MAX
))
189 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
191 * If src is unaligned, don't cross a page boundary,
192 * since we don't know if the next page is mapped.
194 if ((long)src
& (sizeof(long) - 1)) {
195 size_t limit
= PAGE_SIZE
- ((long)src
& (PAGE_SIZE
- 1));
200 /* If src or dest is unaligned, don't do word-at-a-time. */
201 if (((long) dest
| (long) src
) & (sizeof(long) - 1))
205 while (max
>= sizeof(unsigned long)) {
206 unsigned long c
, data
;
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
);
215 *(unsigned long *)(dest
+res
) = c
;
216 res
+= sizeof(unsigned long);
217 count
-= sizeof(unsigned long);
218 max
-= sizeof(unsigned long);
232 /* Hit buffer length without finding a NUL; force NUL-termination. */
238 EXPORT_SYMBOL(strscpy
);
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
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.
251 * If the source string is shorter than the destination buffer, zeros
252 * the tail of the destination buffer.
254 * For full explanation of why you may want to consider using the
255 * 'strscpy' functions please see the function docstring for strscpy().
258 * * The number of characters copied (not including the trailing %NUL)
259 * * -E2BIG if count is 0 or @src was truncated.
261 ssize_t
strscpy_pad(char *dest
, const char *src
, size_t count
)
265 written
= strscpy(dest
, src
, count
);
266 if (written
< 0 || written
== count
- 1)
269 memset(dest
+ written
+ 1, 0, count
- written
- 1);
273 EXPORT_SYMBOL(strscpy_pad
);
275 #ifndef __HAVE_ARCH_STRCAT
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
282 char *strcat(char *dest
, const char *src
)
288 while ((*dest
++ = *src
++) != '\0')
292 EXPORT_SYMBOL(strcat
);
295 #ifndef __HAVE_ARCH_STRNCAT
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
302 * Note that in contrast to strncpy(), strncat() ensures the result is
305 char *strncat(char *dest
, const char *src
, size_t count
)
312 while ((*dest
++ = *src
++) != 0) {
321 EXPORT_SYMBOL(strncat
);
324 #ifndef __HAVE_ARCH_STRLCAT
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.
331 size_t strlcat(char *dest
, const char *src
, size_t count
)
333 size_t dsize
= strlen(dest
);
334 size_t len
= strlen(src
);
335 size_t res
= dsize
+ len
;
337 /* This would be a bug */
338 BUG_ON(dsize
>= count
);
344 memcpy(dest
, src
, len
);
348 EXPORT_SYMBOL(strlcat
);
351 #ifndef __HAVE_ARCH_STRCMP
353 * strcmp - Compare two strings
355 * @ct: Another string
358 int strcmp(const char *cs
, const char *ct
)
360 unsigned char c1
, c2
;
366 return c1
< c2
? -1 : 1;
372 EXPORT_SYMBOL(strcmp
);
375 #ifndef __HAVE_ARCH_STRNCMP
377 * strncmp - Compare two length-limited strings
379 * @ct: Another string
380 * @count: The maximum number of bytes to compare
382 int strncmp(const char *cs
, const char *ct
, size_t count
)
384 unsigned char c1
, c2
;
390 return c1
< c2
? -1 : 1;
397 EXPORT_SYMBOL(strncmp
);
400 #ifndef __HAVE_ARCH_STRCHR
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
406 * Note that the %NUL-terminator is considered part of the string, and can
409 char *strchr(const char *s
, int c
)
411 for (; *s
!= (char)c
; ++s
)
416 EXPORT_SYMBOL(strchr
);
419 #ifndef __HAVE_ARCH_STRCHRNUL
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
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.
428 char *strchrnul(const char *s
, int c
)
430 while (*s
&& *s
!= (char)c
)
434 EXPORT_SYMBOL(strchrnul
);
437 #ifndef __HAVE_ARCH_STRRCHR
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
443 char *strrchr(const char *s
, int c
)
445 const char *last
= NULL
;
452 EXPORT_SYMBOL(strrchr
);
455 #ifndef __HAVE_ARCH_STRNCHR
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
462 * Note that the %NUL-terminator is considered part of the string, and can
465 char *strnchr(const char *s
, size_t count
, int c
)
475 EXPORT_SYMBOL(strnchr
);
479 * skip_spaces - Removes leading whitespace from @str.
480 * @str: The string to be stripped.
482 * Returns a pointer to the first non-whitespace character in @str.
484 char *skip_spaces(const char *str
)
486 while (isspace(*str
))
490 EXPORT_SYMBOL(skip_spaces
);
493 * strim - Removes leading and trailing whitespace from @s.
494 * @s: The string to be stripped.
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
510 while (end
>= s
&& isspace(*end
))
514 return skip_spaces(s
);
516 EXPORT_SYMBOL(strim
);
518 #ifndef __HAVE_ARCH_STRLEN
520 * strlen - Find the length of a string
521 * @s: The string to be sized
523 size_t strlen(const char *s
)
527 for (sc
= s
; *sc
!= '\0'; ++sc
)
531 EXPORT_SYMBOL(strlen
);
534 #ifndef __HAVE_ARCH_STRNLEN
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
540 size_t strnlen(const char *s
, size_t count
)
544 for (sc
= s
; count
-- && *sc
!= '\0'; ++sc
)
548 EXPORT_SYMBOL(strnlen
);
551 #ifndef __HAVE_ARCH_STRSPN
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
557 size_t strspn(const char *s
, const char *accept
)
563 for (p
= s
; *p
!= '\0'; ++p
) {
564 for (a
= accept
; *a
!= '\0'; ++a
) {
575 EXPORT_SYMBOL(strspn
);
578 #ifndef __HAVE_ARCH_STRCSPN
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
584 size_t strcspn(const char *s
, const char *reject
)
590 for (p
= s
; *p
!= '\0'; ++p
) {
591 for (r
= reject
; *r
!= '\0'; ++r
) {
599 EXPORT_SYMBOL(strcspn
);
602 #ifndef __HAVE_ARCH_STRPBRK
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
608 char *strpbrk(const char *cs
, const char *ct
)
610 const char *sc1
, *sc2
;
612 for (sc1
= cs
; *sc1
!= '\0'; ++sc1
) {
613 for (sc2
= ct
; *sc2
!= '\0'; ++sc2
) {
620 EXPORT_SYMBOL(strpbrk
);
623 #ifndef __HAVE_ARCH_STRSEP
625 * strsep - Split a string into tokens
626 * @s: The string to be searched
627 * @ct: The characters to search for
629 * strsep() updates @s to point after the token, ready for the next call.
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. ;)
635 char *strsep(char **s
, const char *ct
)
643 end
= strpbrk(sbegin
, ct
);
649 EXPORT_SYMBOL(strsep
);
653 * sysfs_streq - return true if strings are equal, modulo trailing newline
655 * @s2: another string
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.
662 bool sysfs_streq(const char *s1
, const char *s2
)
664 while (*s1
&& *s1
== *s2
) {
671 if (!*s1
&& *s2
== '\n' && !s2
[1])
673 if (*s1
== '\n' && !s1
[1] && !*s2
)
677 EXPORT_SYMBOL(sysfs_streq
);
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
686 * index of a @string in the @array if matches, or %-EINVAL otherwise.
688 int match_string(const char * const *array
, size_t n
, const char *string
)
693 for (index
= 0; index
< n
; index
++) {
697 if (!strcmp(item
, string
))
703 EXPORT_SYMBOL(match_string
);
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
711 * Returns index of @str in the @array or -EINVAL, just like match_string().
712 * Uses sysfs_streq instead of strcmp for matching.
714 int __sysfs_match_string(const char * const *array
, size_t n
, const char *str
)
719 for (index
= 0; index
< n
; index
++) {
723 if (sysfs_streq(item
, str
))
729 EXPORT_SYMBOL(__sysfs_match_string
);
731 #ifndef __HAVE_ARCH_MEMSET
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.
738 * Do not use memset() to access IO space, use memset_io() instead.
740 void *memset(void *s
, int c
, size_t count
)
748 EXPORT_SYMBOL(memset
);
751 #ifndef __HAVE_ARCH_MEMSET16
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
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.
762 void *memset16(uint16_t *s
, uint16_t v
, size_t count
)
770 EXPORT_SYMBOL(memset16
);
773 #ifndef __HAVE_ARCH_MEMSET32
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
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.
784 void *memset32(uint32_t *s
, uint32_t v
, size_t count
)
792 EXPORT_SYMBOL(memset32
);
795 #ifndef __HAVE_ARCH_MEMSET64
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
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.
806 void *memset64(uint64_t *s
, uint64_t v
, size_t count
)
814 EXPORT_SYMBOL(memset64
);
817 #ifndef __HAVE_ARCH_MEMCPY
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.
824 * You should not use this function to access IO space, use memcpy_toio()
825 * or memcpy_fromio() instead.
827 void *memcpy(void *dest
, const void *src
, size_t count
)
836 EXPORT_SYMBOL(memcpy
);
839 #ifndef __HAVE_ARCH_MEMMOVE
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.
846 * Unlike memcpy(), memmove() copes with overlapping areas.
848 void *memmove(void *dest
, const void *src
, size_t count
)
868 EXPORT_SYMBOL(memmove
);
871 #ifndef __HAVE_ARCH_MEMCMP
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.
879 __visible
int memcmp(const void *cs
, const void *ct
, size_t count
)
881 const unsigned char *su1
, *su2
;
884 for (su1
= cs
, su2
= ct
; 0 < count
; ++su1
, ++su2
, count
--)
885 if ((res
= *su1
- *su2
) != 0)
889 EXPORT_SYMBOL(memcmp
);
892 #ifndef __HAVE_ARCH_BCMP
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.
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.
905 int bcmp(const void *a
, const void *b
, size_t len
)
907 return memcmp(a
, b
, len
);
912 #ifndef __HAVE_ARCH_MEMSCAN
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.
919 * returns the address of the first occurrence of @c, or 1 byte past
920 * the area if @c is not found
922 void *memscan(void *addr
, int c
, size_t size
)
924 unsigned char *p
= addr
;
934 EXPORT_SYMBOL(memscan
);
937 #ifndef __HAVE_ARCH_STRSTR
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
943 char *strstr(const char *s1
, const char *s2
)
953 if (!memcmp(s1
, s2
, l2
))
959 EXPORT_SYMBOL(strstr
);
962 #ifndef __HAVE_ARCH_STRNSTR
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
969 char *strnstr(const char *s1
, const char *s2
, size_t len
)
978 if (!memcmp(s1
, s2
, l2
))
984 EXPORT_SYMBOL(strnstr
);
987 #ifndef __HAVE_ARCH_MEMCHR
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.
994 * returns the address of the first occurrence of @c, or %NULL
997 void *memchr(const void *s
, int c
, size_t n
)
999 const unsigned char *p
= s
;
1001 if ((unsigned char)c
== *p
++) {
1002 return (void *)(p
- 1);
1007 EXPORT_SYMBOL(memchr
);
1010 static void *check_bytes8(const u8
*start
, u8 value
, unsigned int bytes
)
1013 if (*start
!= value
)
1014 return (void *)start
;
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.
1027 * returns the address of the first character other than @c, or %NULL
1028 * if the whole buffer contains just @c.
1030 void *memchr_inv(const void *start
, int c
, size_t bytes
)
1034 unsigned int words
, prefix
;
1037 return check_bytes8(start
, value
, bytes
);
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;
1046 value64
|= value64
<< 8;
1047 value64
|= value64
<< 16;
1048 value64
|= value64
<< 32;
1051 prefix
= (unsigned long)start
% 8;
1055 prefix
= 8 - prefix
;
1056 r
= check_bytes8(start
, value
, prefix
);
1066 if (*(u64
*)start
!= value64
)
1067 return check_bytes8(start
, value
, 8);
1072 return check_bytes8(start
, value
, bytes
% 8);
1074 EXPORT_SYMBOL(memchr_inv
);
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.
1082 * Returns pointer to the nul byte at the end of @s.
1084 char *strreplace(char *s
, char old
, char new)
1091 EXPORT_SYMBOL(strreplace
);
1093 void fortify_panic(const char *name
)
1095 pr_emerg("detected buffer overflow in %s\n", name
);
1098 EXPORT_SYMBOL(fortify_panic
);