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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.
163 * The routine returns the number of characters copied (not including
164 * the trailing NUL) or -E2BIG if the destination buffer wasn't big enough.
165 * The behavior is undefined if the string buffers overlap.
166 * The destination buffer is always NUL terminated, unless it's zero-sized.
168 * Preferred to strlcpy() since the API doesn't require reading memory
169 * from the src string beyond the specified "count" bytes, and since
170 * the return value is easier to error-check than strlcpy()'s.
171 * In addition, the implementation is robust to the string changing out
172 * from underneath it, unlike the current strlcpy() implementation.
174 * Preferred to strncpy() since it always returns a valid string, and
175 * doesn't unnecessarily force the tail of the destination buffer to be
176 * zeroed. If the zeroing is desired, it's likely cleaner to use strscpy()
177 * with an overflow test, then just memset() the tail of the dest buffer.
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
;
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
);
240 #ifndef __HAVE_ARCH_STRCAT
242 * strcat - Append one %NUL-terminated string to another
243 * @dest: The string to be appended to
244 * @src: The string to append to it
247 char *strcat(char *dest
, const char *src
)
253 while ((*dest
++ = *src
++) != '\0')
257 EXPORT_SYMBOL(strcat
);
260 #ifndef __HAVE_ARCH_STRNCAT
262 * strncat - Append a length-limited, C-string to another
263 * @dest: The string to be appended to
264 * @src: The string to append to it
265 * @count: The maximum numbers of bytes to copy
267 * Note that in contrast to strncpy(), strncat() ensures the result is
270 char *strncat(char *dest
, const char *src
, size_t count
)
277 while ((*dest
++ = *src
++) != 0) {
286 EXPORT_SYMBOL(strncat
);
289 #ifndef __HAVE_ARCH_STRLCAT
291 * strlcat - Append a length-limited, C-string to another
292 * @dest: The string to be appended to
293 * @src: The string to append to it
294 * @count: The size of the destination buffer.
296 size_t strlcat(char *dest
, const char *src
, size_t count
)
298 size_t dsize
= strlen(dest
);
299 size_t len
= strlen(src
);
300 size_t res
= dsize
+ len
;
302 /* This would be a bug */
303 BUG_ON(dsize
>= count
);
309 memcpy(dest
, src
, len
);
313 EXPORT_SYMBOL(strlcat
);
316 #ifndef __HAVE_ARCH_STRCMP
318 * strcmp - Compare two strings
320 * @ct: Another string
323 int strcmp(const char *cs
, const char *ct
)
325 unsigned char c1
, c2
;
331 return c1
< c2
? -1 : 1;
337 EXPORT_SYMBOL(strcmp
);
340 #ifndef __HAVE_ARCH_STRNCMP
342 * strncmp - Compare two length-limited strings
344 * @ct: Another string
345 * @count: The maximum number of bytes to compare
347 int strncmp(const char *cs
, const char *ct
, size_t count
)
349 unsigned char c1
, c2
;
355 return c1
< c2
? -1 : 1;
362 EXPORT_SYMBOL(strncmp
);
365 #ifndef __HAVE_ARCH_STRCHR
367 * strchr - Find the first occurrence of a character in a string
368 * @s: The string to be searched
369 * @c: The character to search for
371 char *strchr(const char *s
, int c
)
373 for (; *s
!= (char)c
; ++s
)
378 EXPORT_SYMBOL(strchr
);
381 #ifndef __HAVE_ARCH_STRCHRNUL
383 * strchrnul - Find and return a character in a string, or end of string
384 * @s: The string to be searched
385 * @c: The character to search for
387 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
388 * return a pointer to the null byte at the end of s.
390 char *strchrnul(const char *s
, int c
)
392 while (*s
&& *s
!= (char)c
)
396 EXPORT_SYMBOL(strchrnul
);
399 #ifndef __HAVE_ARCH_STRRCHR
401 * strrchr - Find the last occurrence of a character in a string
402 * @s: The string to be searched
403 * @c: The character to search for
405 char *strrchr(const char *s
, int c
)
407 const char *last
= NULL
;
414 EXPORT_SYMBOL(strrchr
);
417 #ifndef __HAVE_ARCH_STRNCHR
419 * strnchr - Find a character in a length limited string
420 * @s: The string to be searched
421 * @count: The number of characters to be searched
422 * @c: The character to search for
424 char *strnchr(const char *s
, size_t count
, int c
)
426 for (; count
-- && *s
!= '\0'; ++s
)
431 EXPORT_SYMBOL(strnchr
);
435 * skip_spaces - Removes leading whitespace from @str.
436 * @str: The string to be stripped.
438 * Returns a pointer to the first non-whitespace character in @str.
440 char *skip_spaces(const char *str
)
442 while (isspace(*str
))
446 EXPORT_SYMBOL(skip_spaces
);
449 * strim - Removes leading and trailing whitespace from @s.
450 * @s: The string to be stripped.
452 * Note that the first trailing whitespace is replaced with a %NUL-terminator
453 * in the given string @s. Returns a pointer to the first non-whitespace
466 while (end
>= s
&& isspace(*end
))
470 return skip_spaces(s
);
472 EXPORT_SYMBOL(strim
);
474 #ifndef __HAVE_ARCH_STRLEN
476 * strlen - Find the length of a string
477 * @s: The string to be sized
479 size_t strlen(const char *s
)
483 for (sc
= s
; *sc
!= '\0'; ++sc
)
487 EXPORT_SYMBOL(strlen
);
490 #ifndef __HAVE_ARCH_STRNLEN
492 * strnlen - Find the length of a length-limited string
493 * @s: The string to be sized
494 * @count: The maximum number of bytes to search
496 size_t strnlen(const char *s
, size_t count
)
500 for (sc
= s
; count
-- && *sc
!= '\0'; ++sc
)
504 EXPORT_SYMBOL(strnlen
);
507 #ifndef __HAVE_ARCH_STRSPN
509 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
510 * @s: The string to be searched
511 * @accept: The string to search for
513 size_t strspn(const char *s
, const char *accept
)
519 for (p
= s
; *p
!= '\0'; ++p
) {
520 for (a
= accept
; *a
!= '\0'; ++a
) {
531 EXPORT_SYMBOL(strspn
);
534 #ifndef __HAVE_ARCH_STRCSPN
536 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
537 * @s: The string to be searched
538 * @reject: The string to avoid
540 size_t strcspn(const char *s
, const char *reject
)
546 for (p
= s
; *p
!= '\0'; ++p
) {
547 for (r
= reject
; *r
!= '\0'; ++r
) {
555 EXPORT_SYMBOL(strcspn
);
558 #ifndef __HAVE_ARCH_STRPBRK
560 * strpbrk - Find the first occurrence of a set of characters
561 * @cs: The string to be searched
562 * @ct: The characters to search for
564 char *strpbrk(const char *cs
, const char *ct
)
566 const char *sc1
, *sc2
;
568 for (sc1
= cs
; *sc1
!= '\0'; ++sc1
) {
569 for (sc2
= ct
; *sc2
!= '\0'; ++sc2
) {
576 EXPORT_SYMBOL(strpbrk
);
579 #ifndef __HAVE_ARCH_STRSEP
581 * strsep - Split a string into tokens
582 * @s: The string to be searched
583 * @ct: The characters to search for
585 * strsep() updates @s to point after the token, ready for the next call.
587 * It returns empty tokens, too, behaving exactly like the libc function
588 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
589 * Same semantics, slimmer shape. ;)
591 char *strsep(char **s
, const char *ct
)
599 end
= strpbrk(sbegin
, ct
);
605 EXPORT_SYMBOL(strsep
);
609 * sysfs_streq - return true if strings are equal, modulo trailing newline
611 * @s2: another string
613 * This routine returns true iff two strings are equal, treating both
614 * NUL and newline-then-NUL as equivalent string terminations. It's
615 * geared for use with sysfs input strings, which generally terminate
616 * with newlines but are compared against values without newlines.
618 bool sysfs_streq(const char *s1
, const char *s2
)
620 while (*s1
&& *s1
== *s2
) {
627 if (!*s1
&& *s2
== '\n' && !s2
[1])
629 if (*s1
== '\n' && !s1
[1] && !*s2
)
633 EXPORT_SYMBOL(sysfs_streq
);
636 * match_string - matches given string in an array
637 * @array: array of strings
638 * @n: number of strings in the array or -1 for NULL terminated arrays
639 * @string: string to match with
642 * index of a @string in the @array if matches, or %-EINVAL otherwise.
644 int match_string(const char * const *array
, size_t n
, const char *string
)
649 for (index
= 0; index
< n
; index
++) {
653 if (!strcmp(item
, string
))
659 EXPORT_SYMBOL(match_string
);
662 * __sysfs_match_string - matches given string in an array
663 * @array: array of strings
664 * @n: number of strings in the array or -1 for NULL terminated arrays
665 * @str: string to match with
667 * Returns index of @str in the @array or -EINVAL, just like match_string().
668 * Uses sysfs_streq instead of strcmp for matching.
670 int __sysfs_match_string(const char * const *array
, size_t n
, const char *str
)
675 for (index
= 0; index
< n
; index
++) {
679 if (sysfs_streq(item
, str
))
685 EXPORT_SYMBOL(__sysfs_match_string
);
687 #ifndef __HAVE_ARCH_MEMSET
689 * memset - Fill a region of memory with the given value
690 * @s: Pointer to the start of the area.
691 * @c: The byte to fill the area with
692 * @count: The size of the area.
694 * Do not use memset() to access IO space, use memset_io() instead.
696 void *memset(void *s
, int c
, size_t count
)
704 EXPORT_SYMBOL(memset
);
708 * memzero_explicit - Fill a region of memory (e.g. sensitive
709 * keying data) with 0s.
710 * @s: Pointer to the start of the area.
711 * @count: The size of the area.
713 * Note: usually using memset() is just fine (!), but in cases
714 * where clearing out _local_ data at the end of a scope is
715 * necessary, memzero_explicit() should be used instead in
716 * order to prevent the compiler from optimising away zeroing.
718 * memzero_explicit() doesn't need an arch-specific version as
719 * it just invokes the one of memset() implicitly.
721 void memzero_explicit(void *s
, size_t count
)
726 EXPORT_SYMBOL(memzero_explicit
);
728 #ifndef __HAVE_ARCH_MEMSET16
730 * memset16() - Fill a memory area with a uint16_t
731 * @s: Pointer to the start of the area.
732 * @v: The value to fill the area with
733 * @count: The number of values to store
735 * Differs from memset() in that it fills with a uint16_t instead
736 * of a byte. Remember that @count is the number of uint16_ts to
737 * store, not the number of bytes.
739 void *memset16(uint16_t *s
, uint16_t v
, size_t count
)
747 EXPORT_SYMBOL(memset16
);
750 #ifndef __HAVE_ARCH_MEMSET32
752 * memset32() - Fill a memory area with a uint32_t
753 * @s: Pointer to the start of the area.
754 * @v: The value to fill the area with
755 * @count: The number of values to store
757 * Differs from memset() in that it fills with a uint32_t instead
758 * of a byte. Remember that @count is the number of uint32_ts to
759 * store, not the number of bytes.
761 void *memset32(uint32_t *s
, uint32_t v
, size_t count
)
769 EXPORT_SYMBOL(memset32
);
772 #ifndef __HAVE_ARCH_MEMSET64
774 * memset64() - Fill a memory area with a uint64_t
775 * @s: Pointer to the start of the area.
776 * @v: The value to fill the area with
777 * @count: The number of values to store
779 * Differs from memset() in that it fills with a uint64_t instead
780 * of a byte. Remember that @count is the number of uint64_ts to
781 * store, not the number of bytes.
783 void *memset64(uint64_t *s
, uint64_t v
, size_t count
)
791 EXPORT_SYMBOL(memset64
);
794 #ifndef __HAVE_ARCH_MEMCPY
796 * memcpy - Copy one area of memory to another
797 * @dest: Where to copy to
798 * @src: Where to copy from
799 * @count: The size of the area.
801 * You should not use this function to access IO space, use memcpy_toio()
802 * or memcpy_fromio() instead.
804 void *memcpy(void *dest
, const void *src
, size_t count
)
813 EXPORT_SYMBOL(memcpy
);
816 #ifndef __HAVE_ARCH_MEMMOVE
818 * memmove - Copy one area of memory to another
819 * @dest: Where to copy to
820 * @src: Where to copy from
821 * @count: The size of the area.
823 * Unlike memcpy(), memmove() copes with overlapping areas.
825 void *memmove(void *dest
, const void *src
, size_t count
)
845 EXPORT_SYMBOL(memmove
);
848 #ifndef __HAVE_ARCH_MEMCMP
850 * memcmp - Compare two areas of memory
851 * @cs: One area of memory
852 * @ct: Another area of memory
853 * @count: The size of the area.
856 __visible
int memcmp(const void *cs
, const void *ct
, size_t count
)
858 const unsigned char *su1
, *su2
;
861 for (su1
= cs
, su2
= ct
; 0 < count
; ++su1
, ++su2
, count
--)
862 if ((res
= *su1
- *su2
) != 0)
866 EXPORT_SYMBOL(memcmp
);
869 #ifndef __HAVE_ARCH_MEMSCAN
871 * memscan - Find a character in an area of memory.
872 * @addr: The memory area
873 * @c: The byte to search for
874 * @size: The size of the area.
876 * returns the address of the first occurrence of @c, or 1 byte past
877 * the area if @c is not found
879 void *memscan(void *addr
, int c
, size_t size
)
881 unsigned char *p
= addr
;
891 EXPORT_SYMBOL(memscan
);
894 #ifndef __HAVE_ARCH_STRSTR
896 * strstr - Find the first substring in a %NUL terminated string
897 * @s1: The string to be searched
898 * @s2: The string to search for
900 char *strstr(const char *s1
, const char *s2
)
910 if (!memcmp(s1
, s2
, l2
))
916 EXPORT_SYMBOL(strstr
);
919 #ifndef __HAVE_ARCH_STRNSTR
921 * strnstr - Find the first substring in a length-limited string
922 * @s1: The string to be searched
923 * @s2: The string to search for
924 * @len: the maximum number of characters to search
926 char *strnstr(const char *s1
, const char *s2
, size_t len
)
935 if (!memcmp(s1
, s2
, l2
))
941 EXPORT_SYMBOL(strnstr
);
944 #ifndef __HAVE_ARCH_MEMCHR
946 * memchr - Find a character in an area of memory.
947 * @s: The memory area
948 * @c: The byte to search for
949 * @n: The size of the area.
951 * returns the address of the first occurrence of @c, or %NULL
954 void *memchr(const void *s
, int c
, size_t n
)
956 const unsigned char *p
= s
;
958 if ((unsigned char)c
== *p
++) {
959 return (void *)(p
- 1);
964 EXPORT_SYMBOL(memchr
);
967 static void *check_bytes8(const u8
*start
, u8 value
, unsigned int bytes
)
971 return (void *)start
;
979 * memchr_inv - Find an unmatching character in an area of memory.
980 * @start: The memory area
981 * @c: Find a character other than c
982 * @bytes: The size of the area.
984 * returns the address of the first character other than @c, or %NULL
985 * if the whole buffer contains just @c.
987 void *memchr_inv(const void *start
, int c
, size_t bytes
)
991 unsigned int words
, prefix
;
994 return check_bytes8(start
, value
, bytes
);
997 #if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
998 value64
*= 0x0101010101010101ULL
;
999 #elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
1000 value64
*= 0x01010101;
1001 value64
|= value64
<< 32;
1003 value64
|= value64
<< 8;
1004 value64
|= value64
<< 16;
1005 value64
|= value64
<< 32;
1008 prefix
= (unsigned long)start
% 8;
1012 prefix
= 8 - prefix
;
1013 r
= check_bytes8(start
, value
, prefix
);
1023 if (*(u64
*)start
!= value64
)
1024 return check_bytes8(start
, value
, 8);
1029 return check_bytes8(start
, value
, bytes
% 8);
1031 EXPORT_SYMBOL(memchr_inv
);
1034 * strreplace - Replace all occurrences of character in string.
1035 * @s: The string to operate on.
1036 * @old: The character being replaced.
1037 * @new: The character @old is replaced with.
1039 * Returns pointer to the nul byte at the end of @s.
1041 char *strreplace(char *s
, char old
, char new)
1048 EXPORT_SYMBOL(strreplace
);
1050 void fortify_panic(const char *name
)
1052 pr_emerg("detected buffer overflow in %s\n", name
);
1055 EXPORT_SYMBOL(fortify_panic
);