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);
276 * stpcpy - copy a string from src to dest returning a pointer to the new end
277 * of dest, including src's %NUL-terminator. May overrun dest.
278 * @dest: pointer to end of string being copied into. Must be large enough
280 * @src: pointer to the beginning of string being copied from. Must not overlap
283 * stpcpy differs from strcpy in a key way: the return value is a pointer
284 * to the new %NUL-terminating character in @dest. (For strcpy, the return
285 * value is a pointer to the start of @dest). This interface is considered
286 * unsafe as it doesn't perform bounds checking of the inputs. As such it's
287 * not recommended for usage. Instead, its definition is provided in case
288 * the compiler lowers other libcalls to stpcpy.
290 char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
291 char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
293 while ((*dest++ = *src++) != '\0')
297 EXPORT_SYMBOL(stpcpy);
299 #ifndef __HAVE_ARCH_STRCAT
301 * strcat - Append one %NUL-terminated string to another
302 * @dest: The string to be appended to
303 * @src: The string to append to it
306 char *strcat(char *dest, const char *src)
312 while ((*dest++ = *src++) != '\0')
316 EXPORT_SYMBOL(strcat);
319 #ifndef __HAVE_ARCH_STRNCAT
321 * strncat - Append a length-limited, C-string to another
322 * @dest: The string to be appended to
323 * @src: The string to append to it
324 * @count: The maximum numbers of bytes to copy
326 * Note that in contrast to strncpy(), strncat() ensures the result is
329 char *strncat(char *dest, const char *src, size_t count)
336 while ((*dest++ = *src++) != 0) {
345 EXPORT_SYMBOL(strncat);
348 #ifndef __HAVE_ARCH_STRLCAT
350 * strlcat - Append a length-limited, C-string to another
351 * @dest: The string to be appended to
352 * @src: The string to append to it
353 * @count: The size of the destination buffer.
355 size_t strlcat(char *dest, const char *src, size_t count)
357 size_t dsize = strlen(dest);
358 size_t len = strlen(src);
359 size_t res = dsize + len;
361 /* This would be a bug */
362 BUG_ON(dsize >= count);
368 memcpy(dest, src, len);
372 EXPORT_SYMBOL(strlcat);
375 #ifndef __HAVE_ARCH_STRCMP
377 * strcmp - Compare two strings
379 * @ct: Another string
382 int strcmp(const char *cs, const char *ct)
384 unsigned char c1, c2;
390 return c1 < c2 ? -1 : 1;
396 EXPORT_SYMBOL(strcmp);
399 #ifndef __HAVE_ARCH_STRNCMP
401 * strncmp - Compare two length-limited strings
403 * @ct: Another string
404 * @count: The maximum number of bytes to compare
406 int strncmp(const char *cs, const char *ct, size_t count)
408 unsigned char c1, c2;
414 return c1 < c2 ? -1 : 1;
421 EXPORT_SYMBOL(strncmp);
424 #ifndef __HAVE_ARCH_STRCHR
426 * strchr - Find the first occurrence of a character in a string
427 * @s: The string to be searched
428 * @c: The character to search for
430 * Note that the %NUL-terminator is considered part of the string, and can
433 char *strchr(const char *s, int c)
435 for (; *s != (char)c; ++s)
440 EXPORT_SYMBOL(strchr);
443 #ifndef __HAVE_ARCH_STRCHRNUL
445 * strchrnul - Find and return a character in a string, or end of string
446 * @s: The string to be searched
447 * @c: The character to search for
449 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
450 * return a pointer to the null byte at the end of s.
452 char *strchrnul(const char *s, int c)
454 while (*s && *s != (char)c)
458 EXPORT_SYMBOL(strchrnul);
461 #ifndef __HAVE_ARCH_STRRCHR
463 * strrchr - Find the last occurrence of a character in a string
464 * @s: The string to be searched
465 * @c: The character to search for
467 char *strrchr(const char *s, int c)
469 const char *last = NULL;
476 EXPORT_SYMBOL(strrchr);
479 #ifndef __HAVE_ARCH_STRNCHR
481 * strnchr - Find a character in a length limited string
482 * @s: The string to be searched
483 * @count: The number of characters to be searched
484 * @c: The character to search for
486 * Note that the %NUL-terminator is considered part of the string, and can
489 char *strnchr(const char *s, size_t count, int c)
499 EXPORT_SYMBOL(strnchr);
503 * skip_spaces - Removes leading whitespace from @str.
504 * @str: The string to be stripped.
506 * Returns a pointer to the first non-whitespace character in @str.
508 char *skip_spaces(const char *str)
510 while (isspace(*str))
514 EXPORT_SYMBOL(skip_spaces);
517 * strim - Removes leading and trailing whitespace from @s.
518 * @s: The string to be stripped.
520 * Note that the first trailing whitespace is replaced with a %NUL-terminator
521 * in the given string @s. Returns a pointer to the first non-whitespace
534 while (end >= s && isspace(*end))
538 return skip_spaces(s);
540 EXPORT_SYMBOL(strim);
542 #ifndef __HAVE_ARCH_STRLEN
544 * strlen - Find the length of a string
545 * @s: The string to be sized
547 size_t strlen(const char *s)
551 for (sc = s; *sc != '\0'; ++sc)
555 EXPORT_SYMBOL(strlen);
558 #ifndef __HAVE_ARCH_STRNLEN
560 * strnlen - Find the length of a length-limited string
561 * @s: The string to be sized
562 * @count: The maximum number of bytes to search
564 size_t strnlen(const char *s, size_t count)
568 for (sc = s; count-- && *sc != '\0'; ++sc)
572 EXPORT_SYMBOL(strnlen);
575 #ifndef __HAVE_ARCH_STRSPN
577 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
578 * @s: The string to be searched
579 * @accept: The string to search for
581 size_t strspn(const char *s, const char *accept)
587 for (p = s; *p != '\0'; ++p) {
588 for (a = accept; *a != '\0'; ++a) {
599 EXPORT_SYMBOL(strspn);
602 #ifndef __HAVE_ARCH_STRCSPN
604 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
605 * @s: The string to be searched
606 * @reject: The string to avoid
608 size_t strcspn(const char *s, const char *reject)
614 for (p = s; *p != '\0'; ++p) {
615 for (r = reject; *r != '\0'; ++r) {
623 EXPORT_SYMBOL(strcspn);
626 #ifndef __HAVE_ARCH_STRPBRK
628 * strpbrk - Find the first occurrence of a set of characters
629 * @cs: The string to be searched
630 * @ct: The characters to search for
632 char *strpbrk(const char *cs, const char *ct)
634 const char *sc1, *sc2;
636 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
637 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
644 EXPORT_SYMBOL(strpbrk);
647 #ifndef __HAVE_ARCH_STRSEP
649 * strsep - Split a string into tokens
650 * @s: The string to be searched
651 * @ct: The characters to search for
653 * strsep() updates @s to point after the token, ready for the next call.
655 * It returns empty tokens, too, behaving exactly like the libc function
656 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
657 * Same semantics, slimmer shape. ;)
659 char *strsep(char **s, const char *ct)
667 end = strpbrk(sbegin, ct);
673 EXPORT_SYMBOL(strsep);
677 * sysfs_streq - return true if strings are equal, modulo trailing newline
679 * @s2: another string
681 * This routine returns true iff two strings are equal, treating both
682 * NUL and newline-then-NUL as equivalent string terminations. It's
683 * geared for use with sysfs input strings, which generally terminate
684 * with newlines but are compared against values without newlines.
686 bool sysfs_streq(const char *s1, const char *s2)
688 while (*s1 && *s1 == *s2) {
695 if (!*s1 && *s2 == '\n' && !s2[1])
697 if (*s1 == '\n' && !s1[1] && !*s2)
701 EXPORT_SYMBOL(sysfs_streq);
704 * match_string - matches given string in an array
705 * @array: array of strings
706 * @n: number of strings in the array or -1 for NULL terminated arrays
707 * @string: string to match with
710 * index of a @string in the @array if matches, or %-EINVAL otherwise.
712 int match_string(const char * const *array, size_t n, const char *string)
717 for (index = 0; index < n; index++) {
721 if (!strcmp(item, string))
727 EXPORT_SYMBOL(match_string);
730 * __sysfs_match_string - matches given string in an array
731 * @array: array of strings
732 * @n: number of strings in the array or -1 for NULL terminated arrays
733 * @str: string to match with
735 * Returns index of @str in the @array or -EINVAL, just like match_string().
736 * Uses sysfs_streq instead of strcmp for matching.
738 int __sysfs_match_string(const char * const *array, size_t n, const char *str)
743 for (index = 0; index < n; index++) {
747 if (sysfs_streq(item, str))
753 EXPORT_SYMBOL(__sysfs_match_string);
755 #ifndef __HAVE_ARCH_MEMSET
757 * memset - Fill a region of memory with the given value
758 * @s: Pointer to the start of the area.
759 * @c: The byte to fill the area with
760 * @count: The size of the area.
762 * Do not use memset() to access IO space, use memset_io() instead.
764 void *memset(void *s, int c, size_t count)
772 EXPORT_SYMBOL(memset);
775 #ifndef __HAVE_ARCH_MEMSET16
777 * memset16() - Fill a memory area with a uint16_t
778 * @s: Pointer to the start of the area.
779 * @v: The value to fill the area with
780 * @count: The number of values to store
782 * Differs from memset() in that it fills with a uint16_t instead
783 * of a byte. Remember that @count is the number of uint16_ts to
784 * store, not the number of bytes.
786 void *memset16(uint16_t *s, uint16_t v, size_t count)
794 EXPORT_SYMBOL(memset16);
797 #ifndef __HAVE_ARCH_MEMSET32
799 * memset32() - Fill a memory area with a uint32_t
800 * @s: Pointer to the start of the area.
801 * @v: The value to fill the area with
802 * @count: The number of values to store
804 * Differs from memset() in that it fills with a uint32_t instead
805 * of a byte. Remember that @count is the number of uint32_ts to
806 * store, not the number of bytes.
808 void *memset32(uint32_t *s, uint32_t v, size_t count)
816 EXPORT_SYMBOL(memset32);
819 #ifndef __HAVE_ARCH_MEMSET64
821 * memset64() - Fill a memory area with a uint64_t
822 * @s: Pointer to the start of the area.
823 * @v: The value to fill the area with
824 * @count: The number of values to store
826 * Differs from memset() in that it fills with a uint64_t instead
827 * of a byte. Remember that @count is the number of uint64_ts to
828 * store, not the number of bytes.
830 void *memset64(uint64_t *s, uint64_t v, size_t count)
838 EXPORT_SYMBOL(memset64);
841 #ifndef __HAVE_ARCH_MEMCPY
843 * memcpy - Copy one area of memory to another
844 * @dest: Where to copy to
845 * @src: Where to copy from
846 * @count: The size of the area.
848 * You should not use this function to access IO space, use memcpy_toio()
849 * or memcpy_fromio() instead.
851 void *memcpy(void *dest, const void *src, size_t count)
860 EXPORT_SYMBOL(memcpy);
863 #ifndef __HAVE_ARCH_MEMMOVE
865 * memmove - Copy one area of memory to another
866 * @dest: Where to copy to
867 * @src: Where to copy from
868 * @count: The size of the area.
870 * Unlike memcpy(), memmove() copes with overlapping areas.
872 void *memmove(void *dest, const void *src, size_t count)
892 EXPORT_SYMBOL(memmove);
895 #ifndef __HAVE_ARCH_MEMCMP
897 * memcmp - Compare two areas of memory
898 * @cs: One area of memory
899 * @ct: Another area of memory
900 * @count: The size of the area.
903 __visible int memcmp(const void *cs, const void *ct, size_t count)
905 const unsigned char *su1, *su2;
908 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
909 if ((res = *su1 - *su2) != 0)
913 EXPORT_SYMBOL(memcmp);
916 #ifndef __HAVE_ARCH_BCMP
918 * bcmp - returns 0 if and only if the buffers have identical contents.
919 * @a: pointer to first buffer.
920 * @b: pointer to second buffer.
921 * @len: size of buffers.
923 * The sign or magnitude of a non-zero return value has no particular
924 * meaning, and architectures may implement their own more efficient bcmp(). So
925 * while this particular implementation is a simple (tail) call to memcmp, do
926 * not rely on anything but whether the return value is zero or non-zero.
929 int bcmp(const void *a, const void *b, size_t len)
931 return memcmp(a, b, len);
936 #ifndef __HAVE_ARCH_MEMSCAN
938 * memscan - Find a character in an area of memory.
939 * @addr: The memory area
940 * @c: The byte to search for
941 * @size: The size of the area.
943 * returns the address of the first occurrence of @c, or 1 byte past
944 * the area if @c is not found
946 void *memscan(void *addr, int c, size_t size)
948 unsigned char *p = addr;
958 EXPORT_SYMBOL(memscan);
961 #ifndef __HAVE_ARCH_STRSTR
963 * strstr - Find the first substring in a %NUL terminated string
964 * @s1: The string to be searched
965 * @s2: The string to search for
967 char *strstr(const char *s1, const char *s2)
977 if (!memcmp(s1, s2, l2))
983 EXPORT_SYMBOL(strstr);
986 #ifndef __HAVE_ARCH_STRNSTR
988 * strnstr - Find the first substring in a length-limited string
989 * @s1: The string to be searched
990 * @s2: The string to search for
991 * @len: the maximum number of characters to search
993 char *strnstr(const char *s1, const char *s2, size_t len)
1002 if (!memcmp(s1, s2, l2))
1008 EXPORT_SYMBOL(strnstr);
1011 #ifndef __HAVE_ARCH_MEMCHR
1013 * memchr - Find a character in an area of memory.
1014 * @s: The memory area
1015 * @c: The byte to search for
1016 * @n: The size of the area.
1018 * returns the address of the first occurrence of @c, or %NULL
1019 * if @c is not found
1021 void *memchr(const void *s, int c, size_t n)
1023 const unsigned char *p = s;
1025 if ((unsigned char)c == *p++) {
1026 return (void *)(p - 1);
1031 EXPORT_SYMBOL(memchr);
1034 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
1037 if (*start != value)
1038 return (void *)start;
1046 * memchr_inv - Find an unmatching character in an area of memory.
1047 * @start: The memory area
1048 * @c: Find a character other than c
1049 * @bytes: The size of the area.
1051 * returns the address of the first character other than @c, or %NULL
1052 * if the whole buffer contains just @c.
1054 void *memchr_inv(const void *start, int c, size_t bytes)
1058 unsigned int words, prefix;
1061 return check_bytes8(start, value, bytes);
1064 #if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
1065 value64 *= 0x0101010101010101ULL;
1066 #elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
1067 value64 *= 0x01010101;
1068 value64 |= value64 << 32;
1070 value64 |= value64 << 8;
1071 value64 |= value64 << 16;
1072 value64 |= value64 << 32;
1075 prefix = (unsigned long)start % 8;
1079 prefix = 8 - prefix;
1080 r = check_bytes8(start, value, prefix);
1090 if (*(u64 *)start != value64)
1091 return check_bytes8(start, value, 8);
1096 return check_bytes8(start, value, bytes % 8);
1098 EXPORT_SYMBOL(memchr_inv);
1101 * strreplace - Replace all occurrences of character in string.
1102 * @s: The string to operate on.
1103 * @old: The character being replaced.
1104 * @new: The character @old is replaced with.
1106 * Returns pointer to the nul byte at the end of @s.
1108 char *strreplace(char *s, char old, char new)
1115 EXPORT_SYMBOL(strreplace);
1117 void fortify_panic(const char *name)
1119 pr_emerg("detected buffer overflow in %s\n", name);
1122 EXPORT_SYMBOL(fortify_panic);