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().
176 * Return: The number of characters copied (not including the trailing
177 * %NUL) or -E2BIG if the destination buffer wasn't big enough.
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);
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().
256 * Return: The number of characters copied (not including the trailing
257 * %NUL) or -E2BIG if the destination buffer wasn't big enough.
259 ssize_t strscpy_pad(char *dest, const char *src, size_t count)
263 written = strscpy(dest, src, count);
264 if (written < 0 || written == count - 1)
267 memset(dest + written + 1, 0, count - written - 1);
271 EXPORT_SYMBOL(strscpy_pad);
273 #ifndef __HAVE_ARCH_STRCAT
275 * strcat - Append one %NUL-terminated string to another
276 * @dest: The string to be appended to
277 * @src: The string to append to it
280 char *strcat(char *dest, const char *src)
286 while ((*dest++ = *src++) != '\0')
290 EXPORT_SYMBOL(strcat);
293 #ifndef __HAVE_ARCH_STRNCAT
295 * strncat - Append a length-limited, C-string to another
296 * @dest: The string to be appended to
297 * @src: The string to append to it
298 * @count: The maximum numbers of bytes to copy
300 * Note that in contrast to strncpy(), strncat() ensures the result is
303 char *strncat(char *dest, const char *src, size_t count)
310 while ((*dest++ = *src++) != 0) {
319 EXPORT_SYMBOL(strncat);
322 #ifndef __HAVE_ARCH_STRLCAT
324 * strlcat - Append a length-limited, C-string to another
325 * @dest: The string to be appended to
326 * @src: The string to append to it
327 * @count: The size of the destination buffer.
329 size_t strlcat(char *dest, const char *src, size_t count)
331 size_t dsize = strlen(dest);
332 size_t len = strlen(src);
333 size_t res = dsize + len;
335 /* This would be a bug */
336 BUG_ON(dsize >= count);
342 memcpy(dest, src, len);
346 EXPORT_SYMBOL(strlcat);
349 #ifndef __HAVE_ARCH_STRCMP
351 * strcmp - Compare two strings
353 * @ct: Another string
356 int strcmp(const char *cs, const char *ct)
358 unsigned char c1, c2;
364 return c1 < c2 ? -1 : 1;
370 EXPORT_SYMBOL(strcmp);
373 #ifndef __HAVE_ARCH_STRNCMP
375 * strncmp - Compare two length-limited strings
377 * @ct: Another string
378 * @count: The maximum number of bytes to compare
380 int strncmp(const char *cs, const char *ct, size_t count)
382 unsigned char c1, c2;
388 return c1 < c2 ? -1 : 1;
395 EXPORT_SYMBOL(strncmp);
398 #ifndef __HAVE_ARCH_STRCHR
400 * strchr - Find the first occurrence of a character in a string
401 * @s: The string to be searched
402 * @c: The character to search for
404 * Note that the %NUL-terminator is considered part of the string, and can
407 char *strchr(const char *s, int c)
409 for (; *s != (char)c; ++s)
414 EXPORT_SYMBOL(strchr);
417 #ifndef __HAVE_ARCH_STRCHRNUL
419 * strchrnul - Find and return a character in a string, or end of string
420 * @s: The string to be searched
421 * @c: The character to search for
423 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
424 * return a pointer to the null byte at the end of s.
426 char *strchrnul(const char *s, int c)
428 while (*s && *s != (char)c)
432 EXPORT_SYMBOL(strchrnul);
435 #ifndef __HAVE_ARCH_STRRCHR
437 * strrchr - Find the last occurrence of a character in a string
438 * @s: The string to be searched
439 * @c: The character to search for
441 char *strrchr(const char *s, int c)
443 const char *last = NULL;
450 EXPORT_SYMBOL(strrchr);
453 #ifndef __HAVE_ARCH_STRNCHR
455 * strnchr - Find a character in a length limited string
456 * @s: The string to be searched
457 * @count: The number of characters to be searched
458 * @c: The character to search for
460 * Note that the %NUL-terminator is considered part of the string, and can
463 char *strnchr(const char *s, size_t count, int c)
473 EXPORT_SYMBOL(strnchr);
477 * skip_spaces - Removes leading whitespace from @str.
478 * @str: The string to be stripped.
480 * Returns a pointer to the first non-whitespace character in @str.
482 char *skip_spaces(const char *str)
484 while (isspace(*str))
488 EXPORT_SYMBOL(skip_spaces);
491 * strim - Removes leading and trailing whitespace from @s.
492 * @s: The string to be stripped.
494 * Note that the first trailing whitespace is replaced with a %NUL-terminator
495 * in the given string @s. Returns a pointer to the first non-whitespace
508 while (end >= s && isspace(*end))
512 return skip_spaces(s);
514 EXPORT_SYMBOL(strim);
516 #ifndef __HAVE_ARCH_STRLEN
518 * strlen - Find the length of a string
519 * @s: The string to be sized
521 size_t strlen(const char *s)
525 for (sc = s; *sc != '\0'; ++sc)
529 EXPORT_SYMBOL(strlen);
532 #ifndef __HAVE_ARCH_STRNLEN
534 * strnlen - Find the length of a length-limited string
535 * @s: The string to be sized
536 * @count: The maximum number of bytes to search
538 size_t strnlen(const char *s, size_t count)
542 for (sc = s; count-- && *sc != '\0'; ++sc)
546 EXPORT_SYMBOL(strnlen);
549 #ifndef __HAVE_ARCH_STRSPN
551 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
552 * @s: The string to be searched
553 * @accept: The string to search for
555 size_t strspn(const char *s, const char *accept)
561 for (p = s; *p != '\0'; ++p) {
562 for (a = accept; *a != '\0'; ++a) {
573 EXPORT_SYMBOL(strspn);
576 #ifndef __HAVE_ARCH_STRCSPN
578 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
579 * @s: The string to be searched
580 * @reject: The string to avoid
582 size_t strcspn(const char *s, const char *reject)
588 for (p = s; *p != '\0'; ++p) {
589 for (r = reject; *r != '\0'; ++r) {
597 EXPORT_SYMBOL(strcspn);
600 #ifndef __HAVE_ARCH_STRPBRK
602 * strpbrk - Find the first occurrence of a set of characters
603 * @cs: The string to be searched
604 * @ct: The characters to search for
606 char *strpbrk(const char *cs, const char *ct)
608 const char *sc1, *sc2;
610 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
611 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
618 EXPORT_SYMBOL(strpbrk);
621 #ifndef __HAVE_ARCH_STRSEP
623 * strsep - Split a string into tokens
624 * @s: The string to be searched
625 * @ct: The characters to search for
627 * strsep() updates @s to point after the token, ready for the next call.
629 * It returns empty tokens, too, behaving exactly like the libc function
630 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
631 * Same semantics, slimmer shape. ;)
633 char *strsep(char **s, const char *ct)
641 end = strpbrk(sbegin, ct);
647 EXPORT_SYMBOL(strsep);
651 * sysfs_streq - return true if strings are equal, modulo trailing newline
653 * @s2: another string
655 * This routine returns true iff two strings are equal, treating both
656 * NUL and newline-then-NUL as equivalent string terminations. It's
657 * geared for use with sysfs input strings, which generally terminate
658 * with newlines but are compared against values without newlines.
660 bool sysfs_streq(const char *s1, const char *s2)
662 while (*s1 && *s1 == *s2) {
669 if (!*s1 && *s2 == '\n' && !s2[1])
671 if (*s1 == '\n' && !s1[1] && !*s2)
675 EXPORT_SYMBOL(sysfs_streq);
678 * match_string - matches given string in an array
679 * @array: array of strings
680 * @n: number of strings in the array or -1 for NULL terminated arrays
681 * @string: string to match with
684 * index of a @string in the @array if matches, or %-EINVAL otherwise.
686 int match_string(const char * const *array, size_t n, const char *string)
691 for (index = 0; index < n; index++) {
695 if (!strcmp(item, string))
701 EXPORT_SYMBOL(match_string);
704 * __sysfs_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 * @str: string to match with
709 * Returns index of @str in the @array or -EINVAL, just like match_string().
710 * Uses sysfs_streq instead of strcmp for matching.
712 int __sysfs_match_string(const char * const *array, size_t n, const char *str)
717 for (index = 0; index < n; index++) {
721 if (sysfs_streq(item, str))
727 EXPORT_SYMBOL(__sysfs_match_string);
729 #ifndef __HAVE_ARCH_MEMSET
731 * memset - Fill a region of memory with the given value
732 * @s: Pointer to the start of the area.
733 * @c: The byte to fill the area with
734 * @count: The size of the area.
736 * Do not use memset() to access IO space, use memset_io() instead.
738 void *memset(void *s, int c, size_t count)
746 EXPORT_SYMBOL(memset);
750 * memzero_explicit - Fill a region of memory (e.g. sensitive
751 * keying data) with 0s.
752 * @s: Pointer to the start of the area.
753 * @count: The size of the area.
755 * Note: usually using memset() is just fine (!), but in cases
756 * where clearing out _local_ data at the end of a scope is
757 * necessary, memzero_explicit() should be used instead in
758 * order to prevent the compiler from optimising away zeroing.
760 * memzero_explicit() doesn't need an arch-specific version as
761 * it just invokes the one of memset() implicitly.
763 void memzero_explicit(void *s, size_t count)
768 EXPORT_SYMBOL(memzero_explicit);
770 #ifndef __HAVE_ARCH_MEMSET16
772 * memset16() - Fill a memory area with a uint16_t
773 * @s: Pointer to the start of the area.
774 * @v: The value to fill the area with
775 * @count: The number of values to store
777 * Differs from memset() in that it fills with a uint16_t instead
778 * of a byte. Remember that @count is the number of uint16_ts to
779 * store, not the number of bytes.
781 void *memset16(uint16_t *s, uint16_t v, size_t count)
789 EXPORT_SYMBOL(memset16);
792 #ifndef __HAVE_ARCH_MEMSET32
794 * memset32() - Fill a memory area with a uint32_t
795 * @s: Pointer to the start of the area.
796 * @v: The value to fill the area with
797 * @count: The number of values to store
799 * Differs from memset() in that it fills with a uint32_t instead
800 * of a byte. Remember that @count is the number of uint32_ts to
801 * store, not the number of bytes.
803 void *memset32(uint32_t *s, uint32_t v, size_t count)
811 EXPORT_SYMBOL(memset32);
814 #ifndef __HAVE_ARCH_MEMSET64
816 * memset64() - Fill a memory area with a uint64_t
817 * @s: Pointer to the start of the area.
818 * @v: The value to fill the area with
819 * @count: The number of values to store
821 * Differs from memset() in that it fills with a uint64_t instead
822 * of a byte. Remember that @count is the number of uint64_ts to
823 * store, not the number of bytes.
825 void *memset64(uint64_t *s, uint64_t v, size_t count)
833 EXPORT_SYMBOL(memset64);
836 #ifndef __HAVE_ARCH_MEMCPY
838 * memcpy - Copy one area of memory to another
839 * @dest: Where to copy to
840 * @src: Where to copy from
841 * @count: The size of the area.
843 * You should not use this function to access IO space, use memcpy_toio()
844 * or memcpy_fromio() instead.
846 void *memcpy(void *dest, const void *src, size_t count)
855 EXPORT_SYMBOL(memcpy);
858 #ifndef __HAVE_ARCH_MEMMOVE
860 * memmove - Copy one area of memory to another
861 * @dest: Where to copy to
862 * @src: Where to copy from
863 * @count: The size of the area.
865 * Unlike memcpy(), memmove() copes with overlapping areas.
867 void *memmove(void *dest, const void *src, size_t count)
887 EXPORT_SYMBOL(memmove);
890 #ifndef __HAVE_ARCH_MEMCMP
892 * memcmp - Compare two areas of memory
893 * @cs: One area of memory
894 * @ct: Another area of memory
895 * @count: The size of the area.
898 __visible int memcmp(const void *cs, const void *ct, size_t count)
900 const unsigned char *su1, *su2;
903 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
904 if ((res = *su1 - *su2) != 0)
908 EXPORT_SYMBOL(memcmp);
911 #ifndef __HAVE_ARCH_BCMP
913 * bcmp - returns 0 if and only if the buffers have identical contents.
914 * @a: pointer to first buffer.
915 * @b: pointer to second buffer.
916 * @len: size of buffers.
918 * The sign or magnitude of a non-zero return value has no particular
919 * meaning, and architectures may implement their own more efficient bcmp(). So
920 * while this particular implementation is a simple (tail) call to memcmp, do
921 * not rely on anything but whether the return value is zero or non-zero.
924 int bcmp(const void *a, const void *b, size_t len)
926 return memcmp(a, b, len);
931 #ifndef __HAVE_ARCH_MEMSCAN
933 * memscan - Find a character in an area of memory.
934 * @addr: The memory area
935 * @c: The byte to search for
936 * @size: The size of the area.
938 * returns the address of the first occurrence of @c, or 1 byte past
939 * the area if @c is not found
941 void *memscan(void *addr, int c, size_t size)
943 unsigned char *p = addr;
953 EXPORT_SYMBOL(memscan);
956 #ifndef __HAVE_ARCH_STRSTR
958 * strstr - Find the first substring in a %NUL terminated string
959 * @s1: The string to be searched
960 * @s2: The string to search for
962 char *strstr(const char *s1, const char *s2)
972 if (!memcmp(s1, s2, l2))
978 EXPORT_SYMBOL(strstr);
981 #ifndef __HAVE_ARCH_STRNSTR
983 * strnstr - Find the first substring in a length-limited string
984 * @s1: The string to be searched
985 * @s2: The string to search for
986 * @len: the maximum number of characters to search
988 char *strnstr(const char *s1, const char *s2, size_t len)
997 if (!memcmp(s1, s2, l2))
1003 EXPORT_SYMBOL(strnstr);
1006 #ifndef __HAVE_ARCH_MEMCHR
1008 * memchr - Find a character in an area of memory.
1009 * @s: The memory area
1010 * @c: The byte to search for
1011 * @n: The size of the area.
1013 * returns the address of the first occurrence of @c, or %NULL
1014 * if @c is not found
1016 void *memchr(const void *s, int c, size_t n)
1018 const unsigned char *p = s;
1020 if ((unsigned char)c == *p++) {
1021 return (void *)(p - 1);
1026 EXPORT_SYMBOL(memchr);
1029 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
1032 if (*start != value)
1033 return (void *)start;
1041 * memchr_inv - Find an unmatching character in an area of memory.
1042 * @start: The memory area
1043 * @c: Find a character other than c
1044 * @bytes: The size of the area.
1046 * returns the address of the first character other than @c, or %NULL
1047 * if the whole buffer contains just @c.
1049 void *memchr_inv(const void *start, int c, size_t bytes)
1053 unsigned int words, prefix;
1056 return check_bytes8(start, value, bytes);
1059 #if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
1060 value64 *= 0x0101010101010101ULL;
1061 #elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
1062 value64 *= 0x01010101;
1063 value64 |= value64 << 32;
1065 value64 |= value64 << 8;
1066 value64 |= value64 << 16;
1067 value64 |= value64 << 32;
1070 prefix = (unsigned long)start % 8;
1074 prefix = 8 - prefix;
1075 r = check_bytes8(start, value, prefix);
1085 if (*(u64 *)start != value64)
1086 return check_bytes8(start, value, 8);
1091 return check_bytes8(start, value, bytes % 8);
1093 EXPORT_SYMBOL(memchr_inv);
1096 * strreplace - Replace all occurrences of character in string.
1097 * @s: The string to operate on.
1098 * @old: The character being replaced.
1099 * @new: The character @old is replaced with.
1101 * Returns pointer to the nul byte at the end of @s.
1103 char *strreplace(char *s, char old, char new)
1110 EXPORT_SYMBOL(strreplace);
1112 void fortify_panic(const char *name)
1114 pr_emerg("detected buffer overflow in %s\n", name);
1117 EXPORT_SYMBOL(fortify_panic);