cregit-Linux how code gets into the kernel

Release 4.7 lib/string.c

Directory: lib
/*
 *  linux/lib/string.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 * stupid library routines.. The optimized versions should generally be found
 * as inline code in <asm-xx/string.h>
 *
 * These are buggy as well..
 *
 * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de>
 * -  Added strsep() which will replace strtok() soon (because strsep() is
 *    reentrant and should be faster). Use only strsep() in new code, please.
 *
 * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>,
 *                    Matthew Hawkins <matt@mh.dropbear.id.au>
 * -  Kissed strtok() goodbye
 */

#include <linux/types.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/bug.h>
#include <linux/errno.h>

#include <asm/byteorder.h>
#include <asm/word-at-a-time.h>
#include <asm/page.h>

#ifndef __HAVE_ARCH_STRNCASECMP
/**
 * strncasecmp - Case insensitive, length-limited string comparison
 * @s1: One string
 * @s2: The other string
 * @len: the maximum number of characters to compare
 */

int strncasecmp(const char *s1, const char *s2, size_t len) { /* Yes, Virginia, it had better be unsigned */ unsigned char c1, c2; if (!len) return 0; do { c1 = *s1++; c2 = *s2++; if (!c1 || !c2) break; if (c1 == c2) continue; c1 = tolower(c1); c2 = tolower(c2); if (c1 != c2) break; } while (--len); return (int)c1 - (int)c2; }

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Total102100.00%3100.00%

EXPORT_SYMBOL(strncasecmp); #endif #ifndef __HAVE_ARCH_STRCASECMP
int strcasecmp(const char *s1, const char *s2) { int c1, c2; do { c1 = tolower(*s1++); c2 = tolower(*s2++); } while (c1 == c2 && c1 != 0); return c1 - c2; }

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david s. millerdavid s. miller5698.25%150.00%
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EXPORT_SYMBOL(strcasecmp); #endif #ifndef __HAVE_ARCH_STRCPY /** * strcpy - Copy a %NUL terminated string * @dest: Where to copy the string to * @src: Where to copy the string from */ #undef strcpy
char *strcpy(char *dest, const char *src) { char *tmp = dest; while ((*dest++ = *src++) != '\0') /* nothing */; return tmp; }

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EXPORT_SYMBOL(strcpy); #endif #ifndef __HAVE_ARCH_STRNCPY /** * strncpy - Copy a length-limited, C-string * @dest: Where to copy the string to * @src: Where to copy the string from * @count: The maximum number of bytes to copy * * The result is not %NUL-terminated if the source exceeds * @count bytes. * * In the case where the length of @src is less than that of * count, the remainder of @dest will be padded with %NUL. * */
char *strncpy(char *dest, const char *src, size_t count) { char *tmp = dest; while (count) { if ((*tmp = *src) != 0) src++; tmp++; count--; } return dest; }

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pre-gitpre-git3768.52%240.00%
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alan coxalan cox23.70%120.00%
Total54100.00%5100.00%

EXPORT_SYMBOL(strncpy); #endif #ifndef __HAVE_ARCH_STRLCPY /** * strlcpy - Copy a C-string into a sized buffer * @dest: Where to copy the string to * @src: Where to copy the string from * @size: size of destination buffer * * Compatible with *BSD: the result is always a valid * NUL-terminated string that fits in the buffer (unless, * of course, the buffer size is zero). It does not pad * out the result like strncpy() does. */
size_t strlcpy(char *dest, const char *src, size_t size) { size_t ret = strlen(src); if (size) { size_t len = (ret >= size) ? size - 1 : ret; memcpy(dest, src, len); dest[len] = '\0'; } return ret; }

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linus torvaldslinus torvalds65100.00%1100.00%
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EXPORT_SYMBOL(strlcpy); #endif #ifndef __HAVE_ARCH_STRSCPY /** * strscpy - Copy a C-string into a sized buffer * @dest: Where to copy the string to * @src: Where to copy the string from * @count: Size of destination buffer * * Copy the string, or as much of it as fits, into the dest buffer. * The routine returns the number of characters copied (not including * the trailing NUL) or -E2BIG if the destination buffer wasn't big enough. * The behavior is undefined if the string buffers overlap. * The destination buffer is always NUL terminated, unless it's zero-sized. * * Preferred to strlcpy() since the API doesn't require reading memory * from the src string beyond the specified "count" bytes, and since * the return value is easier to error-check than strlcpy()'s. * In addition, the implementation is robust to the string changing out * from underneath it, unlike the current strlcpy() implementation. * * Preferred to strncpy() since it always returns a valid string, and * doesn't unnecessarily force the tail of the destination buffer to be * zeroed. If the zeroing is desired, it's likely cleaner to use strscpy() * with an overflow test, then just memset() the tail of the dest buffer. */
ssize_t strscpy(char *dest, const char *src, size_t count) { const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; size_t max = count; long res = 0; if (count == 0) return -E2BIG; #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS /* * If src is unaligned, don't cross a page boundary, * since we don't know if the next page is mapped. */ if ((long)src & (sizeof(long) - 1)) { size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1)); if (limit < max) max = limit; } #else /* If src or dest is unaligned, don't do word-at-a-time. */ if (((long) dest | (long) src) & (sizeof(long) - 1)) max = 0; #endif while (max >= sizeof(unsigned long)) { unsigned long c, data; c = *(unsigned long *)(src+res); if (has_zero(c, &data, &constants)) { data = prep_zero_mask(c, data, &constants); data = create_zero_mask(data); *(unsigned long *)(dest+res) = c & zero_bytemask(data); return res + find_zero(data); } *(unsigned long *)(dest+res) = c; res += sizeof(unsigned long); count -= sizeof(unsigned long); max -= sizeof(unsigned long); } while (count) { char c; c = src[res]; dest[res] = c; if (!c) return res; res++; count--; } /* Hit buffer length without finding a NUL; force NUL-termination. */ if (res) dest[res-1] = '\0'; return -E2BIG; }

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EXPORT_SYMBOL(strscpy); #endif #ifndef __HAVE_ARCH_STRCAT /** * strcat - Append one %NUL-terminated string to another * @dest: The string to be appended to * @src: The string to append to it */ #undef strcat
char *strcat(char *dest, const char *src) { char *tmp = dest; while (*dest) dest++; while ((*dest++ = *src++) != '\0') ; return tmp; }

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EXPORT_SYMBOL(strcat); #endif #ifndef __HAVE_ARCH_STRNCAT /** * strncat - Append a length-limited, C-string to another * @dest: The string to be appended to * @src: The string to append to it * @count: The maximum numbers of bytes to copy * * Note that in contrast to strncpy(), strncat() ensures the result is * terminated. */
char *strncat(char *dest, const char *src, size_t count) { char *tmp = dest; if (count) { while (*dest) dest++; while ((*dest++ = *src++) != 0) { if (--count == 0) { *dest = '\0'; break; } } } return tmp; }

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EXPORT_SYMBOL(strncat); #endif #ifndef __HAVE_ARCH_STRLCAT /** * strlcat - Append a length-limited, C-string to another * @dest: The string to be appended to * @src: The string to append to it * @count: The size of the destination buffer. */
size_t strlcat(char *dest, const char *src, size_t count) { size_t dsize = strlen(dest); size_t len = strlen(src); size_t res = dsize + len; /* This would be a bug */ BUG_ON(dsize >= count); dest += dsize; count -= dsize; if (len >= count) len = count-1; memcpy(dest, src, len); dest[len] = 0; return res; }

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linus torvaldslinus torvalds87100.00%1100.00%
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EXPORT_SYMBOL(strlcat); #endif #ifndef __HAVE_ARCH_STRCMP /** * strcmp - Compare two strings * @cs: One string * @ct: Another string */ #undef strcmp
int strcmp(const char *cs, const char *ct) { unsigned char c1, c2; while (1) { c1 = *cs++; c2 = *ct++; if (c1 != c2) return c1 < c2 ? -1 : 1; if (!c1) break; } return 0; }

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EXPORT_SYMBOL(strcmp); #endif #ifndef __HAVE_ARCH_STRNCMP /** * strncmp - Compare two length-limited strings * @cs: One string * @ct: Another string * @count: The maximum number of bytes to compare */
int strncmp(const char *cs, const char *ct, size_t count) { unsigned char c1, c2; while (count) { c1 = *cs++; c2 = *ct++; if (c1 != c2) return c1 < c2 ? -1 : 1; if (!c1) break; count--; } return 0; }

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pre-gitpre-git4158.57%150.00%
linus torvaldslinus torvalds2941.43%150.00%
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EXPORT_SYMBOL(strncmp); #endif #ifndef __HAVE_ARCH_STRCHR /** * strchr - Find the first occurrence of a character in a string * @s: The string to be searched * @c: The character to search for */
char *strchr(const char *s, int c) { for (; *s != (char)c; ++s) if (*s == '\0') return NULL; return (char *)s; }

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EXPORT_SYMBOL(strchr); #endif #ifndef __HAVE_ARCH_STRCHRNUL /** * strchrnul - Find and return a character in a string, or end of string * @s: The string to be searched * @c: The character to search for * * Returns pointer to first occurrence of 'c' in s. If c is not found, then * return a pointer to the null byte at the end of s. */
char *strchrnul(const char *s, int c) { while (*s && *s != (char)c) s++; return (char *)s; }

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grant likelygrant likely37100.00%1100.00%
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EXPORT_SYMBOL(strchrnul); #endif #ifndef __HAVE_ARCH_STRRCHR /** * strrchr - Find the last occurrence of a character in a string * @s: The string to be searched * @c: The character to search for */
char *strrchr(const char *s, int c) { const char *last = NULL; do { if (*s == (char)c) last = s; } while (*s++); return (char *)last; }

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pre-gitpre-git3873.08%150.00%
rasmus villemoesrasmus villemoes1426.92%150.00%
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EXPORT_SYMBOL(strrchr); #endif #ifndef __HAVE_ARCH_STRNCHR /** * strnchr - Find a character in a length limited string * @s: The string to be searched * @count: The number of characters to be searched * @c: The character to search for */
char *strnchr(const char *s, size_t count, int c) { for (; count-- && *s != '\0'; ++s) if (*s == (char)c) return (char *)s; return NULL; }

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stephen hemmingerstephen hemminger51100.00%1100.00%
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EXPORT_SYMBOL(strnchr); #endif /** * skip_spaces - Removes leading whitespace from @str. * @str: The string to be stripped. * * Returns a pointer to the first non-whitespace character in @str. */
char *skip_spaces(const char *str) { while (isspace(*str)) ++str; return (char *)str; }

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andre goddard rosaandre goddard rosa29100.00%1100.00%
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EXPORT_SYMBOL(skip_spaces); /** * strim - Removes leading and trailing whitespace from @s. * @s: The string to be stripped. * * Note that the first trailing whitespace is replaced with a %NUL-terminator * in the given string @s. Returns a pointer to the first non-whitespace * character in @s. */
char *strim(char *s) { size_t size; char *end; size = strlen(s); if (!size) return s; end = s + size - 1; while (end >= s && isspace(*end)) end--; *(end + 1) = '\0'; return skip_spaces(s); }

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andre goddard rosaandre goddard rosa11.43%120.00%
kosaki motohirokosaki motohiro11.43%120.00%
Total70100.00%5100.00%

EXPORT_SYMBOL(strim); #ifndef __HAVE_ARCH_STRLEN /** * strlen - Find the length of a string * @s: The string to be sized */
size_t strlen(const char *s) { const char *sc; for (sc = s; *sc != '\0'; ++sc) /* nothing */; return sc - s; }

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EXPORT_SYMBOL(strlen); #endif #ifndef __HAVE_ARCH_STRNLEN /** * strnlen - Find the length of a length-limited string * @s: The string to be sized * @count: The maximum number of bytes to search */
size_t strnlen(const char *s, size_t count) { const char *sc; for (sc = s; count-- && *sc != '\0'; ++sc) /* nothing */; return sc - s; }

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EXPORT_SYMBOL(strnlen); #endif #ifndef __HAVE_ARCH_STRSPN /** * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept * @s: The string to be searched * @accept: The string to search for */
size_t strspn(const char *s, const char *accept) { const char *p; const char *a; size_t count = 0; for (p = s; *p != '\0'; ++p) { for (a = accept; *a != '\0'; ++a) { if (*p == *a) break; } if (*a == '\0') return count; ++count; } return count; }

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EXPORT_SYMBOL(strspn); #endif #ifndef __HAVE_ARCH_STRCSPN /** * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject * @s: The string to be searched * @reject: The string to avoid */
size_t strcspn(const char *s, const char *reject) { const char *p; const char *r; size_t count = 0; for (p = s; *p != '\0'; ++p) { for (r = reject; *r != '\0'; ++r) { if (*p == *r) return count; } ++count; } return count; }

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rusty russellrusty russell79100.00%1100.00%
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EXPORT_SYMBOL(strcspn); #endif #ifndef __HAVE_ARCH_STRPBRK /** * strpbrk - Find the first occurrence of a set of characters * @cs: The string to be searched * @ct: The characters to search for */
char *strpbrk(const char *cs, const char *ct) { const char *sc1, *sc2; for (sc1 = cs; *sc1 != '\0'; ++sc1) { for (sc2 = ct; *sc2 != '\0'; ++sc2) { if (*sc1 == *sc2) return (char *)sc1; } } return NULL; }

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EXPORT_SYMBOL(strpbrk); #endif #ifndef __HAVE_ARCH_STRSEP /** * strsep - Split a string into tokens * @s: The string to be searched * @ct: The characters to search for * * strsep() updates @s to point after the token, ready for the next call. * * It returns empty tokens, too, behaving exactly like the libc function * of that name. In fact, it was stolen from glibc2 and de-fancy-fied. * Same semantics, slimmer shape. ;) */
char *strsep(char **s, const char *ct) { char *sbegin = *s; char *end; if (sbegin == NULL) return NULL; end = strpbrk(sbegin, ct); if (end) *end++ = '\0'; *s = end; return sbegin; }

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pre-gitpre-git5079.37%133.33%
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jesper juhljesper juhl23.17%133.33%
Total63100.00%3100.00%

EXPORT_SYMBOL(strsep); #endif /** * sysfs_streq - return true if strings are equal, modulo trailing newline * @s1: one string * @s2: another string * * This routine returns true iff two strings are equal, treating both * NUL and newline-then-NUL as equivalent string terminations. It's * geared for use with sysfs input strings, which generally terminate * with newlines but are compared against values without newlines. */
bool sysfs_streq(const char *s1, const char *s2) { while (*s1 && *s1 == *s2) { s1++; s2++; } if (*s1 == *s2) return true; if (!*s1 && *s2 == '\n' && !s2[1]) return true; if (*s1 == '\n' && !s1[1] && !*s2) return true; return false; }

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david brownelldavid brownell88100.00%1100.00%
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EXPORT_SYMBOL(sysfs_streq); /** * match_string - matches given string in an array * @array: array of strings * @n: number of strings in the array or -1 for NULL terminated arrays * @string: string to match with * * Return: * index of a @string in the @array if matches, or %-EINVAL otherwise. */
int match_string(const char * const *array, size_t n, const char *string) { int index; const char *item; for (index = 0; index < n; index++) { item = array[index]; if (!item) break; if (!strcmp(item, string)) return index; } return -EINVAL; }

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andy shevchenkoandy shevchenko73100.00%1100.00%
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EXPORT_SYMBOL(match_string); #ifndef __HAVE_ARCH_MEMSET /** * memset - Fill a region of memory with the given value * @s: Pointer to the start of the area. * @c: The byte to fill the area with * @count: The size of the area. * * Do not use memset() to access IO space, use memset_io() instead. */
void *memset(void *s, int c, size_t count) { char *xs = s; while (count--) *xs++ = c; return s; }

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EXPORT_SYMBOL(memset); #endif /** * memzero_explicit - Fill a region of memory (e.g. sensitive * keying data) with 0s. * @s: Pointer to the start of the area. * @count: The size of the area. * * Note: usually using memset() is just fine (!), but in cases * where clearing out _local_ data at the end of a scope is * necessary, memzero_explicit() should be used instead in * order to prevent the compiler from optimising away zeroing. * * memzero_explicit() doesn't need an arch-specific version as * it just invokes the one of memset() implicitly. */
void memzero_explicit(void *s, size_t count) { memset(s, 0, count); barrier_data(s); }

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daniel borkmanndaniel borkmann26100.00%2100.00%
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EXPORT_SYMBOL(memzero_explicit); #ifndef __HAVE_ARCH_MEMCPY /** * memcpy - Copy one area of memory to another * @dest: Where to copy to * @src: Where to copy from * @count: The size of the area. * * You should not use this function to access IO space, use memcpy_toio() * or memcpy_fromio() instead. */
void *memcpy(void *dest, const void *src, size_t count) { char *tmp = dest; const char *s = src; while (count--) *tmp++ = *s++; return dest; }

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EXPORT_SYMBOL(memcpy); #endif #ifndef __HAVE_ARCH_MEMMOVE /** * memmove - Copy one area of memory to another * @dest: Where to copy to * @src: Where to copy from * @count: The size of the area. * * Unlike memcpy(), memmove() copes with overlapping areas. */
void *memmove(void *dest, const void *src, size_t count) { char *tmp; const char *s; if (dest <= src) { tmp = dest; s = src; while (count--) *tmp++ = *s++; } else { tmp = dest; tmp += count; s = src; s += count; while (count--) *--tmp = *--s; } return dest; }

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paul jacksonpaul jackson33.30%125.00%
Total91100.00%4100.00%

EXPORT_SYMBOL(memmove); #endif #ifndef __HAVE_ARCH_MEMCMP /** * memcmp - Compare two areas of memory * @cs: One area of memory * @ct: Another area of memory * @count: The size of the area. */ #undef memcmp
__visible int memcmp(const void *cs, const void *ct, size_t count) { const unsigned char *su1, *su2; int res = 0; for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--) if ((res = *su1 - *su2) != 0) break; return res; }

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pre-gitpre-git7297.30%250.00%
dave jonesdave jones11.35%125.00%
andi kleenandi kleen11.35%125.00%
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EXPORT_SYMBOL(memcmp); #endif #ifndef __HAVE_ARCH_MEMSCAN /** * memscan - Find a character in an area of memory. * @addr: The memory area * @c: The byte to search for * @size: The size of the area. * * returns the address of the first occurrence of @c, or 1 byte past * the area if @c is not found */
void *memscan(void *addr, int c, size_t size) { unsigned char *p = addr; while (size) { if (*p == c) return (void *)p; p++; size--; } return (void *)p; }

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EXPORT_SYMBOL(memscan); #endif #ifndef __HAVE_ARCH_STRSTR /** * strstr - Find the first substring in a %NUL terminated string * @s1: The string to be searched * @s2: The string to search for */
char *strstr(const char *s1, const char *s2) { size_t l1, l2; l2 = strlen(s2); if (!l2) return (char *)s1; l1 = strlen(s1); while (l1 >= l2) { l1--; if (!memcmp(s1, s2, l2)) return (char *)s1; s1++; } return NULL; }

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EXPORT_SYMBOL(strstr); #endif #ifndef __HAVE_ARCH_STRNSTR /** * strnstr - Find the first substring in a length-limited string * @s1: The string to be searched * @s2: The string to search for * @len: the maximum number of characters to search */
char *strnstr(const char *s1, const char *s2, size_t len) { size_t l2; l2 = strlen(s2); if (!l2) return (char *)s1; while (len >= l2) { len--; if (!memcmp(s1, s2, l2)) return (char *)s1; s1++; } return NULL; }

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li zefanli zefan7597.40%150.00%
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EXPORT_SYMBOL(strnstr); #endif #ifndef __HAVE_ARCH_MEMCHR /** * memchr - Find a character in an area of memory. * @s: The memory area * @c: The byte to search for * @n: The size of the area. * * returns the address of the first occurrence of @c, or %NULL * if @c is not found */
void *memchr(const void *s, int c, size_t n) { const unsigned char *p = s; while (n-- != 0) { if ((unsigned char)c == *p++) { return (void *)(p - 1); } } return NULL; }

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EXPORT_SYMBOL(memchr); #endif
static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes) { while (bytes) { if (*start != value) return (void *)start; start++; bytes--; } return NULL; }

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akinobu mitaakinobu mita48100.00%1100.00%
Total48100.00%1100.00%

/** * memchr_inv - Find an unmatching character in an area of memory. * @start: The memory area * @c: Find a character other than c * @bytes: The size of the area. * * returns the address of the first character other than @c, or %NULL * if the whole buffer contains just @c. */
void *memchr_inv(const void *start, int c, size_t bytes) { u8 value = c; u64 value64; unsigned int words, prefix; if (bytes <= 16) return check_bytes8(start, value, bytes); value64 = value; #if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64 value64 *= 0x0101010101010101ULL; #elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) value64 *= 0x01010101; value64 |= value64 << 32; #else value64 |= value64 << 8; value64 |= value64 << 16; value64 |= value64 << 32; #endif prefix = (unsigned long)start % 8; if (prefix) { u8 *r; prefix = 8 - prefix; r = check_bytes8(start, value, prefix); if (r) return r; start += prefix; bytes -= prefix; } words = bytes / 8; while (words) { if (*(u64 *)start != value64) return check_bytes8(start, value, 8); start += 8; words--; } return check_bytes8(start, value, bytes % 8); }

Contributors

PersonTokensPropCommitsCommitProp
akinobu mitaakinobu mita20498.55%250.00%
linus torvaldslinus torvalds20.97%125.00%
andy shevchenkoandy shevchenko10.48%125.00%
Total207100.00%4100.00%

EXPORT_SYMBOL(memchr_inv); /** * strreplace - Replace all occurrences of character in string. * @s: The string to operate on. * @old: The character being replaced. * @new: The character @old is replaced with. * * Returns pointer to the nul byte at the end of @s. */
char *strreplace(char *s, char old, char new) { for (;