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![Kees Cook](/assets/img/avatar_default.png)
The core functions of string.c are those that may be implemented by per-architecture functions, or overloaded by FORTIFY_SOURCE. As a result, it needs to be built with __NO_FORTIFY. Without this, macros will collide with function declarations. This was accidentally working due to -ffreestanding (on some architectures). Make this deterministic by explicitly setting __NO_FORTIFY and move all the helper functions into string_helpers.c so that they gain the fortification coverage they had been missing. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Andy Lavr <andy.lavr@gmail.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com> Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Kees Cook <keescook@chromium.org>
969 lines
21 KiB
C
969 lines
21 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/lib/string.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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/*
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* This file should be used only for "library" routines that may have
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* alternative implementations on specific architectures (generally
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* found in <asm-xx/string.h>), or get overloaded by FORTIFY_SOURCE.
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* (Specifically, this file is built with __NO_FORTIFY.)
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*
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* Other helper functions should live in string_helpers.c.
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*/
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#define __NO_FORTIFY
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#include <linux/types.h>
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#include <linux/string.h>
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#include <linux/ctype.h>
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/bug.h>
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#include <linux/errno.h>
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#include <linux/slab.h>
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#include <asm/unaligned.h>
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#include <asm/byteorder.h>
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#include <asm/word-at-a-time.h>
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#include <asm/page.h>
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#ifndef __HAVE_ARCH_STRNCASECMP
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/**
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* strncasecmp - Case insensitive, length-limited string comparison
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* @s1: One string
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* @s2: The other string
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* @len: the maximum number of characters to compare
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*/
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int strncasecmp(const char *s1, const char *s2, size_t len)
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{
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/* Yes, Virginia, it had better be unsigned */
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unsigned char c1, c2;
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if (!len)
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return 0;
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do {
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c1 = *s1++;
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c2 = *s2++;
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if (!c1 || !c2)
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break;
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if (c1 == c2)
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continue;
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c1 = tolower(c1);
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c2 = tolower(c2);
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if (c1 != c2)
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break;
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} while (--len);
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return (int)c1 - (int)c2;
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}
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EXPORT_SYMBOL(strncasecmp);
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#endif
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#ifndef __HAVE_ARCH_STRCASECMP
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int strcasecmp(const char *s1, const char *s2)
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{
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int c1, c2;
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do {
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c1 = tolower(*s1++);
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c2 = tolower(*s2++);
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} while (c1 == c2 && c1 != 0);
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return c1 - c2;
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}
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EXPORT_SYMBOL(strcasecmp);
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#endif
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#ifndef __HAVE_ARCH_STRCPY
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/**
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* strcpy - Copy a %NUL terminated string
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* @dest: Where to copy the string to
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* @src: Where to copy the string from
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*/
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char *strcpy(char *dest, const char *src)
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{
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char *tmp = dest;
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while ((*dest++ = *src++) != '\0')
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/* nothing */;
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return tmp;
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}
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EXPORT_SYMBOL(strcpy);
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#endif
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#ifndef __HAVE_ARCH_STRNCPY
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/**
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* strncpy - Copy a length-limited, C-string
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* @dest: Where to copy the string to
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* @src: Where to copy the string from
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* @count: The maximum number of bytes to copy
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*
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* The result is not %NUL-terminated if the source exceeds
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* @count bytes.
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*
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* In the case where the length of @src is less than that of
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* count, the remainder of @dest will be padded with %NUL.
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*
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*/
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char *strncpy(char *dest, const char *src, size_t count)
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{
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char *tmp = dest;
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while (count) {
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if ((*tmp = *src) != 0)
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src++;
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tmp++;
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count--;
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}
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return dest;
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}
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EXPORT_SYMBOL(strncpy);
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#endif
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#ifndef __HAVE_ARCH_STRLCPY
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/**
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* strlcpy - Copy a C-string into a sized buffer
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* @dest: Where to copy the string to
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* @src: Where to copy the string from
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* @size: size of destination buffer
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*
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* Compatible with ``*BSD``: the result is always a valid
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* NUL-terminated string that fits in the buffer (unless,
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* of course, the buffer size is zero). It does not pad
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* out the result like strncpy() does.
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*/
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size_t strlcpy(char *dest, const char *src, size_t size)
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{
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size_t ret = strlen(src);
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if (size) {
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size_t len = (ret >= size) ? size - 1 : ret;
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memcpy(dest, src, len);
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dest[len] = '\0';
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}
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return ret;
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}
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EXPORT_SYMBOL(strlcpy);
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#endif
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#ifndef __HAVE_ARCH_STRSCPY
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/**
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* strscpy - Copy a C-string into a sized buffer
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* @dest: Where to copy the string to
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* @src: Where to copy the string from
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* @count: Size of destination buffer
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*
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* Copy the string, or as much of it as fits, into the dest buffer. The
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* behavior is undefined if the string buffers overlap. The destination
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* buffer is always NUL terminated, unless it's zero-sized.
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*
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* Preferred to strlcpy() since the API doesn't require reading memory
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* from the src string beyond the specified "count" bytes, and since
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* the return value is easier to error-check than strlcpy()'s.
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* In addition, the implementation is robust to the string changing out
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* from underneath it, unlike the current strlcpy() implementation.
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*
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* Preferred to strncpy() since it always returns a valid string, and
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* doesn't unnecessarily force the tail of the destination buffer to be
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* zeroed. If zeroing is desired please use strscpy_pad().
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*
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* Returns:
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* * The number of characters copied (not including the trailing %NUL)
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* * -E2BIG if count is 0 or @src was truncated.
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*/
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ssize_t strscpy(char *dest, const char *src, size_t count)
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{
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const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
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size_t max = count;
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long res = 0;
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if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
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return -E2BIG;
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#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
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/*
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* If src is unaligned, don't cross a page boundary,
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* since we don't know if the next page is mapped.
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*/
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if ((long)src & (sizeof(long) - 1)) {
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size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
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if (limit < max)
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max = limit;
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}
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#else
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/* If src or dest is unaligned, don't do word-at-a-time. */
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if (((long) dest | (long) src) & (sizeof(long) - 1))
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max = 0;
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#endif
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while (max >= sizeof(unsigned long)) {
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unsigned long c, data;
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c = read_word_at_a_time(src+res);
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if (has_zero(c, &data, &constants)) {
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data = prep_zero_mask(c, data, &constants);
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data = create_zero_mask(data);
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*(unsigned long *)(dest+res) = c & zero_bytemask(data);
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return res + find_zero(data);
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}
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*(unsigned long *)(dest+res) = c;
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res += sizeof(unsigned long);
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count -= sizeof(unsigned long);
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max -= sizeof(unsigned long);
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}
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while (count) {
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char c;
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c = src[res];
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dest[res] = c;
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if (!c)
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return res;
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res++;
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count--;
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}
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/* Hit buffer length without finding a NUL; force NUL-termination. */
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if (res)
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dest[res-1] = '\0';
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return -E2BIG;
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}
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EXPORT_SYMBOL(strscpy);
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#endif
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/**
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* stpcpy - copy a string from src to dest returning a pointer to the new end
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* of dest, including src's %NUL-terminator. May overrun dest.
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* @dest: pointer to end of string being copied into. Must be large enough
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* to receive copy.
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* @src: pointer to the beginning of string being copied from. Must not overlap
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* dest.
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*
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* stpcpy differs from strcpy in a key way: the return value is a pointer
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* to the new %NUL-terminating character in @dest. (For strcpy, the return
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* value is a pointer to the start of @dest). This interface is considered
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* unsafe as it doesn't perform bounds checking of the inputs. As such it's
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* not recommended for usage. Instead, its definition is provided in case
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* the compiler lowers other libcalls to stpcpy.
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*/
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char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
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char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
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{
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while ((*dest++ = *src++) != '\0')
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/* nothing */;
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return --dest;
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}
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EXPORT_SYMBOL(stpcpy);
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#ifndef __HAVE_ARCH_STRCAT
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/**
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* strcat - Append one %NUL-terminated string to another
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* @dest: The string to be appended to
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* @src: The string to append to it
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*/
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char *strcat(char *dest, const char *src)
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{
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char *tmp = dest;
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while (*dest)
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dest++;
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while ((*dest++ = *src++) != '\0')
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;
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return tmp;
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}
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EXPORT_SYMBOL(strcat);
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#endif
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#ifndef __HAVE_ARCH_STRNCAT
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/**
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* strncat - Append a length-limited, C-string to another
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* @dest: The string to be appended to
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* @src: The string to append to it
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* @count: The maximum numbers of bytes to copy
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*
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* Note that in contrast to strncpy(), strncat() ensures the result is
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* terminated.
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*/
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char *strncat(char *dest, const char *src, size_t count)
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{
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char *tmp = dest;
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if (count) {
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while (*dest)
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dest++;
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while ((*dest++ = *src++) != 0) {
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if (--count == 0) {
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*dest = '\0';
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break;
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}
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}
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}
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return tmp;
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}
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EXPORT_SYMBOL(strncat);
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#endif
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#ifndef __HAVE_ARCH_STRLCAT
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/**
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* strlcat - Append a length-limited, C-string to another
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* @dest: The string to be appended to
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* @src: The string to append to it
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* @count: The size of the destination buffer.
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*/
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size_t strlcat(char *dest, const char *src, size_t count)
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{
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size_t dsize = strlen(dest);
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size_t len = strlen(src);
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size_t res = dsize + len;
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/* This would be a bug */
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BUG_ON(dsize >= count);
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dest += dsize;
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count -= dsize;
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if (len >= count)
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len = count-1;
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memcpy(dest, src, len);
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dest[len] = 0;
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return res;
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}
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EXPORT_SYMBOL(strlcat);
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#endif
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#ifndef __HAVE_ARCH_STRCMP
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/**
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* strcmp - Compare two strings
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* @cs: One string
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* @ct: Another string
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*/
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int strcmp(const char *cs, const char *ct)
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{
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unsigned char c1, c2;
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while (1) {
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c1 = *cs++;
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c2 = *ct++;
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if (c1 != c2)
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return c1 < c2 ? -1 : 1;
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if (!c1)
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break;
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}
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return 0;
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}
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EXPORT_SYMBOL(strcmp);
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#endif
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#ifndef __HAVE_ARCH_STRNCMP
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/**
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* strncmp - Compare two length-limited strings
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* @cs: One string
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* @ct: Another string
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* @count: The maximum number of bytes to compare
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*/
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int strncmp(const char *cs, const char *ct, size_t count)
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{
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unsigned char c1, c2;
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while (count) {
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c1 = *cs++;
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c2 = *ct++;
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if (c1 != c2)
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return c1 < c2 ? -1 : 1;
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if (!c1)
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break;
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count--;
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}
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return 0;
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}
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EXPORT_SYMBOL(strncmp);
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#endif
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#ifndef __HAVE_ARCH_STRCHR
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/**
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* strchr - Find the first occurrence of a character in a string
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* @s: The string to be searched
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* @c: The character to search for
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*
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* Note that the %NUL-terminator is considered part of the string, and can
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* be searched for.
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*/
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char *strchr(const char *s, int c)
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{
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for (; *s != (char)c; ++s)
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if (*s == '\0')
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return NULL;
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return (char *)s;
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}
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EXPORT_SYMBOL(strchr);
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#endif
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#ifndef __HAVE_ARCH_STRCHRNUL
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/**
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* strchrnul - Find and return a character in a string, or end of string
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* @s: The string to be searched
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* @c: The character to search for
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*
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* Returns pointer to first occurrence of 'c' in s. If c is not found, then
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* return a pointer to the null byte at the end of s.
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*/
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char *strchrnul(const char *s, int c)
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{
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while (*s && *s != (char)c)
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s++;
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return (char *)s;
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}
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EXPORT_SYMBOL(strchrnul);
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#endif
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/**
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* strnchrnul - Find and return a character in a length limited string,
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* or end of string
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* @s: The string to be searched
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* @count: The number of characters to be searched
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* @c: The character to search for
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*
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* Returns pointer to the first occurrence of 'c' in s. If c is not found,
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* then return a pointer to the last character of the string.
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*/
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char *strnchrnul(const char *s, size_t count, int c)
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{
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while (count-- && *s && *s != (char)c)
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s++;
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return (char *)s;
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}
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#ifndef __HAVE_ARCH_STRRCHR
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/**
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* strrchr - Find the last occurrence of a character in a string
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* @s: The string to be searched
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* @c: The character to search for
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*/
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char *strrchr(const char *s, int c)
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{
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const char *last = NULL;
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do {
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if (*s == (char)c)
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last = s;
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} while (*s++);
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return (char *)last;
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}
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EXPORT_SYMBOL(strrchr);
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#endif
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#ifndef __HAVE_ARCH_STRNCHR
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/**
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* strnchr - Find a character in a length limited string
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* @s: The string to be searched
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* @count: The number of characters to be searched
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* @c: The character to search for
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*
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* Note that the %NUL-terminator is considered part of the string, and can
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* be searched for.
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*/
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char *strnchr(const char *s, size_t count, int c)
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{
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while (count--) {
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if (*s == (char)c)
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return (char *)s;
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if (*s++ == '\0')
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break;
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}
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return NULL;
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}
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EXPORT_SYMBOL(strnchr);
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#endif
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#ifndef __HAVE_ARCH_STRLEN
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/**
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* strlen - Find the length of a string
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* @s: The string to be sized
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*/
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size_t strlen(const char *s)
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{
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const char *sc;
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for (sc = s; *sc != '\0'; ++sc)
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/* nothing */;
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return sc - s;
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}
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EXPORT_SYMBOL(strlen);
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#endif
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#ifndef __HAVE_ARCH_STRNLEN
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/**
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* strnlen - Find the length of a length-limited string
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* @s: The string to be sized
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* @count: The maximum number of bytes to search
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*/
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size_t strnlen(const char *s, size_t count)
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{
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const char *sc;
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for (sc = s; count-- && *sc != '\0'; ++sc)
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/* nothing */;
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return sc - s;
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}
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EXPORT_SYMBOL(strnlen);
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#endif
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#ifndef __HAVE_ARCH_STRSPN
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/**
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* strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
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* @s: The string to be searched
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* @accept: The string to search for
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*/
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size_t strspn(const char *s, const char *accept)
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{
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const char *p;
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const char *a;
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size_t count = 0;
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for (p = s; *p != '\0'; ++p) {
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for (a = accept; *a != '\0'; ++a) {
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if (*p == *a)
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break;
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}
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if (*a == '\0')
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return count;
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++count;
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}
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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;
|
|
}
|
|
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;
|
|
}
|
|
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;
|
|
}
|
|
EXPORT_SYMBOL(strsep);
|
|
#endif
|
|
|
|
#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;
|
|
}
|
|
EXPORT_SYMBOL(memset);
|
|
#endif
|
|
|
|
#ifndef __HAVE_ARCH_MEMSET16
|
|
/**
|
|
* memset16() - Fill a memory area with a uint16_t
|
|
* @s: Pointer to the start of the area.
|
|
* @v: The value to fill the area with
|
|
* @count: The number of values to store
|
|
*
|
|
* Differs from memset() in that it fills with a uint16_t instead
|
|
* of a byte. Remember that @count is the number of uint16_ts to
|
|
* store, not the number of bytes.
|
|
*/
|
|
void *memset16(uint16_t *s, uint16_t v, size_t count)
|
|
{
|
|
uint16_t *xs = s;
|
|
|
|
while (count--)
|
|
*xs++ = v;
|
|
return s;
|
|
}
|
|
EXPORT_SYMBOL(memset16);
|
|
#endif
|
|
|
|
#ifndef __HAVE_ARCH_MEMSET32
|
|
/**
|
|
* memset32() - Fill a memory area with a uint32_t
|
|
* @s: Pointer to the start of the area.
|
|
* @v: The value to fill the area with
|
|
* @count: The number of values to store
|
|
*
|
|
* Differs from memset() in that it fills with a uint32_t instead
|
|
* of a byte. Remember that @count is the number of uint32_ts to
|
|
* store, not the number of bytes.
|
|
*/
|
|
void *memset32(uint32_t *s, uint32_t v, size_t count)
|
|
{
|
|
uint32_t *xs = s;
|
|
|
|
while (count--)
|
|
*xs++ = v;
|
|
return s;
|
|
}
|
|
EXPORT_SYMBOL(memset32);
|
|
#endif
|
|
|
|
#ifndef __HAVE_ARCH_MEMSET64
|
|
/**
|
|
* memset64() - Fill a memory area with a uint64_t
|
|
* @s: Pointer to the start of the area.
|
|
* @v: The value to fill the area with
|
|
* @count: The number of values to store
|
|
*
|
|
* Differs from memset() in that it fills with a uint64_t instead
|
|
* of a byte. Remember that @count is the number of uint64_ts to
|
|
* store, not the number of bytes.
|
|
*/
|
|
void *memset64(uint64_t *s, uint64_t v, size_t count)
|
|
{
|
|
uint64_t *xs = s;
|
|
|
|
while (count--)
|
|
*xs++ = v;
|
|
return s;
|
|
}
|
|
EXPORT_SYMBOL(memset64);
|
|
#endif
|
|
|
|
#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;
|
|
}
|
|
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;
|
|
}
|
|
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;
|
|
|
|
#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
|
|
if (count >= sizeof(unsigned long)) {
|
|
const unsigned long *u1 = cs;
|
|
const unsigned long *u2 = ct;
|
|
do {
|
|
if (get_unaligned(u1) != get_unaligned(u2))
|
|
break;
|
|
u1++;
|
|
u2++;
|
|
count -= sizeof(unsigned long);
|
|
} while (count >= sizeof(unsigned long));
|
|
cs = u1;
|
|
ct = u2;
|
|
}
|
|
#endif
|
|
for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
|
|
if ((res = *su1 - *su2) != 0)
|
|
break;
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(memcmp);
|
|
#endif
|
|
|
|
#ifndef __HAVE_ARCH_BCMP
|
|
/**
|
|
* bcmp - returns 0 if and only if the buffers have identical contents.
|
|
* @a: pointer to first buffer.
|
|
* @b: pointer to second buffer.
|
|
* @len: size of buffers.
|
|
*
|
|
* The sign or magnitude of a non-zero return value has no particular
|
|
* meaning, and architectures may implement their own more efficient bcmp(). So
|
|
* while this particular implementation is a simple (tail) call to memcmp, do
|
|
* not rely on anything but whether the return value is zero or non-zero.
|
|
*/
|
|
int bcmp(const void *a, const void *b, size_t len)
|
|
{
|
|
return memcmp(a, b, len);
|
|
}
|
|
EXPORT_SYMBOL(bcmp);
|
|
#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 == (unsigned char)c)
|
|
return (void *)p;
|
|
p++;
|
|
size--;
|
|
}
|
|
return (void *)p;
|
|
}
|
|
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;
|
|
}
|
|
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;
|
|
}
|
|
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;
|
|
}
|
|
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;
|
|
}
|
|
|
|
/**
|
|
* 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);
|
|
}
|
|
EXPORT_SYMBOL(memchr_inv);
|