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mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-24 13:13:57 +08:00
linux-next/lib/string.c
Peter Rosin b09757104e lib/string.c: allow searching for NUL with strnchr
Patch series "lib/string: search for NUL with strchr/strnchr".

I noticed an inconsistency where strchr and strnchr do not behave the
same with respect to the trailing NUL.  strchr is standardised and the
kernel function conforms, and the kernel relies on the behavior.  So,
naturally strchr stays as-is and strnchr is what I change.

While writing a few tests to verify that my new strnchr loop was sane, I
noticed that the tests for memset16/32/64 had a problem.  Since it's all
about the lib/string.c file I made a short series of it all...

This patch (of 3):

strchr considers the terminating NUL to be part of the string, and NUL
can thus be searched for with that function.  For consistency, do the
same with strnchr.

Link: http://lkml.kernel.org/r/20190506124634.6807-2-peda@axentia.se
Signed-off-by: Peter Rosin <peda@axentia.se>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-16 19:23:22 -07:00

1118 lines
24 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* 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 <linux/slab.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;
}
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;
}
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;
}
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;
}
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;
}
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
* 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 zeroing is desired please use strscpy_pad().
*
* Return: The number of characters copied (not including the trailing
* %NUL) or -E2BIG if the destination buffer wasn't big enough.
*/
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 = read_word_at_a_time(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;
}
EXPORT_SYMBOL(strscpy);
#endif
/**
* strscpy_pad() - 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
* behavior is undefined if the string buffers overlap. The destination
* buffer is always %NUL terminated, unless it's zero-sized.
*
* If the source string is shorter than the destination buffer, zeros
* the tail of the destination buffer.
*
* For full explanation of why you may want to consider using the
* 'strscpy' functions please see the function docstring for strscpy().
*
* Return: The number of characters copied (not including the trailing
* %NUL) or -E2BIG if the destination buffer wasn't big enough.
*/
ssize_t strscpy_pad(char *dest, const char *src, size_t count)
{
ssize_t written;
written = strscpy(dest, src, count);
if (written < 0 || written == count - 1)
return written;
memset(dest + written + 1, 0, count - written - 1);
return written;
}
EXPORT_SYMBOL(strscpy_pad);
#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;
}
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;
}
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;
}
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;
}
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;
}
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
*
* Note that the %NUL-terminator is considered part of the string, and can
* be searched for.
*/
char *strchr(const char *s, int c)
{
for (; *s != (char)c; ++s)
if (*s == '\0')
return NULL;
return (char *)s;
}
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;
}
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;
}
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
*
* Note that the %NUL-terminator is considered part of the string, and can
* be searched for.
*/
char *strnchr(const char *s, size_t count, int c)
{
while (count--) {
if (*s == (char)c)
return (char *)s;
if (*s++ == '\0')
break;
}
return NULL;
}
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;
}
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);
}
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;
}
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;
}
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;
}
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
/**
* 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;
}
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;
}
EXPORT_SYMBOL(match_string);
/**
* __sysfs_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
* @str: string to match with
*
* Returns index of @str in the @array or -EINVAL, just like match_string().
* Uses sysfs_streq instead of strcmp for matching.
*/
int __sysfs_match_string(const char * const *array, size_t n, const char *str)
{
const char *item;
int index;
for (index = 0; index < n; index++) {
item = array[index];
if (!item)
break;
if (sysfs_streq(item, str))
return index;
}
return -EINVAL;
}
EXPORT_SYMBOL(__sysfs_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;
}
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);
}
EXPORT_SYMBOL(memzero_explicit);
#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;
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.
*/
#undef bcmp
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 == 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);
/**
* 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 (; *s; ++s)
if (*s == old)
*s = new;
return s;
}
EXPORT_SYMBOL(strreplace);
void fortify_panic(const char *name)
{
pr_emerg("detected buffer overflow in %s\n", name);
BUG();
}
EXPORT_SYMBOL(fortify_panic);