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lib: Introduce strnstr()

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It differs strstr() in that it limits the length to be searched
in the first string.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4B4E8743.6030805@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Li Zefan 2010-01-14 10:53:55 +08:00 committed by Steven Rostedt
parent a3291c14ec
commit d5f1fb5335
2 changed files with 30 additions and 2 deletions
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5
include/linux/string.h
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@ -72,7 +72,10 @@ static inline __must_check char *strstrip(char *str)
}
#ifndef __HAVE_ARCH_STRSTR
extern char * strstr(const char *,const char *);
extern char * strstr(const char *, const char *);
#endif
#ifndef __HAVE_ARCH_STRNSTR
extern char * strnstr(const char *, const char *, size_t);
#endif
#ifndef __HAVE_ARCH_STRLEN
extern __kernel_size_t strlen(const char *);

27
lib/string.c
View File

@ -667,7 +667,7 @@ EXPORT_SYMBOL(memscan);
*/
char *strstr(const char *s1, const char *s2)
{
int l1, l2;
size_t l1, l2;
l2 = strlen(s2);
if (!l2)
@ -684,6 +684,31 @@ char *strstr(const char *s1, const char *s2)
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 l1 = len, l2;
l2 = strlen(s2);
if (!l2)
return (char *)s1;
while (l1 >= l2) {
l1--;
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.