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Commit d5f1fb53 authored by Li Zefan's avatar Li Zefan Committed by Steven Rostedt
Browse files

lib: Introduce strnstr() 



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

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4B4E8743.6030805@cn.fujitsu.com>
Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent a3291c14

include/linux/string.h

+4 −1
Original line number Diff line number Diff line
@@ -74,6 +74,9 @@ static inline __must_check char *strstrip(char *str) 
#ifndef __HAVE_ARCH_STRSTR

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 *);

#endif

lib/string.c

+26 −1
Original line number Diff line number Diff line
@@ -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.