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authorLi Zefan <lizf@cn.fujitsu.com>2010-01-14 10:53:55 +0800
committerSteven Rostedt <rostedt@goodmis.org>2010-01-14 22:38:09 -0500
commitd5f1fb53353edc38da326445267c1df0c9676df2 (patch)
tree42def644ebd0d343f2eba9e625f4b9b1ea8a36f0
parenta3291c14ecf0a995e30d993b7f2cae031de98727 (diff)
downloadlinux-linaro-android-d5f1fb53353edc38da326445267c1df0c9676df2.tar.gz
lib: Introduce strnstr()
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>
-rw-r--r--include/linux/string.h5
-rw-r--r--lib/string.c27
2 files changed, 30 insertions, 2 deletions
diff --git a/include/linux/string.h b/include/linux/string.h
index 651839a2a75..a716ee2a8ad 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -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 *);
diff --git a/lib/string.c b/lib/string.c
index 9f75b4ec50b..a1cdcfcc42d 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -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.