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>
diff --git a/lib/string.c b/lib/string.c
index 9f75b4e..a1cdcfcc 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -667,7 +667,7 @@
*/
char *strstr(const char *s1, const char *s2)
{
- int l1, l2;
+ size_t l1, l2;
l2 = strlen(s2);
if (!l2)
@@ -684,6 +684,31 @@
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.