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-rw-r--r--lib/string.c27
1 files changed, 26 insertions, 1 deletions
diff --git a/lib/string.c b/lib/string.c
index 9f75b4ec50b8..a1cdcfcc42d0 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.