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Subject[RFC][PATCH 2/7] implement memmem()
Date
From: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
include/linux/string.h | 1 +
lib/string.c | 34 ++++++++++++++++++++++------------
2 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/include/linux/string.h b/include/linux/string.h
index 2e22a2e..87f9fba 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -75,6 +75,7 @@ extern char * strstr(const char *, const char *);
#endif
#ifndef __HAVE_ARCH_STRNSTR
extern char * strnstr(const char *, const char *, size_t);
+extern void * memmem(const void *, size_t, const void *, 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 1006330..2035dbe 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -740,27 +740,37 @@ EXPORT_SYMBOL(strstr);
#endif

#ifndef __HAVE_ARCH_STRNSTR
+
/**
- * strnstr - Find the first substring in a length-limited string
+ * memmem - Find the first length-limited substring in a length-limited string
* @s1: The string to be searched
+ * @len1: the maximum number of characters to search
* @s2: The string to search for
- * @len: the maximum number of characters to search
+ * @len2: the length of the string being searched
*/
-char *strnstr(const char *s1, const char *s2, size_t len)
+void *memmem(const void *s1, size_t len1, const void *s2, size_t len2)
{
- size_t l2;
-
- l2 = strlen(s2);
- if (!l2)
- return (char *)s1;
- while (len >= l2) {
- len--;
- if (!memcmp(s1, s2, l2))
- return (char *)s1;
+ if (!len2)
+ return (void *)s1;
+ while (len1 >= len2) {
+ len1--;
+ if (!memcmp(s1, s2, len2))
+ return (void *)s1;
s1++;
}
return NULL;
}
+EXPORT_SYMBOL(memmem);
+/**
+ * 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)
+{
+ return memmem(s1, len, s2, strlen(s2));
+}
EXPORT_SYMBOL(strnstr);
#endif

--
2.1.4


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