[syslinux:master] lib: Update memmem function

[syslinux-bot for Liu Aleaxander]

Commit-ID:  a66a47e168804aa0a62a3a5810d7f8dd9b647dab
Gitweb:     http://syslinux.zytor.com/commit/a66a47e168804aa0a62a3a5810d7f8dd9b647dab
Author:     Liu Aleaxander <Aleaxander at gmail.com>
AuthorDate: Sat, 9 Oct 2010 23:10:14 +0800
Committer:  Liu Aleaxander <Aleaxander at gmail.com>
CommitDate: Sat, 9 Oct 2010 23:10:14 +0800

lib: Update memmem function

The current memem implementation can not handle the case that the length
of the third parameter(needle) is equal *ONE*. So that the current
strstr implemention doesn't work when the lenght of substring is ONE.

For example, strstr("linux", "l") it will return NULL instead of
"linux", which is not right.

This code is stolen from klibc ;)

Signed-off-by: Liu Aleaxander <Aleaxander at gmail.com>


---
 com32/lib/memmem.c |   45 +++++++++++++++++++++++++++------------------
 1 files changed, 27 insertions(+), 18 deletions(-)

diff --git a/com32/lib/memmem.c b/com32/lib/memmem.c
index 8558a80..7c42f1c 100644
--- a/com32/lib/memmem.c
+++ b/com32/lib/memmem.c
@@ -18,26 +18,35 @@ void *memmem(const void *haystack, size_t n, const void *needle, size_t m)
 
     size_t j, k, l;
 
-    if (m > n)
-	return NULL;
+    if (m > n || !m || !n)
+        return NULL;
 
-    if (x[0] == x[1]) {
-	k = 2;
-	l = 1;
-    } else {
-	k = 1;
-	l = 2;
-    }
+    if (1 != m) {
+        if (x[0] == x[1]) {
+            k = 2;
+            l = 1;
+        } else {
+            k = 1;
+            l = 2;
+        }
 
-    j = 0;
-    while (j <= n - m) {
-	if (x[1] != y[j + 1]) {
-	    j += k;
-	} else {
-	    if (!memcmp(x + 2, y + j + 2, m - 2) && x[0] == y[j])
-		return (void *)&y[j];
-	    j += l;
-	}
+        j = 0;
+        while (j <= n - m) {
+            if (x[1] != y[j + 1]) {
+                j += k;
+            } else {
+                if (!memcmp(x + 2, y + j + 2, m - 2)
+                    && x[0] == y[j])
+                    return (void *)&y[j];
+                j += l;
+            }
+        }
+    } else {
+        do {
+            if (*y == *x)
+                return (void *)y;
+            y++;
+        } while (--n);
     }
 
     return NULL;