Backport from xs.

xs.h

@@ -914,7 +914,8 @@ void *xs_memmem(const char *haystack, int h_size, const char *needle, int n_size
     char *p, *r = NULL;
     int offset = 0;
 
-    while (!r && h_size - offset > n_size && (p = strchr(haystack + offset, *needle))) {
+    while (!r && h_size - offset > n_size &&
+           (p = memchr(haystack + offset, *needle, h_size - offset))) {
         if (memcmp(p, needle, n_size) == 0)
             r = p;
         else

xs_httpd.h

@@ -131,13 +131,13 @@ d_char *_xs_multipart_form_data(char *payload, int p_size, char *header)
         }
 
         /* find the start of the part content */
-        if ((p = xs_memmem(p, p_size - offset, "\r\n\r\n", 4)) == NULL)
+        if ((p = xs_memmem(p, p_size - (p - payload), "\r\n\r\n", 4)) == NULL)
             break;
 
         p += 4;
 
         /* find the next boundary */
-        if ((q = xs_memmem(p, p_size - offset, boundary, bsz)) == NULL)
+        if ((q = xs_memmem(p, p_size - (p - payload), boundary, bsz)) == NULL)
             break;
 
         po = p - payload;

xs_version.h

@@ -1 +1 @@
-/* 3aa82bc4fc310ec95194602bed88a9767e100350 */
+/* d5a6108812a499a389030a1402ce49f282b4a818 */