1 files changed, 50 insertions, 0 deletions
diff --git a/libc/string/generic/memmem.c b/libc/string/generic/memmem.c
new file mode 100644
index 000000000..c0f2bd192
--- /dev/null
+++ b/libc/string/generic/memmem.c
@@ -0,0 +1,50 @@
+/* Copyright (C) 1991,92,93,94,96,97,98,2000 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <string.h>
+#include <stddef.h>
+
+#undef memmem
+
+/* Return the first occurrence of NEEDLE in HAYSTACK.  */
+void *memmem (const void *haystack, size_t haystack_len,
+			  const void *needle,  size_t needle_len)
+{
+  const char *begin;
+  const char *const last_possible
+    = (const char *) haystack + haystack_len - needle_len;
+
+  if (needle_len == 0)
+    /* The first occurrence of the empty string is deemed to occur at
+       the beginning of the string.  */
+    return (void *) haystack;
+
+  /* Sanity check, otherwise the loop might search through the whole
+     memory.  */
+  if (__builtin_expect (haystack_len < needle_len, 0))
+    return NULL;
+
+  for (begin = (const char *) haystack; begin <= last_possible; ++begin)
+    if (begin[0] == ((const char *) needle)[0] &&
+	!memcmp ((const void *) &begin[1],
+		 (const void *) ((const char *) needle + 1),
+		 needle_len - 1))
+      return (void *) begin;
+
+  return NULL;
+}