1 files changed, 65 insertions, 0 deletions
diff --git a/libglusterfs/src/checksum.c b/libglusterfs/src/checksum.c
new file mode 100644
index 000000000..e14a3044c
--- /dev/null
+++ b/libglusterfs/src/checksum.c
@@ -0,0 +1,65 @@
+/*
+  Copyright (c) 2008-2012 Red Hat, Inc. <http://www.redhat.com>
+  This file is part of GlusterFS.
+
+  This file is licensed to you under your choice of the GNU Lesser
+  General Public License, version 3 or any later version (LGPLv3 or
+  later), or the GNU General Public License, version 2 (GPLv2), in all
+  cases as published by the Free Software Foundation.
+*/
+
+#include <openssl/md5.h>
+#include <stdint.h>
+
+#include "glusterfs.h"
+
+/*
+ * The "weak" checksum required for the rsync algorithm,
+ * adapted from the rsync source code. The following comment
+ * appears there:
+ *
+ * "a simple 32 bit checksum that can be upadted from either end
+ *  (inspired by Mark Adler's Adler-32 checksum)"
+ *
+ * Note: these functions are only called to compute checksums on
+ * pathnames; they don't need to handle arbitrarily long strings of
+ * data. Thus int32_t and uint32_t are sufficient
+ */
+
+uint32_t
+gf_rsync_weak_checksum (unsigned char *buf, size_t len)
+{
+        int32_t i = 0;
+        uint32_t s1, s2;
+
+        uint32_t csum;
+
+        s1 = s2 = 0;
+        if (len >= 4) {
+                for (; i < (len-4); i+=4) {
+                        s2 += 4*(s1 + buf[i]) + 3*buf[i+1] + 2*buf[i+2] + buf[i+3];
+                        s1 += buf[i+0] + buf[i+1] + buf[i+2] + buf[i+3];
+                }
+        }
+
+        for (; i < len; i++) {
+                s1 += buf[i];
+                s2 += s1;
+        }
+
+        csum = (s1 & 0xffff) + (s2 << 16);
+
+        return csum;
+}
+
+
+/*
+ * The "strong" checksum required for the rsync algorithm,
+ * adapted from the rsync source code.
+ */
+
+void
+gf_rsync_strong_checksum (unsigned char *data, size_t len, unsigned char *md5)
+{
+        MD5(data, len, md5);
+}