Add new function to the libext2fs library, ext2fs_dirhash, which
calculates the hash of a filename for indexed directories.
diff --git a/lib/ext2fs/dirhash.c b/lib/ext2fs/dirhash.c
new file mode 100644
index 0000000..5f71c6d
--- /dev/null
+++ b/lib/ext2fs/dirhash.c
@@ -0,0 +1,51 @@
+/*
+ * dirhash.c -- Calculate the hash of a directory entry
+ *
+ * Copyright (c) 2001 Daniel Phillips
+ *
+ * Copyright (c) 2002 Theodore Ts'o.
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License.
+ * %End-Header%
+ */
+
+#include <stdio.h>
+
+#include "ext2_fs.h"
+#include "ext2fs.h"
+
+static ext2_dirhash_t dx_hack_hash (const char *name, int len)
+{
+ __u32 hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
+ while (len--) {
+ __u32 hash = hash1 + (hash0 ^ (*name++ * 7152373));
+
+ if (hash & 0x80000000) hash -= 0x7fffffff;
+ hash1 = hash0;
+ hash0 = hash;
+ }
+ return hash0;
+}
+
+/*
+ * Returns the hash of a filename. If len is 0 and name is NULL, then
+ * this function can be used to test whether or not a hash version is
+ * supported.
+ */
+errcode_t ext2fs_dirhash(int version, const char *name, int len,
+ ext2_dirhash_t *ret_hash)
+{
+ __u32 hash;
+
+ if (version == 0)
+ hash = dx_hack_hash(name, len);
+ else {
+ *ret_hash = 0;
+ return EXT2_ET_DIRHASH_UNSUPP;
+ }
+ *ret_hash = hash;
+ return 0;
+
+}