dirhash.c revision 1acb01b4e28067a37c4f41e0a76df9f429fb417e 
1/*
2 * dirhash.c -- Calculate the hash of a directory entry
3 *
4 * Copyright (c) 2001  Daniel Phillips
5 *
6 * Copyright (c) 2002 Theodore Ts'o.
7 *
8 * %Begin-Header%
9 * This file may be redistributed under the terms of the GNU Public
10 * License.
11 * %End-Header%
12 */
13
14#include <stdio.h>
15
16#include "ext2_fs.h"
17#include "ext2fs.h"
18
19static ext2_dirhash_t dx_hack_hash (const char *name, int len)
20{
21	__u32 hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
22	while (len--) {
23		__u32 hash = hash1 + (hash0 ^ (*name++ * 7152373));
24
25		if (hash & 0x80000000) hash -= 0x7fffffff;
26		hash1 = hash0;
27		hash0 = hash;
28	}
29	return (hash0 << 1);
30}
31
32/*
33 * Returns the hash of a filename.  If len is 0 and name is NULL, then
34 * this function can be used to test whether or not a hash version is
35 * supported.
36 */
37errcode_t ext2fs_dirhash(int version, const char *name, int len,
38			 ext2_dirhash_t *ret_hash)
39{
40	__u32	hash;
41
42	if (version == 0)
43		hash = dx_hack_hash(name, len);
44	else {
45		*ret_hash = 0;
46		return EXT2_ET_DIRHASH_UNSUPP;
47	}
48	*ret_hash = hash;
49	return 0;
50
51}
52