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Dave Kleikampac27a0e2006-10-11 01:20:50 -07001/*
Mingming Cao617ba132006-10-11 01:20:53 -07002 * linux/fs/ext4/hash.c
Dave Kleikampac27a0e2006-10-11 01:20:50 -07003 *
4 * Copyright (C) 2002 by Theodore Ts'o
5 *
6 * This file is released under the GPL v2.
7 *
8 * This file may be redistributed under the terms of the GNU Public
9 * License.
10 */
11
12#include <linux/fs.h>
Mingming Caodab291a2006-10-11 01:21:01 -070013#include <linux/jbd2.h>
Dave Kleikampac27a0e2006-10-11 01:20:50 -070014#include <linux/cryptohash.h>
Christoph Hellwig3dcf5452008-04-29 18:13:32 -040015#include "ext4.h"
Dave Kleikampac27a0e2006-10-11 01:20:50 -070016
17#define DELTA 0x9E3779B9
18
19static void TEA_transform(__u32 buf[4], __u32 const in[])
20{
21 __u32 sum = 0;
22 __u32 b0 = buf[0], b1 = buf[1];
23 __u32 a = in[0], b = in[1], c = in[2], d = in[3];
24 int n = 16;
25
26 do {
27 sum += DELTA;
28 b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
29 b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
Theodore Ts'oaf5bc922008-09-08 22:25:24 -040030 } while (--n);
Dave Kleikampac27a0e2006-10-11 01:20:50 -070031
32 buf[0] += b0;
33 buf[1] += b1;
34}
35
36
37/* The old legacy hash */
Theodore Ts'of99b2582008-10-28 13:21:44 -040038static __u32 dx_hack_hash_unsigned(const char *name, int len)
Dave Kleikampac27a0e2006-10-11 01:20:50 -070039{
Theodore Ts'of99b2582008-10-28 13:21:44 -040040 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
41 const unsigned char *ucp = (const unsigned char *) name;
Dave Kleikampac27a0e2006-10-11 01:20:50 -070042
Theodore Ts'of99b2582008-10-28 13:21:44 -040043 while (len--) {
44 hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));
45
46 if (hash & 0x80000000)
47 hash -= 0x7fffffff;
Dave Kleikampac27a0e2006-10-11 01:20:50 -070048 hash1 = hash0;
49 hash0 = hash;
50 }
Theodore Ts'of99b2582008-10-28 13:21:44 -040051 return hash0 << 1;
Dave Kleikampac27a0e2006-10-11 01:20:50 -070052}
53
Theodore Ts'of99b2582008-10-28 13:21:44 -040054static __u32 dx_hack_hash_signed(const char *name, int len)
55{
56 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
57 const signed char *scp = (const signed char *) name;
58
59 while (len--) {
60 hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));
61
62 if (hash & 0x80000000)
63 hash -= 0x7fffffff;
64 hash1 = hash0;
65 hash0 = hash;
66 }
67 return hash0 << 1;
68}
69
70static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)
Dave Kleikampac27a0e2006-10-11 01:20:50 -070071{
72 __u32 pad, val;
73 int i;
Theodore Ts'of99b2582008-10-28 13:21:44 -040074 const signed char *scp = (const signed char *) msg;
Dave Kleikampac27a0e2006-10-11 01:20:50 -070075
76 pad = (__u32)len | ((__u32)len << 8);
77 pad |= pad << 16;
78
79 val = pad;
80 if (len > num*4)
81 len = num * 4;
Theodore Ts'oaf5bc922008-09-08 22:25:24 -040082 for (i = 0; i < len; i++) {
Dave Kleikampac27a0e2006-10-11 01:20:50 -070083 if ((i % 4) == 0)
84 val = pad;
Theodore Ts'of99b2582008-10-28 13:21:44 -040085 val = ((int) scp[i]) + (val << 8);
86 if ((i % 4) == 3) {
87 *buf++ = val;
88 val = pad;
89 num--;
90 }
91 }
92 if (--num >= 0)
93 *buf++ = val;
94 while (--num >= 0)
95 *buf++ = pad;
96}
97
98static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)
99{
100 __u32 pad, val;
101 int i;
102 const unsigned char *ucp = (const unsigned char *) msg;
103
104 pad = (__u32)len | ((__u32)len << 8);
105 pad |= pad << 16;
106
107 val = pad;
108 if (len > num*4)
109 len = num * 4;
110 for (i = 0; i < len; i++) {
111 if ((i % 4) == 0)
112 val = pad;
113 val = ((int) ucp[i]) + (val << 8);
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700114 if ((i % 4) == 3) {
115 *buf++ = val;
116 val = pad;
117 num--;
118 }
119 }
120 if (--num >= 0)
121 *buf++ = val;
122 while (--num >= 0)
123 *buf++ = pad;
124}
125
126/*
127 * Returns the hash of a filename. If len is 0 and name is NULL, then
128 * this function can be used to test whether or not a hash version is
129 * supported.
130 *
131 * The seed is an 4 longword (32 bits) "secret" which can be used to
132 * uniquify a hash. If the seed is all zero's, then some default seed
133 * may be used.
134 *
135 * A particular hash version specifies whether or not the seed is
136 * represented, and whether or not the returned hash is 32 bits or 64
137 * bits. 32 bit hashes will return 0 for the minor hash.
138 */
Mingming Cao617ba132006-10-11 01:20:53 -0700139int ext4fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700140{
141 __u32 hash;
142 __u32 minor_hash = 0;
143 const char *p;
144 int i;
145 __u32 in[8], buf[4];
Theodore Ts'of99b2582008-10-28 13:21:44 -0400146 void (*str2hashbuf)(const char *, int, __u32 *, int) =
147 str2hashbuf_signed;
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700148
149 /* Initialize the default seed for the hash checksum functions */
150 buf[0] = 0x67452301;
151 buf[1] = 0xefcdab89;
152 buf[2] = 0x98badcfe;
153 buf[3] = 0x10325476;
154
155 /* Check to see if the seed is all zero's */
156 if (hinfo->seed) {
Theodore Ts'oaf5bc922008-09-08 22:25:24 -0400157 for (i = 0; i < 4; i++) {
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700158 if (hinfo->seed[i])
159 break;
160 }
161 if (i < 4)
162 memcpy(buf, hinfo->seed, sizeof(buf));
163 }
164
165 switch (hinfo->hash_version) {
Theodore Ts'of99b2582008-10-28 13:21:44 -0400166 case DX_HASH_LEGACY_UNSIGNED:
167 hash = dx_hack_hash_unsigned(name, len);
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700168 break;
Theodore Ts'of99b2582008-10-28 13:21:44 -0400169 case DX_HASH_LEGACY:
170 hash = dx_hack_hash_signed(name, len);
171 break;
172 case DX_HASH_HALF_MD4_UNSIGNED:
173 str2hashbuf = str2hashbuf_unsigned;
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700174 case DX_HASH_HALF_MD4:
175 p = name;
176 while (len > 0) {
Theodore Ts'of99b2582008-10-28 13:21:44 -0400177 (*str2hashbuf)(p, len, in, 8);
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700178 half_md4_transform(buf, in);
179 len -= 32;
180 p += 32;
181 }
182 minor_hash = buf[2];
183 hash = buf[1];
184 break;
Theodore Ts'of99b2582008-10-28 13:21:44 -0400185 case DX_HASH_TEA_UNSIGNED:
186 str2hashbuf = str2hashbuf_unsigned;
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700187 case DX_HASH_TEA:
188 p = name;
189 while (len > 0) {
Theodore Ts'of99b2582008-10-28 13:21:44 -0400190 (*str2hashbuf)(p, len, in, 4);
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700191 TEA_transform(buf, in);
192 len -= 16;
193 p += 16;
194 }
195 hash = buf[0];
196 minor_hash = buf[1];
197 break;
198 default:
199 hinfo->hash = 0;
200 return -1;
201 }
202 hash = hash & ~1;
Mingming Cao617ba132006-10-11 01:20:53 -0700203 if (hash == (EXT4_HTREE_EOF << 1))
204 hash = (EXT4_HTREE_EOF-1) << 1;
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700205 hinfo->hash = hash;
206 hinfo->minor_hash = minor_hash;
207 return 0;
208}