Loading...
1/*
2 * linux/fs/ext4/hash.c
3 *
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>
13#include <linux/cryptohash.h>
14#include "ext4.h"
15
16#define DELTA 0x9E3779B9
17
18static void TEA_transform(__u32 buf[4], __u32 const in[])
19{
20 __u32 sum = 0;
21 __u32 b0 = buf[0], b1 = buf[1];
22 __u32 a = in[0], b = in[1], c = in[2], d = in[3];
23 int n = 16;
24
25 do {
26 sum += DELTA;
27 b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
28 b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
29 } while (--n);
30
31 buf[0] += b0;
32 buf[1] += b1;
33}
34
35
36/* The old legacy hash */
37static __u32 dx_hack_hash_unsigned(const char *name, int len)
38{
39 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
40 const unsigned char *ucp = (const unsigned char *) name;
41
42 while (len--) {
43 hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));
44
45 if (hash & 0x80000000)
46 hash -= 0x7fffffff;
47 hash1 = hash0;
48 hash0 = hash;
49 }
50 return hash0 << 1;
51}
52
53static __u32 dx_hack_hash_signed(const char *name, int len)
54{
55 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
56 const signed char *scp = (const signed char *) name;
57
58 while (len--) {
59 hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));
60
61 if (hash & 0x80000000)
62 hash -= 0x7fffffff;
63 hash1 = hash0;
64 hash0 = hash;
65 }
66 return hash0 << 1;
67}
68
69static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)
70{
71 __u32 pad, val;
72 int i;
73 const signed char *scp = (const signed char *) msg;
74
75 pad = (__u32)len | ((__u32)len << 8);
76 pad |= pad << 16;
77
78 val = pad;
79 if (len > num*4)
80 len = num * 4;
81 for (i = 0; i < len; i++) {
82 if ((i % 4) == 0)
83 val = pad;
84 val = ((int) scp[i]) + (val << 8);
85 if ((i % 4) == 3) {
86 *buf++ = val;
87 val = pad;
88 num--;
89 }
90 }
91 if (--num >= 0)
92 *buf++ = val;
93 while (--num >= 0)
94 *buf++ = pad;
95}
96
97static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)
98{
99 __u32 pad, val;
100 int i;
101 const unsigned char *ucp = (const unsigned char *) msg;
102
103 pad = (__u32)len | ((__u32)len << 8);
104 pad |= pad << 16;
105
106 val = pad;
107 if (len > num*4)
108 len = num * 4;
109 for (i = 0; i < len; i++) {
110 if ((i % 4) == 0)
111 val = pad;
112 val = ((int) ucp[i]) + (val << 8);
113 if ((i % 4) == 3) {
114 *buf++ = val;
115 val = pad;
116 num--;
117 }
118 }
119 if (--num >= 0)
120 *buf++ = val;
121 while (--num >= 0)
122 *buf++ = pad;
123}
124
125/*
126 * Returns the hash of a filename. If len is 0 and name is NULL, then
127 * this function can be used to test whether or not a hash version is
128 * supported.
129 *
130 * The seed is an 4 longword (32 bits) "secret" which can be used to
131 * uniquify a hash. If the seed is all zero's, then some default seed
132 * may be used.
133 *
134 * A particular hash version specifies whether or not the seed is
135 * represented, and whether or not the returned hash is 32 bits or 64
136 * bits. 32 bit hashes will return 0 for the minor hash.
137 */
138int ext4fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
139{
140 __u32 hash;
141 __u32 minor_hash = 0;
142 const char *p;
143 int i;
144 __u32 in[8], buf[4];
145 void (*str2hashbuf)(const char *, int, __u32 *, int) =
146 str2hashbuf_signed;
147
148 /* Initialize the default seed for the hash checksum functions */
149 buf[0] = 0x67452301;
150 buf[1] = 0xefcdab89;
151 buf[2] = 0x98badcfe;
152 buf[3] = 0x10325476;
153
154 /* Check to see if the seed is all zero's */
155 if (hinfo->seed) {
156 for (i = 0; i < 4; i++) {
157 if (hinfo->seed[i]) {
158 memcpy(buf, hinfo->seed, sizeof(buf));
159 break;
160 }
161 }
162 }
163
164 switch (hinfo->hash_version) {
165 case DX_HASH_LEGACY_UNSIGNED:
166 hash = dx_hack_hash_unsigned(name, len);
167 break;
168 case DX_HASH_LEGACY:
169 hash = dx_hack_hash_signed(name, len);
170 break;
171 case DX_HASH_HALF_MD4_UNSIGNED:
172 str2hashbuf = str2hashbuf_unsigned;
173 case DX_HASH_HALF_MD4:
174 p = name;
175 while (len > 0) {
176 (*str2hashbuf)(p, len, in, 8);
177 half_md4_transform(buf, in);
178 len -= 32;
179 p += 32;
180 }
181 minor_hash = buf[2];
182 hash = buf[1];
183 break;
184 case DX_HASH_TEA_UNSIGNED:
185 str2hashbuf = str2hashbuf_unsigned;
186 case DX_HASH_TEA:
187 p = name;
188 while (len > 0) {
189 (*str2hashbuf)(p, len, in, 4);
190 TEA_transform(buf, in);
191 len -= 16;
192 p += 16;
193 }
194 hash = buf[0];
195 minor_hash = buf[1];
196 break;
197 default:
198 hinfo->hash = 0;
199 return -1;
200 }
201 hash = hash & ~1;
202 if (hash == (EXT4_HTREE_EOF_32BIT << 1))
203 hash = (EXT4_HTREE_EOF_32BIT - 1) << 1;
204 hinfo->hash = hash;
205 hinfo->minor_hash = minor_hash;
206 return 0;
207}
1/*
2 * linux/fs/ext4/hash.c
3 *
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>
13#include <linux/cryptohash.h>
14#include "ext4.h"
15
16#define DELTA 0x9E3779B9
17
18static void TEA_transform(__u32 buf[4], __u32 const in[])
19{
20 __u32 sum = 0;
21 __u32 b0 = buf[0], b1 = buf[1];
22 __u32 a = in[0], b = in[1], c = in[2], d = in[3];
23 int n = 16;
24
25 do {
26 sum += DELTA;
27 b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
28 b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
29 } while (--n);
30
31 buf[0] += b0;
32 buf[1] += b1;
33}
34
35
36/* The old legacy hash */
37static __u32 dx_hack_hash_unsigned(const char *name, int len)
38{
39 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
40 const unsigned char *ucp = (const unsigned char *) name;
41
42 while (len--) {
43 hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));
44
45 if (hash & 0x80000000)
46 hash -= 0x7fffffff;
47 hash1 = hash0;
48 hash0 = hash;
49 }
50 return hash0 << 1;
51}
52
53static __u32 dx_hack_hash_signed(const char *name, int len)
54{
55 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
56 const signed char *scp = (const signed char *) name;
57
58 while (len--) {
59 hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));
60
61 if (hash & 0x80000000)
62 hash -= 0x7fffffff;
63 hash1 = hash0;
64 hash0 = hash;
65 }
66 return hash0 << 1;
67}
68
69static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)
70{
71 __u32 pad, val;
72 int i;
73 const signed char *scp = (const signed char *) msg;
74
75 pad = (__u32)len | ((__u32)len << 8);
76 pad |= pad << 16;
77
78 val = pad;
79 if (len > num*4)
80 len = num * 4;
81 for (i = 0; i < len; i++) {
82 if ((i % 4) == 0)
83 val = pad;
84 val = ((int) scp[i]) + (val << 8);
85 if ((i % 4) == 3) {
86 *buf++ = val;
87 val = pad;
88 num--;
89 }
90 }
91 if (--num >= 0)
92 *buf++ = val;
93 while (--num >= 0)
94 *buf++ = pad;
95}
96
97static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)
98{
99 __u32 pad, val;
100 int i;
101 const unsigned char *ucp = (const unsigned char *) msg;
102
103 pad = (__u32)len | ((__u32)len << 8);
104 pad |= pad << 16;
105
106 val = pad;
107 if (len > num*4)
108 len = num * 4;
109 for (i = 0; i < len; i++) {
110 if ((i % 4) == 0)
111 val = pad;
112 val = ((int) ucp[i]) + (val << 8);
113 if ((i % 4) == 3) {
114 *buf++ = val;
115 val = pad;
116 num--;
117 }
118 }
119 if (--num >= 0)
120 *buf++ = val;
121 while (--num >= 0)
122 *buf++ = pad;
123}
124
125/*
126 * Returns the hash of a filename. If len is 0 and name is NULL, then
127 * this function can be used to test whether or not a hash version is
128 * supported.
129 *
130 * The seed is an 4 longword (32 bits) "secret" which can be used to
131 * uniquify a hash. If the seed is all zero's, then some default seed
132 * may be used.
133 *
134 * A particular hash version specifies whether or not the seed is
135 * represented, and whether or not the returned hash is 32 bits or 64
136 * bits. 32 bit hashes will return 0 for the minor hash.
137 */
138int ext4fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
139{
140 __u32 hash;
141 __u32 minor_hash = 0;
142 const char *p;
143 int i;
144 __u32 in[8], buf[4];
145 void (*str2hashbuf)(const char *, int, __u32 *, int) =
146 str2hashbuf_signed;
147
148 /* Initialize the default seed for the hash checksum functions */
149 buf[0] = 0x67452301;
150 buf[1] = 0xefcdab89;
151 buf[2] = 0x98badcfe;
152 buf[3] = 0x10325476;
153
154 /* Check to see if the seed is all zero's */
155 if (hinfo->seed) {
156 for (i = 0; i < 4; i++) {
157 if (hinfo->seed[i]) {
158 memcpy(buf, hinfo->seed, sizeof(buf));
159 break;
160 }
161 }
162 }
163
164 switch (hinfo->hash_version) {
165 case DX_HASH_LEGACY_UNSIGNED:
166 hash = dx_hack_hash_unsigned(name, len);
167 break;
168 case DX_HASH_LEGACY:
169 hash = dx_hack_hash_signed(name, len);
170 break;
171 case DX_HASH_HALF_MD4_UNSIGNED:
172 str2hashbuf = str2hashbuf_unsigned;
173 case DX_HASH_HALF_MD4:
174 p = name;
175 while (len > 0) {
176 (*str2hashbuf)(p, len, in, 8);
177 half_md4_transform(buf, in);
178 len -= 32;
179 p += 32;
180 }
181 minor_hash = buf[2];
182 hash = buf[1];
183 break;
184 case DX_HASH_TEA_UNSIGNED:
185 str2hashbuf = str2hashbuf_unsigned;
186 case DX_HASH_TEA:
187 p = name;
188 while (len > 0) {
189 (*str2hashbuf)(p, len, in, 4);
190 TEA_transform(buf, in);
191 len -= 16;
192 p += 16;
193 }
194 hash = buf[0];
195 minor_hash = buf[1];
196 break;
197 default:
198 hinfo->hash = 0;
199 return -1;
200 }
201 hash = hash & ~1;
202 if (hash == (EXT4_HTREE_EOF_32BIT << 1))
203 hash = (EXT4_HTREE_EOF_32BIT - 1) << 1;
204 hinfo->hash = hash;
205 hinfo->minor_hash = minor_hash;
206 return 0;
207}