1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
|
/*
* linux/fs/ext4/hash.c
*
* Copyright (C) 2002 by Theodore Ts'o
*
* This file is released under the GPL v2.
*
* This file may be redistributed under the terms of the GNU Public
* License.
*/
#include <linux/fs.h>
#include <linux/jbd.h>
#include <linux/sched.h>
#include <linux/ext4_fs.h>
#include <linux/cryptohash.h>
#define DELTA 0x9E3779B9
static void TEA_transform(__u32 buf[4], __u32 const in[])
{
__u32 sum = 0;
__u32 b0 = buf[0], b1 = buf[1];
__u32 a = in[0], b = in[1], c = in[2], d = in[3];
int n = 16;
do {
sum += DELTA;
b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
} while(--n);
buf[0] += b0;
buf[1] += b1;
}
/* The old legacy hash */
static __u32 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 << 1);
}
static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)
{
__u32 pad, val;
int i;
pad = (__u32)len | ((__u32)len << 8);
pad |= pad << 16;
val = pad;
if (len > num*4)
len = num * 4;
for (i=0; i < len; i++) {
if ((i % 4) == 0)
val = pad;
val = msg[i] + (val << 8);
if ((i % 4) == 3) {
*buf++ = val;
val = pad;
num--;
}
}
if (--num >= 0)
*buf++ = val;
while (--num >= 0)
*buf++ = pad;
}
/*
* 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.
*
* The seed is an 4 longword (32 bits) "secret" which can be used to
* uniquify a hash. If the seed is all zero's, then some default seed
* may be used.
*
* A particular hash version specifies whether or not the seed is
* represented, and whether or not the returned hash is 32 bits or 64
* bits. 32 bit hashes will return 0 for the minor hash.
*/
int ext4fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
{
__u32 hash;
__u32 minor_hash = 0;
const char *p;
int i;
__u32 in[8], buf[4];
/* Initialize the default seed for the hash checksum functions */
buf[0] = 0x67452301;
buf[1] = 0xefcdab89;
buf[2] = 0x98badcfe;
buf[3] = 0x10325476;
/* Check to see if the seed is all zero's */
if (hinfo->seed) {
for (i=0; i < 4; i++) {
if (hinfo->seed[i])
break;
}
if (i < 4)
memcpy(buf, hinfo->seed, sizeof(buf));
}
switch (hinfo->hash_version) {
case DX_HASH_LEGACY:
hash = dx_hack_hash(name, len);
break;
case DX_HASH_HALF_MD4:
p = name;
while (len > 0) {
str2hashbuf(p, len, in, 8);
half_md4_transform(buf, in);
len -= 32;
p += 32;
}
minor_hash = buf[2];
hash = buf[1];
break;
case DX_HASH_TEA:
p = name;
while (len > 0) {
str2hashbuf(p, len, in, 4);
TEA_transform(buf, in);
len -= 16;
p += 16;
}
hash = buf[0];
minor_hash = buf[1];
break;
default:
hinfo->hash = 0;
return -1;
}
hash = hash & ~1;
if (hash == (EXT4_HTREE_EOF << 1))
hash = (EXT4_HTREE_EOF-1) << 1;
hinfo->hash = hash;
hinfo->minor_hash = minor_hash;
return 0;
}
|
