2 * linux/fs/ldiskfs/hash.c
4 * Copyright (C) 2002 by Theodore Ts'o
6 * This file is released under the GPL v2.
8 * This file may be redistributed under the terms of the GNU Public
13 #include <linux/jbd.h>
14 #include <linux/sched.h>
15 #include <linux/ldiskfs_fs.h>
17 #define DELTA 0x9E3779B9
19 static void TEA_transform(__u32 buf[4], __u32 const in[])
22 __u32 b0 = buf[0], b1 = buf[1];
23 __u32 a = in[0], b = in[1], c = in[2], d = in[3];
28 b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
29 b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
36 /* F, G and H are basic MD4 functions: selection, majority, parity */
37 #define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
38 #define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
39 #define H(x, y, z) ((x) ^ (y) ^ (z))
42 * The generic round function. The application is so specific that
43 * we don't bother protecting all the arguments with parens, as is generally
44 * good macro practice, in favor of extra legibility.
45 * Rotation is separate from addition to prevent recomputation
47 #define ROUND(f, a, b, c, d, x, s) \
48 (a += f(b, c, d) + x, a = (a << s) | (a >> (32-s)))
50 #define K2 013240474631UL
51 #define K3 015666365641UL
54 * Basic cut-down MD4 transform. Returns only 32 bits of result.
56 static void halfMD4Transform (__u32 buf[4], __u32 const in[])
58 __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
61 ROUND(F, a, b, c, d, in[0] + K1, 3);
62 ROUND(F, d, a, b, c, in[1] + K1, 7);
63 ROUND(F, c, d, a, b, in[2] + K1, 11);
64 ROUND(F, b, c, d, a, in[3] + K1, 19);
65 ROUND(F, a, b, c, d, in[4] + K1, 3);
66 ROUND(F, d, a, b, c, in[5] + K1, 7);
67 ROUND(F, c, d, a, b, in[6] + K1, 11);
68 ROUND(F, b, c, d, a, in[7] + K1, 19);
71 ROUND(G, a, b, c, d, in[1] + K2, 3);
72 ROUND(G, d, a, b, c, in[3] + K2, 5);
73 ROUND(G, c, d, a, b, in[5] + K2, 9);
74 ROUND(G, b, c, d, a, in[7] + K2, 13);
75 ROUND(G, a, b, c, d, in[0] + K2, 3);
76 ROUND(G, d, a, b, c, in[2] + K2, 5);
77 ROUND(G, c, d, a, b, in[4] + K2, 9);
78 ROUND(G, b, c, d, a, in[6] + K2, 13);
81 ROUND(H, a, b, c, d, in[3] + K3, 3);
82 ROUND(H, d, a, b, c, in[7] + K3, 9);
83 ROUND(H, c, d, a, b, in[2] + K3, 11);
84 ROUND(H, b, c, d, a, in[6] + K3, 15);
85 ROUND(H, a, b, c, d, in[1] + K3, 3);
86 ROUND(H, d, a, b, c, in[5] + K3, 9);
87 ROUND(H, c, d, a, b, in[0] + K3, 11);
88 ROUND(H, b, c, d, a, in[4] + K3, 15);
104 /* The old legacy hash */
105 static __u32 dx_hack_hash (const char *name, int len)
107 __u32 hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
109 __u32 hash = hash1 + (hash0 ^ (*name++ * 7152373));
111 if (hash & 0x80000000) hash -= 0x7fffffff;
118 static __u32 dx_r5_hash(const signed char *msg, int len)
130 static __u32 dx_same_hash(const signed char *msg, int len)
135 static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)
140 pad = (__u32)len | ((__u32)len << 8);
146 for (i=0; i < len; i++) {
149 val = msg[i] + (val << 8);
163 * Returns the hash of a filename. If len is 0 and name is NULL, then
164 * this function can be used to test whether or not a hash version is
167 * The seed is an 4 longword (32 bits) "secret" which can be used to
168 * uniquify a hash. If the seed is all zero's, then some default seed
171 * A particular hash version specifies whether or not the seed is
172 * represented, and whether or not the returned hash is 32 bits or 64
173 * bits. 32 bit hashes will return 0 for the minor hash.
175 int ldiskfsfs_dirhash(const char *name, int len, struct ldiskfs_dx_hash_info *hinfo)
178 __u32 minor_hash = 0;
183 /* Initialize the default seed for the hash checksum functions */
189 /* Check to see if the seed is all zero's */
191 for (i=0; i < 4; i++) {
196 memcpy(buf, hinfo->seed, sizeof(buf));
199 switch (hinfo->hash_version) {
200 case LDISKFS_DX_HASH_LEGACY:
201 hash = dx_hack_hash(name, len);
203 case LDISKFS_DX_HASH_HALF_MD4:
206 str2hashbuf(p, len, in, 8);
207 halfMD4Transform(buf, in);
214 case LDISKFS_DX_HASH_TEA:
217 str2hashbuf(p, len, in, 4);
218 TEA_transform(buf, in);
225 case LDISKFS_DX_HASH_R5:
226 hash = dx_r5_hash(name, len);
228 case LDISKFS_DX_HASH_SAME:
229 hash = dx_same_hash(name, len);
236 if (hash == (LDISKFS_HTREE_EOF << 1))
237 hash = (LDISKFS_HTREE_EOF-1) << 1;
239 hinfo->minor_hash = minor_hash;