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/compiler.h>
14 #include <linux/bitops.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 = rol32(a, s))
50 #define K2 013240474631UL
51 #define K3 015666365641UL
54 * Basic cut-down MD4 transform. Returns only 32 bits of result.
56 static __u32 half_md4_transform(__u32 buf[4], __u32 const in[8])
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);
95 return buf[1]; /* "most hashed" word */
105 /* The old legacy hash */
106 static __u32 dx_hack_hash_unsigned(const char *name, int len)
108 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
109 const unsigned char *ucp = (const unsigned char *) name;
112 hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));
114 if (hash & 0x80000000)
122 static __u32 dx_hack_hash_signed(const char *name, int len)
124 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
125 const signed char *scp = (const signed char *) name;
128 hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));
130 if (hash & 0x80000000)
138 static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)
142 const signed char *scp = (const signed char *) msg;
144 pad = (__u32)len | ((__u32)len << 8);
150 for (i = 0; i < len; i++) {
151 val = ((int) scp[i]) + (val << 8);
164 static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)
168 const unsigned char *ucp = (const unsigned char *) msg;
170 pad = (__u32)len | ((__u32)len << 8);
176 for (i = 0; i < len; i++) {
177 val = ((int) ucp[i]) + (val << 8);
191 * Returns the hash of a filename. If len is 0 and name is NULL, then
192 * this function can be used to test whether or not a hash version is
195 * The seed is an 4 longword (32 bits) "secret" which can be used to
196 * uniquify a hash. If the seed is all zero's, then some default seed
199 * A particular hash version specifies whether or not the seed is
200 * represented, and whether or not the returned hash is 32 bits or 64
201 * bits. 32 bit hashes will return 0 for the minor hash.
203 int ext4fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
206 __u32 minor_hash = 0;
210 void (*str2hashbuf)(const char *, int, __u32 *, int) =
213 /* Initialize the default seed for the hash checksum functions */
219 /* Check to see if the seed is all zero's */
221 for (i = 0; i < 4; i++) {
222 if (hinfo->seed[i]) {
223 memcpy(buf, hinfo->seed, sizeof(buf));
229 switch (hinfo->hash_version) {
230 case DX_HASH_LEGACY_UNSIGNED:
231 hash = dx_hack_hash_unsigned(name, len);
234 hash = dx_hack_hash_signed(name, len);
236 case DX_HASH_HALF_MD4_UNSIGNED:
237 str2hashbuf = str2hashbuf_unsigned;
238 case DX_HASH_HALF_MD4:
241 (*str2hashbuf)(p, len, in, 8);
242 half_md4_transform(buf, in);
249 case DX_HASH_TEA_UNSIGNED:
250 str2hashbuf = str2hashbuf_unsigned;
254 (*str2hashbuf)(p, len, in, 4);
255 TEA_transform(buf, in);
267 if (hash == (EXT4_HTREE_EOF_32BIT << 1))
268 hash = (EXT4_HTREE_EOF_32BIT - 1) << 1;
270 hinfo->minor_hash = minor_hash;