2 * dirhash.c -- Calculate the hash of a directory entry
4 * Copyright (c) 2001 Daniel Phillips
6 * Copyright (c) 2002 Theodore Ts'o.
9 * This file may be redistributed under the terms of the GNU Library
10 * General Public License, version 2.
28 * Keyed 32-bit hash function using TEA in a Davis-Meyer function
30 * Hi = E Mi(Hi-1) + Hi-1
32 * (see Applied Cryptography, 2nd edition, p448).
34 * Jeremy Fitzhardinge <jeremy@zip.com.au> 1998
36 * This code is made available under the terms of the GPL
38 #define DELTA 0x9E3779B9
40 static void TEA_transform(__u32 buf[4], __u32 const in[])
43 __u32 b0 = buf[0], b1 = buf[1];
44 __u32 a = in[0], b = in[1], c = in[2], d = in[3];
49 b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
50 b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
57 /* F, G and H are basic MD4 functions: selection, majority, parity */
58 #define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
59 #define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
60 #define H(x, y, z) ((x) ^ (y) ^ (z))
63 * The generic round function. The application is so specific that
64 * we don't bother protecting all the arguments with parens, as is generally
65 * good macro practice, in favor of extra legibility.
66 * Rotation is separate from addition to prevent recomputation
68 #define ROUND(f, a, b, c, d, x, s) \
69 (a += f(b, c, d) + x, a = (a << s) | (a >> (32-s)))
71 #define K2 013240474631UL
72 #define K3 015666365641UL
75 * Basic cut-down MD4 transform. Returns only 32 bits of result.
77 static void halfMD4Transform (__u32 buf[4], __u32 const in[])
79 __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
82 ROUND(F, a, b, c, d, in[0] + K1, 3);
83 ROUND(F, d, a, b, c, in[1] + K1, 7);
84 ROUND(F, c, d, a, b, in[2] + K1, 11);
85 ROUND(F, b, c, d, a, in[3] + K1, 19);
86 ROUND(F, a, b, c, d, in[4] + K1, 3);
87 ROUND(F, d, a, b, c, in[5] + K1, 7);
88 ROUND(F, c, d, a, b, in[6] + K1, 11);
89 ROUND(F, b, c, d, a, in[7] + K1, 19);
92 ROUND(G, a, b, c, d, in[1] + K2, 3);
93 ROUND(G, d, a, b, c, in[3] + K2, 5);
94 ROUND(G, c, d, a, b, in[5] + K2, 9);
95 ROUND(G, b, c, d, a, in[7] + K2, 13);
96 ROUND(G, a, b, c, d, in[0] + K2, 3);
97 ROUND(G, d, a, b, c, in[2] + K2, 5);
98 ROUND(G, c, d, a, b, in[4] + K2, 9);
99 ROUND(G, b, c, d, a, in[6] + K2, 13);
102 ROUND(H, a, b, c, d, in[3] + K3, 3);
103 ROUND(H, d, a, b, c, in[7] + K3, 9);
104 ROUND(H, c, d, a, b, in[2] + K3, 11);
105 ROUND(H, b, c, d, a, in[6] + K3, 15);
106 ROUND(H, a, b, c, d, in[1] + K3, 3);
107 ROUND(H, d, a, b, c, in[5] + K3, 9);
108 ROUND(H, c, d, a, b, in[0] + K3, 11);
109 ROUND(H, b, c, d, a, in[4] + K3, 15);
125 /* The old legacy hash */
126 static ext2_dirhash_t dx_hack_hash (const char *name, int len,
129 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
130 const unsigned char *ucp = (const unsigned char *) name;
131 const signed char *scp = (const signed char *) name;
139 hash = hash1 + (hash0 ^ (c * 7152373));
141 if (hash & 0x80000000) hash -= 0x7fffffff;
148 static void str2hashbuf(const char *msg, int len, __u32 *buf, int num,
153 const unsigned char *ucp = (const unsigned char *) msg;
154 const signed char *scp = (const signed char *) msg;
156 pad = (__u32)len | ((__u32)len << 8);
162 for (i=0; i < len; i++) {
168 val = c + (val << 8);
182 * Returns the hash of a filename. If len is 0 and name is NULL, then
183 * this function can be used to test whether or not a hash version is
186 * The seed is an 4 longword (32 bits) "secret" which can be used to
187 * uniquify a hash. If the seed is all zero's, then some default seed
190 * A particular hash version specifies whether or not the seed is
191 * represented, and whether or not the returned hash is 32 bits or 64
192 * bits. 32 bit hashes will return 0 for the minor hash.
194 * This function doesn't do any normalization or casefolding of the
195 * input string. To take charset encoding into account, use
199 errcode_t ext2fs_dirhash(int version, const char *name, int len,
201 ext2_dirhash_t *ret_hash,
202 ext2_dirhash_t *ret_minor_hash)
205 __u32 minor_hash = 0;
209 int unsigned_flag = 0;
211 /* Initialize the default seed for the hash checksum functions */
217 /* Check to see if the seed is all zero's */
219 for (i=0; i < 4; i++) {
224 memcpy(buf, seed, sizeof(buf));
228 case EXT2_HASH_LEGACY_UNSIGNED:
231 case EXT2_HASH_LEGACY:
232 hash = dx_hack_hash(name, len, unsigned_flag);
234 case EXT2_HASH_HALF_MD4_UNSIGNED:
237 case EXT2_HASH_HALF_MD4:
240 str2hashbuf(p, len, in, 8, unsigned_flag);
241 halfMD4Transform(buf, in);
248 case EXT2_HASH_TEA_UNSIGNED:
254 str2hashbuf(p, len, in, 4, unsigned_flag);
255 TEA_transform(buf, in);
264 return EXT2_ET_DIRHASH_UNSUPP;
266 *ret_hash = hash & ~1;
268 *ret_minor_hash = minor_hash;
273 * Returns the hash of a filename considering normalization and
274 * casefolding. This is a wrapper around ext2fs_dirhash with string
275 * encoding support based on the nls_table and the flags. Check
276 * ext2fs_dirhash for documentation on the input and output parameters.
278 errcode_t ext2fs_dirhash2(int version, const char *name, int len,
279 const struct ext2fs_nls_table *charset,
280 int hash_flags, const __u32 *seed,
281 ext2_dirhash_t *ret_hash,
282 ext2_dirhash_t *ret_minor_hash)
287 if (len && charset && (hash_flags & EXT4_CASEFOLD_FL)) {
290 dlen = charset->ops->casefold(charset,
291 (const unsigned char *) name, len,
292 (unsigned char *) buff, sizeof(buff));
299 r = ext2fs_dirhash(version, buff, dlen, seed, ret_hash,
305 return ext2fs_dirhash(version, name, len, seed, ret_hash,