ref: c2de0281bf8490efacec1a3009e7a3ba11ed3dbe
dir: /src/ext4_hash.c/
/*
* Copyright (c) 2013 Grzegorz Kostka ([email protected])
*
* FreeBSD:
* Copyright (c) 2010, 2013 Zheng Liu <[email protected]>
* Copyright (c) 2012, Vyacheslav Matyushin
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
/*
* The following notice applies to the code in ext2_half_md4():
*
* Copyright (C) 1990-2, RSA Data Security, Inc. All rights reserved.
*
* License to copy and use this software is granted provided that it
* is identified as the "RSA Data Security, Inc. MD4 Message-Digest
* Algorithm" in all material mentioning or referencing this software
* or this function.
*
* License is also granted to make and use derivative works provided
* that such works are identified as "derived from the RSA Data
* Security, Inc. MD4 Message-Digest Algorithm" in all material
* mentioning or referencing the derived work.
*
* RSA Data Security, Inc. makes no representations concerning either
* the merchantability of this software or the suitability of this
* software for any particular purpose. It is provided "as is"
* without express or implied warranty of any kind.
*
* These notices must be retained in any copies of any part of this
* documentation and/or software.
*/
/** @addtogroup lwext4
* @{
*/
/**
* @file ext4_hash.c
* @brief Directory indexing hash functions.
*/
#include <ext4_config.h>
#include <ext4_types.h>
#include <ext4_misc.h>
#include <ext4_errno.h>
#include <ext4_debug.h>
#include <string.h>
/* F, G, and H are MD4 functions */
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (y)) | ((x) & (z)) | ((y) & (z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
/* ROTATE_LEFT rotates x left n bits */
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32 - (n))))
/*
* FF, GG, and HH are transformations for rounds 1, 2, and 3.
* Rotation is separated from addition to prevent recomputation.
*/
#define FF(a, b, c, d, x, s) \
{ \
(a) += F((b), (c), (d)) + (x); \
(a) = ROTATE_LEFT((a), (s)); \
\
}
#define GG(a, b, c, d, x, s) \
{ \
(a) += G((b), (c), (d)) + (x) + (uint32_t)0x5A827999; \
(a) = ROTATE_LEFT((a), (s)); \
\
}
#define HH(a, b, c, d, x, s) \
{ \
(a) += H((b), (c), (d)) + (x) + (uint32_t)0x6ED9EBA1; \
(a) = ROTATE_LEFT((a), (s)); \
\
}
/*
* MD4 basic transformation. It transforms state based on block.
*
* This is a half md4 algorithm since Linux uses this algorithm for dir
* index. This function is derived from the RSA Data Security, Inc. MD4
* Message-Digest Algorithm and was modified as necessary.
*
* The return value of this function is uint32_t in Linux, but actually we don't
* need to check this value, so in our version this function doesn't return any
* value.
*/
static void ext2_half_md4(uint32_t hash[4], uint32_t data[8])
{
uint32_t a = hash[0], b = hash[1], c = hash[2], d = hash[3];
/* Round 1 */
FF(a, b, c, d, data[0], 3);
FF(d, a, b, c, data[1], 7);
FF(c, d, a, b, data[2], 11);
FF(b, c, d, a, data[3], 19);
FF(a, b, c, d, data[4], 3);
FF(d, a, b, c, data[5], 7);
FF(c, d, a, b, data[6], 11);
FF(b, c, d, a, data[7], 19);
/* Round 2 */
GG(a, b, c, d, data[1], 3);
GG(d, a, b, c, data[3], 5);
GG(c, d, a, b, data[5], 9);
GG(b, c, d, a, data[7], 13);
GG(a, b, c, d, data[0], 3);
GG(d, a, b, c, data[2], 5);
GG(c, d, a, b, data[4], 9);
GG(b, c, d, a, data[6], 13);
/* Round 3 */
HH(a, b, c, d, data[3], 3);
HH(d, a, b, c, data[7], 9);
HH(c, d, a, b, data[2], 11);
HH(b, c, d, a, data[6], 15);
HH(a, b, c, d, data[1], 3);
HH(d, a, b, c, data[5], 9);
HH(c, d, a, b, data[0], 11);
HH(b, c, d, a, data[4], 15);
hash[0] += a;
hash[1] += b;
hash[2] += c;
hash[3] += d;
}
/*
* Tiny Encryption Algorithm.
*/
static void ext2_tea(uint32_t hash[4], uint32_t data[8])
{
uint32_t tea_delta = 0x9E3779B9;
uint32_t sum;
uint32_t x = hash[0], y = hash[1];
int n = 16;
int i = 1;
while (n-- > 0) {
sum = i * tea_delta;
x += ((y << 4) + data[0]) ^ (y + sum) ^ ((y >> 5) + data[1]);
y += ((x << 4) + data[2]) ^ (x + sum) ^ ((x >> 5) + data[3]);
i++;
}
hash[0] += x;
hash[1] += y;
}
static uint32_t ext2_legacy_hash(const char *name, int len, int unsigned_char)
{
uint32_t h0, h1 = 0x12A3FE2D, h2 = 0x37ABE8F9;
uint32_t multi = 0x6D22F5;
const unsigned char *uname = (const unsigned char *)name;
const signed char *sname = (const signed char *)name;
int val, i;
for (i = 0; i < len; i++) {
if (unsigned_char)
val = (unsigned int)*uname++;
else
val = (int)*sname++;
h0 = h2 + (h1 ^ (val * multi));
if (h0 & 0x80000000)
h0 -= 0x7FFFFFFF;
h2 = h1;
h1 = h0;
}
return (h1 << 1);
}
static void ext2_prep_hashbuf(const char *src, uint32_t slen, uint32_t *dst,
int dlen, int unsigned_char)
{
uint32_t padding = slen | (slen << 8) | (slen << 16) | (slen << 24);
uint32_t buf_val;
int len, i;
int buf_byte;
const unsigned char *ubuf = (const unsigned char *)src;
const signed char *sbuf = (const signed char *)src;
if (slen > (uint32_t)dlen)
len = dlen;
else
len = slen;
buf_val = padding;
for (i = 0; i < len; i++) {
if (unsigned_char)
buf_byte = (unsigned int)ubuf[i];
else
buf_byte = (int)sbuf[i];
if ((i % 4) == 0)
buf_val = padding;
buf_val <<= 8;
buf_val += buf_byte;
if ((i % 4) == 3) {
*dst++ = buf_val;
dlen -= sizeof(uint32_t);
buf_val = padding;
}
}
dlen -= sizeof(uint32_t);
if (dlen >= 0)
*dst++ = buf_val;
dlen -= sizeof(uint32_t);
while (dlen >= 0) {
*dst++ = padding;
dlen -= sizeof(uint32_t);
}
}
int ext2_htree_hash(const char *name, int len, const uint32_t *hash_seed,
int hash_version, uint32_t *hash_major,
uint32_t *hash_minor)
{
uint32_t hash[4];
uint32_t data[8];
uint32_t major, minor = 0;
int unsigned_char = 0;
if (!name || !hash_major)
return (-1);
if (len < 1 || len > 255)
goto error;
hash[0] = 0x67452301;
hash[1] = 0xEFCDAB89;
hash[2] = 0x98BADCFE;
hash[3] = 0x10325476;
if (hash_seed)
memcpy(hash, hash_seed, sizeof(hash));
switch (hash_version) {
case EXT2_HTREE_TEA_UNSIGNED:
unsigned_char = 1;
/* FALLTHRU */
case EXT2_HTREE_TEA:
while (len > 0) {
ext2_prep_hashbuf(name, len, data, 16, unsigned_char);
ext2_tea(hash, data);
len -= 16;
name += 16;
}
major = hash[0];
minor = hash[1];
break;
case EXT2_HTREE_LEGACY_UNSIGNED:
unsigned_char = 1;
/* FALLTHRU */
case EXT2_HTREE_LEGACY:
major = ext2_legacy_hash(name, len, unsigned_char);
break;
case EXT2_HTREE_HALF_MD4_UNSIGNED:
unsigned_char = 1;
/* FALLTHRU */
case EXT2_HTREE_HALF_MD4:
while (len > 0) {
ext2_prep_hashbuf(name, len, data, 32, unsigned_char);
ext2_half_md4(hash, data);
len -= 32;
name += 32;
}
major = hash[1];
minor = hash[2];
break;
default:
goto error;
}
major &= ~1;
if (major == (EXT2_HTREE_EOF << 1))
major = (EXT2_HTREE_EOF - 1) << 1;
*hash_major = major;
if (hash_minor)
*hash_minor = minor;
return EOK;
error:
*hash_major = 0;
if (hash_minor)
*hash_minor = 0;
return ENOTSUP;
}
/**
* @}
*/