[mirror_ubuntu-artful-kernel.git] / fs / ext4 / hash.c

/*
 *  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/compiler.h>
#include <linux/bitops.h>
#include "ext4.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;
}

/* F, G and H are basic MD4 functions: selection, majority, parity */
#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
#define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))

/*
 * The generic round function.  The application is so specific that
 * we don't bother protecting all the arguments with parens, as is generally
 * good macro practice, in favor of extra legibility.
 * Rotation is separate from addition to prevent recomputation
 */
#define ROUND(f, a, b, c, d, x, s)	\
	(a += f(b, c, d) + x, a = rol32(a, s))
#define K1 0
#define K2 013240474631UL
#define K3 015666365641UL

/*
 * Basic cut-down MD4 transform.  Returns only 32 bits of result.
 */
static __u32 half_md4_transform(__u32 buf[4], __u32 const in[8])
{
	__u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];

	/* Round 1 */
	ROUND(F, a, b, c, d, in[0] + K1,  3);
	ROUND(F, d, a, b, c, in[1] + K1,  7);
	ROUND(F, c, d, a, b, in[2] + K1, 11);
	ROUND(F, b, c, d, a, in[3] + K1, 19);
	ROUND(F, a, b, c, d, in[4] + K1,  3);
	ROUND(F, d, a, b, c, in[5] + K1,  7);
	ROUND(F, c, d, a, b, in[6] + K1, 11);
	ROUND(F, b, c, d, a, in[7] + K1, 19);

	/* Round 2 */
	ROUND(G, a, b, c, d, in[1] + K2,  3);
	ROUND(G, d, a, b, c, in[3] + K2,  5);
	ROUND(G, c, d, a, b, in[5] + K2,  9);
	ROUND(G, b, c, d, a, in[7] + K2, 13);
	ROUND(G, a, b, c, d, in[0] + K2,  3);
	ROUND(G, d, a, b, c, in[2] + K2,  5);
	ROUND(G, c, d, a, b, in[4] + K2,  9);
	ROUND(G, b, c, d, a, in[6] + K2, 13);

	/* Round 3 */
	ROUND(H, a, b, c, d, in[3] + K3,  3);
	ROUND(H, d, a, b, c, in[7] + K3,  9);
	ROUND(H, c, d, a, b, in[2] + K3, 11);
	ROUND(H, b, c, d, a, in[6] + K3, 15);
	ROUND(H, a, b, c, d, in[1] + K3,  3);
	ROUND(H, d, a, b, c, in[5] + K3,  9);
	ROUND(H, c, d, a, b, in[0] + K3, 11);
	ROUND(H, b, c, d, a, in[4] + K3, 15);

	buf[0] += a;
	buf[1] += b;
	buf[2] += c;
	buf[3] += d;

	return buf[1]; /* "most hashed" word */
}
#undef ROUND
#undef K1
#undef K2
#undef K3
#undef F
#undef G
#undef H

/* The old legacy hash */
static __u32 dx_hack_hash_unsigned(const char *name, int len)
{
	__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
	const unsigned char *ucp = (const unsigned char *) name;

	while (len--) {
		hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));

		if (hash & 0x80000000)
			hash -= 0x7fffffff;
		hash1 = hash0;
		hash0 = hash;
	}
	return hash0 << 1;
}

static __u32 dx_hack_hash_signed(const char *name, int len)
{
	__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
	const signed char *scp = (const signed char *) name;

	while (len--) {
		hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));

		if (hash & 0x80000000)
			hash -= 0x7fffffff;
		hash1 = hash0;
		hash0 = hash;
	}
	return hash0 << 1;
}

static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)
{
	__u32	pad, val;
	int	i;
	const signed char *scp = (const signed char *) msg;

	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 = ((int) scp[i]) + (val << 8);
		if ((i % 4) == 3) {
			*buf++ = val;
			val = pad;
			num--;
		}
	}
	if (--num >= 0)
		*buf++ = val;
	while (--num >= 0)
		*buf++ = pad;
}

static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)
{
	__u32	pad, val;
	int	i;
	const unsigned char *ucp = (const unsigned char *) msg;

	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 = ((int) ucp[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];
	void		(*str2hashbuf)(const char *, int, __u32 *, int) =
				str2hashbuf_signed;

	/* 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]) {
				memcpy(buf, hinfo->seed, sizeof(buf));
				break;
			}
		}
	}

	switch (hinfo->hash_version) {
	case DX_HASH_LEGACY_UNSIGNED:
		hash = dx_hack_hash_unsigned(name, len);
		break;
	case DX_HASH_LEGACY:
		hash = dx_hack_hash_signed(name, len);
		break;
	case DX_HASH_HALF_MD4_UNSIGNED:
		str2hashbuf = str2hashbuf_unsigned;
	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_UNSIGNED:
		str2hashbuf = str2hashbuf_unsigned;
	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_32BIT << 1))
		hash = (EXT4_HTREE_EOF_32BIT - 1) << 1;
	hinfo->hash = hash;
	hinfo->minor_hash = minor_hash;
	return 0;
}
Commit	Line	Data
ac27a0ec	1	/*
617ba13b	2	* linux/fs/ext4/hash.c
ac27a0ec DK	3	*
	4	* Copyright (C) 2002 by Theodore Ts'o
	5	*
	6	* This file is released under the GPL v2.
	7	*
	8	* This file may be redistributed under the terms of the GNU Public
	9	* License.
	10	*/
	11
	12	#include <linux/fs.h>
1c83a9aa JD	13	#include <linux/compiler.h>
1c83a9aa JD	14	#include <linux/bitops.h>
3dcf5451	15	#include "ext4.h"
ac27a0ec DK	16
	17	#define DELTA 0x9E3779B9
	18
	19	static void TEA_transform(__u32 buf[4], __u32 const in[])
	20	{
	21	__u32 sum = 0;
	22	__u32 b0 = buf[0], b1 = buf[1];
	23	__u32 a = in[0], b = in[1], c = in[2], d = in[3];
	24	int n = 16;
	25
	26	do {
	27	sum += DELTA;
	28	b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
	29	b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
af5bc92d	30	} while (--n);
ac27a0ec DK	31
	32	buf[0] += b0;
	33	buf[1] += b1;
	34	}
	35
1c83a9aa JD	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))
	40
	41	/*
	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
	46	*/
	47	#define ROUND(f, a, b, c, d, x, s) \
	48	(a += f(b, c, d) + x, a = rol32(a, s))
	49	#define K1 0
	50	#define K2 013240474631UL
	51	#define K3 015666365641UL
	52
	53	/*
	54	* Basic cut-down MD4 transform. Returns only 32 bits of result.
	55	*/
	56	static __u32 half_md4_transform(__u32 buf[4], __u32 const in[8])
	57	{
	58	__u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
	59
	60	/* Round 1 */
	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);
	69
	70	/* Round 2 */
	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);
	79
	80	/* Round 3 */
	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);
	89
	90	buf[0] += a;
	91	buf[1] += b;
	92	buf[2] += c;
	93	buf[3] += d;
	94
	95	return buf[1]; /* "most hashed" word */
	96	}
	97	#undef ROUND
	98	#undef K1
	99	#undef K2
100	#undef K3
101	#undef F
102	#undef G
103	#undef H
ac27a0ec DK	104
ac27a0ec DK	105	/* The old legacy hash */
f99b2589	106	static __u32 dx_hack_hash_unsigned(const char *name, int len)
ac27a0ec	107	{
f99b2589 TT	108	__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
	109	const unsigned char ucp = (const unsigned char ) name;
	110
	111	while (len--) {
	112	hash = hash1 + (hash0 ^ (((int) ucp++) 7152373));
	113
	114	if (hash & 0x80000000)
	115	hash -= 0x7fffffff;
	116	hash1 = hash0;
	117	hash0 = hash;
	118	}
	119	return hash0 << 1;
	120	}
	121
	122	static __u32 dx_hack_hash_signed(const char *name, int len)
	123	{
	124	__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
	125	const signed char scp = (const signed char ) name;
	126
ac27a0ec	127	while (len--) {
f99b2589	128	hash = hash1 + (hash0 ^ (((int) scp++) 7152373));
ac27a0ec	129
f99b2589 TT	130	if (hash & 0x80000000)
f99b2589 TT	131	hash -= 0x7fffffff;
ac27a0ec DK	132	hash1 = hash0;
	133	hash0 = hash;
	134	}
f99b2589 TT	135	return hash0 << 1;
	136	}
	137
	138	static void str2hashbuf_signed(const char msg, int len, __u32 buf, int num)
	139	{
	140	__u32 pad, val;
	141	int i;
	142	const signed char scp = (const signed char ) msg;
	143
	144	pad = (__u32)len \| ((__u32)len << 8);
	145	pad \|= pad << 16;
	146
	147	val = pad;
	148	if (len > num*4)
	149	len = num * 4;
	150	for (i = 0; i < len; i++) {
	151	if ((i % 4) == 0)
	152	val = pad;
	153	val = ((int) scp[i]) + (val << 8);
	154	if ((i % 4) == 3) {
	155	*buf++ = val;
	156	val = pad;
	157	num--;
	158	}
	159	}
	160	if (--num >= 0)
	161	*buf++ = val;
	162	while (--num >= 0)
	163	*buf++ = pad;
ac27a0ec DK	164	}
ac27a0ec DK	165
f99b2589	166	static void str2hashbuf_unsigned(const char msg, int len, __u32 buf, int num)
ac27a0ec DK	167	{
	168	__u32 pad, val;
	169	int i;
f99b2589	170	const unsigned char ucp = (const unsigned char ) msg;
ac27a0ec DK	171
	172	pad = (__u32)len \| ((__u32)len << 8);
	173	pad \|= pad << 16;
	174
	175	val = pad;
	176	if (len > num*4)
	177	len = num * 4;
af5bc92d	178	for (i = 0; i < len; i++) {
ac27a0ec DK	179	if ((i % 4) == 0)
ac27a0ec DK	180	val = pad;
f99b2589	181	val = ((int) ucp[i]) + (val << 8);
ac27a0ec DK	182	if ((i % 4) == 3) {
	183	*buf++ = val;
	184	val = pad;
	185	num--;
	186	}
	187	}
	188	if (--num >= 0)
	189	*buf++ = val;
	190	while (--num >= 0)
	191	*buf++ = pad;
	192	}
	193
	194	/*
	195	* Returns the hash of a filename. If len is 0 and name is NULL, then
	196	* this function can be used to test whether or not a hash version is
	197	* supported.
	198	*
	199	* The seed is an 4 longword (32 bits) "secret" which can be used to
	200	* uniquify a hash. If the seed is all zero's, then some default seed
	201	* may be used.
	202	*
	203	* A particular hash version specifies whether or not the seed is
	204	* represented, and whether or not the returned hash is 32 bits or 64
	205	* bits. 32 bit hashes will return 0 for the minor hash.
	206	*/
617ba13b	207	int ext4fs_dirhash(const char name, int len, struct dx_hash_info hinfo)
ac27a0ec DK	208	{
	209	__u32 hash;
	210	__u32 minor_hash = 0;
	211	const char *p;
	212	int i;
	213	__u32 in[8], buf[4];
f99b2589 TT	214	void (str2hashbuf)(const char , int, __u32 *, int) =
f99b2589 TT	215	str2hashbuf_signed;
ac27a0ec DK	216
	217	/* Initialize the default seed for the hash checksum functions */
	218	buf[0] = 0x67452301;
	219	buf[1] = 0xefcdab89;
	220	buf[2] = 0x98badcfe;
	221	buf[3] = 0x10325476;
	222
	223	/* Check to see if the seed is all zero's */
	224	if (hinfo->seed) {
af5bc92d	225	for (i = 0; i < 4; i++) {
0e79537d CD	226	if (hinfo->seed[i]) {
0e79537d CD	227	memcpy(buf, hinfo->seed, sizeof(buf));
ac27a0ec	228	break;
0e79537d	229	}
ac27a0ec	230	}
ac27a0ec DK	231	}
	232
	233	switch (hinfo->hash_version) {
f99b2589 TT	234	case DX_HASH_LEGACY_UNSIGNED:
	235	hash = dx_hack_hash_unsigned(name, len);
	236	break;
ac27a0ec	237	case DX_HASH_LEGACY:
f99b2589	238	hash = dx_hack_hash_signed(name, len);
ac27a0ec	239	break;
f99b2589 TT	240	case DX_HASH_HALF_MD4_UNSIGNED:
f99b2589 TT	241	str2hashbuf = str2hashbuf_unsigned;
ac27a0ec DK	242	case DX_HASH_HALF_MD4:
	243	p = name;
	244	while (len > 0) {
f99b2589	245	(*str2hashbuf)(p, len, in, 8);
ac27a0ec DK	246	half_md4_transform(buf, in);
	247	len -= 32;
	248	p += 32;
	249	}
	250	minor_hash = buf[2];
	251	hash = buf[1];
	252	break;
f99b2589 TT	253	case DX_HASH_TEA_UNSIGNED:
f99b2589 TT	254	str2hashbuf = str2hashbuf_unsigned;
ac27a0ec DK	255	case DX_HASH_TEA:
	256	p = name;
	257	while (len > 0) {
f99b2589	258	(*str2hashbuf)(p, len, in, 4);
ac27a0ec DK	259	TEA_transform(buf, in);
	260	len -= 16;
	261	p += 16;
	262	}
	263	hash = buf[0];
	264	minor_hash = buf[1];
	265	break;
	266	default:
	267	hinfo->hash = 0;
	268	return -1;
	269	}
	270	hash = hash & ~1;
d1f5273e FY	271	if (hash == (EXT4_HTREE_EOF_32BIT << 1))
d1f5273e FY	272	hash = (EXT4_HTREE_EOF_32BIT - 1) << 1;
ac27a0ec DK	273	hinfo->hash = hash;
	274	hinfo->minor_hash = minor_hash;
	275	return 0;
	276	}