/* vi: set sw=4 ts=4: *//* * dirhash.c -- Calculate the hash of a directory entry * * Copyright (c) 2001  Daniel Phillips * * Copyright (c) 2002 Theodore Ts'o. * * %Begin-Header% * This file may be redistributed under the terms of the GNU Public * License. * %End-Header% */#include <stdio.h>#include <string.h>#include "ext2_fs.h"#include "ext2fs.h"/* * Keyed 32-bit hash function using TEA in a Davis-Meyer function *   H0 = Key *   Hi = E Mi(Hi-1) + Hi-1 * * (see Applied Cryptography, 2nd edition, p448). * * Jeremy Fitzhardinge <jeremy@zip.com.au> 1998 * * This code is made available under the terms of the GPL */#define DELTA 0x9E3779B9static 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 = (a << s) | (a >> (32-s)))#define K1 0#define K2 013240474631UL#define K3 015666365641UL/* * Basic cut-down MD4 transform.  Returns only 32 bits of result. */static void halfMD4Transform (__u32 buf[4], __u32 const in[]){	__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;}#undef ROUND#undef F#undef G#undef H#undef K1#undef K2#undef K3/* The old legacy hash */static ext2_dirhash_t dx_hack_hash (const char *name, int len){	__u32 hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;	while (len--) {		__u32 hash = hash1 + (hash0 ^ (*name++ * 7152373));		if (hash & 0x80000000) hash -= 0x7fffffff;		hash1 = hash0;		hash0 = hash;	}	return (hash0 << 1);}static void str2hashbuf(const char *msg, int len, __u32 *buf, int num){	__u32	pad, val;	int	i;	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 = msg[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. */errcode_t ext2fs_dirhash(int version, const char *name, int len,			 const __u32 *seed,			 ext2_dirhash_t *ret_hash,			 ext2_dirhash_t *ret_minor_hash){	__u32	hash;	__u32	minor_hash = 0;	const char	*p;	int		i;	__u32		in[8], buf[4];	/* 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 (seed) {		for (i=0; i < 4; i++) {			if (seed[i])				break;		}		if (i < 4)			memcpy(buf, seed, sizeof(buf));	}	switch (version) {	case EXT2_HASH_LEGACY:		hash = dx_hack_hash(name, len);		break;	case EXT2_HASH_HALF_MD4:		p = name;		while (len > 0) {			str2hashbuf(p, len, in, 8);			halfMD4Transform(buf, in);			len -= 32;			p += 32;		}		minor_hash = buf[2];		hash = buf[1];		break;	case EXT2_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:		*ret_hash = 0;		return EXT2_ET_DIRHASH_UNSUPP;	}	*ret_hash = hash & ~1;	if (ret_minor_hash)		*ret_minor_hash = minor_hash;	return 0;}