1 files changed, 307 insertions, 0 deletions
diff --git a/lib/ext2fs/dirhash.c b/lib/ext2fs/dirhash.c
new file mode 100644
index 0000000..42fe98b
--- /dev/null
+++ b/lib/ext2fs/dirhash.c
@@ -0,0 +1,307 @@
+/*
+ * 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 Library
+ * General Public License, version 2.
+ * %End-Header%
+ */
+
+#include "config.h"
+#include <stdio.h>
+#include <string.h>
+#include <limits.h>
+
+#include "ext2_fs.h"
+#include "ext2fs.h"
+#include "ext2fsP.h"
+
+#ifndef PATH_MAX
+#define PATH_MAX 4096
+#endif
+
+/*
+ * 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 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 = (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,
+				    int unsigned_flag)
+{
+	__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
+	const unsigned char *ucp = (const unsigned char *) name;
+	const signed char *scp = (const signed char *) name;
+	int c;
+
+	while (len--) {
+		if (unsigned_flag)
+			c = (int) *ucp++;
+		else
+			c = (int) *scp++;
+		hash = hash1 + (hash0 ^ (c * 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,
+			int unsigned_flag)
+{
+	__u32	pad, val;
+	int	i, c;
+	const unsigned char *ucp = (const unsigned char *) msg;
+	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 (unsigned_flag)
+			c = (int) ucp[i];
+		else
+			c = (int) scp[i];
+
+		val = c + (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.
+ *
+ * This function doesn't do any normalization or casefolding of the
+ * input string.  To take charset encoding into account, use
+ * ext2fs_dirhash2.
+ *
+ */
+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];
+	int		unsigned_flag = 0;
+
+	/* 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_UNSIGNED:
+		unsigned_flag++;
+		/* fallthrough */
+	case EXT2_HASH_LEGACY:
+		hash = dx_hack_hash(name, len, unsigned_flag);
+		break;
+	case EXT2_HASH_HALF_MD4_UNSIGNED:
+		unsigned_flag++;
+		/* fallthrough */
+	case EXT2_HASH_HALF_MD4:
+		p = name;
+		while (len > 0) {
+			str2hashbuf(p, len, in, 8, unsigned_flag);
+			halfMD4Transform(buf, in);
+			len -= 32;
+			p += 32;
+		}
+		minor_hash = buf[2];
+		hash = buf[1];
+		break;
+	case EXT2_HASH_TEA_UNSIGNED:
+		unsigned_flag++;
+		/* fallthrough */
+	case EXT2_HASH_TEA:
+		p = name;
+		while (len > 0) {
+			str2hashbuf(p, len, in, 4, unsigned_flag);
+			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;
+}
+
+/*
+ * Returns the hash of a filename considering normalization and
+ * casefolding.  This is a wrapper around ext2fs_dirhash with string
+ * encoding support based on the nls_table and the flags. Check
+ * ext2fs_dirhash for documentation on the input and output parameters.
+ */
+errcode_t ext2fs_dirhash2(int version, const char *name, int len,
+			  const struct ext2fs_nls_table *charset,
+			  int hash_flags, const __u32 *seed,
+			  ext2_dirhash_t *ret_hash,
+			  ext2_dirhash_t *ret_minor_hash)
+{
+	errcode_t r;
+	int dlen;
+
+	if (len && charset && (hash_flags & EXT4_CASEFOLD_FL)) {
+		char buff[PATH_MAX];
+
+		dlen = charset->ops->casefold(charset,
+			      (const unsigned char *) name, len,
+			      (unsigned char *) buff, sizeof(buff));
+		if (dlen < 0) {
+			if (dlen == -EINVAL)
+				goto opaque_seq;
+
+			return dlen;
+		}
+		r = ext2fs_dirhash(version, buff, dlen, seed, ret_hash,
+				   ret_minor_hash);
+		return r;
+	}
+
+opaque_seq:
+	return ext2fs_dirhash(version, name, len, seed, ret_hash,
+			      ret_minor_hash);
+}