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ext3: Add support for non-native signed/unsigned htree hash algorithms

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The original ext3 hash algorithms assumed that variables of type char
were signed, as God and K&R intended.  Unfortunately, this assumption
is not true on some architectures.  Userspace support for marking
filesystems with non-native signed/unsigned chars was added two years
ago, but the kernel-side support was never added (until now).

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org
This commit is contained in:
Theodore Ts'o
2008-10-28 13:21:55 -04:00
parent 8f72fbdf0d
commit 5e1f8c9e20
5 changed files with 116 additions and 13 deletions
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81
fs/ext3/hash.c
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@ -35,23 +35,71 @@ static void TEA_transform(__u32 buf[4], __u32 const in[])
/* The old legacy hash */
static __u32 dx_hack_hash (const char *name, int len)
static __u32 dx_hack_hash_unsigned(const char *name, int len)
{
__u32 hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
while (len--) {
__u32 hash = hash1 + (hash0 ^ (*name++ * 7152373));
__u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
const unsigned char *ucp = (const unsigned char *) name;
if (hash & 0x80000000) hash -= 0x7fffffff;
while (len--) {
hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));
if (hash & 0x80000000)
hash -= 0x7fffffff;
hash1 = hash0;
hash0 = hash;
}
return (hash0 << 1);
return hash0 << 1;
}
static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)
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;
@ -62,7 +110,7 @@ static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)
for (i=0; i < len; i++) {
if ((i % 4) == 0)
val = pad;
val = msg[i] + (val << 8);
val = ((int) ucp[i]) + (val << 8);
if ((i % 4) == 3) {
*buf++ = val;
val = pad;
@ -95,6 +143,8 @@ int ext3fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
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;
@ -113,13 +163,18 @@ int ext3fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
}
switch (hinfo->hash_version) {
case DX_HASH_LEGACY:
hash = dx_hack_hash(name, len);
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);
(*str2hashbuf)(p, len, in, 8);
half_md4_transform(buf, in);
len -= 32;
p += 32;
@ -127,10 +182,12 @@ int ext3fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
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);
(*str2hashbuf)(p, len, in, 4);
TEA_transform(buf, in);
len -= 16;
p += 16;