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authorTheodore Ts'o <tytso@mit.edu>2008-10-28 13:21:55 -0400
committerTheodore Ts'o <tytso@mit.edu>2008-10-28 13:21:55 -0400
commit5e1f8c9e20a92743eefc9a82c2db835213905e26 (patch)
tree0c945d1e31b87d1d8c18381f4ffe99122ddb797b /fs/ext3/hash.c
parent8f72fbdf0d92e6127583cc548bf043c60cd4720f (diff)
ext3: Add support for non-native signed/unsigned htree hash algorithms
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
Diffstat (limited to 'fs/ext3/hash.c')
-rw-r--r--fs/ext3/hash.c77
1 files changed, 67 insertions, 10 deletions
diff --git a/fs/ext3/hash.c b/fs/ext3/hash.c
index c30e149fbd2e..7d215b4d4f2e 100644
--- a/fs/ext3/hash.c
+++ b/fs/ext3/hash.c
@@ -35,23 +35,71 @@ static void TEA_transform(__u32 buf[4], __u32 const in[])
35 35
36 36
37/* The old legacy hash */ 37/* The old legacy hash */
38static __u32 dx_hack_hash (const char *name, int len) 38static __u32 dx_hack_hash_unsigned(const char *name, int len)
39{ 39{
40 __u32 hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9; 40 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
41 const unsigned char *ucp = (const unsigned char *) name;
42
43 while (len--) {
44 hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));
45
46 if (hash & 0x80000000)
47 hash -= 0x7fffffff;
48 hash1 = hash0;
49 hash0 = hash;
50 }
51 return hash0 << 1;
52}
53
54static __u32 dx_hack_hash_signed(const char *name, int len)
55{
56 __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
57 const signed char *scp = (const signed char *) name;
58
41 while (len--) { 59 while (len--) {
42 __u32 hash = hash1 + (hash0 ^ (*name++ * 7152373)); 60 hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));
43 61
44 if (hash & 0x80000000) hash -= 0x7fffffff; 62 if (hash & 0x80000000)
63 hash -= 0x7fffffff;
45 hash1 = hash0; 64 hash1 = hash0;
46 hash0 = hash; 65 hash0 = hash;
47 } 66 }
48 return (hash0 << 1); 67 return hash0 << 1;
49} 68}
50 69
51static void str2hashbuf(const char *msg, int len, __u32 *buf, int num) 70static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)
52{ 71{
53 __u32 pad, val; 72 __u32 pad, val;
54 int i; 73 int i;
74 const signed char *scp = (const signed char *) msg;
75
76 pad = (__u32)len | ((__u32)len << 8);
77 pad |= pad << 16;
78
79 val = pad;
80 if (len > num*4)
81 len = num * 4;
82 for (i = 0; i < len; i++) {
83 if ((i % 4) == 0)
84 val = pad;
85 val = ((int) scp[i]) + (val << 8);
86 if ((i % 4) == 3) {
87 *buf++ = val;
88 val = pad;
89 num--;
90 }
91 }
92 if (--num >= 0)
93 *buf++ = val;
94 while (--num >= 0)
95 *buf++ = pad;
96}
97
98static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)
99{
100 __u32 pad, val;
101 int i;
102 const unsigned char *ucp = (const unsigned char *) msg;
55 103
56 pad = (__u32)len | ((__u32)len << 8); 104 pad = (__u32)len | ((__u32)len << 8);
57 pad |= pad << 16; 105 pad |= pad << 16;
@@ -62,7 +110,7 @@ static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)
62 for (i=0; i < len; i++) { 110 for (i=0; i < len; i++) {
63 if ((i % 4) == 0) 111 if ((i % 4) == 0)
64 val = pad; 112 val = pad;
65 val = msg[i] + (val << 8); 113 val = ((int) ucp[i]) + (val << 8);
66 if ((i % 4) == 3) { 114 if ((i % 4) == 3) {
67 *buf++ = val; 115 *buf++ = val;
68 val = pad; 116 val = pad;
@@ -95,6 +143,8 @@ int ext3fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
95 const char *p; 143 const char *p;
96 int i; 144 int i;
97 __u32 in[8], buf[4]; 145 __u32 in[8], buf[4];
146 void (*str2hashbuf)(const char *, int, __u32 *, int) =
147 str2hashbuf_signed;
98 148
99 /* Initialize the default seed for the hash checksum functions */ 149 /* Initialize the default seed for the hash checksum functions */
100 buf[0] = 0x67452301; 150 buf[0] = 0x67452301;
@@ -113,13 +163,18 @@ int ext3fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
113 } 163 }
114 164
115 switch (hinfo->hash_version) { 165 switch (hinfo->hash_version) {
166 case DX_HASH_LEGACY_UNSIGNED:
167 hash = dx_hack_hash_unsigned(name, len);
168 break;
116 case DX_HASH_LEGACY: 169 case DX_HASH_LEGACY:
117 hash = dx_hack_hash(name, len); 170 hash = dx_hack_hash_signed(name, len);
118 break; 171 break;
172 case DX_HASH_HALF_MD4_UNSIGNED:
173 str2hashbuf = str2hashbuf_unsigned;
119 case DX_HASH_HALF_MD4: 174 case DX_HASH_HALF_MD4:
120 p = name; 175 p = name;
121 while (len > 0) { 176 while (len > 0) {
122 str2hashbuf(p, len, in, 8); 177 (*str2hashbuf)(p, len, in, 8);
123 half_md4_transform(buf, in); 178 half_md4_transform(buf, in);
124 len -= 32; 179 len -= 32;
125 p += 32; 180 p += 32;
@@ -127,10 +182,12 @@ int ext3fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
127 minor_hash = buf[2]; 182 minor_hash = buf[2];
128 hash = buf[1]; 183 hash = buf[1];
129 break; 184 break;
185 case DX_HASH_TEA_UNSIGNED:
186 str2hashbuf = str2hashbuf_unsigned;
130 case DX_HASH_TEA: 187 case DX_HASH_TEA:
131 p = name; 188 p = name;
132 while (len > 0) { 189 while (len > 0) {
133 str2hashbuf(p, len, in, 4); 190 (*str2hashbuf)(p, len, in, 4);
134 TEA_transform(buf, in); 191 TEA_transform(buf, in);
135 len -= 16; 192 len -= 16;
136 p += 16; 193 p += 16;