1 /*
2 * ext_attr.c --- extended attribute blocks
3 *
4 * Copyright (C) 2001 Andreas Gruenbacher, <a.gruenbacher@computer.org>
5 *
6 * Copyright (C) 2002 Theodore Ts'o.
7 *
8 * %Begin-Header%
9 * This file may be redistributed under the terms of the GNU Library
10 * General Public License, version 2.
11 * %End-Header%
12 */
13
14 #include <stdio.h>
15 #if HAVE_UNISTD_H
16 #include <unistd.h>
17 #endif
18 #include <string.h>
19 #include <time.h>
20
21 #include "ext2_fs.h"
22 #include "ext2_ext_attr.h"
23
24 #include "ext2fs.h"
25
26 #define NAME_HASH_SHIFT 5
27 #define VALUE_HASH_SHIFT 16
28
29 /*
30 * ext2_xattr_hash_entry()
31 *
32 * Compute the hash of an extended attribute.
33 */
ext2fs_ext_attr_hash_entry(struct ext2_ext_attr_entry * entry,void * data)34 __u32 ext2fs_ext_attr_hash_entry(struct ext2_ext_attr_entry *entry, void *data)
35 {
36 __u32 hash = 0;
37 char *name = ((char *) entry) + sizeof(struct ext2_ext_attr_entry);
38 int n;
39
40 for (n = 0; n < entry->e_name_len; n++) {
41 hash = (hash << NAME_HASH_SHIFT) ^
42 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
43 *name++;
44 }
45
46 /* The hash needs to be calculated on the data in little-endian. */
47 if (entry->e_value_block == 0 && entry->e_value_size != 0) {
48 __u32 *value = (__u32 *)data;
49 for (n = (entry->e_value_size + EXT2_EXT_ATTR_ROUND) >>
50 EXT2_EXT_ATTR_PAD_BITS; n; n--) {
51 hash = (hash << VALUE_HASH_SHIFT) ^
52 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
53 ext2fs_le32_to_cpu(*value++);
54 }
55 }
56
57 return hash;
58 }
59
60 #undef NAME_HASH_SHIFT
61 #undef VALUE_HASH_SHIFT
62
ext2fs_read_ext_attr2(ext2_filsys fs,blk64_t block,void * buf)63 errcode_t ext2fs_read_ext_attr2(ext2_filsys fs, blk64_t block, void *buf)
64 {
65 errcode_t retval;
66
67 retval = io_channel_read_blk64(fs->io, block, 1, buf);
68 if (retval)
69 return retval;
70 #ifdef WORDS_BIGENDIAN
71 ext2fs_swap_ext_attr(buf, buf, fs->blocksize, 1);
72 #endif
73 return 0;
74 }
75
ext2fs_read_ext_attr(ext2_filsys fs,blk_t block,void * buf)76 errcode_t ext2fs_read_ext_attr(ext2_filsys fs, blk_t block, void *buf)
77 {
78 return ext2fs_read_ext_attr2(fs, block, buf);
79 }
80
ext2fs_write_ext_attr2(ext2_filsys fs,blk64_t block,void * inbuf)81 errcode_t ext2fs_write_ext_attr2(ext2_filsys fs, blk64_t block, void *inbuf)
82 {
83 errcode_t retval;
84 char *write_buf;
85 #ifdef WORDS_BIGENDIAN
86 char *buf = NULL;
87
88 retval = ext2fs_get_mem(fs->blocksize, &buf);
89 if (retval)
90 return retval;
91 write_buf = buf;
92 ext2fs_swap_ext_attr(buf, inbuf, fs->blocksize, 1);
93 #else
94 write_buf = (char *) inbuf;
95 #endif
96 retval = io_channel_write_blk64(fs->io, block, 1, write_buf);
97 #ifdef WORDS_BIGENDIAN
98 ext2fs_free_mem(&buf);
99 #endif
100 if (!retval)
101 ext2fs_mark_changed(fs);
102 return retval;
103 }
104
ext2fs_write_ext_attr(ext2_filsys fs,blk_t block,void * inbuf)105 errcode_t ext2fs_write_ext_attr(ext2_filsys fs, blk_t block, void *inbuf)
106 {
107 return ext2fs_write_ext_attr2(fs, block, inbuf);
108 }
109
110 /*
111 * This function adjusts the reference count of the EA block.
112 */
ext2fs_adjust_ea_refcount2(ext2_filsys fs,blk64_t blk,char * block_buf,int adjust,__u32 * newcount)113 errcode_t ext2fs_adjust_ea_refcount2(ext2_filsys fs, blk64_t blk,
114 char *block_buf, int adjust,
115 __u32 *newcount)
116 {
117 errcode_t retval;
118 struct ext2_ext_attr_header *header;
119 char *buf = 0;
120
121 if ((blk >= ext2fs_blocks_count(fs->super)) ||
122 (blk < fs->super->s_first_data_block))
123 return EXT2_ET_BAD_EA_BLOCK_NUM;
124
125 if (!block_buf) {
126 retval = ext2fs_get_mem(fs->blocksize, &buf);
127 if (retval)
128 return retval;
129 block_buf = buf;
130 }
131
132 retval = ext2fs_read_ext_attr2(fs, blk, block_buf);
133 if (retval)
134 goto errout;
135
136 header = (struct ext2_ext_attr_header *) block_buf;
137 header->h_refcount += adjust;
138 if (newcount)
139 *newcount = header->h_refcount;
140
141 retval = ext2fs_write_ext_attr2(fs, blk, block_buf);
142 if (retval)
143 goto errout;
144
145 errout:
146 if (buf)
147 ext2fs_free_mem(&buf);
148 return retval;
149 }
150
ext2fs_adjust_ea_refcount(ext2_filsys fs,blk_t blk,char * block_buf,int adjust,__u32 * newcount)151 errcode_t ext2fs_adjust_ea_refcount(ext2_filsys fs, blk_t blk,
152 char *block_buf, int adjust,
153 __u32 *newcount)
154 {
155 return ext2fs_adjust_ea_refcount(fs, blk, block_buf, adjust, newcount);
156 }
157