symlink.c
3.29 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
/*
* symlink.c
*
* PURPOSE
* Symlink handling routines for the OSTA-UDF(tm) filesystem.
*
* COPYRIGHT
* This file is distributed under the terms of the GNU General Public
* License (GPL). Copies of the GPL can be obtained from:
* ftp://prep.ai.mit.edu/pub/gnu/GPL
* Each contributing author retains all rights to their own work.
*
* (C) 1998-2001 Ben Fennema
* (C) 1999 Stelias Computing Inc
*
* HISTORY
*
* 04/16/99 blf Created.
*
*/
#include "udfdecl.h"
#include <linux/uaccess.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/stat.h>
#include <linux/pagemap.h>
#include "udf_i.h"
static int udf_pc_to_char(struct super_block *sb, unsigned char *from,
int fromlen, unsigned char *to, int tolen)
{
struct pathComponent *pc;
int elen = 0;
int comp_len;
unsigned char *p = to;
/* Reserve one byte for terminating \0 */
tolen--;
while (elen < fromlen) {
pc = (struct pathComponent *)(from + elen);
elen += sizeof(struct pathComponent);
switch (pc->componentType) {
case 1:
/*
* Symlink points to some place which should be agreed
* upon between originator and receiver of the media. Ignore.
*/
if (pc->lengthComponentIdent > 0) {
elen += pc->lengthComponentIdent;
break;
}
/* Fall through */
case 2:
if (tolen == 0)
return -ENAMETOOLONG;
p = to;
*p++ = '/';
tolen--;
break;
case 3:
if (tolen < 3)
return -ENAMETOOLONG;
memcpy(p, "../", 3);
p += 3;
tolen -= 3;
break;
case 4:
if (tolen < 2)
return -ENAMETOOLONG;
memcpy(p, "./", 2);
p += 2;
tolen -= 2;
/* that would be . - just ignore */
break;
case 5:
elen += pc->lengthComponentIdent;
if (elen > fromlen)
return -EIO;
comp_len = udf_get_filename(sb, pc->componentIdent,
pc->lengthComponentIdent,
p, tolen);
if (comp_len < 0)
return comp_len;
p += comp_len;
tolen -= comp_len;
if (tolen == 0)
return -ENAMETOOLONG;
*p++ = '/';
tolen--;
break;
}
}
if (p > to + 1)
p[-1] = '\0';
else
p[0] = '\0';
return 0;
}
static int udf_symlink_filler(struct file *file, struct page *page)
{
struct inode *inode = page->mapping->host;
struct buffer_head *bh = NULL;
unsigned char *symlink;
int err;
unsigned char *p = kmap(page);
struct udf_inode_info *iinfo;
uint32_t pos;
/* We don't support symlinks longer than one block */
if (inode->i_size > inode->i_sb->s_blocksize) {
err = -ENAMETOOLONG;
goto out_unmap;
}
iinfo = UDF_I(inode);
pos = udf_block_map(inode, 0);
down_read(&iinfo->i_data_sem);
if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
symlink = iinfo->i_ext.i_data + iinfo->i_lenEAttr;
} else {
bh = sb_bread(inode->i_sb, pos);
if (!bh) {
err = -EIO;
goto out_unlock_inode;
}
symlink = bh->b_data;
}
err = udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p, PAGE_SIZE);
brelse(bh);
if (err)
goto out_unlock_inode;
up_read(&iinfo->i_data_sem);
SetPageUptodate(page);
kunmap(page);
unlock_page(page);
return 0;
out_unlock_inode:
up_read(&iinfo->i_data_sem);
SetPageError(page);
out_unmap:
kunmap(page);
unlock_page(page);
return err;
}
/*
* symlinks can't do much...
*/
const struct address_space_operations udf_symlink_aops = {
.readpage = udf_symlink_filler,
};