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