splice: implement default splice_read method
[linux-2.6.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/slab.h>
30 #include <linux/pagemap.h>
31 #include <linux/smp_lock.h>
32 #include <linux/buffer_head.h>
33 #include "udf_i.h"
34
35 static void udf_pc_to_char(struct super_block *sb, char *from, int fromlen,
36                            char *to)
37 {
38         struct pathComponent *pc;
39         int elen = 0;
40         char *p = to;
41
42         while (elen < fromlen) {
43                 pc = (struct pathComponent *)(from + elen);
44                 switch (pc->componentType) {
45                 case 1:
46                         if (pc->lengthComponentIdent == 0) {
47                                 p = to;
48                                 *p++ = '/';
49                         }
50                         break;
51                 case 3:
52                         memcpy(p, "../", 3);
53                         p += 3;
54                         break;
55                 case 4:
56                         memcpy(p, "./", 2);
57                         p += 2;
58                         /* that would be . - just ignore */
59                         break;
60                 case 5:
61                         p += udf_get_filename(sb, pc->componentIdent, p,
62                                               pc->lengthComponentIdent);
63                         *p++ = '/';
64                         break;
65                 }
66                 elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
67         }
68         if (p > to + 1)
69                 p[-1] = '\0';
70         else
71                 p[0] = '\0';
72 }
73
74 static int udf_symlink_filler(struct file *file, struct page *page)
75 {
76         struct inode *inode = page->mapping->host;
77         struct buffer_head *bh = NULL;
78         char *symlink;
79         int err = -EIO;
80         char *p = kmap(page);
81         struct udf_inode_info *iinfo;
82
83         lock_kernel();
84         iinfo = UDF_I(inode);
85         if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
86                 symlink = iinfo->i_ext.i_data + iinfo->i_lenEAttr;
87         } else {
88                 bh = sb_bread(inode->i_sb, udf_block_map(inode, 0));
89
90                 if (!bh)
91                         goto out;
92
93                 symlink = bh->b_data;
94         }
95
96         udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p);
97         brelse(bh);
98
99         unlock_kernel();
100         SetPageUptodate(page);
101         kunmap(page);
102         unlock_page(page);
103         return 0;
104
105 out:
106         unlock_kernel();
107         SetPageError(page);
108         kunmap(page);
109         unlock_page(page);
110         return err;
111 }
112
113 /*
114  * symlinks can't do much...
115  */
116 const struct address_space_operations udf_symlink_aops = {
117         .readpage               = udf_symlink_filler,
118 };