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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 <linux/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 "udf_i.h"
31
32static int udf_pc_to_char(struct super_block *sb, unsigned char *from,
33 int fromlen, unsigned char *to, int tolen)
34{
35 struct pathComponent *pc;
36 int elen = 0;
37 int comp_len;
38 unsigned char *p = to;
39
40 /* Reserve one byte for terminating \0 */
41 tolen--;
42 while (elen < fromlen) {
43 pc = (struct pathComponent *)(from + elen);
44 elen += sizeof(struct pathComponent);
45 switch (pc->componentType) {
46 case 1:
47 /*
48 * Symlink points to some place which should be agreed
49 * upon between originator and receiver of the media. Ignore.
50 */
51 if (pc->lengthComponentIdent > 0) {
52 elen += pc->lengthComponentIdent;
53 break;
54 }
55 fallthrough;
56 case 2:
57 if (tolen == 0)
58 return -ENAMETOOLONG;
59 p = to;
60 *p++ = '/';
61 tolen--;
62 break;
63 case 3:
64 if (tolen < 3)
65 return -ENAMETOOLONG;
66 memcpy(p, "../", 3);
67 p += 3;
68 tolen -= 3;
69 break;
70 case 4:
71 if (tolen < 2)
72 return -ENAMETOOLONG;
73 memcpy(p, "./", 2);
74 p += 2;
75 tolen -= 2;
76 /* that would be . - just ignore */
77 break;
78 case 5:
79 elen += pc->lengthComponentIdent;
80 if (elen > fromlen)
81 return -EIO;
82 comp_len = udf_get_filename(sb, pc->componentIdent,
83 pc->lengthComponentIdent,
84 p, tolen);
85 if (comp_len < 0)
86 return comp_len;
87
88 p += comp_len;
89 tolen -= comp_len;
90 if (tolen == 0)
91 return -ENAMETOOLONG;
92 *p++ = '/';
93 tolen--;
94 break;
95 }
96 }
97 if (p > to + 1)
98 p[-1] = '\0';
99 else
100 p[0] = '\0';
101 return 0;
102}
103
104static int udf_symlink_filler(struct file *file, struct page *page)
105{
106 struct inode *inode = page->mapping->host;
107 struct buffer_head *bh = NULL;
108 unsigned char *symlink;
109 int err;
110 unsigned char *p = page_address(page);
111 struct udf_inode_info *iinfo;
112 uint32_t pos;
113
114 /* We don't support symlinks longer than one block */
115 if (inode->i_size > inode->i_sb->s_blocksize) {
116 err = -ENAMETOOLONG;
117 goto out_unmap;
118 }
119
120 iinfo = UDF_I(inode);
121 pos = udf_block_map(inode, 0);
122
123 down_read(&iinfo->i_data_sem);
124 if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
125 symlink = iinfo->i_data + iinfo->i_lenEAttr;
126 } else {
127 bh = sb_bread(inode->i_sb, pos);
128
129 if (!bh) {
130 err = -EIO;
131 goto out_unlock_inode;
132 }
133
134 symlink = bh->b_data;
135 }
136
137 err = udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p, PAGE_SIZE);
138 brelse(bh);
139 if (err)
140 goto out_unlock_inode;
141
142 up_read(&iinfo->i_data_sem);
143 SetPageUptodate(page);
144 unlock_page(page);
145 return 0;
146
147out_unlock_inode:
148 up_read(&iinfo->i_data_sem);
149 SetPageError(page);
150out_unmap:
151 unlock_page(page);
152 return err;
153}
154
155static int udf_symlink_getattr(struct user_namespace *mnt_userns,
156 const struct path *path, struct kstat *stat,
157 u32 request_mask, unsigned int flags)
158{
159 struct dentry *dentry = path->dentry;
160 struct inode *inode = d_backing_inode(dentry);
161 struct page *page;
162
163 generic_fillattr(&init_user_ns, inode, stat);
164 page = read_mapping_page(inode->i_mapping, 0, NULL);
165 if (IS_ERR(page))
166 return PTR_ERR(page);
167 /*
168 * UDF uses non-trivial encoding of symlinks so i_size does not match
169 * number of characters reported by readlink(2) which apparently some
170 * applications expect. Also POSIX says that "The value returned in the
171 * st_size field shall be the length of the contents of the symbolic
172 * link, and shall not count a trailing null if one is present." So
173 * let's report the length of string returned by readlink(2) for
174 * st_size.
175 */
176 stat->size = strlen(page_address(page));
177 put_page(page);
178
179 return 0;
180}
181
182/*
183 * symlinks can't do much...
184 */
185const struct address_space_operations udf_symlink_aops = {
186 .readpage = udf_symlink_filler,
187};
188
189const struct inode_operations udf_symlink_inode_operations = {
190 .get_link = page_get_link,
191 .getattr = udf_symlink_getattr,
192};
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
33static 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 if (pc->lengthComponentIdent == 0) {
45 p = to;
46 *p++ = '/';
47 }
48 break;
49 case 3:
50 memcpy(p, "../", 3);
51 p += 3;
52 break;
53 case 4:
54 memcpy(p, "./", 2);
55 p += 2;
56 /* that would be . - just ignore */
57 break;
58 case 5:
59 p += udf_get_filename(sb, pc->componentIdent, p,
60 pc->lengthComponentIdent);
61 *p++ = '/';
62 break;
63 }
64 elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
65 }
66 if (p > to + 1)
67 p[-1] = '\0';
68 else
69 p[0] = '\0';
70}
71
72static int udf_symlink_filler(struct file *file, struct page *page)
73{
74 struct inode *inode = page->mapping->host;
75 struct buffer_head *bh = NULL;
76 unsigned char *symlink;
77 int err = -EIO;
78 unsigned char *p = kmap(page);
79 struct udf_inode_info *iinfo;
80 uint32_t pos;
81
82 iinfo = UDF_I(inode);
83 pos = udf_block_map(inode, 0);
84
85 down_read(&iinfo->i_data_sem);
86 if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
87 symlink = iinfo->i_ext.i_data + iinfo->i_lenEAttr;
88 } else {
89 bh = sb_bread(inode->i_sb, pos);
90
91 if (!bh)
92 goto out;
93
94 symlink = bh->b_data;
95 }
96
97 udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p);
98 brelse(bh);
99
100 up_read(&iinfo->i_data_sem);
101 SetPageUptodate(page);
102 kunmap(page);
103 unlock_page(page);
104 return 0;
105
106out:
107 up_read(&iinfo->i_data_sem);
108 SetPageError(page);
109 kunmap(page);
110 unlock_page(page);
111 return err;
112}
113
114/*
115 * symlinks can't do much...
116 */
117const struct address_space_operations udf_symlink_aops = {
118 .readpage = udf_symlink_filler,
119};