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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 folio *folio)
105{
106 struct page *page = &folio->page;
107 struct inode *inode = page->mapping->host;
108 struct buffer_head *bh = NULL;
109 unsigned char *symlink;
110 int err;
111 unsigned char *p = page_address(page);
112 struct udf_inode_info *iinfo;
113 uint32_t pos;
114
115 /* We don't support symlinks longer than one block */
116 if (inode->i_size > inode->i_sb->s_blocksize) {
117 err = -ENAMETOOLONG;
118 goto out_unmap;
119 }
120
121 iinfo = UDF_I(inode);
122 pos = udf_block_map(inode, 0);
123
124 down_read(&iinfo->i_data_sem);
125 if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
126 symlink = iinfo->i_data + iinfo->i_lenEAttr;
127 } else {
128 bh = sb_bread(inode->i_sb, pos);
129
130 if (!bh) {
131 err = -EIO;
132 goto out_unlock_inode;
133 }
134
135 symlink = bh->b_data;
136 }
137
138 err = udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p, PAGE_SIZE);
139 brelse(bh);
140 if (err)
141 goto out_unlock_inode;
142
143 up_read(&iinfo->i_data_sem);
144 SetPageUptodate(page);
145 unlock_page(page);
146 return 0;
147
148out_unlock_inode:
149 up_read(&iinfo->i_data_sem);
150 SetPageError(page);
151out_unmap:
152 unlock_page(page);
153 return err;
154}
155
156static int udf_symlink_getattr(struct user_namespace *mnt_userns,
157 const struct path *path, struct kstat *stat,
158 u32 request_mask, unsigned int flags)
159{
160 struct dentry *dentry = path->dentry;
161 struct inode *inode = d_backing_inode(dentry);
162 struct page *page;
163
164 generic_fillattr(&init_user_ns, inode, stat);
165 page = read_mapping_page(inode->i_mapping, 0, NULL);
166 if (IS_ERR(page))
167 return PTR_ERR(page);
168 /*
169 * UDF uses non-trivial encoding of symlinks so i_size does not match
170 * number of characters reported by readlink(2) which apparently some
171 * applications expect. Also POSIX says that "The value returned in the
172 * st_size field shall be the length of the contents of the symbolic
173 * link, and shall not count a trailing null if one is present." So
174 * let's report the length of string returned by readlink(2) for
175 * st_size.
176 */
177 stat->size = strlen(page_address(page));
178 put_page(page);
179
180 return 0;
181}
182
183/*
184 * symlinks can't do much...
185 */
186const struct address_space_operations udf_symlink_aops = {
187 .read_folio = udf_symlink_filler,
188};
189
190const struct inode_operations udf_symlink_inode_operations = {
191 .get_link = page_get_link,
192 .getattr = udf_symlink_getattr,
193};
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};