Commit | Line | Data |
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5ce34554 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * symlink.c | |
4 | * | |
5 | * PURPOSE | |
6 | * Symlink handling routines for the OSTA-UDF(tm) filesystem. | |
7 | * | |
1da177e4 | 8 | * COPYRIGHT |
1da177e4 | 9 | * (C) 1998-2001 Ben Fennema |
28de7948 | 10 | * (C) 1999 Stelias Computing Inc |
1da177e4 LT |
11 | * |
12 | * HISTORY | |
13 | * | |
14 | * 04/16/99 blf Created. | |
15 | * | |
16 | */ | |
17 | ||
18 | #include "udfdecl.h" | |
e973606c | 19 | #include <linux/uaccess.h> |
1da177e4 LT |
20 | #include <linux/errno.h> |
21 | #include <linux/fs.h> | |
1da177e4 LT |
22 | #include <linux/time.h> |
23 | #include <linux/mm.h> | |
24 | #include <linux/stat.h> | |
1da177e4 | 25 | #include <linux/pagemap.h> |
1da177e4 LT |
26 | #include "udf_i.h" |
27 | ||
0e5cc9a4 JK |
28 | static int udf_pc_to_char(struct super_block *sb, unsigned char *from, |
29 | int fromlen, unsigned char *to, int tolen) | |
1da177e4 LT |
30 | { |
31 | struct pathComponent *pc; | |
32 | int elen = 0; | |
0e5cc9a4 | 33 | int comp_len; |
391e8bbd | 34 | unsigned char *p = to; |
1da177e4 | 35 | |
0e5cc9a4 JK |
36 | /* Reserve one byte for terminating \0 */ |
37 | tolen--; | |
cb00ea35 | 38 | while (elen < fromlen) { |
1da177e4 | 39 | pc = (struct pathComponent *)(from + elen); |
e237ec37 | 40 | elen += sizeof(struct pathComponent); |
cb00ea35 CG |
41 | switch (pc->componentType) { |
42 | case 1: | |
fef2e9f3 JK |
43 | /* |
44 | * Symlink points to some place which should be agreed | |
45 | * upon between originator and receiver of the media. Ignore. | |
46 | */ | |
e237ec37 JK |
47 | if (pc->lengthComponentIdent > 0) { |
48 | elen += pc->lengthComponentIdent; | |
fef2e9f3 | 49 | break; |
e237ec37 | 50 | } |
df561f66 | 51 | fallthrough; |
fef2e9f3 | 52 | case 2: |
0e5cc9a4 JK |
53 | if (tolen == 0) |
54 | return -ENAMETOOLONG; | |
fef2e9f3 JK |
55 | p = to; |
56 | *p++ = '/'; | |
0e5cc9a4 | 57 | tolen--; |
cb00ea35 CG |
58 | break; |
59 | case 3: | |
0e5cc9a4 JK |
60 | if (tolen < 3) |
61 | return -ENAMETOOLONG; | |
cb00ea35 CG |
62 | memcpy(p, "../", 3); |
63 | p += 3; | |
0e5cc9a4 | 64 | tolen -= 3; |
cb00ea35 CG |
65 | break; |
66 | case 4: | |
0e5cc9a4 JK |
67 | if (tolen < 2) |
68 | return -ENAMETOOLONG; | |
cb00ea35 CG |
69 | memcpy(p, "./", 2); |
70 | p += 2; | |
0e5cc9a4 | 71 | tolen -= 2; |
cb00ea35 CG |
72 | /* that would be . - just ignore */ |
73 | break; | |
74 | case 5: | |
e237ec37 JK |
75 | elen += pc->lengthComponentIdent; |
76 | if (elen > fromlen) | |
77 | return -EIO; | |
0e5cc9a4 JK |
78 | comp_len = udf_get_filename(sb, pc->componentIdent, |
79 | pc->lengthComponentIdent, | |
80 | p, tolen); | |
5ceb8b55 FF |
81 | if (comp_len < 0) |
82 | return comp_len; | |
83 | ||
0e5cc9a4 JK |
84 | p += comp_len; |
85 | tolen -= comp_len; | |
86 | if (tolen == 0) | |
87 | return -ENAMETOOLONG; | |
cb00ea35 | 88 | *p++ = '/'; |
0e5cc9a4 | 89 | tolen--; |
cb00ea35 | 90 | break; |
1da177e4 | 91 | } |
1da177e4 | 92 | } |
cb00ea35 | 93 | if (p > to + 1) |
1da177e4 LT |
94 | p[-1] = '\0'; |
95 | else | |
96 | p[0] = '\0'; | |
0e5cc9a4 | 97 | return 0; |
1da177e4 LT |
98 | } |
99 | ||
0c698cc5 | 100 | static int udf_symlink_filler(struct file *file, struct folio *folio) |
1da177e4 | 101 | { |
0c698cc5 | 102 | struct page *page = &folio->page; |
1da177e4 LT |
103 | struct inode *inode = page->mapping->host; |
104 | struct buffer_head *bh = NULL; | |
391e8bbd | 105 | unsigned char *symlink; |
15a08f51 | 106 | int err = 0; |
21fc61c7 | 107 | unsigned char *p = page_address(page); |
f33321b2 | 108 | struct udf_inode_info *iinfo = UDF_I(inode); |
1da177e4 | 109 | |
a1d47b26 JK |
110 | /* We don't support symlinks longer than one block */ |
111 | if (inode->i_size > inode->i_sb->s_blocksize) { | |
112 | err = -ENAMETOOLONG; | |
f33321b2 | 113 | goto out_unlock; |
a1d47b26 JK |
114 | } |
115 | ||
48d6d8ff | 116 | if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) { |
382a2287 | 117 | symlink = iinfo->i_data + iinfo->i_lenEAttr; |
28de7948 | 118 | } else { |
15a08f51 | 119 | bh = udf_bread(inode, 0, 0, &err); |
a1d47b26 | 120 | if (!bh) { |
15a08f51 JK |
121 | if (!err) |
122 | err = -EFSCORRUPTED; | |
f33321b2 | 123 | goto out_err; |
a1d47b26 | 124 | } |
1da177e4 LT |
125 | symlink = bh->b_data; |
126 | } | |
127 | ||
0e5cc9a4 | 128 | err = udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p, PAGE_SIZE); |
3bf25cb4 | 129 | brelse(bh); |
0e5cc9a4 | 130 | if (err) |
f33321b2 | 131 | goto out_err; |
1da177e4 | 132 | |
1da177e4 | 133 | SetPageUptodate(page); |
1da177e4 LT |
134 | unlock_page(page); |
135 | return 0; | |
28de7948 | 136 | |
f33321b2 | 137 | out_err: |
1da177e4 | 138 | SetPageError(page); |
f33321b2 | 139 | out_unlock: |
1da177e4 LT |
140 | unlock_page(page); |
141 | return err; | |
142 | } | |
143 | ||
b74d24f7 | 144 | static int udf_symlink_getattr(struct mnt_idmap *idmap, |
549c7297 CB |
145 | const struct path *path, struct kstat *stat, |
146 | u32 request_mask, unsigned int flags) | |
ad4d0532 | 147 | { |
a528d35e | 148 | struct dentry *dentry = path->dentry; |
ad4d0532 JK |
149 | struct inode *inode = d_backing_inode(dentry); |
150 | struct page *page; | |
151 | ||
b74d24f7 | 152 | generic_fillattr(&nop_mnt_idmap, inode, stat); |
ad4d0532 JK |
153 | page = read_mapping_page(inode->i_mapping, 0, NULL); |
154 | if (IS_ERR(page)) | |
155 | return PTR_ERR(page); | |
156 | /* | |
157 | * UDF uses non-trivial encoding of symlinks so i_size does not match | |
158 | * number of characters reported by readlink(2) which apparently some | |
159 | * applications expect. Also POSIX says that "The value returned in the | |
160 | * st_size field shall be the length of the contents of the symbolic | |
161 | * link, and shall not count a trailing null if one is present." So | |
162 | * let's report the length of string returned by readlink(2) for | |
163 | * st_size. | |
164 | */ | |
165 | stat->size = strlen(page_address(page)); | |
166 | put_page(page); | |
167 | ||
168 | return 0; | |
169 | } | |
170 | ||
1da177e4 LT |
171 | /* |
172 | * symlinks can't do much... | |
173 | */ | |
f5e54d6e | 174 | const struct address_space_operations udf_symlink_aops = { |
0c698cc5 | 175 | .read_folio = udf_symlink_filler, |
1da177e4 | 176 | }; |
ad4d0532 JK |
177 | |
178 | const struct inode_operations udf_symlink_inode_operations = { | |
179 | .get_link = page_get_link, | |
180 | .getattr = udf_symlink_getattr, | |
181 | }; |