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1/*
2 * linux/fs/isofs/namei.c
3 *
4 * (C) 1992 Eric Youngdale Modified for ISO 9660 filesystem.
5 *
6 * (C) 1991 Linus Torvalds - minix filesystem
7 */
8
9#include <linux/gfp.h>
10#include "isofs.h"
11
12/*
13 * ok, we cannot use strncmp, as the name is not in our data space.
14 * Thus we'll have to use isofs_match. No big problem. Match also makes
15 * some sanity tests.
16 */
17static int
18isofs_cmp(struct dentry *dentry, const char *compare, int dlen)
19{
20 struct qstr qstr;
21
22 if (!compare)
23 return 1;
24
25 /* check special "." and ".." files */
26 if (dlen == 1) {
27 /* "." */
28 if (compare[0] == 0) {
29 if (!dentry->d_name.len)
30 return 0;
31 compare = ".";
32 } else if (compare[0] == 1) {
33 compare = "..";
34 dlen = 2;
35 }
36 }
37
38 qstr.name = compare;
39 qstr.len = dlen;
40 return dentry->d_op->d_compare(NULL, NULL, NULL, NULL,
41 dentry->d_name.len, dentry->d_name.name, &qstr);
42}
43
44/*
45 * isofs_find_entry()
46 *
47 * finds an entry in the specified directory with the wanted name. It
48 * returns the inode number of the found entry, or 0 on error.
49 */
50static unsigned long
51isofs_find_entry(struct inode *dir, struct dentry *dentry,
52 unsigned long *block_rv, unsigned long *offset_rv,
53 char *tmpname, struct iso_directory_record *tmpde)
54{
55 unsigned long bufsize = ISOFS_BUFFER_SIZE(dir);
56 unsigned char bufbits = ISOFS_BUFFER_BITS(dir);
57 unsigned long block, f_pos, offset, block_saved, offset_saved;
58 struct buffer_head *bh = NULL;
59 struct isofs_sb_info *sbi = ISOFS_SB(dir->i_sb);
60
61 if (!ISOFS_I(dir)->i_first_extent)
62 return 0;
63
64 f_pos = 0;
65 offset = 0;
66 block = 0;
67
68 while (f_pos < dir->i_size) {
69 struct iso_directory_record *de;
70 int de_len, match, i, dlen;
71 char *dpnt;
72
73 if (!bh) {
74 bh = isofs_bread(dir, block);
75 if (!bh)
76 return 0;
77 }
78
79 de = (struct iso_directory_record *) (bh->b_data + offset);
80
81 de_len = *(unsigned char *) de;
82 if (!de_len) {
83 brelse(bh);
84 bh = NULL;
85 f_pos = (f_pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1);
86 block = f_pos >> bufbits;
87 offset = 0;
88 continue;
89 }
90
91 block_saved = bh->b_blocknr;
92 offset_saved = offset;
93 offset += de_len;
94 f_pos += de_len;
95
96 /* Make sure we have a full directory entry */
97 if (offset >= bufsize) {
98 int slop = bufsize - offset + de_len;
99 memcpy(tmpde, de, slop);
100 offset &= bufsize - 1;
101 block++;
102 brelse(bh);
103 bh = NULL;
104 if (offset) {
105 bh = isofs_bread(dir, block);
106 if (!bh)
107 return 0;
108 memcpy((void *) tmpde + slop, bh->b_data, offset);
109 }
110 de = tmpde;
111 }
112
113 dlen = de->name_len[0];
114 dpnt = de->name;
115 /* Basic sanity check, whether name doesn't exceed dir entry */
116 if (de_len < dlen + sizeof(struct iso_directory_record)) {
117 printk(KERN_NOTICE "iso9660: Corrupted directory entry"
118 " in block %lu of inode %lu\n", block,
119 dir->i_ino);
120 return 0;
121 }
122
123 if (sbi->s_rock &&
124 ((i = get_rock_ridge_filename(de, tmpname, dir)))) {
125 dlen = i; /* possibly -1 */
126 dpnt = tmpname;
127#ifdef CONFIG_JOLIET
128 } else if (sbi->s_joliet_level) {
129 dlen = get_joliet_filename(de, tmpname, dir);
130 dpnt = tmpname;
131#endif
132 } else if (sbi->s_mapping == 'a') {
133 dlen = get_acorn_filename(de, tmpname, dir);
134 dpnt = tmpname;
135 } else if (sbi->s_mapping == 'n') {
136 dlen = isofs_name_translate(de, tmpname, dir);
137 dpnt = tmpname;
138 }
139
140 /*
141 * Skip hidden or associated files unless hide or showassoc,
142 * respectively, is set
143 */
144 match = 0;
145 if (dlen > 0 &&
146 (!sbi->s_hide ||
147 (!(de->flags[-sbi->s_high_sierra] & 1))) &&
148 (sbi->s_showassoc ||
149 (!(de->flags[-sbi->s_high_sierra] & 4)))) {
150 match = (isofs_cmp(dentry, dpnt, dlen) == 0);
151 }
152 if (match) {
153 isofs_normalize_block_and_offset(de,
154 &block_saved,
155 &offset_saved);
156 *block_rv = block_saved;
157 *offset_rv = offset_saved;
158 brelse(bh);
159 return 1;
160 }
161 }
162 brelse(bh);
163 return 0;
164}
165
166struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
167{
168 int found;
169 unsigned long uninitialized_var(block);
170 unsigned long uninitialized_var(offset);
171 struct inode *inode;
172 struct page *page;
173
174 page = alloc_page(GFP_USER);
175 if (!page)
176 return ERR_PTR(-ENOMEM);
177
178 found = isofs_find_entry(dir, dentry,
179 &block, &offset,
180 page_address(page),
181 1024 + page_address(page));
182 __free_page(page);
183
184 inode = found ? isofs_iget(dir->i_sb, block, offset) : NULL;
185
186 return d_splice_alias(inode, dentry);
187}