1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/isofs/namei.c
4 *
5 * (C) 1992 Eric Youngdale Modified for ISO 9660 filesystem.
6 *
7 * (C) 1991 Linus Torvalds - minix filesystem
8 */
9
10 #include <linux/gfp.h>
11 #include "isofs.h"
12
13 static int
isofs_cmp(struct dentry * dentry,const char * compare,int dlen)14 isofs_cmp(struct dentry *dentry, const char *compare, int dlen)
15 {
16 if (likely(!dentry->d_op))
17 return dentry->d_name.len != dlen || memcmp(dentry->d_name.name, compare, dlen);
18 return dentry->d_op->d_compare(NULL, dentry->d_name.len, dentry->d_name.name,
19 &QSTR_LEN(compare, dlen));
20 }
21
22 /*
23 * isofs_find_entry()
24 *
25 * finds an entry in the specified directory with the wanted name. It
26 * returns the inode number of the found entry, or 0 on error.
27 */
28 static unsigned long
isofs_find_entry(struct inode * dir,struct dentry * dentry,unsigned long * block_rv,unsigned long * offset_rv,char * tmpname,struct iso_directory_record * tmpde)29 isofs_find_entry(struct inode *dir, struct dentry *dentry,
30 unsigned long *block_rv, unsigned long *offset_rv,
31 char *tmpname, struct iso_directory_record *tmpde)
32 {
33 unsigned long bufsize = ISOFS_BUFFER_SIZE(dir);
34 unsigned char bufbits = ISOFS_BUFFER_BITS(dir);
35 unsigned long block, f_pos, offset, block_saved, offset_saved;
36 struct buffer_head *bh = NULL;
37 struct isofs_sb_info *sbi = ISOFS_SB(dir->i_sb);
38
39 if (!ISOFS_I(dir)->i_first_extent)
40 return 0;
41
42 f_pos = 0;
43 offset = 0;
44 block = 0;
45
46 while (f_pos < dir->i_size) {
47 struct iso_directory_record *de;
48 int de_len, match, i, dlen;
49 char *dpnt;
50
51 if (!bh) {
52 bh = isofs_bread(dir, block);
53 if (!bh)
54 return 0;
55 }
56
57 de = (struct iso_directory_record *) (bh->b_data + offset);
58
59 de_len = *(unsigned char *) de;
60 if (!de_len) {
61 brelse(bh);
62 bh = NULL;
63 f_pos = (f_pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1);
64 block = f_pos >> bufbits;
65 offset = 0;
66 continue;
67 }
68
69 block_saved = bh->b_blocknr;
70 offset_saved = offset;
71 offset += de_len;
72 f_pos += de_len;
73
74 /* Make sure we have a full directory entry */
75 if (offset >= bufsize) {
76 int slop = bufsize - offset + de_len;
77 memcpy(tmpde, de, slop);
78 offset &= bufsize - 1;
79 block++;
80 brelse(bh);
81 bh = NULL;
82 if (offset) {
83 bh = isofs_bread(dir, block);
84 if (!bh)
85 return 0;
86 memcpy((void *) tmpde + slop, bh->b_data, offset);
87 }
88 de = tmpde;
89 }
90
91 dlen = de->name_len[0];
92 dpnt = de->name;
93 /* Basic sanity check, whether name doesn't exceed dir entry */
94 if (de_len < dlen + sizeof(struct iso_directory_record)) {
95 printk(KERN_NOTICE "iso9660: Corrupted directory entry"
96 " in block %lu of inode %llu\n", block,
97 dir->i_ino);
98 brelse(bh);
99 return 0;
100 }
101
102 if (sbi->s_rock &&
103 ((i = get_rock_ridge_filename(de, tmpname, dir)))) {
104 dlen = i; /* possibly -1 */
105 dpnt = tmpname;
106 #ifdef CONFIG_JOLIET
107 } else if (sbi->s_joliet_level) {
108 dlen = get_joliet_filename(de, tmpname, dir);
109 dpnt = tmpname;
110 #endif
111 } else if (sbi->s_mapping == 'a') {
112 dlen = get_acorn_filename(de, tmpname, dir);
113 dpnt = tmpname;
114 } else if (sbi->s_mapping == 'n') {
115 dlen = isofs_name_translate(de, tmpname, dir);
116 dpnt = tmpname;
117 }
118
119 /*
120 * Skip hidden or associated files unless hide or showassoc,
121 * respectively, is set
122 */
123 match = 0;
124 if (dlen > 0 &&
125 (!sbi->s_hide ||
126 (!(de->flags[-sbi->s_high_sierra] & 1))) &&
127 (sbi->s_showassoc ||
128 (!(de->flags[-sbi->s_high_sierra] & 4)))) {
129 if (dpnt && (dlen > 1 || dpnt[0] > 1))
130 match = (isofs_cmp(dentry, dpnt, dlen) == 0);
131 }
132 if (match) {
133 isofs_normalize_block_and_offset(de,
134 &block_saved,
135 &offset_saved);
136 *block_rv = block_saved;
137 *offset_rv = offset_saved;
138 brelse(bh);
139 return 1;
140 }
141 }
142 brelse(bh);
143 return 0;
144 }
145
isofs_lookup(struct inode * dir,struct dentry * dentry,unsigned int flags)146 struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
147 {
148 int found;
149 unsigned long block;
150 unsigned long offset;
151 struct inode *inode;
152 struct page *page;
153
154 page = alloc_page(GFP_USER);
155 if (!page)
156 return ERR_PTR(-ENOMEM);
157
158 found = isofs_find_entry(dir, dentry,
159 &block, &offset,
160 page_address(page),
161 1024 + page_address(page));
162 __free_page(page);
163
164 inode = found ? isofs_iget(dir->i_sb, block, offset) : NULL;
165
166 return d_splice_alias(inode, dentry);
167 }
168