1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * QNX4 file system, Linux implementation.
4 *
5 * Version : 0.2.1
6 *
7 * Using parts of the xiafs filesystem.
8 *
9 * History :
10 *
11 * 01-06-1998 by Richard Frowijn : first release.
12 * 21-06-1998 by Frank Denis : dcache support, fixed error codes.
13 * 04-07-1998 by Frank Denis : first step for rmdir/unlink.
14 */
15
16 #include <linux/buffer_head.h>
17 #include "qnx4.h"
18
19
20 /*
21 * check if the filename is correct. For some obscure reason, qnx writes a
22 * new file twice in the directory entry, first with all possible options at 0
23 * and for a second time the way it is, they want us not to access the qnx
24 * filesystem when whe are using linux.
25 */
26 static int qnx4_match(int len, const char *name,
27 struct buffer_head *bh, unsigned long *offset)
28 {
29 union qnx4_directory_entry *de;
30 const char *fname;
31 int fnamelen;
32
33 if (bh == NULL) {
34 printk(KERN_WARNING "qnx4: matching unassigned buffer !\n");
35 return 0;
36 }
37 de = (union qnx4_directory_entry *) (bh->b_data + *offset);
38 *offset += QNX4_DIR_ENTRY_SIZE;
39
40 fname = get_entry_fname(de, &fnamelen);
41 if (!fname || len != fnamelen)
42 return 0;
43
44 if (strncmp(name, fname, len) == 0)
45 return 1;
46
47 return 0;
48 }
49
50 static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
51 const char *name, struct qnx4_inode_entry **res_dir, int *ino)
52 {
53 unsigned long block, offset, blkofs;
54 struct buffer_head *bh;
55
56 *res_dir = NULL;
57 bh = NULL;
58 block = offset = blkofs = 0;
59 while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
60 if (!bh) {
61 block = qnx4_block_map(dir, blkofs);
62 if (block)
63 bh = sb_bread(dir->i_sb, block);
64 if (!bh) {
65 blkofs++;
66 continue;
67 }
68 }
69 *res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
70 if (qnx4_match(len, name, bh, &offset)) {
71 *ino = block * QNX4_INODES_PER_BLOCK +
72 (offset / QNX4_DIR_ENTRY_SIZE) - 1;
73 return bh;
74 }
75 if (offset < bh->b_size) {
76 continue;
77 }
78 brelse(bh);
79 bh = NULL;
80 offset = 0;
81 blkofs++;
82 }
83 brelse(bh);
84 *res_dir = NULL;
85 return NULL;
86 }
87
88 struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
89 {
90 int ino;
91 struct qnx4_inode_entry *de;
92 struct qnx4_link_info *lnk;
93 struct buffer_head *bh;
94 const char *name = dentry->d_name.name;
95 int len = dentry->d_name.len;
96 struct inode *foundinode = NULL;
97
98 if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))
99 goto out;
100 /* The entry is linked, let's get the real info */
101 if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {
102 lnk = (struct qnx4_link_info *) de;
103 ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) *
104 QNX4_INODES_PER_BLOCK +
105 lnk->dl_inode_ndx;
106 }
107 brelse(bh);
108
109 foundinode = qnx4_iget(dir->i_sb, ino);
110 if (IS_ERR(foundinode))
111 QNX4DEBUG((KERN_ERR "qnx4: lookup->iget -> error %ld\n",
112 PTR_ERR(foundinode)));
113 out:
114 return d_splice_alias(foundinode, dentry);
115 }
116
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