xref: /kernel/linux/linux-5.10/fs/qnx4/namei.c (revision 8c2ecf20) 
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 */
26static int qnx4_match(int len, const char *name,
27		      struct buffer_head *bh, unsigned long *offset)
28{
29	struct qnx4_inode_entry *de;
30	int namelen, thislen;
31
32	if (bh == NULL) {
33		printk(KERN_WARNING "qnx4: matching unassigned buffer !\n");
34		return 0;
35	}
36	de = (struct qnx4_inode_entry *) (bh->b_data + *offset);
37	*offset += QNX4_DIR_ENTRY_SIZE;
38	if ((de->di_status & QNX4_FILE_LINK) != 0) {
39		namelen = QNX4_NAME_MAX;
40	} else {
41		namelen = QNX4_SHORT_NAME_MAX;
42	}
43	thislen = strlen( de->di_fname );
44	if ( thislen > namelen )
45		thislen = namelen;
46	if (len != thislen) {
47		return 0;
48	}
49	if (strncmp(name, de->di_fname, len) == 0) {
50		if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) != 0) {
51			return 1;
52		}
53	}
54	return 0;
55}
56
57static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
58	   const char *name, struct qnx4_inode_entry **res_dir, int *ino)
59{
60	unsigned long block, offset, blkofs;
61	struct buffer_head *bh;
62
63	*res_dir = NULL;
64	bh = NULL;
65	block = offset = blkofs = 0;
66	while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
67		if (!bh) {
68			block = qnx4_block_map(dir, blkofs);
69			if (block)
70				bh = sb_bread(dir->i_sb, block);
71			if (!bh) {
72				blkofs++;
73				continue;
74			}
75		}
76		*res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
77		if (qnx4_match(len, name, bh, &offset)) {
78			*ino = block * QNX4_INODES_PER_BLOCK +
79			    (offset / QNX4_DIR_ENTRY_SIZE) - 1;
80			return bh;
81		}
82		if (offset < bh->b_size) {
83			continue;
84		}
85		brelse(bh);
86		bh = NULL;
87		offset = 0;
88		blkofs++;
89	}
90	brelse(bh);
91	*res_dir = NULL;
92	return NULL;
93}
94
95struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
96{
97	int ino;
98	struct qnx4_inode_entry *de;
99	struct qnx4_link_info *lnk;
100	struct buffer_head *bh;
101	const char *name = dentry->d_name.name;
102	int len = dentry->d_name.len;
103	struct inode *foundinode = NULL;
104
105	if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))
106		goto out;
107	/* The entry is linked, let's get the real info */
108	if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {
109		lnk = (struct qnx4_link_info *) de;
110		ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) *
111                    QNX4_INODES_PER_BLOCK +
112		    lnk->dl_inode_ndx;
113	}
114	brelse(bh);
115
116	foundinode = qnx4_iget(dir->i_sb, ino);
117	if (IS_ERR(foundinode))
118		QNX4DEBUG((KERN_ERR "qnx4: lookup->iget -> error %ld\n",
119			   PTR_ERR(foundinode)));
120out:
121	return d_splice_alias(foundinode, dentry);
122}
123