1/*
2 * QNX4 file system, Linux implementation.
3 *
4 * Version : 0.2.1
5 *
6 * Using parts of the xiafs filesystem.
7 *
8 * History :
9 *
10 * 01-06-1998 by Richard Frowijn : first release.
11 * 21-06-1998 by Frank Denis : dcache support, fixed error codes.
12 * 04-07-1998 by Frank Denis : first step for rmdir/unlink.
13 */
14
15#include <linux/buffer_head.h>
16#include "qnx4.h"
17
18
19/*
20 * check if the filename is correct. For some obscure reason, qnx writes a
21 * new file twice in the directory entry, first with all possible options at 0
22 * and for a second time the way it is, they want us not to access the qnx
23 * filesystem when whe are using linux.
24 */
25static int qnx4_match(int len, const char *name,
26		      struct buffer_head *bh, unsigned long *offset)
27{
28	struct qnx4_inode_entry *de;
29	int namelen, thislen;
30
31	if (bh == NULL) {
32		printk(KERN_WARNING "qnx4: matching unassigned buffer !\n");
33		return 0;
34	}
35	de = (struct qnx4_inode_entry *) (bh->b_data + *offset);
36	*offset += QNX4_DIR_ENTRY_SIZE;
37	if ((de->di_status & QNX4_FILE_LINK) != 0) {
38		namelen = QNX4_NAME_MAX;
39	} else {
40		namelen = QNX4_SHORT_NAME_MAX;
41	}
42	thislen = strlen( de->di_fname );
43	if ( thislen > namelen )
44		thislen = namelen;
45	if (len != thislen) {
46		return 0;
47	}
48	if (strncmp(name, de->di_fname, len) == 0) {
49		if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) != 0) {
50			return 1;
51		}
52	}
53	return 0;
54}
55
56static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
57	   const char *name, struct qnx4_inode_entry **res_dir, int *ino)
58{
59	unsigned long block, offset, blkofs;
60	struct buffer_head *bh;
61
62	*res_dir = NULL;
63	bh = NULL;
64	block = offset = blkofs = 0;
65	while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
66		if (!bh) {
67			block = qnx4_block_map(dir, blkofs);
68			if (block)
69				bh = sb_bread(dir->i_sb, block);
70			if (!bh) {
71				blkofs++;
72				continue;
73			}
74		}
75		*res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
76		if (qnx4_match(len, name, bh, &offset)) {
77			*ino = block * QNX4_INODES_PER_BLOCK +
78			    (offset / QNX4_DIR_ENTRY_SIZE) - 1;
79			return bh;
80		}
81		if (offset < bh->b_size) {
82			continue;
83		}
84		brelse(bh);
85		bh = NULL;
86		offset = 0;
87		blkofs++;
88	}
89	brelse(bh);
90	*res_dir = NULL;
91	return NULL;
92}
93
94struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
95{
96	int ino;
97	struct qnx4_inode_entry *de;
98	struct qnx4_link_info *lnk;
99	struct buffer_head *bh;
100	const char *name = dentry->d_name.name;
101	int len = dentry->d_name.len;
102	struct inode *foundinode = NULL;
103
104	if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))
105		goto out;
106	/* The entry is linked, let's get the real info */
107	if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {
108		lnk = (struct qnx4_link_info *) de;
109		ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) *
110                    QNX4_INODES_PER_BLOCK +
111		    lnk->dl_inode_ndx;
112	}
113	brelse(bh);
114
115	foundinode = qnx4_iget(dir->i_sb, ino);
116	if (IS_ERR(foundinode)) {
117		QNX4DEBUG((KERN_ERR "qnx4: lookup->iget -> error %ld\n",
118			   PTR_ERR(foundinode)));
119		return ERR_CAST(foundinode);
120	}
121out:
122	d_add(dentry, foundinode);
123
124	return NULL;
125}
126