Root/fs/qnx4/namei.c

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    /* "" means "." ---> so paths like "/usr/lib//libc.a" work */
43    if (!len && (de->di_fname[0] == '.') && (de->di_fname[1] == '\0')) {
44        return 1;
45    }
46    thislen = strlen( de->di_fname );
47    if ( thislen > namelen )
48        thislen = namelen;
49    if (len != thislen) {
50        return 0;
51    }
52    if (strncmp(name, de->di_fname, len) == 0) {
53        if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) != 0) {
54            return 1;
55        }
56    }
57    return 0;
58}
59
60static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
61       const char *name, struct qnx4_inode_entry **res_dir, int *ino)
62{
63    unsigned long block, offset, blkofs;
64    struct buffer_head *bh;
65
66    *res_dir = NULL;
67    if (!dir->i_sb) {
68        printk(KERN_WARNING "qnx4: no superblock on dir.\n");
69        return NULL;
70    }
71    bh = NULL;
72    block = offset = blkofs = 0;
73    while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
74        if (!bh) {
75            bh = qnx4_bread(dir, blkofs, 0);
76            if (!bh) {
77                blkofs++;
78                continue;
79            }
80        }
81        *res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
82        if (qnx4_match(len, name, bh, &offset)) {
83            block = qnx4_block_map( dir, blkofs );
84            *ino = block * QNX4_INODES_PER_BLOCK +
85                (offset / QNX4_DIR_ENTRY_SIZE) - 1;
86            return bh;
87        }
88        if (offset < bh->b_size) {
89            continue;
90        }
91        brelse(bh);
92        bh = NULL;
93        offset = 0;
94        blkofs++;
95    }
96    brelse(bh);
97    *res_dir = NULL;
98    return NULL;
99}
100
101struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
102{
103    int ino;
104    struct qnx4_inode_entry *de;
105    struct qnx4_link_info *lnk;
106    struct buffer_head *bh;
107    const char *name = dentry->d_name.name;
108    int len = dentry->d_name.len;
109    struct inode *foundinode = NULL;
110
111    if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))
112        goto out;
113    /* The entry is linked, let's get the real info */
114    if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {
115        lnk = (struct qnx4_link_info *) de;
116        ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) *
117                    QNX4_INODES_PER_BLOCK +
118            lnk->dl_inode_ndx;
119    }
120    brelse(bh);
121
122    foundinode = qnx4_iget(dir->i_sb, ino);
123    if (IS_ERR(foundinode)) {
124        QNX4DEBUG((KERN_ERR "qnx4: lookup->iget -> error %ld\n",
125               PTR_ERR(foundinode)));
126        return ERR_CAST(foundinode);
127    }
128out:
129    d_add(dentry, foundinode);
130
131    return NULL;
132}
133

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