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 */
qnx4_match(int len,const char * name,struct buffer_head * bh,unsigned long * offset)25 static 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
qnx4_find_entry(int len,struct inode * dir,const char * name,struct qnx4_inode_entry ** res_dir,int * ino)60 static 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
qnx4_lookup(struct inode * dir,struct dentry * dentry,struct nameidata * nd)101 struct 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 }
128 out:
129 d_add(dentry, foundinode);
130
131 return NULL;
132 }
133