namei.c
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/*
* QNX4 file system, Linux implementation.
*
* Version : 0.2.1
*
* Using parts of the xiafs filesystem.
*
* History :
*
* 01-06-1998 by Richard Frowijn : first release.
* 21-06-1998 by Frank Denis : dcache support, fixed error codes.
* 04-07-1998 by Frank Denis : first step for rmdir/unlink.
*/
#include <linux/buffer_head.h>
#include "qnx4.h"
/*
* check if the filename is correct. For some obscure reason, qnx writes a
* new file twice in the directory entry, first with all possible options at 0
* and for a second time the way it is, they want us not to access the qnx
* filesystem when whe are using linux.
*/
static int qnx4_match(int len, const char *name,
struct buffer_head *bh, unsigned long *offset)
{
struct qnx4_inode_entry *de;
int namelen, thislen;
if (bh == NULL) {
printk(KERN_WARNING "qnx4: matching unassigned buffer !\n");
return 0;
}
de = (struct qnx4_inode_entry *) (bh->b_data + *offset);
*offset += QNX4_DIR_ENTRY_SIZE;
if ((de->di_status & QNX4_FILE_LINK) != 0) {
namelen = QNX4_NAME_MAX;
} else {
namelen = QNX4_SHORT_NAME_MAX;
}
thislen = strlen( de->di_fname );
if ( thislen > namelen )
thislen = namelen;
if (len != thislen) {
return 0;
}
if (strncmp(name, de->di_fname, len) == 0) {
if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) != 0) {
return 1;
}
}
return 0;
}
static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
const char *name, struct qnx4_inode_entry **res_dir, int *ino)
{
unsigned long block, offset, blkofs;
struct buffer_head *bh;
*res_dir = NULL;
bh = NULL;
block = offset = blkofs = 0;
while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
if (!bh) {
block = qnx4_block_map(dir, blkofs);
if (block)
bh = sb_bread(dir->i_sb, block);
if (!bh) {
blkofs++;
continue;
}
}
*res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
if (qnx4_match(len, name, bh, &offset)) {
*ino = block * QNX4_INODES_PER_BLOCK +
(offset / QNX4_DIR_ENTRY_SIZE) - 1;
return bh;
}
if (offset < bh->b_size) {
continue;
}
brelse(bh);
bh = NULL;
offset = 0;
blkofs++;
}
brelse(bh);
*res_dir = NULL;
return NULL;
}
struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
{
int ino;
struct qnx4_inode_entry *de;
struct qnx4_link_info *lnk;
struct buffer_head *bh;
const char *name = dentry->d_name.name;
int len = dentry->d_name.len;
struct inode *foundinode = NULL;
if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))
goto out;
/* The entry is linked, let's get the real info */
if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {
lnk = (struct qnx4_link_info *) de;
ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) *
QNX4_INODES_PER_BLOCK +
lnk->dl_inode_ndx;
}
brelse(bh);
foundinode = qnx4_iget(dir->i_sb, ino);
if (IS_ERR(foundinode)) {
QNX4DEBUG((KERN_ERR "qnx4: lookup->iget -> error %ld\n",
PTR_ERR(foundinode)));
return ERR_CAST(foundinode);
}
out:
d_add(dentry, foundinode);
return NULL;
}