130 lines
3.1 KiB
C
130 lines
3.1 KiB
C
/*
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* QNX4 file system, Linux implementation.
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*
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* Version : 0.2.1
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*
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* Using parts of the xiafs filesystem.
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*
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* History :
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*
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* 01-06-1998 by Richard Frowijn : first release.
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* 21-06-1998 by Frank Denis : dcache support, fixed error codes.
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* 04-07-1998 by Frank Denis : first step for rmdir/unlink.
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*/
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#include <linux/buffer_head.h>
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#include "qnx4.h"
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/*
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* check if the filename is correct. For some obscure reason, qnx writes a
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* new file twice in the directory entry, first with all possible options at 0
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* and for a second time the way it is, they want us not to access the qnx
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* filesystem when whe are using linux.
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*/
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static int qnx4_match(int len, const char *name,
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struct buffer_head *bh, unsigned long *offset)
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{
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struct qnx4_inode_entry *de;
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int namelen, thislen;
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if (bh == NULL) {
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printk(KERN_WARNING "qnx4: matching unassigned buffer !\n");
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return 0;
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}
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de = (struct qnx4_inode_entry *) (bh->b_data + *offset);
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*offset += QNX4_DIR_ENTRY_SIZE;
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if ((de->di_status & QNX4_FILE_LINK) != 0) {
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namelen = QNX4_NAME_MAX;
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} else {
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namelen = QNX4_SHORT_NAME_MAX;
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}
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thislen = strlen( de->di_fname );
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if ( thislen > namelen )
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thislen = namelen;
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if (len != thislen) {
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return 0;
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}
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if (strncmp(name, de->di_fname, len) == 0) {
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if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) != 0) {
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return 1;
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}
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}
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return 0;
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}
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static struct buffer_head *qnx4_find_entry(int len, struct inode *dir,
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const char *name, struct qnx4_inode_entry **res_dir, int *ino)
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{
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unsigned long block, offset, blkofs;
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struct buffer_head *bh;
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*res_dir = NULL;
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if (!dir->i_sb) {
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printk(KERN_WARNING "qnx4: no superblock on dir.\n");
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return NULL;
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}
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bh = NULL;
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block = offset = blkofs = 0;
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while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
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if (!bh) {
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block = qnx4_block_map(dir, blkofs);
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if (block)
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bh = sb_bread(dir->i_sb, block);
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if (!bh) {
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blkofs++;
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continue;
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}
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}
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*res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
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if (qnx4_match(len, name, bh, &offset)) {
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*ino = block * QNX4_INODES_PER_BLOCK +
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(offset / QNX4_DIR_ENTRY_SIZE) - 1;
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return bh;
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}
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if (offset < bh->b_size) {
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continue;
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}
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brelse(bh);
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bh = NULL;
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offset = 0;
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blkofs++;
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}
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brelse(bh);
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*res_dir = NULL;
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return NULL;
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}
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struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
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{
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int ino;
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struct qnx4_inode_entry *de;
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struct qnx4_link_info *lnk;
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struct buffer_head *bh;
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const char *name = dentry->d_name.name;
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int len = dentry->d_name.len;
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struct inode *foundinode = NULL;
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if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino)))
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goto out;
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/* The entry is linked, let's get the real info */
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if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) {
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lnk = (struct qnx4_link_info *) de;
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ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) *
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QNX4_INODES_PER_BLOCK +
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lnk->dl_inode_ndx;
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}
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brelse(bh);
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foundinode = qnx4_iget(dir->i_sb, ino);
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if (IS_ERR(foundinode)) {
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QNX4DEBUG((KERN_ERR "qnx4: lookup->iget -> error %ld\n",
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PTR_ERR(foundinode)));
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return ERR_CAST(foundinode);
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}
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out:
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d_add(dentry, foundinode);
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return NULL;
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}
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