/* 
   * 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 !
  ");

  		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;
  	}
  	/* "" means "." ---> so paths like "/usr/lib//libc.a" work */
  	if (!len && (de->di_fname[0] == '.') && (de->di_fname[1] == '\0')) {
  		return 1;
  	}
  	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;
  	if (!dir->i_sb) {

  		printk(KERN_WARNING "qnx4: no superblock on dir.
  ");

  		return NULL;
  	}
  	bh = NULL;
  	block = offset = blkofs = 0;
  	while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
  		if (!bh) {
  			bh = qnx4_bread(dir, blkofs, 0);
  			if (!bh) {
  				blkofs++;
  				continue;
  			}
  		}
  		*res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset);
  		if (qnx4_match(len, name, bh, &offset)) {
  			block = qnx4_block_map( dir, blkofs );
  			*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, struct nameidata *nd)
  {
  	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
  ",

  			   PTR_ERR(foundinode)));
  		return ERR_CAST(foundinode);

  	}
  out:

  	d_add(dentry, foundinode);
  
  	return NULL;
  }