inode.c

LINUX1.0内核源代码,学习LINUX编程的一定要看。

	  goto fail;
	}
	
	pnt = ((unsigned char *) bh->b_data
	       + (inode->i_ino & (bufsize - 1)));
	raw_inode = ((struct iso_directory_record *) pnt);
	high_sierra = inode->i_sb->u.isofs_sb.s_high_sierra;

	if ((inode->i_ino & (bufsize - 1)) + *pnt > bufsize){
		cpnt = kmalloc(1 << ISOFS_BLOCK_BITS, GFP_KERNEL);
		if (cpnt == NULL) {
			printk(KERN_INFO "NoMem ISO inode %d\n",inode->i_ino);
			brelse(bh);
			goto fail;
		}
		memcpy(cpnt, bh->b_data, bufsize);
		brelse(bh);
		if (!(bh = bread(inode->i_dev,++block, bufsize))) {
			kfree_s(cpnt, 1 << ISOFS_BLOCK_BITS);
			printk("unable to read i-node block");
			goto fail;
		}
		memcpy((char *)cpnt + bufsize, bh->b_data, bufsize);
		pnt = ((unsigned char *) cpnt
		       + (inode->i_ino & (bufsize - 1)));
		raw_inode = ((struct iso_directory_record *) pnt);
	}

	inode->i_mode = S_IRUGO; /* Everybody gets to read the file. */
	inode->i_nlink = 1;
	
	if (raw_inode->flags[-high_sierra] & 2) {
		inode->i_mode = S_IRUGO | S_IXUGO | S_IFDIR;
		inode->i_nlink = 2; /* There are always at least 2.  It is
				       hard to figure out what is correct*/
	} else {
		inode->i_mode = S_IRUGO; /* Everybody gets to read the file. */
		inode->i_nlink = 1;
	        inode->i_mode |= S_IFREG;
/* If there are no periods in the name, then set the execute permission bit */
		for(i=0; i< raw_inode->name_len[0]; i++)
			if(raw_inode->name[i]=='.' || raw_inode->name[i]==';')
				break;
		if(i == raw_inode->name_len[0] || raw_inode->name[i] == ';') 
			inode->i_mode |= S_IXUGO; /* execute permission */
	}
	inode->i_uid = 0;
	inode->i_gid = 0;
	inode->i_size = isonum_733 (raw_inode->size);

	/* There are defective discs out there - we do this to protect
	   ourselves.  A cdrom will never contain more than 700Mb */
	if((inode->i_size < 0 || inode->i_size > 700000000) &&
	    inode->i_sb->u.isofs_sb.s_cruft == 'n') {
	  printk("Warning: defective cdrom.  Enabling \"cruft\" mount option.\n");
	  inode->i_sb->u.isofs_sb.s_cruft = 'y';
	}

/* Some dipshit decided to store some other bit of information in the high
   byte of the file length.  Catch this and holler.  WARNING: this will make
   it impossible for a file to be > 16Mb on the CDROM!!!*/

	if(inode->i_sb->u.isofs_sb.s_cruft == 'y' && 
	   inode->i_size & 0xff000000){
/*	  printk("Illegal format on cdrom.  Pester manufacturer.\n"); */
	  inode->i_size &= 0x00ffffff;
	}
	
	if (raw_inode->interleave[0]) {
		printk("Interleaved files not (yet) supported.\n");
		inode->i_size = 0;
	}

#ifdef DEBUG
	/* I have no idea what extended attributes are used for, so
	   we will flag it for now */
	if(raw_inode->ext_attr_length[0] != 0){
		printk("Extended attributes present for ISO file (%ld).\n",
		       inode->i_ino);
	}
#endif
	
	/* I have no idea what file_unit_size is used for, so
	   we will flag it for now */
	if(raw_inode->file_unit_size[0] != 0){
		printk("File unit size != 0 for ISO file (%ld).\n",inode->i_ino);
	}

	/* I have no idea what other flag bits are used for, so
	   we will flag it for now */
	if((raw_inode->flags[-high_sierra] & ~2)!= 0){
		printk("Unusual flag settings for ISO file (%ld %x).\n",
		       inode->i_ino, raw_inode->flags[-high_sierra]);
	}

#ifdef DEBUG
	printk("Get inode %d: %d %d: %d\n",inode->i_ino, block, 
	       ((int)pnt) & 0x3ff, inode->i_size);
#endif
	
	inode->i_mtime = inode->i_atime = inode->i_ctime = 
	  iso_date(raw_inode->date, high_sierra);

	inode->u.isofs_i.i_first_extent = isonum_733 (raw_inode->extent) << 
		(ISOFS_BLOCK_BITS - ISOFS_BUFFER_BITS(inode));
	
	inode->u.isofs_i.i_backlink = 0xffffffff; /* Will be used for previous directory */
	switch (inode->i_sb->u.isofs_sb.s_conversion){
	case 'a':
	  inode->u.isofs_i.i_file_format = ISOFS_FILE_UNKNOWN; /* File type */
	  break;
	case 'b':
	  inode->u.isofs_i.i_file_format = ISOFS_FILE_BINARY; /* File type */
	  break;
	case 't':
	  inode->u.isofs_i.i_file_format = ISOFS_FILE_TEXT; /* File type */
	  break;
	case 'm':
	  inode->u.isofs_i.i_file_format = ISOFS_FILE_TEXT_M; /* File type */
	  break;
	}

/* Now test for possible Rock Ridge extensions which will override some of
   these numbers in the inode structure. */

	if (!high_sierra)
	  parse_rock_ridge_inode(raw_inode, inode);
	
#ifdef DEBUG
	printk("Inode: %x extent: %x\n",inode->i_ino, inode->u.isofs_i.i_first_extent);
#endif
	brelse(bh);
	
	inode->i_op = NULL;
	if (inode->i_sb->u.isofs_sb.s_cruft != 'y' && 
	    isonum_723 (raw_inode->volume_sequence_number) != 1) {
		printk("Multi volume CD somehow got mounted.\n");
	} else {
	  if (S_ISREG(inode->i_mode))
	    inode->i_op = &isofs_file_inode_operations;
	  else if (S_ISDIR(inode->i_mode))
	    inode->i_op = &isofs_dir_inode_operations;
	  else if (S_ISLNK(inode->i_mode))
	    inode->i_op = &isofs_symlink_inode_operations;
	  else if (S_ISCHR(inode->i_mode))
	    inode->i_op = &chrdev_inode_operations;
	  else if (S_ISBLK(inode->i_mode))
	    inode->i_op = &blkdev_inode_operations;
	  else if (S_ISFIFO(inode->i_mode))
	    init_fifo(inode);
	}
	if (cpnt) {
		kfree_s (cpnt, 1 << ISOFS_BLOCK_BITS);
		cpnt = NULL;
	}
	return;
      fail:
	/* With a data error we return this information */
	inode->i_mtime = inode->i_atime = inode->i_ctime = 0;
	inode->u.isofs_i.i_first_extent = 0;
	inode->u.isofs_i.i_backlink = 0xffffffff;
	inode->i_size = 0;
	inode->i_nlink = 1;
	inode->i_uid = inode->i_gid = 0;
	inode->i_mode = S_IFREG;  /*Regular file, noone gets to read*/
	inode->i_op = NULL;
	return;
}

/* There are times when we need to know the inode number of a parent of
   a particular directory.  When control passes through a routine that
   has access to the parent information, it fills it into the inode structure,
   but sometimes the inode gets flushed out of the queue, and someone
   remmembers the number.  When they try to open up again, we have lost
   the information.  The '..' entry on the disc points to the data area
   for a particular inode, so we can follow these links back up, but since
   we do not know the inode number, we do not actually know how large the
   directory is.  The disc is almost always correct, and there is
   enough error checking on the drive itself, but an open ended search
   makes me a little nervous.

   The bsd iso filesystem uses the extent number for an inode, and this
   would work really nicely for us except that the read_inode function
   would not have any clean way of finding the actual directory record
   that goes with the file.  If we had such info, then it would pay
   to change the inode numbers and eliminate this function.
*/

int isofs_lookup_grandparent(struct inode * parent, int extent)
{
	unsigned long bufsize = ISOFS_BUFFER_SIZE(parent);
	unsigned char bufbits = ISOFS_BUFFER_BITS(parent);
	unsigned int block,offset;
	int parent_dir, inode_number;
	int old_offset;
	void * cpnt = NULL;
	int result;
	struct buffer_head * bh;
	struct iso_directory_record * de;
	
	offset = 0;
	block = extent << (ISOFS_BLOCK_BITS - bufbits);
	if (!(bh = bread(parent->i_dev, block, bufsize)))  return -1;
	
	while (1 == 1) {
		de = (struct iso_directory_record *) (bh->b_data + offset);
		if (*((unsigned char *) de) == 0) 
		{
			brelse(bh);
			return -1;
		}
		
		offset += *((unsigned char *) de);

		if (offset >= bufsize) 
		{
			printk(".. Directory not in first block"
			       " of directory.\n");
			brelse(bh);
			return -1;
		}
		
		if (de->name_len[0] == 1 && de->name[0] == 1) 
		{
			parent_dir = find_rock_ridge_relocation(de, parent);
			brelse(bh);
			break;
		}
	}
#ifdef DEBUG
	printk("Parent dir:%x\n",parent_dir);
#endif
	/* Now we know the extent where the parent dir starts on.  We have no
	   idea how long it is, so we just start reading until we either find
	   it or we find some kind of unreasonable circumstance. */
	
	result = -1;

	offset = 0;
	block = parent_dir << (ISOFS_BLOCK_BITS - bufbits);
	if (!block || !(bh = bread(parent->i_dev,block, bufsize)))
		return -1;
	
	for(;;)
	{
		de = (struct iso_directory_record *) (bh->b_data + offset);
		inode_number = (block << bufbits)+(offset & (bufsize - 1));
		
		/* If the length byte is zero, we should move on to the next
		   CDROM sector.  If we are at the end of the directory, we
		   kick out of the while loop. */
		
		if (*((unsigned char *) de) == 0) 
		{
			brelse(bh);
			offset = 0;
			block++;
			if(block & 1) return -1;
			if (!block
			    || !(bh = bread(parent->i_dev,block, bufsize)))
				return -1;
			continue;
		}
		
		/* Make sure that the entire directory record is in the current
		   bh block.  If not, we malloc a buffer, and put the two
		   halves together, so that we can cleanly read the block.  */

		old_offset = offset;
		offset += *((unsigned char *) de);

		if (offset >= bufsize)
		{
			if((block & 1) != 0) return -1;
			cpnt = kmalloc(1<<ISOFS_BLOCK_BITS,GFP_KERNEL);
			memcpy(cpnt, bh->b_data, bufsize);
			de = (struct iso_directory_record *)
				((char *)cpnt + old_offset);
			brelse(bh);
			offset -= bufsize;
			block++;
			if (!(bh = bread(parent->i_dev,block,bufsize))) {
			        kfree_s(cpnt, 1 << ISOFS_BLOCK_BITS);
				return -1;
			};
			memcpy((char *)cpnt+bufsize, bh->b_data, bufsize);
		}
		
		if (find_rock_ridge_relocation(de, parent) == extent){
			result = inode_number;
			goto out;
		}
		
		if (cpnt) {
			kfree_s(cpnt, 1 << ISOFS_BLOCK_BITS);
			cpnt = NULL;
		}
	}

	/* We go here for any condition we cannot handle.
	   We also drop through to here at the end of the directory. */

 out:
	if (cpnt) {
	        kfree_s(cpnt, 1 << ISOFS_BLOCK_BITS);
		cpnt = NULL;
	}
	brelse(bh);
#ifdef DEBUG
	printk("Resultant Inode %d\n",result);
#endif
	return result;
}
    
#ifdef LEAK_CHECK
#undef malloc
#undef free_s
#undef bread
#undef brelse

void * leak_check_malloc(unsigned int size){
  void * tmp;
  check_malloc++;
  tmp = kmalloc(size, GFP_KERNEL);
  return tmp;
}

void leak_check_free_s(void * obj, int size){
  check_malloc--;
  return kfree_s(obj, size);
}

struct buffer_head * leak_check_bread(int dev, int block, int size){
  check_bread++;
  return bread(dev, block, size);
}

void leak_check_brelse(struct buffer_head * bh){
  check_bread--;
  return brelse(bh);
}

#endif