squashfs-tools/squashfs-tools/unsquash-4.c - nest-cam/4320010/squashfs-tools - Git at Google

 /*
  * Unsquash a squashfs filesystem.  This is a highly compressed read only
  * filesystem.
  *
  * Copyright (c) 2009, 2010, 2011, 2012, 2013
  * Phillip Lougher <phillip@squashfs.org.uk>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version 2,
  * or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  *
  * unsquash-4.c
  */

 #include "unsquashfs.h"
 #include "squashfs_swap.h"

 static struct squashfs_fragment_entry *fragment_table;
 static unsigned int *id_table;

 int read_fragment_table_4(long long *directory_table_end)
 {
 	int res, i;
 	int bytes = SQUASHFS_FRAGMENT_BYTES(sBlk.s.fragments);
 	int  indexes = SQUASHFS_FRAGMENT_INDEXES(sBlk.s.fragments);
 	long long fragment_table_index[indexes];

 	TRACE("read_fragment_table: %d fragments, reading %d fragment indexes "
 		"from 0x%llx\n", sBlk.s.fragments, indexes,
 		sBlk.s.fragment_table_start);

 	if(sBlk.s.fragments == 0) {
 		*directory_table_end = sBlk.s.fragment_table_start;
 		return TRUE;
 	}

 	fragment_table = malloc(bytes);
 	if(fragment_table == NULL)
 		EXIT_UNSQUASH("read_fragment_table: failed to allocate "
 			"fragment table\n");

 	res = read_fs_bytes(fd, sBlk.s.fragment_table_start,
 		SQUASHFS_FRAGMENT_INDEX_BYTES(sBlk.s.fragments),
 		fragment_table_index);
 	if(res == FALSE) {
 		ERROR("read_fragment_table: failed to read fragment table "
 			"index\n");
 		return FALSE;
 	}
 	SQUASHFS_INSWAP_FRAGMENT_INDEXES(fragment_table_index, indexes);

 	for(i = 0; i < indexes; i++) {
 		int expected = (i + 1) != indexes ? SQUASHFS_METADATA_SIZE :
 					bytes & (SQUASHFS_METADATA_SIZE - 1);
 		int length = read_block(fd, fragment_table_index[i], NULL,
 			expected, ((char *) fragment_table) + (i *
 			SQUASHFS_METADATA_SIZE));
 		TRACE("Read fragment table block %d, from 0x%llx, length %d\n",
 			i, fragment_table_index[i], length);
 		if(length == FALSE) {
 			ERROR("read_fragment_table: failed to read fragment "
 				"table index\n");
 			return FALSE;
 		}
 	}

 	for(i = 0; i < sBlk.s.fragments; i++)
 		SQUASHFS_INSWAP_FRAGMENT_ENTRY(&fragment_table[i]);

 	*directory_table_end = fragment_table_index[0];
 	return TRUE;
 }


 void read_fragment_4(unsigned int fragment, long long *start_block, int *size)
 {
 	TRACE("read_fragment: reading fragment %d\n", fragment);

 	struct squashfs_fragment_entry *fragment_entry;

 	fragment_entry = &fragment_table[fragment];
 	*start_block = fragment_entry->start_block;
 	*size = fragment_entry->size;
 }


 struct inode *read_inode_4(unsigned int start_block, unsigned int offset)
 {
 	static union squashfs_inode_header header;
 	long long start = sBlk.s.inode_table_start + start_block;
 	int bytes = lookup_entry(inode_table_hash, start);
 	char *block_ptr = inode_table + bytes + offset;
 	static struct inode i;

 	TRACE("read_inode: reading inode [%d:%d]\n", start_block,  offset);

 	if(bytes == -1)
 		EXIT_UNSQUASH("read_inode: inode table block %lld not found\n",
 			start);

 	SQUASHFS_SWAP_BASE_INODE_HEADER(block_ptr, &header.base);

 	i.uid = (uid_t) id_table[header.base.uid];
 	i.gid = (uid_t) id_table[header.base.guid];
 	i.mode = lookup_type[header.base.inode_type] | header.base.mode;
 	i.type = header.base.inode_type;
 	i.time = header.base.mtime;
 	i.inode_number = header.base.inode_number;

 	switch(header.base.inode_type) {
 		case SQUASHFS_DIR_TYPE: {
 			struct squashfs_dir_inode_header *inode = &header.dir;

 			SQUASHFS_SWAP_DIR_INODE_HEADER(block_ptr, inode);

 			i.data = inode->file_size;
 			i.offset = inode->offset;
 			i.start = inode->start_block;
 			i.xattr = SQUASHFS_INVALID_XATTR;
 			break;
 		}
 		case SQUASHFS_LDIR_TYPE: {
 			struct squashfs_ldir_inode_header *inode = &header.ldir;

 			SQUASHFS_SWAP_LDIR_INODE_HEADER(block_ptr, inode);

 			i.data = inode->file_size;
 			i.offset = inode->offset;
 			i.start = inode->start_block;
 			i.xattr = inode->xattr;
 			break;
 		}
 		case SQUASHFS_FILE_TYPE: {
 			struct squashfs_reg_inode_header *inode = &header.reg;

 			SQUASHFS_SWAP_REG_INODE_HEADER(block_ptr, inode);

 			i.data = inode->file_size;
 			i.frag_bytes = inode->fragment == SQUASHFS_INVALID_FRAG
 				?  0 : inode->file_size % sBlk.s.block_size;
 			i.fragment = inode->fragment;
 			i.offset = inode->offset;
 			i.blocks = inode->fragment == SQUASHFS_INVALID_FRAG ?
 				(i.data + sBlk.s.block_size - 1) >>
 				sBlk.s.block_log :
 				i.data >> sBlk.s.block_log;
 			i.start = inode->start_block;
 			i.sparse = 0;
 			i.block_ptr = block_ptr + sizeof(*inode);
 			i.xattr = SQUASHFS_INVALID_XATTR;
 			break;
 		}
 		case SQUASHFS_LREG_TYPE: {
 			struct squashfs_lreg_inode_header *inode = &header.lreg;

 			SQUASHFS_SWAP_LREG_INODE_HEADER(block_ptr, inode);

 			i.data = inode->file_size;
 			i.frag_bytes = inode->fragment == SQUASHFS_INVALID_FRAG
 				?  0 : inode->file_size % sBlk.s.block_size;
 			i.fragment = inode->fragment;
 			i.offset = inode->offset;
 			i.blocks = inode->fragment == SQUASHFS_INVALID_FRAG ?
 				(inode->file_size + sBlk.s.block_size - 1) >>
 				sBlk.s.block_log :
 				inode->file_size >> sBlk.s.block_log;
 			i.start = inode->start_block;
 			i.sparse = inode->sparse != 0;
 			i.block_ptr = block_ptr + sizeof(*inode);
 			i.xattr = inode->xattr;
 			break;
 		}
 		case SQUASHFS_SYMLINK_TYPE:
 		case SQUASHFS_LSYMLINK_TYPE: {
 			struct squashfs_symlink_inode_header *inode = &header.symlink;

 			SQUASHFS_SWAP_SYMLINK_INODE_HEADER(block_ptr, inode);

 			i.symlink = malloc(inode->symlink_size + 1);
 			if(i.symlink == NULL)
 				EXIT_UNSQUASH("read_inode: failed to malloc "
 					"symlink data\n");
 			strncpy(i.symlink, block_ptr +
 				sizeof(struct squashfs_symlink_inode_header),
 				inode->symlink_size);
 			i.symlink[inode->symlink_size] = '\0';
 			i.data = inode->symlink_size;

 			if(header.base.inode_type == SQUASHFS_LSYMLINK_TYPE)
 				SQUASHFS_SWAP_INTS(block_ptr +
 					sizeof(struct squashfs_symlink_inode_header) +
 					inode->symlink_size, &i.xattr, 1);
 			else
 				i.xattr = SQUASHFS_INVALID_XATTR;
 			break;
 		}
  		case SQUASHFS_BLKDEV_TYPE:
 	 	case SQUASHFS_CHRDEV_TYPE: {
 			struct squashfs_dev_inode_header *inode = &header.dev;

 			SQUASHFS_SWAP_DEV_INODE_HEADER(block_ptr, inode);

 			i.data = inode->rdev;
 			i.xattr = SQUASHFS_INVALID_XATTR;
 			break;
 		}
  		case SQUASHFS_LBLKDEV_TYPE:
 	 	case SQUASHFS_LCHRDEV_TYPE: {
 			struct squashfs_ldev_inode_header *inode = &header.ldev;

 			SQUASHFS_SWAP_LDEV_INODE_HEADER(block_ptr, inode);

 			i.data = inode->rdev;
 			i.xattr = inode->xattr;
 			break;
 		}
 		case SQUASHFS_FIFO_TYPE:
 		case SQUASHFS_SOCKET_TYPE:
 			i.data = 0;
 			i.xattr = SQUASHFS_INVALID_XATTR;
 			break;
 		case SQUASHFS_LFIFO_TYPE:
 		case SQUASHFS_LSOCKET_TYPE: {
 			struct squashfs_lipc_inode_header *inode = &header.lipc;

 			SQUASHFS_SWAP_LIPC_INODE_HEADER(block_ptr, inode);

 			i.data = 0;
 			i.xattr = inode->xattr;
 			break;
 		}
 		default:
 			EXIT_UNSQUASH("Unknown inode type %d in read_inode!\n",
 				header.base.inode_type);
 	}
 	return &i;
 }


 struct dir *squashfs_opendir_4(unsigned int block_start, unsigned int offset,
 	struct inode **i)
 {
 	struct squashfs_dir_header dirh;
 	char buffer[sizeof(struct squashfs_dir_entry) + SQUASHFS_NAME_LEN + 1]
 		__attribute__((aligned));
 	struct squashfs_dir_entry *dire = (struct squashfs_dir_entry *) buffer;
 	long long start;
 	int bytes;
 	int dir_count, size;
 	struct dir_ent *new_dir;
 	struct dir *dir;

 	TRACE("squashfs_opendir: inode start block %d, offset %d\n",
 		block_start, offset);

 	*i = s_ops.read_inode(block_start, offset);

 	dir = malloc(sizeof(struct dir));
 	if(dir == NULL)
 		EXIT_UNSQUASH("squashfs_opendir: malloc failed!\n");

 	dir->dir_count = 0;
 	dir->cur_entry = 0;
 	dir->mode = (*i)->mode;
 	dir->uid = (*i)->uid;
 	dir->guid = (*i)->gid;
 	dir->mtime = (*i)->time;
 	dir->xattr = (*i)->xattr;
 	dir->dirs = NULL;

 	if ((*i)->data == 3)
 		/*
 		 * if the directory is empty, skip the unnecessary
 		 * lookup_entry, this fixes the corner case with
 		 * completely empty filesystems where lookup_entry correctly
 		 * returning -1 is incorrectly treated as an error
 		 */
 		return dir;

 	start = sBlk.s.directory_table_start + (*i)->start;
 	bytes = lookup_entry(directory_table_hash, start);

 	if(bytes == -1)
 		EXIT_UNSQUASH("squashfs_opendir: directory block %d not "
 			"found!\n", block_start);

 	bytes += (*i)->offset;
 	size = (*i)->data + bytes - 3;

 	while(bytes < size) {
 		SQUASHFS_SWAP_DIR_HEADER(directory_table + bytes, &dirh);

 		dir_count = dirh.count + 1;
 		TRACE("squashfs_opendir: Read directory header @ byte position "
 			"%d, %d directory entries\n", bytes, dir_count);
 		bytes += sizeof(dirh);

 		/* dir_count should never be larger than 256 */
 	 	if(dir_count > 256)
 			goto corrupted;

 		while(dir_count--) {
 			SQUASHFS_SWAP_DIR_ENTRY(directory_table + bytes, dire);

 			bytes += sizeof(*dire);

 			/* size should never be larger than SQUASHFS_NAME_LEN */
 			if(dire->size > SQUASHFS_NAME_LEN)
 				goto corrupted;

 			memcpy(dire->name, directory_table + bytes,
 				dire->size + 1);
 			dire->name[dire->size + 1] = '\0';
 			TRACE("squashfs_opendir: directory entry %s, inode "
 				"%d:%d, type %d\n", dire->name,
 				dirh.start_block, dire->offset, dire->type);
 			if((dir->dir_count % DIR_ENT_SIZE) == 0) {
 				new_dir = realloc(dir->dirs, (dir->dir_count +
 					DIR_ENT_SIZE) * sizeof(struct dir_ent));
 				if(new_dir == NULL)
 					EXIT_UNSQUASH("squashfs_opendir: "
 						"realloc failed!\n");
 				dir->dirs = new_dir;
 			}
 			strcpy(dir->dirs[dir->dir_count].name, dire->name);
 			dir->dirs[dir->dir_count].start_block =
 				dirh.start_block;
 			dir->dirs[dir->dir_count].offset = dire->offset;
 			dir->dirs[dir->dir_count].type = dire->type;
 			dir->dir_count ++;
 			bytes += dire->size + 1;
 		}
 	}

 	return dir;

 corrupted:
 	free(dir->dirs);
 	free(dir);
 	return NULL;
 }


 int read_uids_guids_4()
 {
 	int res, i;
 	int bytes = SQUASHFS_ID_BYTES(sBlk.s.no_ids);
 	int indexes = SQUASHFS_ID_BLOCKS(sBlk.s.no_ids);
 	long long id_index_table[indexes];

 	TRACE("read_uids_guids: no_ids %d\n", sBlk.s.no_ids);

 	id_table = malloc(bytes);
 	if(id_table == NULL) {
 		ERROR("read_uids_guids: failed to allocate id table\n");
 		return FALSE;
 	}

 	res = read_fs_bytes(fd, sBlk.s.id_table_start,
 		SQUASHFS_ID_BLOCK_BYTES(sBlk.s.no_ids), id_index_table);
 	if(res == FALSE) {
 		ERROR("read_uids_guids: failed to read id index table\n");
 		return FALSE;
 	}
 	SQUASHFS_INSWAP_ID_BLOCKS(id_index_table, indexes);

 	for(i = 0; i < indexes; i++) {
 		int expected = (i + 1) != indexes ? SQUASHFS_METADATA_SIZE :
 					bytes & (SQUASHFS_METADATA_SIZE - 1);
 		res = read_block(fd, id_index_table[i], NULL, expected,
 			((char *) id_table) + i * SQUASHFS_METADATA_SIZE);
 		if(res == FALSE) {
 			ERROR("read_uids_guids: failed to read id table block"
 				"\n");
 			return FALSE;
 		}
 	}

 	SQUASHFS_INSWAP_INTS(id_table, sBlk.s.no_ids);

 	return TRUE;
 }
	/*
	* Unsquash a squashfs filesystem. This is a highly compressed read only
	* filesystem.
	*
	* Copyright (c) 2009, 2010, 2011, 2012, 2013
	* Phillip Lougher <phillip@squashfs.org.uk>
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version 2,
	* or (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	*
	* unsquash-4.c
	*/

	#include "unsquashfs.h"
	#include "squashfs_swap.h"

	static struct squashfs_fragment_entry *fragment_table;
	static unsigned int *id_table;

	int read_fragment_table_4(long long *directory_table_end)
	{
	int res, i;
	int bytes = SQUASHFS_FRAGMENT_BYTES(sBlk.s.fragments);
	int indexes = SQUASHFS_FRAGMENT_INDEXES(sBlk.s.fragments);
	long long fragment_table_index[indexes];

	TRACE("read_fragment_table: %d fragments, reading %d fragment indexes "
	"from 0x%llx\n", sBlk.s.fragments, indexes,
	sBlk.s.fragment_table_start);

	if(sBlk.s.fragments == 0) {
	*directory_table_end = sBlk.s.fragment_table_start;
	return TRUE;
	}

	fragment_table = malloc(bytes);
	if(fragment_table == NULL)
	EXIT_UNSQUASH("read_fragment_table: failed to allocate "
	"fragment table\n");

	res = read_fs_bytes(fd, sBlk.s.fragment_table_start,
	SQUASHFS_FRAGMENT_INDEX_BYTES(sBlk.s.fragments),
	fragment_table_index);
	if(res == FALSE) {
	ERROR("read_fragment_table: failed to read fragment table "
	"index\n");
	return FALSE;
	}
	SQUASHFS_INSWAP_FRAGMENT_INDEXES(fragment_table_index, indexes);

	for(i = 0; i < indexes; i++) {
	int expected = (i + 1) != indexes ? SQUASHFS_METADATA_SIZE :
	bytes & (SQUASHFS_METADATA_SIZE - 1);
	int length = read_block(fd, fragment_table_index[i], NULL,
	expected, ((char ) fragment_table) + (i
	SQUASHFS_METADATA_SIZE));
	TRACE("Read fragment table block %d, from 0x%llx, length %d\n",
	i, fragment_table_index[i], length);
	if(length == FALSE) {
	ERROR("read_fragment_table: failed to read fragment "
	"table index\n");
	return FALSE;
	}
	}

	for(i = 0; i < sBlk.s.fragments; i++)
	SQUASHFS_INSWAP_FRAGMENT_ENTRY(&fragment_table[i]);

	*directory_table_end = fragment_table_index[0];
	return TRUE;
	}


	void read_fragment_4(unsigned int fragment, long long start_block, int size)
	{
	TRACE("read_fragment: reading fragment %d\n", fragment);

	struct squashfs_fragment_entry *fragment_entry;

	fragment_entry = &fragment_table[fragment];
	*start_block = fragment_entry->start_block;
	*size = fragment_entry->size;
	}


	struct inode *read_inode_4(unsigned int start_block, unsigned int offset)
	{
	static union squashfs_inode_header header;
	long long start = sBlk.s.inode_table_start + start_block;
	int bytes = lookup_entry(inode_table_hash, start);
	char *block_ptr = inode_table + bytes + offset;
	static struct inode i;

	TRACE("read_inode: reading inode [%d:%d]\n", start_block, offset);

	if(bytes == -1)
	EXIT_UNSQUASH("read_inode: inode table block %lld not found\n",
	start);

	SQUASHFS_SWAP_BASE_INODE_HEADER(block_ptr, &header.base);

	i.uid = (uid_t) id_table[header.base.uid];
	i.gid = (uid_t) id_table[header.base.guid];
	i.mode = lookup_type[header.base.inode_type] \| header.base.mode;
	i.type = header.base.inode_type;
	i.time = header.base.mtime;
	i.inode_number = header.base.inode_number;

	switch(header.base.inode_type) {
	case SQUASHFS_DIR_TYPE: {
	struct squashfs_dir_inode_header *inode = &header.dir;

	SQUASHFS_SWAP_DIR_INODE_HEADER(block_ptr, inode);

	i.data = inode->file_size;
	i.offset = inode->offset;
	i.start = inode->start_block;
	i.xattr = SQUASHFS_INVALID_XATTR;
	break;
	}
	case SQUASHFS_LDIR_TYPE: {
	struct squashfs_ldir_inode_header *inode = &header.ldir;

	SQUASHFS_SWAP_LDIR_INODE_HEADER(block_ptr, inode);

	i.data = inode->file_size;
	i.offset = inode->offset;
	i.start = inode->start_block;
	i.xattr = inode->xattr;
	break;
	}
	case SQUASHFS_FILE_TYPE: {
	struct squashfs_reg_inode_header *inode = &header.reg;

	SQUASHFS_SWAP_REG_INODE_HEADER(block_ptr, inode);

	i.data = inode->file_size;
	i.frag_bytes = inode->fragment == SQUASHFS_INVALID_FRAG
	? 0 : inode->file_size % sBlk.s.block_size;
	i.fragment = inode->fragment;
	i.offset = inode->offset;
	i.blocks = inode->fragment == SQUASHFS_INVALID_FRAG ?
	(i.data + sBlk.s.block_size - 1) >>
	sBlk.s.block_log :
	i.data >> sBlk.s.block_log;
	i.start = inode->start_block;
	i.sparse = 0;
	i.block_ptr = block_ptr + sizeof(*inode);
	i.xattr = SQUASHFS_INVALID_XATTR;
	break;
	}
	case SQUASHFS_LREG_TYPE: {
	struct squashfs_lreg_inode_header *inode = &header.lreg;

	SQUASHFS_SWAP_LREG_INODE_HEADER(block_ptr, inode);

	i.data = inode->file_size;
	i.frag_bytes = inode->fragment == SQUASHFS_INVALID_FRAG
	? 0 : inode->file_size % sBlk.s.block_size;
	i.fragment = inode->fragment;
	i.offset = inode->offset;
	i.blocks = inode->fragment == SQUASHFS_INVALID_FRAG ?
	(inode->file_size + sBlk.s.block_size - 1) >>
	sBlk.s.block_log :
	inode->file_size >> sBlk.s.block_log;
	i.start = inode->start_block;
	i.sparse = inode->sparse != 0;
	i.block_ptr = block_ptr + sizeof(*inode);
	i.xattr = inode->xattr;
	break;
	}
	case SQUASHFS_SYMLINK_TYPE:
	case SQUASHFS_LSYMLINK_TYPE: {
	struct squashfs_symlink_inode_header *inode = &header.symlink;

	SQUASHFS_SWAP_SYMLINK_INODE_HEADER(block_ptr, inode);

	i.symlink = malloc(inode->symlink_size + 1);
	if(i.symlink == NULL)
	EXIT_UNSQUASH("read_inode: failed to malloc "
	"symlink data\n");
	strncpy(i.symlink, block_ptr +
	sizeof(struct squashfs_symlink_inode_header),
	inode->symlink_size);
	i.symlink[inode->symlink_size] = '\0';
	i.data = inode->symlink_size;

	if(header.base.inode_type == SQUASHFS_LSYMLINK_TYPE)
	SQUASHFS_SWAP_INTS(block_ptr +
	sizeof(struct squashfs_symlink_inode_header) +
	inode->symlink_size, &i.xattr, 1);
	else
	i.xattr = SQUASHFS_INVALID_XATTR;
	break;
	}
	case SQUASHFS_BLKDEV_TYPE:
	case SQUASHFS_CHRDEV_TYPE: {
	struct squashfs_dev_inode_header *inode = &header.dev;

	SQUASHFS_SWAP_DEV_INODE_HEADER(block_ptr, inode);

	i.data = inode->rdev;
	i.xattr = SQUASHFS_INVALID_XATTR;
	break;
	}
	case SQUASHFS_LBLKDEV_TYPE:
	case SQUASHFS_LCHRDEV_TYPE: {
	struct squashfs_ldev_inode_header *inode = &header.ldev;

	SQUASHFS_SWAP_LDEV_INODE_HEADER(block_ptr, inode);

	i.data = inode->rdev;
	i.xattr = inode->xattr;
	break;
	}
	case SQUASHFS_FIFO_TYPE:
	case SQUASHFS_SOCKET_TYPE:
	i.data = 0;
	i.xattr = SQUASHFS_INVALID_XATTR;
	break;
	case SQUASHFS_LFIFO_TYPE:
	case SQUASHFS_LSOCKET_TYPE: {
	struct squashfs_lipc_inode_header *inode = &header.lipc;

	SQUASHFS_SWAP_LIPC_INODE_HEADER(block_ptr, inode);

	i.data = 0;
	i.xattr = inode->xattr;
	break;
	}
	default:
	EXIT_UNSQUASH("Unknown inode type %d in read_inode!\n",
	header.base.inode_type);
	}
	return &i;
	}


	struct dir *squashfs_opendir_4(unsigned int block_start, unsigned int offset,
	struct inode **i)
	{
	struct squashfs_dir_header dirh;
	char buffer[sizeof(struct squashfs_dir_entry) + SQUASHFS_NAME_LEN + 1]
	__attribute__((aligned));
	struct squashfs_dir_entry dire = (struct squashfs_dir_entry ) buffer;
	long long start;
	int bytes;
	int dir_count, size;
	struct dir_ent *new_dir;
	struct dir *dir;

	TRACE("squashfs_opendir: inode start block %d, offset %d\n",
	block_start, offset);

	*i = s_ops.read_inode(block_start, offset);

	dir = malloc(sizeof(struct dir));
	if(dir == NULL)
	EXIT_UNSQUASH("squashfs_opendir: malloc failed!\n");

	dir->dir_count = 0;
	dir->cur_entry = 0;
	dir->mode = (*i)->mode;
	dir->uid = (*i)->uid;
	dir->guid = (*i)->gid;
	dir->mtime = (*i)->time;
	dir->xattr = (*i)->xattr;
	dir->dirs = NULL;

	if ((*i)->data == 3)
	/*
	* if the directory is empty, skip the unnecessary
	* lookup_entry, this fixes the corner case with
	* completely empty filesystems where lookup_entry correctly
	* returning -1 is incorrectly treated as an error
	*/
	return dir;

	start = sBlk.s.directory_table_start + (*i)->start;
	bytes = lookup_entry(directory_table_hash, start);

	if(bytes == -1)
	EXIT_UNSQUASH("squashfs_opendir: directory block %d not "
	"found!\n", block_start);

	bytes += (*i)->offset;
	size = (*i)->data + bytes - 3;

	while(bytes < size) {
	SQUASHFS_SWAP_DIR_HEADER(directory_table + bytes, &dirh);

	dir_count = dirh.count + 1;
	TRACE("squashfs_opendir: Read directory header @ byte position "
	"%d, %d directory entries\n", bytes, dir_count);
	bytes += sizeof(dirh);

	/* dir_count should never be larger than 256 */
	if(dir_count > 256)
	goto corrupted;

	while(dir_count--) {
	SQUASHFS_SWAP_DIR_ENTRY(directory_table + bytes, dire);

	bytes += sizeof(*dire);

	/* size should never be larger than SQUASHFS_NAME_LEN */
	if(dire->size > SQUASHFS_NAME_LEN)
	goto corrupted;

	memcpy(dire->name, directory_table + bytes,
	dire->size + 1);
	dire->name[dire->size + 1] = '\0';
	TRACE("squashfs_opendir: directory entry %s, inode "
	"%d:%d, type %d\n", dire->name,
	dirh.start_block, dire->offset, dire->type);
	if((dir->dir_count % DIR_ENT_SIZE) == 0) {
	new_dir = realloc(dir->dirs, (dir->dir_count +
	DIR_ENT_SIZE) * sizeof(struct dir_ent));
	if(new_dir == NULL)
	EXIT_UNSQUASH("squashfs_opendir: "
	"realloc failed!\n");
	dir->dirs = new_dir;
	}
	strcpy(dir->dirs[dir->dir_count].name, dire->name);
	dir->dirs[dir->dir_count].start_block =
	dirh.start_block;
	dir->dirs[dir->dir_count].offset = dire->offset;
	dir->dirs[dir->dir_count].type = dire->type;
	dir->dir_count ++;
	bytes += dire->size + 1;
	}
	}

	return dir;

	corrupted:
	free(dir->dirs);
	free(dir);
	return NULL;
	}


	int read_uids_guids_4()
	{
	int res, i;
	int bytes = SQUASHFS_ID_BYTES(sBlk.s.no_ids);
	int indexes = SQUASHFS_ID_BLOCKS(sBlk.s.no_ids);
	long long id_index_table[indexes];

	TRACE("read_uids_guids: no_ids %d\n", sBlk.s.no_ids);

	id_table = malloc(bytes);
	if(id_table == NULL) {
	ERROR("read_uids_guids: failed to allocate id table\n");
	return FALSE;
	}

	res = read_fs_bytes(fd, sBlk.s.id_table_start,
	SQUASHFS_ID_BLOCK_BYTES(sBlk.s.no_ids), id_index_table);
	if(res == FALSE) {
	ERROR("read_uids_guids: failed to read id index table\n");
	return FALSE;
	}
	SQUASHFS_INSWAP_ID_BLOCKS(id_index_table, indexes);

	for(i = 0; i < indexes; i++) {
	int expected = (i + 1) != indexes ? SQUASHFS_METADATA_SIZE :
	bytes & (SQUASHFS_METADATA_SIZE - 1);
	res = read_block(fd, id_index_table[i], NULL, expected,
	((char ) id_table) + i SQUASHFS_METADATA_SIZE);
	if(res == FALSE) {
	ERROR("read_uids_guids: failed to read id table block"
	"\n");
	return FALSE;
	}
	}

	SQUASHFS_INSWAP_INTS(id_table, sBlk.s.no_ids);

	return TRUE;
	}