fs/squashfs/dir.c - third_party/linux - Git at Google

 /*
  * Squashfs - a compressed read only filesystem for Linux
  *
  * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
  * Phillip Lougher <phillip@lougher.demon.co.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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  *
  * dir.c
  */

 /*
  * This file implements code to read directories from disk.
  *
  * See namei.c for a description of directory organisation on disk.
  */

 #include <linux/fs.h>
 #include <linux/vfs.h>
 #include <linux/slab.h>

 #include "squashfs_fs.h"
 #include "squashfs_fs_sb.h"
 #include "squashfs_fs_i.h"
 #include "squashfs.h"

 static const unsigned char squashfs_filetype_table[] = {
 	DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_FIFO, DT_SOCK
 };

 /*
  * Lookup offset (f_pos) in the directory index, returning the
  * metadata block containing it.
  *
  * If we get an error reading the index then return the part of the index
  * (if any) we have managed to read - the index isn't essential, just
  * quicker.
  */
 static int get_dir_index_using_offset(struct super_block *sb,
 	u64 *next_block, int *next_offset, u64 index_start, int index_offset,
 	int i_count, u64 f_pos)
 {
 	struct squashfs_sb_info *msblk = sb->s_fs_info;
 	int err, i, index, length = 0;
 	struct squashfs_dir_index dir_index;

 	TRACE("Entered get_dir_index_using_offset, i_count %d, f_pos %lld\n",
 					i_count, f_pos);

 	/*
 	 * Translate from external f_pos to the internal f_pos.  This
 	 * is offset by 3 because we invent "." and ".." entries which are
 	 * not actually stored in the directory.
 	 */
 	if (f_pos < 3)
 		return f_pos;
 	f_pos -= 3;

 	for (i = 0; i < i_count; i++) {
 		err = squashfs_read_metadata(sb, &dir_index, &index_start,
 				&index_offset, sizeof(dir_index));
 		if (err < 0)
 			break;

 		index = le32_to_cpu(dir_index.index);
 		if (index > f_pos)
 			/*
 			 * Found the index we're looking for.
 			 */
 			break;

 		err = squashfs_read_metadata(sb, NULL, &index_start,
 				&index_offset, le32_to_cpu(dir_index.size) + 1);
 		if (err < 0)
 			break;

 		length = index;
 		*next_block = le32_to_cpu(dir_index.start_block) +
 					msblk->directory_table;
 	}

 	*next_offset = (length + *next_offset) % SQUASHFS_METADATA_SIZE;

 	/*
 	 * Translate back from internal f_pos to external f_pos.
 	 */
 	return length + 3;
 }


 static int squashfs_readdir(struct file *file, void *dirent, filldir_t filldir)
 {
 	struct inode *inode = file->f_dentry->d_inode;
 	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
 	u64 block = squashfs_i(inode)->start + msblk->directory_table;
 	int offset = squashfs_i(inode)->offset, length = 0, dir_count, size,
 				type, err;
 	unsigned int inode_number;
 	struct squashfs_dir_header dirh;
 	struct squashfs_dir_entry *dire;

 	TRACE("Entered squashfs_readdir [%llx:%x]\n", block, offset);

 	dire = kmalloc(sizeof(*dire) + SQUASHFS_NAME_LEN + 1, GFP_KERNEL);
 	if (dire == NULL) {
 		ERROR("Failed to allocate squashfs_dir_entry\n");
 		goto finish;
 	}

 	/*
 	 * Return "." and  ".." entries as the first two filenames in the
 	 * directory.  To maximise compression these two entries are not
 	 * stored in the directory, and so we invent them here.
 	 *
 	 * It also means that the external f_pos is offset by 3 from the
 	 * on-disk directory f_pos.
 	 */
 	while (file->f_pos < 3) {
 		char *name;
 		int i_ino;

 		if (file->f_pos == 0) {
 			name = ".";
 			size = 1;
 			i_ino = inode->i_ino;
 		} else {
 			name = "..";
 			size = 2;
 			i_ino = squashfs_i(inode)->parent;
 		}

 		TRACE("Calling filldir(%p, %s, %d, %lld, %d, %d)\n",
 				dirent, name, size, file->f_pos, i_ino,
 				squashfs_filetype_table[1]);

 		if (filldir(dirent, name, size, file->f_pos, i_ino,
 				squashfs_filetype_table[1]) < 0) {
 				TRACE("Filldir returned less than 0\n");
 			goto finish;
 		}

 		file->f_pos += size;
 	}

 	length = get_dir_index_using_offset(inode->i_sb, &block, &offset,
 				squashfs_i(inode)->dir_idx_start,
 				squashfs_i(inode)->dir_idx_offset,
 				squashfs_i(inode)->dir_idx_cnt,
 				file->f_pos);

 	while (length < i_size_read(inode)) {
 		/*
 		 * Read directory header
 		 */
 		err = squashfs_read_metadata(inode->i_sb, &dirh, &block,
 					&offset, sizeof(dirh));
 		if (err < 0)
 			goto failed_read;

 		length += sizeof(dirh);

 		dir_count = le32_to_cpu(dirh.count) + 1;

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

 		while (dir_count--) {
 			/*
 			 * Read directory entry.
 			 */
 			err = squashfs_read_metadata(inode->i_sb, dire, &block,
 					&offset, sizeof(*dire));
 			if (err < 0)
 				goto failed_read;

 			size = le16_to_cpu(dire->size) + 1;

 			/* size should never be larger than SQUASHFS_NAME_LEN */
 			if (size > SQUASHFS_NAME_LEN)
 				goto failed_read;

 			err = squashfs_read_metadata(inode->i_sb, dire->name,
 					&block, &offset, size);
 			if (err < 0)
 				goto failed_read;

 			length += sizeof(*dire) + size;

 			if (file->f_pos >= length)
 				continue;

 			dire->name[size] = '\0';
 			inode_number = le32_to_cpu(dirh.inode_number) +
 				((short) le16_to_cpu(dire->inode_number));
 			type = le16_to_cpu(dire->type);

 			TRACE("Calling filldir(%p, %s, %d, %lld, %x:%x, %d, %d)"
 					"\n", dirent, dire->name, size,
 					file->f_pos,
 					le32_to_cpu(dirh.start_block),
 					le16_to_cpu(dire->offset),
 					inode_number,
 					squashfs_filetype_table[type]);

 			if (filldir(dirent, dire->name, size, file->f_pos,
 					inode_number,
 					squashfs_filetype_table[type]) < 0) {
 				TRACE("Filldir returned less than 0\n");
 				goto finish;
 			}

 			file->f_pos = length;
 		}
 	}

 finish:
 	kfree(dire);
 	return 0;

 failed_read:
 	ERROR("Unable to read directory block [%llx:%x]\n", block, offset);
 	kfree(dire);
 	return 0;
 }


 const struct file_operations squashfs_dir_ops = {
 	.read = generic_read_dir,
 	.readdir = squashfs_readdir,
 	.llseek = default_llseek,
 };
	/*
	* Squashfs - a compressed read only filesystem for Linux
	*
	* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
	* Phillip Lougher <phillip@lougher.demon.co.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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
	*
	* dir.c
	*/

	/*
	* This file implements code to read directories from disk.
	*
	* See namei.c for a description of directory organisation on disk.
	*/

	#include <linux/fs.h>
	#include <linux/vfs.h>
	#include <linux/slab.h>

	#include "squashfs_fs.h"
	#include "squashfs_fs_sb.h"
	#include "squashfs_fs_i.h"
	#include "squashfs.h"

	static const unsigned char squashfs_filetype_table[] = {
	DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_FIFO, DT_SOCK
	};

	/*
	* Lookup offset (f_pos) in the directory index, returning the
	* metadata block containing it.
	*
	* If we get an error reading the index then return the part of the index
	* (if any) we have managed to read - the index isn't essential, just
	* quicker.
	*/
	static int get_dir_index_using_offset(struct super_block *sb,
	u64 next_block, int next_offset, u64 index_start, int index_offset,
	int i_count, u64 f_pos)
	{
	struct squashfs_sb_info *msblk = sb->s_fs_info;
	int err, i, index, length = 0;
	struct squashfs_dir_index dir_index;

	TRACE("Entered get_dir_index_using_offset, i_count %d, f_pos %lld\n",
	i_count, f_pos);

	/*
	* Translate from external f_pos to the internal f_pos. This
	* is offset by 3 because we invent "." and ".." entries which are
	* not actually stored in the directory.
	*/
	if (f_pos < 3)
	return f_pos;
	f_pos -= 3;

	for (i = 0; i < i_count; i++) {
	err = squashfs_read_metadata(sb, &dir_index, &index_start,
	&index_offset, sizeof(dir_index));
	if (err < 0)
	break;

	index = le32_to_cpu(dir_index.index);
	if (index > f_pos)
	/*
	* Found the index we're looking for.
	*/
	break;

	err = squashfs_read_metadata(sb, NULL, &index_start,
	&index_offset, le32_to_cpu(dir_index.size) + 1);
	if (err < 0)
	break;

	length = index;
	*next_block = le32_to_cpu(dir_index.start_block) +
	msblk->directory_table;
	}

	next_offset = (length + next_offset) % SQUASHFS_METADATA_SIZE;

	/*
	* Translate back from internal f_pos to external f_pos.
	*/
	return length + 3;
	}


	static int squashfs_readdir(struct file file, void dirent, filldir_t filldir)
	{
	struct inode *inode = file->f_dentry->d_inode;
	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
	u64 block = squashfs_i(inode)->start + msblk->directory_table;
	int offset = squashfs_i(inode)->offset, length = 0, dir_count, size,
	type, err;
	unsigned int inode_number;
	struct squashfs_dir_header dirh;
	struct squashfs_dir_entry *dire;

	TRACE("Entered squashfs_readdir [%llx:%x]\n", block, offset);

	dire = kmalloc(sizeof(*dire) + SQUASHFS_NAME_LEN + 1, GFP_KERNEL);
	if (dire == NULL) {
	ERROR("Failed to allocate squashfs_dir_entry\n");
	goto finish;
	}

	/*
	* Return "." and ".." entries as the first two filenames in the
	* directory. To maximise compression these two entries are not
	* stored in the directory, and so we invent them here.
	*
	* It also means that the external f_pos is offset by 3 from the
	* on-disk directory f_pos.
	*/
	while (file->f_pos < 3) {
	char *name;
	int i_ino;

	if (file->f_pos == 0) {
	name = ".";
	size = 1;
	i_ino = inode->i_ino;
	} else {
	name = "..";
	size = 2;
	i_ino = squashfs_i(inode)->parent;
	}

	TRACE("Calling filldir(%p, %s, %d, %lld, %d, %d)\n",
	dirent, name, size, file->f_pos, i_ino,
	squashfs_filetype_table[1]);

	if (filldir(dirent, name, size, file->f_pos, i_ino,
	squashfs_filetype_table[1]) < 0) {
	TRACE("Filldir returned less than 0\n");
	goto finish;
	}

	file->f_pos += size;
	}

	length = get_dir_index_using_offset(inode->i_sb, &block, &offset,
	squashfs_i(inode)->dir_idx_start,
	squashfs_i(inode)->dir_idx_offset,
	squashfs_i(inode)->dir_idx_cnt,
	file->f_pos);

	while (length < i_size_read(inode)) {
	/*
	* Read directory header
	*/
	err = squashfs_read_metadata(inode->i_sb, &dirh, &block,
	&offset, sizeof(dirh));
	if (err < 0)
	goto failed_read;

	length += sizeof(dirh);

	dir_count = le32_to_cpu(dirh.count) + 1;

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

	while (dir_count--) {
	/*
	* Read directory entry.
	*/
	err = squashfs_read_metadata(inode->i_sb, dire, &block,
	&offset, sizeof(*dire));
	if (err < 0)
	goto failed_read;

	size = le16_to_cpu(dire->size) + 1;

	/* size should never be larger than SQUASHFS_NAME_LEN */
	if (size > SQUASHFS_NAME_LEN)
	goto failed_read;

	err = squashfs_read_metadata(inode->i_sb, dire->name,
	&block, &offset, size);
	if (err < 0)
	goto failed_read;

	length += sizeof(*dire) + size;

	if (file->f_pos >= length)
	continue;

	dire->name[size] = '\0';
	inode_number = le32_to_cpu(dirh.inode_number) +
	((short) le16_to_cpu(dire->inode_number));
	type = le16_to_cpu(dire->type);

	TRACE("Calling filldir(%p, %s, %d, %lld, %x:%x, %d, %d)"
	"\n", dirent, dire->name, size,
	file->f_pos,
	le32_to_cpu(dirh.start_block),
	le16_to_cpu(dire->offset),
	inode_number,
	squashfs_filetype_table[type]);

	if (filldir(dirent, dire->name, size, file->f_pos,
	inode_number,
	squashfs_filetype_table[type]) < 0) {
	TRACE("Filldir returned less than 0\n");
	goto finish;
	}

	file->f_pos = length;
	}
	}

	finish:
	kfree(dire);
	return 0;

	failed_read:
	ERROR("Unable to read directory block [%llx:%x]\n", block, offset);
	kfree(dire);
	return 0;
	}


	const struct file_operations squashfs_dir_ops = {
	.read = generic_read_dir,
	.readdir = squashfs_readdir,
	.llseek = default_llseek,
	};