[linux-2.6-block.git] / fs / squashfs / dir.c

/*
 * 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;
		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;

			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
};
Commit	Line	Data
07972dde PL	1	/*
	2	* Squashfs - a compressed read only filesystem for Linux
	3	*
	4	* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
	5	* Phillip Lougher <phillip@lougher.demon.co.uk>
	6	*
	7	* This program is free software; you can redistribute it and/or
	8	* modify it under the terms of the GNU General Public License
	9	* as published by the Free Software Foundation; either version 2,
	10	* or (at your option) any later version.
	11	*
	12	* This program is distributed in the hope that it will be useful,
	13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	* GNU General Public License for more details.
	16	*
	17	* You should have received a copy of the GNU General Public License
	18	* along with this program; if not, write to the Free Software
	19	* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
	20	*
	21	* dir.c
	22	*/
	23
	24	/*
	25	* This file implements code to read directories from disk.
	26	*
	27	* See namei.c for a description of directory organisation on disk.
	28	*/
	29
	30	#include <linux/fs.h>
	31	#include <linux/vfs.h>
	32	#include <linux/slab.h>
07972dde PL	33
	34	#include "squashfs_fs.h"
	35	#include "squashfs_fs_sb.h"
	36	#include "squashfs_fs_i.h"
	37	#include "squashfs.h"
	38
	39	static const unsigned char squashfs_filetype_table[] = {
	40	DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_FIFO, DT_SOCK
	41	};
	42
	43	/*
	44	* Lookup offset (f_pos) in the directory index, returning the
	45	* metadata block containing it.
	46	*
	47	* If we get an error reading the index then return the part of the index
	48	* (if any) we have managed to read - the index isn't essential, just
	49	* quicker.
	50	*/
	51	static int get_dir_index_using_offset(struct super_block *sb,
	52	u64 next_block, int next_offset, u64 index_start, int index_offset,
	53	int i_count, u64 f_pos)
	54	{
	55	struct squashfs_sb_info *msblk = sb->s_fs_info;
	56	int err, i, index, length = 0;
	57	struct squashfs_dir_index dir_index;
	58
	59	TRACE("Entered get_dir_index_using_offset, i_count %d, f_pos %lld\n",
	60	i_count, f_pos);
	61
	62	/*
	63	* Translate from external f_pos to the internal f_pos. This
	64	* is offset by 3 because we invent "." and ".." entries which are
	65	* not actually stored in the directory.
	66	*/
	67	if (f_pos < 3)
	68	return f_pos;
	69	f_pos -= 3;
	70
	71	for (i = 0; i < i_count; i++) {
	72	err = squashfs_read_metadata(sb, &dir_index, &index_start,
	73	&index_offset, sizeof(dir_index));
	74	if (err < 0)
	75	break;
	76
	77	index = le32_to_cpu(dir_index.index);
	78	if (index > f_pos)
	79	/*
	80	* Found the index we're looking for.
	81	*/
	82	break;
	83
	84	err = squashfs_read_metadata(sb, NULL, &index_start,
	85	&index_offset, le32_to_cpu(dir_index.size) + 1);
	86	if (err < 0)
	87	break;
	88
	89	length = index;
	90	*next_block = le32_to_cpu(dir_index.start_block) +
	91	msblk->directory_table;
	92	}
	93
	94	next_offset = (length + next_offset) % SQUASHFS_METADATA_SIZE;
	95
	96	/*
97	* Translate back from internal f_pos to external f_pos.
98	*/
99	return length + 3;
100	}
101
102
103	static int squashfs_readdir(struct file file, void dirent, filldir_t filldir)
104	{
105	struct inode *inode = file->f_dentry->d_inode;
106	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
107	u64 block = squashfs_i(inode)->start + msblk->directory_table;
108	int offset = squashfs_i(inode)->offset, length = 0, dir_count, size,
109	type, err;
110	unsigned int inode_number;
111	struct squashfs_dir_header dirh;
112	struct squashfs_dir_entry *dire;
113
114	TRACE("Entered squashfs_readdir [%llx:%x]\n", block, offset);
115
116	dire = kmalloc(sizeof(*dire) + SQUASHFS_NAME_LEN + 1, GFP_KERNEL);
117	if (dire == NULL) {
118	ERROR("Failed to allocate squashfs_dir_entry\n");
119	goto finish;
120	}
121
122	/*
123	* Return "." and ".." entries as the first two filenames in the
124	* directory. To maximise compression these two entries are not
125	* stored in the directory, and so we invent them here.
126	*
127	* It also means that the external f_pos is offset by 3 from the
128	* on-disk directory f_pos.
129	*/
130	while (file->f_pos < 3) {
131	char *name;
132	int i_ino;
133
134	if (file->f_pos == 0) {
135	name = ".";
136	size = 1;
137	i_ino = inode->i_ino;
138	} else {
139	name = "..";
140	size = 2;
141	i_ino = squashfs_i(inode)->parent;
142	}
143
144	TRACE("Calling filldir(%p, %s, %d, %lld, %d, %d)\n",
145	dirent, name, size, file->f_pos, i_ino,
146	squashfs_filetype_table[1]);
147
148	if (filldir(dirent, name, size, file->f_pos, i_ino,
149	squashfs_filetype_table[1]) < 0) {
150	TRACE("Filldir returned less than 0\n");
151	goto finish;
152	}
153
154	file->f_pos += size;
155	}
156
157	length = get_dir_index_using_offset(inode->i_sb, &block, &offset,
158	squashfs_i(inode)->dir_idx_start,
159	squashfs_i(inode)->dir_idx_offset,
160	squashfs_i(inode)->dir_idx_cnt,
161	file->f_pos);
162
163	while (length < i_size_read(inode)) {
164	/*
165	* Read directory header
166	*/
167	err = squashfs_read_metadata(inode->i_sb, &dirh, &block,
168	&offset, sizeof(dirh));
169	if (err < 0)
170	goto failed_read;
171
172	length += sizeof(dirh);
173
174	dir_count = le32_to_cpu(dirh.count) + 1;
175	while (dir_count--) {
176	/*
177	* Read directory entry.
178	*/
179	err = squashfs_read_metadata(inode->i_sb, dire, &block,
180	&offset, sizeof(*dire));
181	if (err < 0)
182	goto failed_read;
183
184	size = le16_to_cpu(dire->size) + 1;
185
186	err = squashfs_read_metadata(inode->i_sb, dire->name,
187	&block, &offset, size);
188	if (err < 0)
189	goto failed_read;
190
191	length += sizeof(*dire) + size;
192
193	if (file->f_pos >= length)
194	continue;
195
196	dire->name[size] = '\0';
197	inode_number = le32_to_cpu(dirh.inode_number) +
198	((short) le16_to_cpu(dire->inode_number));
199	type = le16_to_cpu(dire->type);
200
201	TRACE("Calling filldir(%p, %s, %d, %lld, %x:%x, %d, %d)"
202	"\n", dirent, dire->name, size,
203	file->f_pos,
204	le32_to_cpu(dirh.start_block),
205	le16_to_cpu(dire->offset),
206	inode_number,
207	squashfs_filetype_table[type]);
208
209	if (filldir(dirent, dire->name, size, file->f_pos,
210	inode_number,
211	squashfs_filetype_table[type]) < 0) {
212	TRACE("Filldir returned less than 0\n");
213	goto finish;
214	}
215
216	file->f_pos = length;
217	}
218	}
219
220	finish:
221	kfree(dire);
222	return 0;
223
224	failed_read:
225	ERROR("Unable to read directory block [%llx:%x]\n", block, offset);
226	kfree(dire);
227	return 0;
228	}
229
230
231	const struct file_operations squashfs_dir_ops = {
232	.read = generic_read_dir,
233	.readdir = squashfs_readdir
234	};