mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 01:10:04 +00:00
![Al Viro](/assets/img/avatar_default.png)
don't need to lock directory in ->llseek(), either Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
236 lines
5.9 KiB
C
236 lines
5.9 KiB
C
/*
|
|
* Squashfs - a compressed read only filesystem for Linux
|
|
*
|
|
* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
|
|
* 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, 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;
|
|
unsigned int size;
|
|
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;
|
|
|
|
size = le32_to_cpu(dir_index.size) + 1;
|
|
|
|
/* size should never be larger than SQUASHFS_NAME_LEN */
|
|
if (size > SQUASHFS_NAME_LEN)
|
|
break;
|
|
|
|
err = squashfs_read_metadata(sb, NULL, &index_start,
|
|
&index_offset, size);
|
|
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, struct dir_context *ctx)
|
|
{
|
|
struct inode *inode = file_inode(file);
|
|
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, err;
|
|
unsigned int inode_number, dir_count, size, type;
|
|
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 (ctx->pos < 3) {
|
|
char *name;
|
|
int i_ino;
|
|
|
|
if (ctx->pos == 0) {
|
|
name = ".";
|
|
size = 1;
|
|
i_ino = inode->i_ino;
|
|
} else {
|
|
name = "..";
|
|
size = 2;
|
|
i_ino = squashfs_i(inode)->parent;
|
|
}
|
|
|
|
if (!dir_emit(ctx, name, size, i_ino,
|
|
squashfs_filetype_table[1]))
|
|
goto finish;
|
|
|
|
ctx->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,
|
|
ctx->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;
|
|
|
|
if (dir_count > SQUASHFS_DIR_COUNT)
|
|
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 (ctx->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);
|
|
|
|
if (type > SQUASHFS_MAX_DIR_TYPE)
|
|
goto failed_read;
|
|
|
|
if (!dir_emit(ctx, dire->name, size,
|
|
inode_number,
|
|
squashfs_filetype_table[type]))
|
|
goto finish;
|
|
|
|
ctx->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,
|
|
.iterate_shared = squashfs_readdir,
|
|
.llseek = generic_file_llseek,
|
|
};
|