| /* |
| * 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; |
| 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; |
| |
| 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 (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, |
| }; |