1e2780ab1SPhillip Lougher /* 2e2780ab1SPhillip Lougher * Squashfs - a compressed read only filesystem for Linux 3e2780ab1SPhillip Lougher * 4e2780ab1SPhillip Lougher * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 5e2780ab1SPhillip Lougher * Phillip Lougher <phillip@lougher.demon.co.uk> 6e2780ab1SPhillip Lougher * 7e2780ab1SPhillip Lougher * This program is free software; you can redistribute it and/or 8e2780ab1SPhillip Lougher * modify it under the terms of the GNU General Public License 9e2780ab1SPhillip Lougher * as published by the Free Software Foundation; either version 2, 10e2780ab1SPhillip Lougher * or (at your option) any later version. 11e2780ab1SPhillip Lougher * 12e2780ab1SPhillip Lougher * This program is distributed in the hope that it will be useful, 13e2780ab1SPhillip Lougher * but WITHOUT ANY WARRANTY; without even the implied warranty of 14e2780ab1SPhillip Lougher * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15e2780ab1SPhillip Lougher * GNU General Public License for more details. 16e2780ab1SPhillip Lougher * 17e2780ab1SPhillip Lougher * You should have received a copy of the GNU General Public License 18e2780ab1SPhillip Lougher * along with this program; if not, write to the Free Software 19e2780ab1SPhillip Lougher * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. 20e2780ab1SPhillip Lougher * 21e2780ab1SPhillip Lougher * block.c 22e2780ab1SPhillip Lougher */ 23e2780ab1SPhillip Lougher 24e2780ab1SPhillip Lougher /* 25e2780ab1SPhillip Lougher * This file implements the low-level routines to read and decompress 26e2780ab1SPhillip Lougher * datablocks and metadata blocks. 27e2780ab1SPhillip Lougher */ 28e2780ab1SPhillip Lougher 29e2780ab1SPhillip Lougher #include <linux/fs.h> 30e2780ab1SPhillip Lougher #include <linux/vfs.h> 31e2780ab1SPhillip Lougher #include <linux/slab.h> 32e2780ab1SPhillip Lougher #include <linux/string.h> 33e2780ab1SPhillip Lougher #include <linux/buffer_head.h> 34e2780ab1SPhillip Lougher 35e2780ab1SPhillip Lougher #include "squashfs_fs.h" 36e2780ab1SPhillip Lougher #include "squashfs_fs_sb.h" 37e2780ab1SPhillip Lougher #include "squashfs_fs_i.h" 38e2780ab1SPhillip Lougher #include "squashfs.h" 394c0f0bb2SPhillip Lougher #include "decompressor.h" 40e2780ab1SPhillip Lougher 41e2780ab1SPhillip Lougher /* 42e2780ab1SPhillip Lougher * Read the metadata block length, this is stored in the first two 43e2780ab1SPhillip Lougher * bytes of the metadata block. 44e2780ab1SPhillip Lougher */ 45e2780ab1SPhillip Lougher static struct buffer_head *get_block_length(struct super_block *sb, 46e2780ab1SPhillip Lougher u64 *cur_index, int *offset, int *length) 47e2780ab1SPhillip Lougher { 48e2780ab1SPhillip Lougher struct squashfs_sb_info *msblk = sb->s_fs_info; 49e2780ab1SPhillip Lougher struct buffer_head *bh; 50e2780ab1SPhillip Lougher 51e2780ab1SPhillip Lougher bh = sb_bread(sb, *cur_index); 52e2780ab1SPhillip Lougher if (bh == NULL) 53e2780ab1SPhillip Lougher return NULL; 54e2780ab1SPhillip Lougher 55e2780ab1SPhillip Lougher if (msblk->devblksize - *offset == 1) { 56e2780ab1SPhillip Lougher *length = (unsigned char) bh->b_data[*offset]; 57e2780ab1SPhillip Lougher put_bh(bh); 58e2780ab1SPhillip Lougher bh = sb_bread(sb, ++(*cur_index)); 59e2780ab1SPhillip Lougher if (bh == NULL) 60e2780ab1SPhillip Lougher return NULL; 61e2780ab1SPhillip Lougher *length |= (unsigned char) bh->b_data[0] << 8; 62e2780ab1SPhillip Lougher *offset = 1; 63e2780ab1SPhillip Lougher } else { 64e2780ab1SPhillip Lougher *length = (unsigned char) bh->b_data[*offset] | 65e2780ab1SPhillip Lougher (unsigned char) bh->b_data[*offset + 1] << 8; 66e2780ab1SPhillip Lougher *offset += 2; 67e2780ab1SPhillip Lougher } 68e2780ab1SPhillip Lougher 69e2780ab1SPhillip Lougher return bh; 70e2780ab1SPhillip Lougher } 71e2780ab1SPhillip Lougher 72e2780ab1SPhillip Lougher 73e2780ab1SPhillip Lougher /* 74e2780ab1SPhillip Lougher * Read and decompress a metadata block or datablock. Length is non-zero 75e2780ab1SPhillip Lougher * if a datablock is being read (the size is stored elsewhere in the 76e2780ab1SPhillip Lougher * filesystem), otherwise the length is obtained from the first two bytes of 77e2780ab1SPhillip Lougher * the metadata block. A bit in the length field indicates if the block 78e2780ab1SPhillip Lougher * is stored uncompressed in the filesystem (usually because compression 79e2780ab1SPhillip Lougher * generated a larger block - this does occasionally happen with zlib). 80e2780ab1SPhillip Lougher */ 81e2780ab1SPhillip Lougher int squashfs_read_data(struct super_block *sb, void **buffer, u64 index, 82118e1ef6SPhillip Lougher int length, u64 *next_index, int srclength, int pages) 83e2780ab1SPhillip Lougher { 84e2780ab1SPhillip Lougher struct squashfs_sb_info *msblk = sb->s_fs_info; 85e2780ab1SPhillip Lougher struct buffer_head **bh; 86e2780ab1SPhillip Lougher int offset = index & ((1 << msblk->devblksize_log2) - 1); 87e2780ab1SPhillip Lougher u64 cur_index = index >> msblk->devblksize_log2; 88e2780ab1SPhillip Lougher int bytes, compressed, b = 0, k = 0, page = 0, avail; 89e2780ab1SPhillip Lougher 90e2780ab1SPhillip Lougher 91e2780ab1SPhillip Lougher bh = kcalloc((msblk->block_size >> msblk->devblksize_log2) + 1, 92e2780ab1SPhillip Lougher sizeof(*bh), GFP_KERNEL); 93e2780ab1SPhillip Lougher if (bh == NULL) 94e2780ab1SPhillip Lougher return -ENOMEM; 95e2780ab1SPhillip Lougher 96e2780ab1SPhillip Lougher if (length) { 97e2780ab1SPhillip Lougher /* 98e2780ab1SPhillip Lougher * Datablock. 99e2780ab1SPhillip Lougher */ 100e2780ab1SPhillip Lougher bytes = -offset; 101e2780ab1SPhillip Lougher compressed = SQUASHFS_COMPRESSED_BLOCK(length); 102e2780ab1SPhillip Lougher length = SQUASHFS_COMPRESSED_SIZE_BLOCK(length); 103e2780ab1SPhillip Lougher if (next_index) 104e2780ab1SPhillip Lougher *next_index = index + length; 105e2780ab1SPhillip Lougher 106e2780ab1SPhillip Lougher TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n", 107e2780ab1SPhillip Lougher index, compressed ? "" : "un", length, srclength); 108e2780ab1SPhillip Lougher 109e2780ab1SPhillip Lougher if (length < 0 || length > srclength || 110e2780ab1SPhillip Lougher (index + length) > msblk->bytes_used) 111e2780ab1SPhillip Lougher goto read_failure; 112e2780ab1SPhillip Lougher 113e2780ab1SPhillip Lougher for (b = 0; bytes < length; b++, cur_index++) { 114e2780ab1SPhillip Lougher bh[b] = sb_getblk(sb, cur_index); 115e2780ab1SPhillip Lougher if (bh[b] == NULL) 116e2780ab1SPhillip Lougher goto block_release; 117e2780ab1SPhillip Lougher bytes += msblk->devblksize; 118e2780ab1SPhillip Lougher } 119e2780ab1SPhillip Lougher ll_rw_block(READ, b, bh); 120e2780ab1SPhillip Lougher } else { 121e2780ab1SPhillip Lougher /* 122e2780ab1SPhillip Lougher * Metadata block. 123e2780ab1SPhillip Lougher */ 124e2780ab1SPhillip Lougher if ((index + 2) > msblk->bytes_used) 125e2780ab1SPhillip Lougher goto read_failure; 126e2780ab1SPhillip Lougher 127e2780ab1SPhillip Lougher bh[0] = get_block_length(sb, &cur_index, &offset, &length); 128e2780ab1SPhillip Lougher if (bh[0] == NULL) 129e2780ab1SPhillip Lougher goto read_failure; 130e2780ab1SPhillip Lougher b = 1; 131e2780ab1SPhillip Lougher 132e2780ab1SPhillip Lougher bytes = msblk->devblksize - offset; 133e2780ab1SPhillip Lougher compressed = SQUASHFS_COMPRESSED(length); 134e2780ab1SPhillip Lougher length = SQUASHFS_COMPRESSED_SIZE(length); 135e2780ab1SPhillip Lougher if (next_index) 136e2780ab1SPhillip Lougher *next_index = index + length + 2; 137e2780ab1SPhillip Lougher 138e2780ab1SPhillip Lougher TRACE("Block @ 0x%llx, %scompressed size %d\n", index, 139e2780ab1SPhillip Lougher compressed ? "" : "un", length); 140e2780ab1SPhillip Lougher 141e2780ab1SPhillip Lougher if (length < 0 || length > srclength || 142e2780ab1SPhillip Lougher (index + length) > msblk->bytes_used) 143e2780ab1SPhillip Lougher goto block_release; 144e2780ab1SPhillip Lougher 145e2780ab1SPhillip Lougher for (; bytes < length; b++) { 146e2780ab1SPhillip Lougher bh[b] = sb_getblk(sb, ++cur_index); 147e2780ab1SPhillip Lougher if (bh[b] == NULL) 148e2780ab1SPhillip Lougher goto block_release; 149e2780ab1SPhillip Lougher bytes += msblk->devblksize; 150e2780ab1SPhillip Lougher } 151e2780ab1SPhillip Lougher ll_rw_block(READ, b - 1, bh + 1); 152e2780ab1SPhillip Lougher } 153e2780ab1SPhillip Lougher 154e2780ab1SPhillip Lougher if (compressed) { 1554c0f0bb2SPhillip Lougher length = squashfs_decompress(msblk, buffer, bh, b, offset, 156e6a6d379SPhillip Lougher length, srclength, pages); 157e6a6d379SPhillip Lougher if (length < 0) 158e6a6d379SPhillip Lougher goto read_failure; 159e2780ab1SPhillip Lougher } else { 160e2780ab1SPhillip Lougher /* 161e2780ab1SPhillip Lougher * Block is uncompressed. 162e2780ab1SPhillip Lougher */ 163e2780ab1SPhillip Lougher int i, in, pg_offset = 0; 164e2780ab1SPhillip Lougher 165e2780ab1SPhillip Lougher for (i = 0; i < b; i++) { 166e2780ab1SPhillip Lougher wait_on_buffer(bh[i]); 167e2780ab1SPhillip Lougher if (!buffer_uptodate(bh[i])) 168e2780ab1SPhillip Lougher goto block_release; 169e2780ab1SPhillip Lougher } 170e2780ab1SPhillip Lougher 171e2780ab1SPhillip Lougher for (bytes = length; k < b; k++) { 172e2780ab1SPhillip Lougher in = min(bytes, msblk->devblksize - offset); 173e2780ab1SPhillip Lougher bytes -= in; 174e2780ab1SPhillip Lougher while (in) { 175e2780ab1SPhillip Lougher if (pg_offset == PAGE_CACHE_SIZE) { 176e2780ab1SPhillip Lougher page++; 177e2780ab1SPhillip Lougher pg_offset = 0; 178e2780ab1SPhillip Lougher } 179e2780ab1SPhillip Lougher avail = min_t(int, in, PAGE_CACHE_SIZE - 180e2780ab1SPhillip Lougher pg_offset); 181e2780ab1SPhillip Lougher memcpy(buffer[page] + pg_offset, 182e2780ab1SPhillip Lougher bh[k]->b_data + offset, avail); 183e2780ab1SPhillip Lougher in -= avail; 184e2780ab1SPhillip Lougher pg_offset += avail; 185e2780ab1SPhillip Lougher offset += avail; 186e2780ab1SPhillip Lougher } 187e2780ab1SPhillip Lougher offset = 0; 188e2780ab1SPhillip Lougher put_bh(bh[k]); 189e2780ab1SPhillip Lougher } 190e2780ab1SPhillip Lougher } 191e2780ab1SPhillip Lougher 192e2780ab1SPhillip Lougher kfree(bh); 193e2780ab1SPhillip Lougher return length; 194e2780ab1SPhillip Lougher 195e2780ab1SPhillip Lougher block_release: 196e2780ab1SPhillip Lougher for (; k < b; k++) 197e2780ab1SPhillip Lougher put_bh(bh[k]); 198e2780ab1SPhillip Lougher 199e2780ab1SPhillip Lougher read_failure: 200118e1ef6SPhillip Lougher ERROR("squashfs_read_data failed to read block 0x%llx\n", 201118e1ef6SPhillip Lougher (unsigned long long) index); 202e2780ab1SPhillip Lougher kfree(bh); 203e2780ab1SPhillip Lougher return -EIO; 204e2780ab1SPhillip Lougher } 205