Phillip Lougher | e2780ab | 2009-01-05 08:46:27 +0000 | [diff] [blame] | 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 | * block.c |
| 22 | */ |
| 23 | |
| 24 | /* |
| 25 | * This file implements the low-level routines to read and decompress |
| 26 | * datablocks and metadata blocks. |
| 27 | */ |
| 28 | |
| 29 | #include <linux/fs.h> |
| 30 | #include <linux/vfs.h> |
| 31 | #include <linux/slab.h> |
| 32 | #include <linux/mutex.h> |
| 33 | #include <linux/string.h> |
| 34 | #include <linux/buffer_head.h> |
| 35 | #include <linux/zlib.h> |
| 36 | |
| 37 | #include "squashfs_fs.h" |
| 38 | #include "squashfs_fs_sb.h" |
| 39 | #include "squashfs_fs_i.h" |
| 40 | #include "squashfs.h" |
| 41 | |
| 42 | /* |
| 43 | * Read the metadata block length, this is stored in the first two |
| 44 | * bytes of the metadata block. |
| 45 | */ |
| 46 | static struct buffer_head *get_block_length(struct super_block *sb, |
| 47 | u64 *cur_index, int *offset, int *length) |
| 48 | { |
| 49 | struct squashfs_sb_info *msblk = sb->s_fs_info; |
| 50 | struct buffer_head *bh; |
| 51 | |
| 52 | bh = sb_bread(sb, *cur_index); |
| 53 | if (bh == NULL) |
| 54 | return NULL; |
| 55 | |
| 56 | if (msblk->devblksize - *offset == 1) { |
| 57 | *length = (unsigned char) bh->b_data[*offset]; |
| 58 | put_bh(bh); |
| 59 | bh = sb_bread(sb, ++(*cur_index)); |
| 60 | if (bh == NULL) |
| 61 | return NULL; |
| 62 | *length |= (unsigned char) bh->b_data[0] << 8; |
| 63 | *offset = 1; |
| 64 | } else { |
| 65 | *length = (unsigned char) bh->b_data[*offset] | |
| 66 | (unsigned char) bh->b_data[*offset + 1] << 8; |
| 67 | *offset += 2; |
| 68 | } |
| 69 | |
| 70 | return bh; |
| 71 | } |
| 72 | |
| 73 | |
| 74 | /* |
| 75 | * Read and decompress a metadata block or datablock. Length is non-zero |
| 76 | * if a datablock is being read (the size is stored elsewhere in the |
| 77 | * filesystem), otherwise the length is obtained from the first two bytes of |
| 78 | * the metadata block. A bit in the length field indicates if the block |
| 79 | * is stored uncompressed in the filesystem (usually because compression |
| 80 | * generated a larger block - this does occasionally happen with zlib). |
| 81 | */ |
| 82 | int squashfs_read_data(struct super_block *sb, void **buffer, u64 index, |
Phillip Lougher | 118e1ef | 2009-03-05 00:31:12 +0000 | [diff] [blame] | 83 | int length, u64 *next_index, int srclength, int pages) |
Phillip Lougher | e2780ab | 2009-01-05 08:46:27 +0000 | [diff] [blame] | 84 | { |
| 85 | struct squashfs_sb_info *msblk = sb->s_fs_info; |
| 86 | struct buffer_head **bh; |
| 87 | int offset = index & ((1 << msblk->devblksize_log2) - 1); |
| 88 | u64 cur_index = index >> msblk->devblksize_log2; |
| 89 | int bytes, compressed, b = 0, k = 0, page = 0, avail; |
| 90 | |
| 91 | |
| 92 | bh = kcalloc((msblk->block_size >> msblk->devblksize_log2) + 1, |
| 93 | sizeof(*bh), GFP_KERNEL); |
| 94 | if (bh == NULL) |
| 95 | return -ENOMEM; |
| 96 | |
| 97 | if (length) { |
| 98 | /* |
| 99 | * Datablock. |
| 100 | */ |
| 101 | bytes = -offset; |
| 102 | compressed = SQUASHFS_COMPRESSED_BLOCK(length); |
| 103 | length = SQUASHFS_COMPRESSED_SIZE_BLOCK(length); |
| 104 | if (next_index) |
| 105 | *next_index = index + length; |
| 106 | |
| 107 | TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n", |
| 108 | index, compressed ? "" : "un", length, srclength); |
| 109 | |
| 110 | if (length < 0 || length > srclength || |
| 111 | (index + length) > msblk->bytes_used) |
| 112 | goto read_failure; |
| 113 | |
| 114 | for (b = 0; bytes < length; b++, cur_index++) { |
| 115 | bh[b] = sb_getblk(sb, cur_index); |
| 116 | if (bh[b] == NULL) |
| 117 | goto block_release; |
| 118 | bytes += msblk->devblksize; |
| 119 | } |
| 120 | ll_rw_block(READ, b, bh); |
| 121 | } else { |
| 122 | /* |
| 123 | * Metadata block. |
| 124 | */ |
| 125 | if ((index + 2) > msblk->bytes_used) |
| 126 | goto read_failure; |
| 127 | |
| 128 | bh[0] = get_block_length(sb, &cur_index, &offset, &length); |
| 129 | if (bh[0] == NULL) |
| 130 | goto read_failure; |
| 131 | b = 1; |
| 132 | |
| 133 | bytes = msblk->devblksize - offset; |
| 134 | compressed = SQUASHFS_COMPRESSED(length); |
| 135 | length = SQUASHFS_COMPRESSED_SIZE(length); |
| 136 | if (next_index) |
| 137 | *next_index = index + length + 2; |
| 138 | |
| 139 | TRACE("Block @ 0x%llx, %scompressed size %d\n", index, |
| 140 | compressed ? "" : "un", length); |
| 141 | |
| 142 | if (length < 0 || length > srclength || |
| 143 | (index + length) > msblk->bytes_used) |
| 144 | goto block_release; |
| 145 | |
| 146 | for (; bytes < length; b++) { |
| 147 | bh[b] = sb_getblk(sb, ++cur_index); |
| 148 | if (bh[b] == NULL) |
| 149 | goto block_release; |
| 150 | bytes += msblk->devblksize; |
| 151 | } |
| 152 | ll_rw_block(READ, b - 1, bh + 1); |
| 153 | } |
| 154 | |
| 155 | if (compressed) { |
| 156 | int zlib_err = 0, zlib_init = 0; |
| 157 | |
| 158 | /* |
| 159 | * Uncompress block. |
| 160 | */ |
| 161 | |
| 162 | mutex_lock(&msblk->read_data_mutex); |
| 163 | |
| 164 | msblk->stream.avail_out = 0; |
| 165 | msblk->stream.avail_in = 0; |
| 166 | |
| 167 | bytes = length; |
| 168 | do { |
| 169 | if (msblk->stream.avail_in == 0 && k < b) { |
| 170 | avail = min(bytes, msblk->devblksize - offset); |
| 171 | bytes -= avail; |
| 172 | wait_on_buffer(bh[k]); |
| 173 | if (!buffer_uptodate(bh[k])) |
| 174 | goto release_mutex; |
| 175 | |
| 176 | if (avail == 0) { |
| 177 | offset = 0; |
| 178 | put_bh(bh[k++]); |
| 179 | continue; |
| 180 | } |
| 181 | |
| 182 | msblk->stream.next_in = bh[k]->b_data + offset; |
| 183 | msblk->stream.avail_in = avail; |
| 184 | offset = 0; |
| 185 | } |
| 186 | |
Phillip Lougher | 363911d | 2009-03-12 03:23:48 +0000 | [diff] [blame^] | 187 | if (msblk->stream.avail_out == 0 && page < pages) { |
Phillip Lougher | e2780ab | 2009-01-05 08:46:27 +0000 | [diff] [blame] | 188 | msblk->stream.next_out = buffer[page++]; |
| 189 | msblk->stream.avail_out = PAGE_CACHE_SIZE; |
| 190 | } |
| 191 | |
| 192 | if (!zlib_init) { |
| 193 | zlib_err = zlib_inflateInit(&msblk->stream); |
| 194 | if (zlib_err != Z_OK) { |
| 195 | ERROR("zlib_inflateInit returned" |
| 196 | " unexpected result 0x%x," |
| 197 | " srclength %d\n", zlib_err, |
| 198 | srclength); |
| 199 | goto release_mutex; |
| 200 | } |
| 201 | zlib_init = 1; |
| 202 | } |
| 203 | |
Phillip Lougher | 363911d | 2009-03-12 03:23:48 +0000 | [diff] [blame^] | 204 | zlib_err = zlib_inflate(&msblk->stream, Z_SYNC_FLUSH); |
Phillip Lougher | e2780ab | 2009-01-05 08:46:27 +0000 | [diff] [blame] | 205 | |
| 206 | if (msblk->stream.avail_in == 0 && k < b) |
| 207 | put_bh(bh[k++]); |
| 208 | } while (zlib_err == Z_OK); |
| 209 | |
| 210 | if (zlib_err != Z_STREAM_END) { |
Phillip Lougher | 363911d | 2009-03-12 03:23:48 +0000 | [diff] [blame^] | 211 | ERROR("zlib_inflate error, data probably corrupt\n"); |
Phillip Lougher | e2780ab | 2009-01-05 08:46:27 +0000 | [diff] [blame] | 212 | goto release_mutex; |
| 213 | } |
| 214 | |
| 215 | zlib_err = zlib_inflateEnd(&msblk->stream); |
| 216 | if (zlib_err != Z_OK) { |
Phillip Lougher | 363911d | 2009-03-12 03:23:48 +0000 | [diff] [blame^] | 217 | ERROR("zlib_inflate error, data probably corrupt\n"); |
Phillip Lougher | e2780ab | 2009-01-05 08:46:27 +0000 | [diff] [blame] | 218 | goto release_mutex; |
| 219 | } |
| 220 | length = msblk->stream.total_out; |
| 221 | mutex_unlock(&msblk->read_data_mutex); |
| 222 | } else { |
| 223 | /* |
| 224 | * Block is uncompressed. |
| 225 | */ |
| 226 | int i, in, pg_offset = 0; |
| 227 | |
| 228 | for (i = 0; i < b; i++) { |
| 229 | wait_on_buffer(bh[i]); |
| 230 | if (!buffer_uptodate(bh[i])) |
| 231 | goto block_release; |
| 232 | } |
| 233 | |
| 234 | for (bytes = length; k < b; k++) { |
| 235 | in = min(bytes, msblk->devblksize - offset); |
| 236 | bytes -= in; |
| 237 | while (in) { |
| 238 | if (pg_offset == PAGE_CACHE_SIZE) { |
| 239 | page++; |
| 240 | pg_offset = 0; |
| 241 | } |
| 242 | avail = min_t(int, in, PAGE_CACHE_SIZE - |
| 243 | pg_offset); |
| 244 | memcpy(buffer[page] + pg_offset, |
| 245 | bh[k]->b_data + offset, avail); |
| 246 | in -= avail; |
| 247 | pg_offset += avail; |
| 248 | offset += avail; |
| 249 | } |
| 250 | offset = 0; |
| 251 | put_bh(bh[k]); |
| 252 | } |
| 253 | } |
| 254 | |
| 255 | kfree(bh); |
| 256 | return length; |
| 257 | |
| 258 | release_mutex: |
| 259 | mutex_unlock(&msblk->read_data_mutex); |
| 260 | |
| 261 | block_release: |
| 262 | for (; k < b; k++) |
| 263 | put_bh(bh[k]); |
| 264 | |
| 265 | read_failure: |
Phillip Lougher | 118e1ef | 2009-03-05 00:31:12 +0000 | [diff] [blame] | 266 | ERROR("squashfs_read_data failed to read block 0x%llx\n", |
| 267 | (unsigned long long) index); |
Phillip Lougher | e2780ab | 2009-01-05 08:46:27 +0000 | [diff] [blame] | 268 | kfree(bh); |
| 269 | return -EIO; |
| 270 | } |