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![Peter Wu](/assets/img/avatar_default.png)
Extract the mish block decoder such that this can be used for other formats in the future. A new DmgHeaderState struct is introduced to share state while decoding. The code is kept unchanged as much as possible, a "fail" label is added for example where a simple return would probably do. In dmg_open, the variable "tmp" is renamed to "rsrc_data_offset" for clarity and comments have been added explaining various data. Note that this patch has one subtle difference with the previous version which should not affect functionality. In the previous code, the end of a resource was inferred from the mish block (the offsets would be increased by the fields). In this patch, the resource length is used instead to avoid the need to rely on the previous offsets. Signed-off-by: Peter Wu <peter@lekensteyn.nl> Reviewed-by: John Snow <jsnow@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 1420566495-13284-3-git-send-email-peter@lekensteyn.nl Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
534 lines
16 KiB
C
534 lines
16 KiB
C
/*
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* QEMU Block driver for DMG images
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*
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* Copyright (c) 2004 Johannes E. Schindelin
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "qemu-common.h"
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#include "block/block_int.h"
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#include "qemu/bswap.h"
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#include "qemu/module.h"
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#include <zlib.h>
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enum {
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/* Limit chunk sizes to prevent unreasonable amounts of memory being used
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* or truncating when converting to 32-bit types
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*/
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DMG_LENGTHS_MAX = 64 * 1024 * 1024, /* 64 MB */
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DMG_SECTORCOUNTS_MAX = DMG_LENGTHS_MAX / 512,
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};
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typedef struct BDRVDMGState {
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CoMutex lock;
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/* each chunk contains a certain number of sectors,
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* offsets[i] is the offset in the .dmg file,
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* lengths[i] is the length of the compressed chunk,
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* sectors[i] is the sector beginning at offsets[i],
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* sectorcounts[i] is the number of sectors in that chunk,
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* the sectors array is ordered
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* 0<=i<n_chunks */
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uint32_t n_chunks;
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uint32_t* types;
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uint64_t* offsets;
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uint64_t* lengths;
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uint64_t* sectors;
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uint64_t* sectorcounts;
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uint32_t current_chunk;
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uint8_t *compressed_chunk;
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uint8_t *uncompressed_chunk;
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z_stream zstream;
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} BDRVDMGState;
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static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
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{
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int len;
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if (!filename) {
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return 0;
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}
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len = strlen(filename);
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if (len > 4 && !strcmp(filename + len - 4, ".dmg")) {
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return 2;
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}
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return 0;
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}
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static int read_uint64(BlockDriverState *bs, int64_t offset, uint64_t *result)
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{
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uint64_t buffer;
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int ret;
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ret = bdrv_pread(bs->file, offset, &buffer, 8);
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if (ret < 0) {
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return ret;
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}
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*result = be64_to_cpu(buffer);
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return 0;
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}
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static int read_uint32(BlockDriverState *bs, int64_t offset, uint32_t *result)
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{
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uint32_t buffer;
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int ret;
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ret = bdrv_pread(bs->file, offset, &buffer, 4);
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if (ret < 0) {
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return ret;
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}
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*result = be32_to_cpu(buffer);
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return 0;
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}
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/* Increase max chunk sizes, if necessary. This function is used to calculate
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* the buffer sizes needed for compressed/uncompressed chunk I/O.
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*/
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static void update_max_chunk_size(BDRVDMGState *s, uint32_t chunk,
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uint32_t *max_compressed_size,
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uint32_t *max_sectors_per_chunk)
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{
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uint32_t compressed_size = 0;
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uint32_t uncompressed_sectors = 0;
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switch (s->types[chunk]) {
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case 0x80000005: /* zlib compressed */
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compressed_size = s->lengths[chunk];
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uncompressed_sectors = s->sectorcounts[chunk];
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break;
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case 1: /* copy */
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uncompressed_sectors = (s->lengths[chunk] + 511) / 512;
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break;
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case 2: /* zero */
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uncompressed_sectors = s->sectorcounts[chunk];
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break;
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}
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if (compressed_size > *max_compressed_size) {
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*max_compressed_size = compressed_size;
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}
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if (uncompressed_sectors > *max_sectors_per_chunk) {
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*max_sectors_per_chunk = uncompressed_sectors;
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}
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}
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static int64_t dmg_find_koly_offset(BlockDriverState *file_bs, Error **errp)
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{
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int64_t length;
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int64_t offset = 0;
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uint8_t buffer[515];
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int i, ret;
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/* bdrv_getlength returns a multiple of block size (512), rounded up. Since
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* dmg images can have odd sizes, try to look for the "koly" magic which
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* marks the begin of the UDIF trailer (512 bytes). This magic can be found
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* in the last 511 bytes of the second-last sector or the first 4 bytes of
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* the last sector (search space: 515 bytes) */
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length = bdrv_getlength(file_bs);
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if (length < 0) {
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error_setg_errno(errp, -length,
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"Failed to get file size while reading UDIF trailer");
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return length;
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} else if (length < 512) {
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error_setg(errp, "dmg file must be at least 512 bytes long");
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return -EINVAL;
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}
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if (length > 511 + 512) {
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offset = length - 511 - 512;
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}
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length = length < 515 ? length : 515;
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ret = bdrv_pread(file_bs, offset, buffer, length);
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if (ret < 0) {
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error_setg_errno(errp, -ret, "Failed while reading UDIF trailer");
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return ret;
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}
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for (i = 0; i < length - 3; i++) {
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if (buffer[i] == 'k' && buffer[i+1] == 'o' &&
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buffer[i+2] == 'l' && buffer[i+3] == 'y') {
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return offset + i;
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}
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}
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error_setg(errp, "Could not locate UDIF trailer in dmg file");
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return -EINVAL;
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}
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/* used when building the sector table */
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typedef struct DmgHeaderState {
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/* used internally by dmg_read_mish_block to remember offsets of blocks
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* across calls */
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uint64_t last_in_offset;
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uint64_t last_out_offset;
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/* exported for dmg_open */
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uint32_t max_compressed_size;
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uint32_t max_sectors_per_chunk;
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} DmgHeaderState;
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static int dmg_read_mish_block(BlockDriverState *bs, DmgHeaderState *ds,
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int64_t offset, uint32_t count)
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{
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BDRVDMGState *s = bs->opaque;
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uint32_t type, i;
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int ret;
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size_t new_size;
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uint32_t chunk_count;
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ret = read_uint32(bs, offset, &type);
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if (ret < 0) {
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goto fail;
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}
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/* skip data that is not a valid MISH block (invalid magic or too small) */
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if (type != 0x6d697368 || count < 244) {
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/* assume success for now */
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return 0;
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}
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offset += 4;
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offset += 200;
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chunk_count = (count - 204) / 40;
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new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
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s->types = g_realloc(s->types, new_size / 2);
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s->offsets = g_realloc(s->offsets, new_size);
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s->lengths = g_realloc(s->lengths, new_size);
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s->sectors = g_realloc(s->sectors, new_size);
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s->sectorcounts = g_realloc(s->sectorcounts, new_size);
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for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
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ret = read_uint32(bs, offset, &s->types[i]);
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if (ret < 0) {
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goto fail;
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}
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offset += 4;
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if (s->types[i] != 0x80000005 && s->types[i] != 1 &&
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s->types[i] != 2) {
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if (s->types[i] == 0xffffffff && i > 0) {
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ds->last_in_offset = s->offsets[i - 1] + s->lengths[i - 1];
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ds->last_out_offset = s->sectors[i - 1] +
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s->sectorcounts[i - 1];
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}
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chunk_count--;
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i--;
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offset += 36;
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continue;
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}
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offset += 4;
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ret = read_uint64(bs, offset, &s->sectors[i]);
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if (ret < 0) {
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goto fail;
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}
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s->sectors[i] += ds->last_out_offset;
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offset += 8;
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ret = read_uint64(bs, offset, &s->sectorcounts[i]);
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if (ret < 0) {
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goto fail;
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}
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offset += 8;
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if (s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
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error_report("sector count %" PRIu64 " for chunk %" PRIu32
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" is larger than max (%u)",
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s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
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ret = -EINVAL;
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goto fail;
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}
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ret = read_uint64(bs, offset, &s->offsets[i]);
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if (ret < 0) {
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goto fail;
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}
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s->offsets[i] += ds->last_in_offset;
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offset += 8;
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ret = read_uint64(bs, offset, &s->lengths[i]);
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if (ret < 0) {
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goto fail;
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}
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offset += 8;
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if (s->lengths[i] > DMG_LENGTHS_MAX) {
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error_report("length %" PRIu64 " for chunk %" PRIu32
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" is larger than max (%u)",
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s->lengths[i], i, DMG_LENGTHS_MAX);
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ret = -EINVAL;
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goto fail;
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}
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update_max_chunk_size(s, i, &ds->max_compressed_size,
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&ds->max_sectors_per_chunk);
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}
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s->n_chunks += chunk_count;
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return 0;
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fail:
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return ret;
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}
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static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
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Error **errp)
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{
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BDRVDMGState *s = bs->opaque;
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DmgHeaderState ds;
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uint64_t info_begin, info_end;
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uint32_t count, rsrc_data_offset;
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int64_t offset;
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int ret;
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bs->read_only = 1;
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s->n_chunks = 0;
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s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
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/* used by dmg_read_mish_block to keep track of the current I/O position */
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ds.last_in_offset = 0;
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ds.last_out_offset = 0;
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ds.max_compressed_size = 1;
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ds.max_sectors_per_chunk = 1;
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/* locate the UDIF trailer */
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offset = dmg_find_koly_offset(bs->file, errp);
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if (offset < 0) {
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ret = offset;
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goto fail;
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}
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ret = read_uint64(bs, offset + 0x28, &info_begin);
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if (ret < 0) {
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goto fail;
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} else if (info_begin == 0) {
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ret = -EINVAL;
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goto fail;
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}
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ret = read_uint32(bs, info_begin, &rsrc_data_offset);
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if (ret < 0) {
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goto fail;
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} else if (rsrc_data_offset != 0x100) {
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ret = -EINVAL;
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goto fail;
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}
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ret = read_uint32(bs, info_begin + 4, &count);
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if (ret < 0) {
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goto fail;
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} else if (count == 0) {
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ret = -EINVAL;
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goto fail;
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}
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/* end of resource data, ignoring the following resource map */
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info_end = info_begin + count;
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/* begin of resource data (consisting of one or more resources) */
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offset = info_begin + 0x100;
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/* read offsets (mish blocks) from one or more resources in resource data */
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while (offset < info_end) {
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/* size of following resource */
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ret = read_uint32(bs, offset, &count);
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if (ret < 0) {
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goto fail;
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} else if (count == 0) {
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ret = -EINVAL;
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goto fail;
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}
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offset += 4;
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ret = dmg_read_mish_block(bs, &ds, offset, count);
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if (ret < 0) {
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goto fail;
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}
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/* advance offset by size of resource */
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offset += count;
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}
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/* initialize zlib engine */
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s->compressed_chunk = qemu_try_blockalign(bs->file,
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ds.max_compressed_size + 1);
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s->uncompressed_chunk = qemu_try_blockalign(bs->file,
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512 * ds.max_sectors_per_chunk);
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if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
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ret = -ENOMEM;
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goto fail;
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}
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if (inflateInit(&s->zstream) != Z_OK) {
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ret = -EINVAL;
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goto fail;
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}
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s->current_chunk = s->n_chunks;
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qemu_co_mutex_init(&s->lock);
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return 0;
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fail:
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g_free(s->types);
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g_free(s->offsets);
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g_free(s->lengths);
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g_free(s->sectors);
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g_free(s->sectorcounts);
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qemu_vfree(s->compressed_chunk);
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qemu_vfree(s->uncompressed_chunk);
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return ret;
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}
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static inline int is_sector_in_chunk(BDRVDMGState* s,
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uint32_t chunk_num, uint64_t sector_num)
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{
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if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
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s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
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return 0;
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} else {
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return -1;
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}
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}
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static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
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{
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/* binary search */
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uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
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while (chunk1 != chunk2) {
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chunk3 = (chunk1 + chunk2) / 2;
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if (s->sectors[chunk3] > sector_num) {
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chunk2 = chunk3;
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} else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
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return chunk3;
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} else {
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chunk1 = chunk3;
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}
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}
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return s->n_chunks; /* error */
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}
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static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
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{
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BDRVDMGState *s = bs->opaque;
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if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
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int ret;
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uint32_t chunk = search_chunk(s, sector_num);
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if (chunk >= s->n_chunks) {
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return -1;
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}
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s->current_chunk = s->n_chunks;
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switch (s->types[chunk]) {
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case 0x80000005: { /* zlib compressed */
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/* we need to buffer, because only the chunk as whole can be
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* inflated. */
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ret = bdrv_pread(bs->file, s->offsets[chunk],
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s->compressed_chunk, s->lengths[chunk]);
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if (ret != s->lengths[chunk]) {
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return -1;
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}
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s->zstream.next_in = s->compressed_chunk;
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s->zstream.avail_in = s->lengths[chunk];
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s->zstream.next_out = s->uncompressed_chunk;
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s->zstream.avail_out = 512 * s->sectorcounts[chunk];
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ret = inflateReset(&s->zstream);
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if (ret != Z_OK) {
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return -1;
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}
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ret = inflate(&s->zstream, Z_FINISH);
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if (ret != Z_STREAM_END ||
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s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
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return -1;
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}
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break; }
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case 1: /* copy */
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ret = bdrv_pread(bs->file, s->offsets[chunk],
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s->uncompressed_chunk, s->lengths[chunk]);
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if (ret != s->lengths[chunk]) {
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return -1;
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}
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break;
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case 2: /* zero */
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memset(s->uncompressed_chunk, 0, 512 * s->sectorcounts[chunk]);
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break;
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}
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s->current_chunk = chunk;
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}
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return 0;
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}
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static int dmg_read(BlockDriverState *bs, int64_t sector_num,
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uint8_t *buf, int nb_sectors)
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{
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BDRVDMGState *s = bs->opaque;
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int i;
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for (i = 0; i < nb_sectors; i++) {
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uint32_t sector_offset_in_chunk;
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if (dmg_read_chunk(bs, sector_num + i) != 0) {
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return -1;
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}
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sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
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memcpy(buf + i * 512,
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s->uncompressed_chunk + sector_offset_in_chunk * 512, 512);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static coroutine_fn int dmg_co_read(BlockDriverState *bs, int64_t sector_num,
|
|
uint8_t *buf, int nb_sectors)
|
|
{
|
|
int ret;
|
|
BDRVDMGState *s = bs->opaque;
|
|
qemu_co_mutex_lock(&s->lock);
|
|
ret = dmg_read(bs, sector_num, buf, nb_sectors);
|
|
qemu_co_mutex_unlock(&s->lock);
|
|
return ret;
|
|
}
|
|
|
|
static void dmg_close(BlockDriverState *bs)
|
|
{
|
|
BDRVDMGState *s = bs->opaque;
|
|
|
|
g_free(s->types);
|
|
g_free(s->offsets);
|
|
g_free(s->lengths);
|
|
g_free(s->sectors);
|
|
g_free(s->sectorcounts);
|
|
qemu_vfree(s->compressed_chunk);
|
|
qemu_vfree(s->uncompressed_chunk);
|
|
|
|
inflateEnd(&s->zstream);
|
|
}
|
|
|
|
static BlockDriver bdrv_dmg = {
|
|
.format_name = "dmg",
|
|
.instance_size = sizeof(BDRVDMGState),
|
|
.bdrv_probe = dmg_probe,
|
|
.bdrv_open = dmg_open,
|
|
.bdrv_read = dmg_co_read,
|
|
.bdrv_close = dmg_close,
|
|
};
|
|
|
|
static void bdrv_dmg_init(void)
|
|
{
|
|
bdrv_register(&bdrv_dmg);
|
|
}
|
|
|
|
block_init(bdrv_dmg_init);
|