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qemu/block/dmg.c
Fam Zheng 27685a8dd0 dmg: Move libbz2 code to dmg-bz2.so 
dmg.o was moved to block-obj-m in 5505e8b76 to become a separate module,
so that its reference to libbz2, since 6b383c08c, doesn't add an extra
library to the main executable.

Until recently, commit 06e60f70a (blockdev: Add dynamic module loading
for block drivers) moved it back to block-obj-y to simplify the design
of dynamic loading of block modules. But we don't want to lose the
feature of less library dependency on the main executable.

The solution here is to move only the bz2 related code to a separate
DSO file, and load it when dmg_open is called.

dmg_probe doesn't depend on bz2 support to work, and is the only code in
this file which can run before dmg_open.

While we are at it, fix the unhelpful cast of last argument passed to
dmg_uncompress_bz2.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-id: 1473043845-13197-4-git-send-email-famz@redhat.com
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2016-10-07 14:14:06 +02:00

704 lines
21 KiB
C
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/*
* QEMU Block driver for DMG images
*
* Copyright (c) 2004 Johannes E. Schindelin
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu-common.h"
#include "block/block_int.h"
#include "qemu/bswap.h"
#include "qemu/error-report.h"
#include "qemu/module.h"
#include "dmg.h"
int (*dmg_uncompress_bz2)(char *next_in, unsigned int avail_in,
char *next_out, unsigned int avail_out);
enum {
/* Limit chunk sizes to prevent unreasonable amounts of memory being used
* or truncating when converting to 32-bit types
*/
DMG_LENGTHS_MAX = 64 * 1024 * 1024, /* 64 MB */
DMG_SECTORCOUNTS_MAX = DMG_LENGTHS_MAX / 512,
};
static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
{
int len;
if (!filename) {
return 0;
}
len = strlen(filename);
if (len > 4 && !strcmp(filename + len - 4, ".dmg")) {
return 2;
}
return 0;
}
static int read_uint64(BlockDriverState *bs, int64_t offset, uint64_t *result)
{
uint64_t buffer;
int ret;
ret = bdrv_pread(bs->file, offset, &buffer, 8);
if (ret < 0) {
return ret;
}
*result = be64_to_cpu(buffer);
return 0;
}
static int read_uint32(BlockDriverState *bs, int64_t offset, uint32_t *result)
{
uint32_t buffer;
int ret;
ret = bdrv_pread(bs->file, offset, &buffer, 4);
if (ret < 0) {
return ret;
}
*result = be32_to_cpu(buffer);
return 0;
}
static inline uint64_t buff_read_uint64(const uint8_t *buffer, int64_t offset)
{
return be64_to_cpu(*(uint64_t *)&buffer[offset]);
}
static inline uint32_t buff_read_uint32(const uint8_t *buffer, int64_t offset)
{
return be32_to_cpu(*(uint32_t *)&buffer[offset]);
}
/* Increase max chunk sizes, if necessary. This function is used to calculate
* the buffer sizes needed for compressed/uncompressed chunk I/O.
*/
static void update_max_chunk_size(BDRVDMGState *s, uint32_t chunk,
uint32_t *max_compressed_size,
uint32_t *max_sectors_per_chunk)
{
uint32_t compressed_size = 0;
uint32_t uncompressed_sectors = 0;
switch (s->types[chunk]) {
case 0x80000005: /* zlib compressed */
case 0x80000006: /* bzip2 compressed */
compressed_size = s->lengths[chunk];
uncompressed_sectors = s->sectorcounts[chunk];
break;
case 1: /* copy */
uncompressed_sectors = (s->lengths[chunk] + 511) / 512;
break;
case 2: /* zero */
/* as the all-zeroes block may be large, it is treated specially: the
* sector is not copied from a large buffer, a simple memset is used
* instead. Therefore uncompressed_sectors does not need to be set. */
break;
}
if (compressed_size > *max_compressed_size) {
*max_compressed_size = compressed_size;
}
if (uncompressed_sectors > *max_sectors_per_chunk) {
*max_sectors_per_chunk = uncompressed_sectors;
}
}
static int64_t dmg_find_koly_offset(BdrvChild *file, Error **errp)
{
BlockDriverState *file_bs = file->bs;
int64_t length;
int64_t offset = 0;
uint8_t buffer[515];
int i, ret;
/* bdrv_getlength returns a multiple of block size (512), rounded up. Since
* dmg images can have odd sizes, try to look for the "koly" magic which
* marks the begin of the UDIF trailer (512 bytes). This magic can be found
* in the last 511 bytes of the second-last sector or the first 4 bytes of
* the last sector (search space: 515 bytes) */
length = bdrv_getlength(file_bs);
if (length < 0) {
error_setg_errno(errp, -length,
"Failed to get file size while reading UDIF trailer");
return length;
} else if (length < 512) {
error_setg(errp, "dmg file must be at least 512 bytes long");
return -EINVAL;
}
if (length > 511 + 512) {
offset = length - 511 - 512;
}
length = length < 515 ? length : 515;
ret = bdrv_pread(file, offset, buffer, length);
if (ret < 0) {
error_setg_errno(errp, -ret, "Failed while reading UDIF trailer");
return ret;
}
for (i = 0; i < length - 3; i++) {
if (buffer[i] == 'k' && buffer[i+1] == 'o' &&
buffer[i+2] == 'l' && buffer[i+3] == 'y') {
return offset + i;
}
}
error_setg(errp, "Could not locate UDIF trailer in dmg file");
return -EINVAL;
}
/* used when building the sector table */
typedef struct DmgHeaderState {
/* used internally by dmg_read_mish_block to remember offsets of blocks
* across calls */
uint64_t data_fork_offset;
/* exported for dmg_open */
uint32_t max_compressed_size;
uint32_t max_sectors_per_chunk;
} DmgHeaderState;
static bool dmg_is_known_block_type(uint32_t entry_type)
{
switch (entry_type) {
case 0x00000001: /* uncompressed */
case 0x00000002: /* zeroes */
case 0x80000005: /* zlib */
return true;
case 0x80000006: /* bzip2 */
return !!dmg_uncompress_bz2;
default:
return false;
}
}
static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds,
uint8_t *buffer, uint32_t count)
{
uint32_t type, i;
int ret;
size_t new_size;
uint32_t chunk_count;
int64_t offset = 0;
uint64_t data_offset;
uint64_t in_offset = ds->data_fork_offset;
uint64_t out_offset;
type = buff_read_uint32(buffer, offset);
/* skip data that is not a valid MISH block (invalid magic or too small) */
if (type != 0x6d697368 || count < 244) {
/* assume success for now */
return 0;
}
/* chunk offsets are relative to this sector number */
out_offset = buff_read_uint64(buffer, offset + 8);
/* location in data fork for (compressed) blob (in bytes) */
data_offset = buff_read_uint64(buffer, offset + 0x18);
in_offset += data_offset;
/* move to begin of chunk entries */
offset += 204;
chunk_count = (count - 204) / 40;
new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
s->types = g_realloc(s->types, new_size / 2);
s->offsets = g_realloc(s->offsets, new_size);
s->lengths = g_realloc(s->lengths, new_size);
s->sectors = g_realloc(s->sectors, new_size);
s->sectorcounts = g_realloc(s->sectorcounts, new_size);
for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
s->types[i] = buff_read_uint32(buffer, offset);
if (!dmg_is_known_block_type(s->types[i])) {
chunk_count--;
i--;
offset += 40;
continue;
}
/* sector number */
s->sectors[i] = buff_read_uint64(buffer, offset + 8);
s->sectors[i] += out_offset;
/* sector count */
s->sectorcounts[i] = buff_read_uint64(buffer, offset + 0x10);
/* all-zeroes sector (type 2) does not need to be "uncompressed" and can
* therefore be unbounded. */
if (s->types[i] != 2 && s->sectorcounts[i] > DMG_SECTORCOUNTS_MAX) {
error_report("sector count %" PRIu64 " for chunk %" PRIu32
" is larger than max (%u)",
s->sectorcounts[i], i, DMG_SECTORCOUNTS_MAX);
ret = -EINVAL;
goto fail;
}
/* offset in (compressed) data fork */
s->offsets[i] = buff_read_uint64(buffer, offset + 0x18);
s->offsets[i] += in_offset;
/* length in (compressed) data fork */
s->lengths[i] = buff_read_uint64(buffer, offset + 0x20);
if (s->lengths[i] > DMG_LENGTHS_MAX) {
error_report("length %" PRIu64 " for chunk %" PRIu32
" is larger than max (%u)",
s->lengths[i], i, DMG_LENGTHS_MAX);
ret = -EINVAL;
goto fail;
}
update_max_chunk_size(s, i, &ds->max_compressed_size,
&ds->max_sectors_per_chunk);
offset += 40;
}
s->n_chunks += chunk_count;
return 0;
fail:
return ret;
}
static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds,
uint64_t info_begin, uint64_t info_length)
{
BDRVDMGState *s = bs->opaque;
int ret;
uint32_t count, rsrc_data_offset;
uint8_t *buffer = NULL;
uint64_t info_end;
uint64_t offset;
/* read offset from begin of resource fork (info_begin) to resource data */
ret = read_uint32(bs, info_begin, &rsrc_data_offset);
if (ret < 0) {
goto fail;
} else if (rsrc_data_offset > info_length) {
ret = -EINVAL;
goto fail;
}
/* read length of resource data */
ret = read_uint32(bs, info_begin + 8, &count);
if (ret < 0) {
goto fail;
} else if (count == 0 || rsrc_data_offset + count > info_length) {
ret = -EINVAL;
goto fail;
}
/* begin of resource data (consisting of one or more resources) */
offset = info_begin + rsrc_data_offset;
/* end of resource data (there is possibly a following resource map
* which will be ignored). */
info_end = offset + count;
/* read offsets (mish blocks) from one or more resources in resource data */
while (offset < info_end) {
/* size of following resource */
ret = read_uint32(bs, offset, &count);
if (ret < 0) {
goto fail;
} else if (count == 0 || count > info_end - offset) {
ret = -EINVAL;
goto fail;
}
offset += 4;
buffer = g_realloc(buffer, count);
ret = bdrv_pread(bs->file, offset, buffer, count);
if (ret < 0) {
goto fail;
}
ret = dmg_read_mish_block(s, ds, buffer, count);
if (ret < 0) {
goto fail;
}
/* advance offset by size of resource */
offset += count;
}
ret = 0;
fail:
g_free(buffer);
return ret;
}
static int dmg_read_plist_xml(BlockDriverState *bs, DmgHeaderState *ds,
uint64_t info_begin, uint64_t info_length)
{
BDRVDMGState *s = bs->opaque;
int ret;
uint8_t *buffer = NULL;
char *data_begin, *data_end;
/* Have at least some length to avoid NULL for g_malloc. Attempt to set a
* safe upper cap on the data length. A test sample had a XML length of
* about 1 MiB. */
if (info_length == 0 || info_length > 16 * 1024 * 1024) {
ret = -EINVAL;
goto fail;
}
buffer = g_malloc(info_length + 1);
buffer[info_length] = '\0';
ret = bdrv_pread(bs->file, info_begin, buffer, info_length);
if (ret != info_length) {
ret = -EINVAL;
goto fail;
}
/* look for <data>...</data>. The data is 284 (0x11c) bytes after base64
* decode. The actual data element has 431 (0x1af) bytes which includes tabs
* and line feeds. */
data_end = (char *)buffer;
while ((data_begin = strstr(data_end, "<data>")) != NULL) {
guchar *mish;
gsize out_len = 0;
data_begin += 6;
data_end = strstr(data_begin, "</data>");
/* malformed XML? */
if (data_end == NULL) {
ret = -EINVAL;
goto fail;
}
*data_end++ = '\0';
mish = g_base64_decode(data_begin, &out_len);
ret = dmg_read_mish_block(s, ds, mish, (uint32_t)out_len);
g_free(mish);
if (ret < 0) {
goto fail;
}
}
ret = 0;
fail:
g_free(buffer);
return ret;
}
static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
BDRVDMGState *s = bs->opaque;
DmgHeaderState ds;
uint64_t rsrc_fork_offset, rsrc_fork_length;
uint64_t plist_xml_offset, plist_xml_length;
int64_t offset;
int ret;
block_module_load_one("dmg-bz2");
bs->read_only = true;
s->n_chunks = 0;
s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
/* used by dmg_read_mish_block to keep track of the current I/O position */
ds.data_fork_offset = 0;
ds.max_compressed_size = 1;
ds.max_sectors_per_chunk = 1;
/* locate the UDIF trailer */
offset = dmg_find_koly_offset(bs->file, errp);
if (offset < 0) {
ret = offset;
goto fail;
}
/* offset of data fork (DataForkOffset) */
ret = read_uint64(bs, offset + 0x18, &ds.data_fork_offset);
if (ret < 0) {
goto fail;
} else if (ds.data_fork_offset > offset) {
ret = -EINVAL;
goto fail;
}
/* offset of resource fork (RsrcForkOffset) */
ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
if (ret < 0) {
goto fail;
}
ret = read_uint64(bs, offset + 0x30, &rsrc_fork_length);
if (ret < 0) {
goto fail;
}
if (rsrc_fork_offset >= offset ||
rsrc_fork_length > offset - rsrc_fork_offset) {
ret = -EINVAL;
goto fail;
}
/* offset of property list (XMLOffset) */
ret = read_uint64(bs, offset + 0xd8, &plist_xml_offset);
if (ret < 0) {
goto fail;
}
ret = read_uint64(bs, offset + 0xe0, &plist_xml_length);
if (ret < 0) {
goto fail;
}
if (plist_xml_offset >= offset ||
plist_xml_length > offset - plist_xml_offset) {
ret = -EINVAL;
goto fail;
}
ret = read_uint64(bs, offset + 0x1ec, (uint64_t *)&bs->total_sectors);
if (ret < 0) {
goto fail;
}
if (bs->total_sectors < 0) {
ret = -EINVAL;
goto fail;
}
if (rsrc_fork_length != 0) {
ret = dmg_read_resource_fork(bs, &ds,
rsrc_fork_offset, rsrc_fork_length);
if (ret < 0) {
goto fail;
}
} else if (plist_xml_length != 0) {
ret = dmg_read_plist_xml(bs, &ds, plist_xml_offset, plist_xml_length);
if (ret < 0) {
goto fail;
}
} else {
ret = -EINVAL;
goto fail;
}
/* initialize zlib engine */
s->compressed_chunk = qemu_try_blockalign(bs->file->bs,
ds.max_compressed_size + 1);
s->uncompressed_chunk = qemu_try_blockalign(bs->file->bs,
512 * ds.max_sectors_per_chunk);
if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
ret = -ENOMEM;
goto fail;
}
if (inflateInit(&s->zstream) != Z_OK) {
ret = -EINVAL;
goto fail;
}
s->current_chunk = s->n_chunks;
qemu_co_mutex_init(&s->lock);
return 0;
fail:
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);
return ret;
}
static void dmg_refresh_limits(BlockDriverState *bs, Error **errp)
{
bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
}
static inline int is_sector_in_chunk(BDRVDMGState* s,
uint32_t chunk_num, uint64_t sector_num)
{
if (chunk_num >= s->n_chunks || s->sectors[chunk_num] > sector_num ||
s->sectors[chunk_num] + s->sectorcounts[chunk_num] <= sector_num) {
return 0;
} else {
return -1;
}
}
static inline uint32_t search_chunk(BDRVDMGState *s, uint64_t sector_num)
{
/* binary search */
uint32_t chunk1 = 0, chunk2 = s->n_chunks, chunk3;
while (chunk1 != chunk2) {
chunk3 = (chunk1 + chunk2) / 2;
if (s->sectors[chunk3] > sector_num) {
chunk2 = chunk3;
} else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_num) {
return chunk3;
} else {
chunk1 = chunk3;
}
}
return s->n_chunks; /* error */
}
static inline int dmg_read_chunk(BlockDriverState *bs, uint64_t sector_num)
{
BDRVDMGState *s = bs->opaque;
if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
int ret;
uint32_t chunk = search_chunk(s, sector_num);
if (chunk >= s->n_chunks) {
return -1;
}
s->current_chunk = s->n_chunks;
switch (s->types[chunk]) { /* block entry type */
case 0x80000005: { /* zlib compressed */
/* we need to buffer, because only the chunk as whole can be
* inflated. */
ret = bdrv_pread(bs->file, s->offsets[chunk],
s->compressed_chunk, s->lengths[chunk]);
if (ret != s->lengths[chunk]) {
return -1;
}
s->zstream.next_in = s->compressed_chunk;
s->zstream.avail_in = s->lengths[chunk];
s->zstream.next_out = s->uncompressed_chunk;
s->zstream.avail_out = 512 * s->sectorcounts[chunk];
ret = inflateReset(&s->zstream);
if (ret != Z_OK) {
return -1;
}
ret = inflate(&s->zstream, Z_FINISH);
if (ret != Z_STREAM_END ||
s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
return -1;
}
break; }
case 0x80000006: /* bzip2 compressed */
if (!dmg_uncompress_bz2) {
break;
}
/* we need to buffer, because only the chunk as whole can be
* inflated. */
ret = bdrv_pread(bs->file, s->offsets[chunk],
s->compressed_chunk, s->lengths[chunk]);
if (ret != s->lengths[chunk]) {
return -1;
}
ret = dmg_uncompress_bz2((char *)s->compressed_chunk,
(unsigned int) s->lengths[chunk],
(char *)s->uncompressed_chunk,
(unsigned int)
(512 * s->sectorcounts[chunk]));
if (ret < 0) {
return ret;
}
break;
case 1: /* copy */
ret = bdrv_pread(bs->file, s->offsets[chunk],
s->uncompressed_chunk, s->lengths[chunk]);
if (ret != s->lengths[chunk]) {
return -1;
}
break;
case 2: /* zero */
/* see dmg_read, it is treated specially. No buffer needs to be
* pre-filled, the zeroes can be set directly. */
break;
}
s->current_chunk = chunk;
}
return 0;
}
static int coroutine_fn
dmg_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
BDRVDMGState *s = bs->opaque;
uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
int nb_sectors = bytes >> BDRV_SECTOR_BITS;
int ret, i;
assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
qemu_co_mutex_lock(&s->lock);
for (i = 0; i < nb_sectors; i++) {
uint32_t sector_offset_in_chunk;
void *data;
if (dmg_read_chunk(bs, sector_num + i) != 0) {
ret = -EIO;
goto fail;
}
/* Special case: current chunk is all zeroes. Do not perform a memcpy as
* s->uncompressed_chunk may be too small to cover the large all-zeroes
* section. dmg_read_chunk is called to find s->current_chunk */
if (s->types[s->current_chunk] == 2) { /* all zeroes block entry */
qemu_iovec_memset(qiov, i * 512, 0, 512);
continue;
}
sector_offset_in_chunk = sector_num + i - s->sectors[s->current_chunk];
data = s->uncompressed_chunk + sector_offset_in_chunk * 512;
qemu_iovec_from_buf(qiov, i * 512, data, 512);
}
ret = 0;
fail:
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_refresh_limits = dmg_refresh_limits,
.bdrv_co_preadv = dmg_co_preadv,
.bdrv_close = dmg_close,
};
static void bdrv_dmg_init(void)
{
bdrv_register(&bdrv_dmg);
}
block_init(bdrv_dmg_init);
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