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Re: [Qemu-devel] [PATCH 09/10] block/dmg: support bzip2 block entry type
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From: |
John Snow |
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Subject: |
Re: [Qemu-devel] [PATCH 09/10] block/dmg: support bzip2 block entry types |
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Date: |
Mon, 05 Jan 2015 14:32:29 -0500 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 |
On 12/27/2014 10:01 AM, Peter Wu wrote:
This patch adds support for bzip2-compressed block entries as introduced
with OS X 10.4 (source: https://en.wikipedia.org/wiki/Apple_Disk_Image).
It was tested against a 5.2G "OS X Yosemite" installation image which
stores the BLXX block in the XML property list (instead of resource
forks) and has over 5k chunks.
New configure entries are added (--enable-bzip2 / --disable-bzip2) to
control inclusion of bzip2 functionality (which requires linking against
libbz2). The help message suggests that this option is needed for DMG
files, but the tests are generic enough that other parts of QEMU can use
bzip2 if needed.
The identifiers are based on http://newosxbook.com/DMG.html.
The decompression routines are based on the zlib case, but as there is
no way to reset the decompression state (unlike zlib), memory is
allocated and deallocated for every decompression. This should not be
problematic as the decompression takes most of the time and as blocks
are typically about/over 1 MiB in size, only one allocation is done
every 2000 sectors.
Signed-off-by: Peter Wu <address@hidden>
---
block/dmg.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++---
configure | 31 +++++++++++++++++++++++++++++++
2 files changed, 84 insertions(+), 3 deletions(-)
diff --git a/block/dmg.c b/block/dmg.c
index 93b597f..67d4e2b 100644
--- a/block/dmg.c
+++ b/block/dmg.c
@@ -26,6 +26,9 @@
#include "qemu/bswap.h"
#include "qemu/module.h"
#include <zlib.h>
+#ifdef CONFIG_BZIP2
+#include <bzlib.h>
+#endif
#include <glib.h>
enum {
@@ -56,6 +59,9 @@ typedef struct BDRVDMGState {
uint8_t *compressed_chunk;
uint8_t *uncompressed_chunk;
z_stream zstream;
+#ifdef CONFIG_BZIP2
+ bz_stream bzstream;
+#endif
} BDRVDMGState;
static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
@@ -123,6 +129,7 @@ static void update_max_chunk_size(BDRVDMGState *s, uint32_t
chunk,
switch (s->types[chunk]) {
case 0x80000005: /* zlib compressed */
+ case 0x80000006: /* bzip2 compressed */
compressed_size = s->lengths[chunk];
uncompressed_sectors = s->sectorcounts[chunk];
break;
@@ -187,6 +194,21 @@ typedef struct DmgHeaderState {
uint32_t max_sectors_per_chunk;
} DmgHeaderState;
+static bool dmg_is_valid_block_type(uint32_t entry_type)
+{
+ switch (entry_type) {
+ case 0x00000001: /* uncompressed */
+ case 0x00000002: /* zeroes */
+ case 0x80000005: /* zlib */
+#ifdef CONFIG_BZIP2
+ case 0x80000006: /* bzip2 */
+#endif
+ return true;
+ default:
+ return false;
+ }
+}
+
Wish I had read this patch first before trying to read the blob of
conditionals this replaces. :)
static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds,
uint8_t *buffer, uint32_t count)
{
@@ -218,8 +240,7 @@ static int dmg_read_mish_block(BDRVDMGState *s,
DmgHeaderState *ds,
for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
s->types[i] = buff_read_uint32(buffer, offset);
offset += 4;
- if (s->types[i] != 0x80000005 && s->types[i] != 1 &&
- s->types[i] != 2) {
+ if (!dmg_is_valid_block_type(s->types[i])) {
if (s->types[i] == 0xffffffff && i > 0) {
ds->last_in_offset = s->offsets[i - 1] + s->lengths[i - 1];
ds->last_out_offset = s->sectors[i - 1] +
@@ -534,13 +555,14 @@ static inline int dmg_read_chunk(BlockDriverState *bs,
uint64_t sector_num)
if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
int ret;
uint32_t chunk = search_chunk(s, sector_num);
+ uint64_t total_out;
This breaks compilation when configured with --disable-bzip2. (unused
variable)
if (chunk >= s->n_chunks) {
return -1;
}
s->current_chunk = s->n_chunks;
- switch (s->types[chunk]) {
+ switch (s->types[chunk]) { /* block entry type */
case 0x80000005: { /* zlib compressed */
/* we need to buffer, because only the chunk as whole can be
* inflated. */
@@ -564,6 +586,34 @@ static inline int dmg_read_chunk(BlockDriverState *bs,
uint64_t sector_num)
return -1;
}
break; }
+#ifdef CONFIG_BZIP2
+ case 0x80000006: /* bzip2 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;
+ }
+
+ ret = BZ2_bzDecompressInit(&s->bzstream, 0, 0);
+ if (ret != BZ_OK) {
+ return -1;
+ }
+ s->bzstream.next_in = (char *)s->compressed_chunk;
+ s->bzstream.avail_in = (unsigned int) s->lengths[chunk];
+ s->bzstream.next_out = (char *)s->uncompressed_chunk;
+ s->bzstream.avail_out = (unsigned int) 512 *
s->sectorcounts[chunk];
+ ret = BZ2_bzDecompress(&s->bzstream);
+ total_out = ((uint64_t)s->bzstream.total_out_hi32 << 32) +
+ s->bzstream.total_out_lo32;
+ BZ2_bzDecompressEnd(&s->bzstream);
+ if (ret != BZ_STREAM_END ||
+ total_out != 512 * s->sectorcounts[chunk]) {
+ return -1;
+ }
+ break;
+#endif /* CONFIG_BZIP2 */
case 1: /* copy */
ret = bdrv_pread(bs->file, s->offsets[chunk],
s->uncompressed_chunk, s->lengths[chunk]);
diff --git a/configure b/configure
index cae588c..eadae63 100755
--- a/configure
+++ b/configure
@@ -313,6 +313,7 @@ glx=""
zlib="yes"
lzo=""
snappy=""
+bzip2=""
guest_agent=""
guest_agent_with_vss="no"
vss_win32_sdk=""
@@ -1060,6 +1061,10 @@ for opt do
;;
--enable-snappy) snappy="yes"
;;
+ --disable-bzip2) bzip2="no"
+ ;;
+ --enable-bzip2) bzip2="yes"
+ ;;
--enable-guest-agent) guest_agent="yes"
;;
--disable-guest-agent) guest_agent="no"
@@ -1374,6 +1379,8 @@ Advanced options (experts only):
--enable-usb-redir enable usb network redirection support
--enable-lzo enable the support of lzo compression library
--enable-snappy enable the support of snappy compression library
+ --enable-bzip2 enable the support of bzip2 compression library (for
+ reading bzip2-compressed dmg images)
--disable-guest-agent disable building of the QEMU Guest Agent
--enable-guest-agent enable building of the QEMU Guest Agent
--with-vss-sdk=SDK-path enable Windows VSS support in QEMU Guest Agent
@@ -1820,6 +1827,25 @@ EOF
fi
##########################################
+# bzip2 check
+
+if test "$bzip2" != "no" ; then
+ cat > $TMPC << EOF
+#include <bzlib.h>
+int main(void) { BZ2_bzlibVersion(); return 0; }
+EOF
+ if compile_prog "" "-lbz2" ; then
+ libs_softmmu="$libs_softmmu -lbz2"
+ bzip2="yes"
+ else
+ if test "$bzip2" = "yes"; then
+ feature_not_found "libbzip2" "Install libbzip2 devel"
+ fi
+ bzip2="no"
+ fi
+fi
+
+##########################################
# libseccomp check
if test "$seccomp" != "no" ; then
@@ -4340,6 +4366,7 @@ echo "vhdx $vhdx"
echo "Quorum $quorum"
echo "lzo support $lzo"
echo "snappy support $snappy"
+echo "bzip2 support $bzip2"
echo "NUMA host support $numa"
if test "$sdl_too_old" = "yes"; then
@@ -4695,6 +4722,10 @@ if test "$snappy" = "yes" ; then
echo "CONFIG_SNAPPY=y" >> $config_host_mak
fi
+if test "$bzip2" = "yes" ; then
+ echo "CONFIG_BZIP2=y" >> $config_host_mak
+fi
+
if test "$libiscsi" = "yes" ; then
echo "CONFIG_LIBISCSI=m" >> $config_host_mak
echo "LIBISCSI_CFLAGS=$libiscsi_cflags" >> $config_host_mak
Looks good otherwise. CCing Paolo so he can take a quick peek at the
configure script. It looks sane to me, though.
- Re: [Qemu-devel] [PATCH 09/10] block/dmg: support bzip2 block entry types,
John Snow <=