qemu/tests/qemu-iotests/214

#!/usr/bin/env bash
#
# Test qcow2 image compression
#
# Copyright (C) 2018 Igalia, S.L.
# Author: Alberto Garcia <berto@igalia.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

seq=$(basename "$0")
echo "QA output created by $seq"

status=1	# failure is the default!

_cleanup()
{
    _cleanup_test_img
}
trap "_cleanup; exit \$status" 0 1 2 3 15

# get standard environment, filters and checks
. ./common.rc
. ./common.filter

_supported_fmt qcow2
_supported_proto file

# Repairing the corrupted image requires qemu-img check to store a
# refcount up to 3, which requires at least two refcount bits.
_unsupported_imgopts 'refcount_bits=1[^0-9]'


echo
echo "=== Corrupted size field in compressed cluster descriptor ==="
echo
# Create an empty image and fill half of it with compressed data.
# The L2 entries of the two compressed clusters are located at
# 0x800000 and 0x800008, their original values are 0x4008000000a00000
# and 0x4008000000a00802 (5 sectors for compressed data each).
_make_test_img 8M -o cluster_size=2M
$QEMU_IO -c "write -c -P 0x11 0 2M" -c "write -c -P 0x11 2M 2M" "$TEST_IMG" \
         2>&1 | _filter_qemu_io | _filter_testdir

# Reduce size of compressed data to 4 sectors: this corrupts the image.
poke_file "$TEST_IMG" $((0x800000)) "\x40\x06"
$QEMU_IO -c "read  -P 0x11 0 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir

# 'qemu-img check' however doesn't see anything wrong because it
# doesn't try to decompress the data and the refcounts are consistent.
# TODO: update qemu-img so this can be detected.
_check_test_img

# Increase size of compressed data to the maximum (8192 sectors).
# This makes QEMU read more data (8192 sectors instead of 5, host
# addresses [0xa00000, 0xdfffff]), but the decompression algorithm
# stops once we have enough to restore the uncompressed cluster, so
# the rest of the data is ignored.
poke_file "$TEST_IMG" $((0x800000)) "\x7f\xfe"
# Do it also for the second compressed cluster (L2 entry at 0x800008).
# In this case the compressed data would span 3 host clusters
# (host addresses: [0xa00802, 0xe00801])
poke_file "$TEST_IMG" $((0x800008)) "\x7f\xfe"

# Here the image is too small so we're asking QEMU to read beyond the
# end of the image.
$QEMU_IO -c "read  -P 0x11  0 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
# But if we grow the image we won't be reading beyond its end anymore.
$QEMU_IO -c "write -P 0x22 4M 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
$QEMU_IO -c "read  -P 0x11  0 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir

# The refcount data is however wrong because due to the increased size
# of the compressed data it now reaches the following host clusters.
# This can be repaired by qemu-img check by increasing the refcount of
# those clusters.
# TODO: update qemu-img to correct the compressed cluster size instead.
_check_test_img -r all
$QEMU_IO -c "read  -P 0x11  0 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
$QEMU_IO -c "read  -P 0x22 4M 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir

# success, all done
echo '*** done'
rm -f $seq.full
status=0