1#!/usr/bin/env bash
2#
3# Test qcow2 image compression
4#
5# Copyright (C) 2018 Igalia, S.L.
6# Author: Alberto Garcia <berto@igalia.com>
7#
8# This program is free software; you can redistribute it and/or modify
9# it under the terms of the GNU General Public License as published by
10# the Free Software Foundation; either version 2 of the License, or
11# (at your option) any later version.
12#
13# This program is distributed in the hope that it will be useful,
14# but WITHOUT ANY WARRANTY; without even the implied warranty of
15# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16# GNU General Public License for more details.
17#
18# You should have received a copy of the GNU General Public License
19# along with this program.  If not, see <http://www.gnu.org/licenses/>.
20#
21
22seq=$(basename "$0")
23echo "QA output created by $seq"
24
25status=1	# failure is the default!
26
27_cleanup()
28{
29    _cleanup_test_img
30}
31trap "_cleanup; exit \$status" 0 1 2 3 15
32
33# get standard environment, filters and checks
34. ./common.rc
35. ./common.filter
36
37_supported_fmt qcow2
38_supported_proto file
39
40# Repairing the corrupted image requires qemu-img check to store a
41# refcount up to 3, which requires at least two refcount bits.
42_unsupported_imgopts 'refcount_bits=1[^0-9]'
43
44
45echo
46echo "=== Corrupted size field in compressed cluster descriptor ==="
47echo
48# Create an empty image and fill half of it with compressed data.
49# The L2 entries of the two compressed clusters are located at
50# 0x800000 and 0x800008, their original values are 0x4008000000a00000
51# and 0x4008000000a00802 (5 sectors for compressed data each).
52_make_test_img 8M -o cluster_size=2M
53$QEMU_IO -c "write -c -P 0x11 0 2M" -c "write -c -P 0x11 2M 2M" "$TEST_IMG" \
54         2>&1 | _filter_qemu_io | _filter_testdir
55
56# Reduce size of compressed data to 4 sectors: this corrupts the image.
57poke_file "$TEST_IMG" $((0x800000)) "\x40\x06"
58$QEMU_IO -c "read  -P 0x11 0 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
59
60# 'qemu-img check' however doesn't see anything wrong because it
61# doesn't try to decompress the data and the refcounts are consistent.
62# TODO: update qemu-img so this can be detected.
63_check_test_img
64
65# Increase size of compressed data to the maximum (8192 sectors).
66# This makes QEMU read more data (8192 sectors instead of 5, host
67# addresses [0xa00000, 0xdfffff]), but the decompression algorithm
68# stops once we have enough to restore the uncompressed cluster, so
69# the rest of the data is ignored.
70poke_file "$TEST_IMG" $((0x800000)) "\x7f\xfe"
71# Do it also for the second compressed cluster (L2 entry at 0x800008).
72# In this case the compressed data would span 3 host clusters
73# (host addresses: [0xa00802, 0xe00801])
74poke_file "$TEST_IMG" $((0x800008)) "\x7f\xfe"
75
76# Here the image is too small so we're asking QEMU to read beyond the
77# end of the image.
78$QEMU_IO -c "read  -P 0x11  0 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
79# But if we grow the image we won't be reading beyond its end anymore.
80$QEMU_IO -c "write -P 0x22 4M 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
81$QEMU_IO -c "read  -P 0x11  0 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
82
83# The refcount data is however wrong because due to the increased size
84# of the compressed data it now reaches the following host clusters.
85# This can be repaired by qemu-img check by increasing the refcount of
86# those clusters.
87# TODO: update qemu-img to correct the compressed cluster size instead.
88_check_test_img -r all
89$QEMU_IO -c "read  -P 0x11  0 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
90$QEMU_IO -c "read  -P 0x22 4M 4M" "$TEST_IMG" 2>&1 | _filter_qemu_io | _filter_testdir
91
92# success, all done
93echo '*** done'
94rm -f $seq.full
95status=0
96