tests/qemu-iotests/308

#!/usr/bin/env bash
# group: rw
#
# Test FUSE exports (in ways that are not captured by the generic
# tests)
#
# Copyright (C) 2020 Red Hat, Inc.
#
# 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_qemu
    _cleanup_test_img
    rmdir "$EXT_MP" 2>/dev/null
    rm -f "$EXT_MP"
    rm -f "$COPIED_IMG"
}
trap "_cleanup; exit \$status" 0 1 2 3 15

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

# Generic format, but needs a plain filename
_supported_fmt generic
if [ "$IMGOPTSSYNTAX" = "true" ]; then
    _unsupported_fmt $IMGFMT
fi
# We need the image to have exactly the specified size, and VPC does
# not allow that by default
_unsupported_fmt vpc

_supported_proto file # We create the FUSE export manually
_supported_os Linux # We need /dev/urandom

# $1: Export ID
# $2: Options (beyond the node-name and ID)
# $3: Expected return value (defaults to 'return')
# $4: Node to export (defaults to 'node-format')
fuse_export_add()
{
    # The grep -v is a filter for errors when /etc/fuse.conf does not contain
    # user_allow_other.  (The error is benign, but it is printed by fusermount
    # on the first mount attempt, so our export code cannot hide it.)
    _send_qemu_cmd $QEMU_HANDLE \
        "{'execute': 'block-export-add',
          'arguments': {
              'type': 'fuse',
              'id': '$1',
              'node-name': '${4:-node-format}',
              $2
          } }" \
        "${3:-return}" \
        | _filter_imgfmt \
        | grep -v 'option allow_other only allowed if'
}

# $1: Export ID
fuse_export_del()
{
    _send_qemu_cmd $QEMU_HANDLE \
        "{'execute': 'block-export-del',
          'arguments': {
              'id': '$1'
          } }" \
        'return'

    _send_qemu_cmd $QEMU_HANDLE \
        '' \
        'BLOCK_EXPORT_DELETED'
}

# Return the length of the protocol file
# $1: Protocol node export mount point
# $2: Original file (to compare)
get_proto_len()
{
    len1=$(stat -c '%s' "$1")
    len2=$(stat -c '%s' "$2")

    if [ "$len1" != "$len2" ]; then
        echo 'ERROR: Length of export and original differ:' >&2
        echo "$len1 != $len2" >&2
    else
        echo '(OK: Lengths of export and original are the same)' >&2
    fi

    echo "$len1"
}

COPIED_IMG="$TEST_IMG.copy"
EXT_MP="$TEST_IMG.fuse"

echo '=== Set up ==='

# Create image with random data
_make_test_img 64M
$QEMU_IO -c 'write -s /dev/urandom 0 64M' "$TEST_IMG" | _filter_qemu_io

_launch_qemu
_send_qemu_cmd $QEMU_HANDLE \
    "{'execute': 'qmp_capabilities'}" \
    'return'

# Separate blockdev-add calls for format and protocol so we can remove
# the format layer later on
_send_qemu_cmd $QEMU_HANDLE \
    "{'execute': 'blockdev-add',
      'arguments': {
          'driver': 'file',
          'node-name': 'node-protocol',
          'filename': '$TEST_IMG'
      } }" \
    'return'

_send_qemu_cmd $QEMU_HANDLE \
    "{'execute': 'blockdev-add',
      'arguments': {
          'driver': '$IMGFMT',
          'node-name': 'node-format',
          'file': 'node-protocol'
      } }" \
    'return'

echo
echo '=== Mountpoint not present ==='

rmdir "$EXT_MP" 2>/dev/null
rm -f "$EXT_MP"
output=$(fuse_export_add 'export-err' "'mountpoint': '$EXT_MP'" error)

if echo "$output" | grep -q "Parameter 'type' does not accept value 'fuse'"; then
    _notrun 'No FUSE support'
fi

echo "$output"

echo
echo '=== Mountpoint is a directory ==='

mkdir "$EXT_MP"
fuse_export_add 'export-err' "'mountpoint': '$EXT_MP'" error
rmdir "$EXT_MP"

echo
echo '=== Mountpoint is a regular file ==='

touch "$EXT_MP"
fuse_export_add 'export-mp' "'mountpoint': '$EXT_MP'"

# Check that the export presents the same data as the original image
$QEMU_IMG compare -f raw -F $IMGFMT -U "$EXT_MP" "$TEST_IMG"

# Some quick chmod tests
stat -c 'Permissions pre-chmod: %a' "$EXT_MP"

# Verify that we cannot set +w
chmod u+w "$EXT_MP" 2>&1 | _filter_testdir | _filter_imgfmt
stat -c 'Permissions post-+w: %a' "$EXT_MP"

# But that we can set, say, +x (if we are so inclined)
chmod u+x "$EXT_MP" 2>&1 | _filter_testdir | _filter_imgfmt
stat -c 'Permissions post-+x: %a' "$EXT_MP"

echo
echo '=== Mount over existing file ==='

# This is the coolest feature of FUSE exports: You can transparently
# make images in any format appear as raw images
fuse_export_add 'export-img' "'mountpoint': '$TEST_IMG'"

# Accesses both exports at the same time, so we get a concurrency test
$QEMU_IMG compare -f raw -F raw -U "$EXT_MP" "$TEST_IMG"

# Just to be sure, we later want to compare the data offline.  Also,
# this allows us to see that cp works without complaining.
# (This is not a given, because cp will expect a short read at EOF.
# Internally, qemu does not allow short reads, so we have to check
# whether the FUSE export driver lets them work.)
cp "$TEST_IMG" "$COPIED_IMG"

# $TEST_IMG will be in mode 0400 because it is read-only; we are going
# to write to the copy, so make it writable
chmod 0600 "$COPIED_IMG"

echo
echo '=== Double export ==='

# We have already seen that exporting a node twice works fine, but you
# cannot export anything twice on the same mount point.  The reason is
# that qemu has to stat the given mount point, and this would have to
# be answered by the same qemu instance if it already has an export
# there.  However, it cannot answer the stat because it is itself
# caught up in that same stat.
fuse_export_add 'export-err' "'mountpoint': '$EXT_MP'" error

echo
echo '=== Remove export ==='

# Double-check that $EXT_MP appears as a non-empty file (the raw image)
$QEMU_IMG info -f raw "$EXT_MP" | grep 'virtual size'

fuse_export_del 'export-mp'

# See that the file appears empty again
$QEMU_IMG info -f raw "$EXT_MP" | grep 'virtual size'

echo
echo '=== Writable export ==='

fuse_export_add 'export-mp' "'mountpoint': '$EXT_MP', 'writable': true"

# Check that writing to the read-only export fails
output=$($QEMU_IO -f raw -c 'write -P 42 1M 64k' "$TEST_IMG" 2>&1 \
             | _filter_qemu_io | _filter_testdir | _filter_imgfmt)

# Expected reference output: Opening the file fails because it has no
# write permission
reference="Could not open 'TEST_DIR/t.IMGFMT': Permission denied"

if echo "$output" | grep -q "$reference"; then
    echo "Writing to read-only export failed: OK"
elif echo "$output" | grep -q "write failed: Permission denied"; then
    # With CAP_DAC_OVERRIDE (e.g. when running this test as root), the export
    # can be opened regardless of its file permissions, but writing will then
    # fail.  This is not the result for which we want to test, so count this as
    # a SKIP.
    _casenotrun "Opening RO export as R/W succeeded, perhaps because of" \
        "CAP_DAC_OVERRIDE"

    # Still, write this to the reference output to make the test pass
    echo "Writing to read-only export failed: OK"
else
    echo "Writing to read-only export failed: ERROR"
    echo "$output"
fi

# But here it should work
$QEMU_IO -f raw -c 'write -P 42 1M 64k' "$EXT_MP" | _filter_qemu_io

# (Adjust the copy, too)
$QEMU_IO -f raw -c 'write -P 42 1M 64k' "$COPIED_IMG" | _filter_qemu_io

echo
echo '=== Resizing exports ==='

# Here, we need to export the protocol node -- the format layer may
# not be growable, simply because the format does not support it.

# Remove all exports and the format node first so permissions will not
# get in the way
fuse_export_del 'export-mp'
fuse_export_del 'export-img'

_send_qemu_cmd $QEMU_HANDLE \
    "{'execute': 'blockdev-del',
      'arguments': {
          'node-name': 'node-format'
      } }" \
    'return'

# Now export the protocol node
fuse_export_add \
    'export-mp' \
    "'mountpoint': '$EXT_MP', 'writable': true" \
    'return' \
    'node-protocol'

echo
echo '--- Try growing non-growable export ---'

# Get the current size so we can write beyond the EOF
orig_len=$(get_proto_len "$EXT_MP" "$TEST_IMG")
orig_disk_usage=$(stat -c '%b' "$TEST_IMG")

# Should fail (exports are non-growable by default)
# (Note that qemu-io can never write beyond the EOF, so we have to use
# dd here)
dd if=/dev/zero of="$EXT_MP" bs=1 count=64k seek=$orig_len 2>&1 \
    | _filter_testdir | _filter_imgfmt

echo
echo '--- Resize export ---'

# But we can truncate it explicitly; even with fallocate
fallocate -o "$orig_len" -l 64k "$EXT_MP"

new_len=$(get_proto_len "$EXT_MP" "$TEST_IMG")
if [ "$new_len" != "$((orig_len + 65536))" ]; then
    echo 'ERROR: Unexpected post-truncate image size:'
    echo "$new_len != $((orig_len + 65536))"
else
    echo 'OK: Post-truncate image size is as expected'
fi

new_disk_usage=$(stat -c '%b' "$TEST_IMG")
if [ "$new_disk_usage" -gt "$orig_disk_usage" ]; then
    echo 'OK: Disk usage grew with fallocate'
else
    echo 'ERROR: Disk usage did not grow despite fallocate:'
    echo "$orig_disk_usage => $new_disk_usage"
fi

echo
echo '--- Try growing growable export ---'

# Now export as growable
fuse_export_del 'export-mp'
fuse_export_add \
    'export-mp' \
    "'mountpoint': '$EXT_MP', 'writable': true, 'growable': true" \
    'return' \
    'node-protocol'

# Now we should be able to write beyond the EOF
dd if=/dev/zero of="$EXT_MP" bs=1 count=64k seek=$new_len 2>&1 \
    | _filter_testdir | _filter_imgfmt

new_len=$(get_proto_len "$EXT_MP" "$TEST_IMG")
if [ "$new_len" != "$((orig_len + 131072))" ]; then
    echo 'ERROR: Unexpected post-grow image size:'
    echo "$new_len != $((orig_len + 131072))"
else
    echo 'OK: Post-grow image size is as expected'
fi

echo
echo '--- Shrink export ---'

# Now go back to the original size
truncate -s "$orig_len" "$EXT_MP"

new_len=$(get_proto_len "$EXT_MP" "$TEST_IMG")
if [ "$new_len" != "$orig_len" ]; then
    echo 'ERROR: Unexpected post-truncate image size:'
    echo "$new_len != $orig_len"
else
    echo 'OK: Post-truncate image size is as expected'
fi

echo
echo '=== Tear down ==='

_send_qemu_cmd $QEMU_HANDLE \
    "{'execute': 'quit'}" \
    'return'

wait=yes _cleanup_qemu

echo
echo '=== Compare copy with original ==='

$QEMU_IMG compare -f raw -F $IMGFMT "$COPIED_IMG" "$TEST_IMG"

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