iotests: Test convert to qcow2 compressed to NBD

Add test for "qemu-img convert -O qcow2 -c" to NBD target. The tests    
create a OVA file and write compressed qcow2 disk content directly into
the OVA file via qemu-nbd.

Signed-off-by: Nir Soffer <nsoffer@redhat.com>
Message-Id: <20200727215846.395443-5-nsoffer@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>

tests/qemu-iotests/302

@@ -0,0 +1,127 @@
+#!/usr/bin/env python3
+#
+# Tests converting qcow2 compressed to NBD
+#
+# Copyright (c) 2020 Nir Soffer <nirsof@gmail.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/>.
+#
+# owner=nirsof@gmail.com
+
+import io
+import tarfile
+
+import iotests
+
+from iotests import (
+    file_path,
+    qemu_img,
+    qemu_img_check,
+    qemu_img_create,
+    qemu_img_log,
+    qemu_img_measure,
+    qemu_io,
+    qemu_nbd_popen,
+)
+
+iotests.script_initialize(supported_fmts=["qcow2"])
+
+# Create source disk. Using qcow2 to enable strict comparing later, and
+# avoid issues with random filesystem on CI environment.
+src_disk = file_path("disk.qcow2")
+qemu_img_create("-f", iotests.imgfmt, src_disk, "1g")
+qemu_io("-f", iotests.imgfmt, "-c", "write 1m 64k", src_disk)
+
+# The use case is writing qcow2 image directly into an ova file, which
+# is a tar file with specific layout. This is tricky since we don't know the
+# size of the image before compressing, so we have to do:
+# 1. Add an ovf file.
+# 2. Find the offset of the next member data.
+# 3. Make room for image data, allocating for the worst case.
+# 4. Write compressed image data into the tar.
+# 5. Add a tar entry with the actual image size.
+# 6. Shrink the tar to the actual size, aligned to 512 bytes.
+
+tar_file = file_path("test.ova")
+
+with tarfile.open(tar_file, "w") as tar:
+
+    # 1. Add an ovf file.
+
+    ovf_data = b"<xml/>"
+    ovf = tarfile.TarInfo("vm.ovf")
+    ovf.size = len(ovf_data)
+    tar.addfile(ovf, io.BytesIO(ovf_data))
+
+    # 2. Find the offset of the next member data.
+
+    offset = tar.fileobj.tell() + 512
+
+    # 3. Make room for image data, allocating for the worst case.
+
+    measure = qemu_img_measure("-O", "qcow2", src_disk)
+    tar.fileobj.truncate(offset + measure["required"])
+
+    # 4. Write compressed image data into the tar.
+
+    nbd_sock = file_path("nbd-sock", base_dir=iotests.sock_dir)
+    nbd_uri = "nbd+unix:///exp?socket=" + nbd_sock
+
+    # Use raw format to allow creating qcow2 directly into tar file.
+    with qemu_nbd_popen(
+            "--socket", nbd_sock,
+            "--export-name", "exp",
+            "--format", "raw",
+            "--offset", str(offset),
+            tar_file):
+
+        iotests.log("=== Target image info ===")
+        qemu_img_log("info", nbd_uri)
+
+        qemu_img(
+            "convert",
+            "-f", iotests.imgfmt,
+            "-O", "qcow2",
+            "-c",
+            src_disk,
+            nbd_uri)
+
+        iotests.log("=== Converted image info ===")
+        qemu_img_log("info", nbd_uri)
+
+        iotests.log("=== Converted image check ===")
+        qemu_img_log("check", nbd_uri)
+
+        iotests.log("=== Comparing to source disk ===")
+        qemu_img_log("compare", src_disk, nbd_uri)
+
+        actual_size = qemu_img_check(nbd_uri)["image-end-offset"]
+
+    # 5. Add a tar entry with the actual image size.
+
+    disk = tarfile.TarInfo("disk")
+    disk.size = actual_size
+    tar.addfile(disk)
+
+    # 6. Shrink the tar to the actual size, aligned to 512 bytes.
+
+    tar_size = offset + (disk.size + 511) & ~511
+    tar.fileobj.seek(tar_size)
+    tar.fileobj.truncate(tar_size)
+
+with tarfile.open(tar_file) as tar:
+    members = [{"name": m.name, "size": m.size, "offset": m.offset_data}
+               for m in tar]
+    iotests.log("=== OVA file contents ===")
+    iotests.log(members)

tests/qemu-iotests/302.out

@@ -0,0 +1,31 @@
+Start NBD server
+=== Target image info ===
+image: nbd+unix:///exp?socket=SOCK_DIR/PID-nbd-sock
+file format: raw
+virtual size: 448 KiB (458752 bytes)
+disk size: unavailable
+
+=== Converted image info ===
+image: nbd+unix:///exp?socket=SOCK_DIR/PID-nbd-sock
+file format: qcow2
+virtual size: 1 GiB (1073741824 bytes)
+disk size: unavailable
+cluster_size: 65536
+Format specific information:
+    compat: 1.1
+    compression type: zlib
+    lazy refcounts: false
+    refcount bits: 16
+    corrupt: false
+
+=== Converted image check ===
+No errors were found on the image.
+1/16384 = 0.01% allocated, 100.00% fragmented, 100.00% compressed clusters
+Image end offset: 393216
+
+=== Comparing to source disk ===
+Images are identical.
+
+Kill NBD server
+=== OVA file contents ===
+[{"name": "vm.ovf", "offset": 512, "size": 6}, {"name": "disk", "offset": 1536, "size": 393216}]

tests/qemu-iotests/group

@@ -308,3 +308,4 @@
 297 meta
 299 auto quick
 301 backing quick
+302 quick