plugin: dir: handle ova files for import

since we want to handle ova files (which are only ovf+images bundled in
a tar file) for import, add code that handles that.

we introduce a valid volname for files contained in ovas like this:

 storage:import/archive.ova/disk-1.vmdk

by basically treating the last part of the path as the name for the
contained disk we want.

in that case we return 'import' as type with 'vmdk/qcow2/raw' as format
(we cannot use something like 'ova+vmdk' without extending the 'format'
parsing to that for all storages/formats. This is because it runs
though a verify format check at least once)

we then provide a function to use for that:

* extract_disk_from_import_file: this actually extracts the file from
  the archive. Currently only ova is supported, so the extraction with
  'tar' is hardcoded, but again we can easily extend/modify that should
  we need to.

  we currently extract into the either the import storage or a given
  target storage in the images directory so if the cleanup does not
  happen, the user can still see and interact with the image via
  api/cli/gui

we have to modify the `parse_ovf` a bit to handle the missing disk
images, and we parse the size out of the ovf part (since this is
informal only, it should be no problem if we cannot parse it sometimes)

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
Reviewed-by: Fiona Ebner <f.ebner@proxmox.com>

src/PVE/GuestImport.pm

@@ -0,0 +1,79 @@
+package PVE::GuestImport;
+
+use strict;
+use warnings;
+
+use File::Path;
+
+use PVE::Storage;
+use PVE::Tools qw(run_command);
+
+sub extract_disk_from_import_file {
+    my ($volid, $vmid, $target_storeid) = @_;
+
+    my ($source_storeid, $volname) = PVE::Storage::parse_volume_id($volid);
+    $target_storeid //= $source_storeid;
+    my $cfg = PVE::Storage::config();
+
+    my ($vtype, $name, undef, undef, undef, undef, $fmt) =
+	PVE::Storage::parse_volname($cfg, $volid);
+
+    die "only files with content type 'import' can be extracted\n"
+	if $vtype ne 'import';
+
+    die "only files from 'ova' format can be extracted\n"
+	if $fmt !~ m/^ova\+/;
+
+    # extract the inner file from the name
+    my $archive_volid;
+    my $inner_file;
+    my $inner_fmt;
+    if ($name =~ m!^(.*\.ova)/(${PVE::Storage::SAFE_CHAR_CLASS_RE}+)$!) {
+	$archive_volid = "$source_storeid:import/$1";
+	$inner_file = $2;
+	($inner_fmt) = $fmt =~ /^ova\+(.*)$/;
+    } else {
+	die "cannot extract $volid - invalid volname $volname\n";
+    }
+
+    my $ova_path = PVE::Storage::path($cfg, $archive_volid);
+
+    my $tmpdir = PVE::Storage::get_image_dir($cfg, $target_storeid, $vmid);
+    my $pid = $$;
+    $tmpdir .= "/tmp_${pid}_${vmid}";
+    mkpath $tmpdir;
+
+    my $source_path = "$tmpdir/$inner_file";
+    my $target_path;
+    my $target_volid;
+    eval {
+	run_command(['tar', '-x', '--force-local', '-C', $tmpdir, '-f', $ova_path, $inner_file]);
+
+	# check for symlinks and other non regular files
+	if (-l $source_path || ! -f $source_path) {
+	    die "extracted file '$inner_file' from archive '$archive_volid' is not a regular file\n";
+	}
+
+	# check potentially untrusted image file!
+	PVE::Storage::file_size_info($source_path, undef, 1);
+
+	# create temporary 1M image that will get overwritten by the rename
+	# to reserve the filename and take care of locking
+	$target_volid = PVE::Storage::vdisk_alloc($cfg, $target_storeid, $vmid, $inner_fmt, undef, 1024);
+	$target_path = PVE::Storage::path($cfg, $target_volid);
+
+	print "renaming $source_path to $target_path\n";
+
+	rename($source_path, $target_path) or die "unable to move - $!\n";
+    };
+    if (my $err = $@) {
+	File::Path::remove_tree($tmpdir);
+	die "error during extraction: $err\n";
+    }
+
+    File::Path::remove_tree($tmpdir);
+
+    return $target_volid;
+}
+
+1;