Fixed ayufan proxmox differential backup for QemuServer part of pve-manager-3.4-14

QemuServer.pm.diff

diff --git a/QemuServer.pm b/QemuServer.pm
index 970edb5..9e7b281 100644
--- a/QemuServer.pm
+++ b/QemuServer.pm
@@ -4749,10 +4749,20 @@ sub tar_archive_read_firstfile {
 
     die "ERROR: file '$archive' does not exist\n" if ! -f $archive;
 
+    my $cmd = undef;
+
+    if ($archive =~ m!([^/]*vzdump-([a-z]*)-(\d*)-(\d{4})_(\d{2})_(\d{2})-(\d{2})_(\d{2})_(\d{2})\.(tgz|(tar(\.(gz|lzo))?)))--differential-(\d{4})_(\d{2})_(\d{2})-(\d{2})_(\d{2})_(\d{2})\.vcdiff(\.(gz|lzo))?$!) {
+       my $fullbackup = $archive;
+       $fullbackup =~ s!([^/]*vzdump-([a-z]+)-(\d+)-(\d{4})_(\d{2})_(\d{2})-(\d{2})_(\d{2})_(\d{2})\.(tgz|(tar(\.(gz|lzo))?)))--differential-(\d{4})_(\d{2})_(\d{2})-(\d{2})_(\d{2})_(\d{2})\.vcdiff(\.(gz|lzo))?!$1!;
+       $cmd = "pve-xdelta3 -q -d -c -R -s '$fullbackup' '$archive' |tar t|";
+    } else {
+       $cmd = "tar tf '$archive'|";
+    }
+
     # try to detect archive type first
-    my $pid = open (my $fh, '-|', 'tar', 'tf', $archive) ||
+    my $pid = open (TMP, $cmd) ||
        die "unable to open file '$archive'\n";
-    my $firstfile = <$fh>;
+    my $firstfile = <TMP>;
     kill 15, $pid;
-    close $fh;
+    close TMP;