[pmg-devel] [PATCH pmg-api] adapt journalctl invocation to buster

[Stoiko Ivanov]

With Debian Buster the behavior of `journalctl` has changed when it finds
no entries for a given selection:
* The exit code was 0 in stretch, but is 1 in buster
* The output changed slightly - a header got added

Since PMG::Utils::scan_journal_for_rbl_rejects uses journalctl for reading the
IPs blocked by postscreen it needs to adapt for the new behavior
(otherwise the journal gets filled with spurious log-messages)

The patch addresses the problem by checking the die-message for
'failed: exit code 1`, and ignoring the error if the '-- No entries --' line
was found and no rbl-counter got incremented

Signed-off-by: Stoiko Ivanov <s.ivanov at proxmox.com>
---
Thanks @Fabian for reporting the issue initially. I verified that the spamming
in the journal started after an experimental upgrade to buster.

 src/PMG/Utils.pm | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/PMG/Utils.pm b/src/PMG/Utils.pm
index aa6aac7..385b6d3 100644
--- a/src/PMG/Utils.pm
+++ b/src/PMG/Utils.pm
@@ -1298,6 +1298,7 @@ sub scan_journal_for_rbl_rejects {
 
     my $rbl_count = 0;
     my $pregreet_count = 0;
+    my $noentries = 0;
 
     my $parser = sub {
 	my $line = shift;
@@ -1305,6 +1306,8 @@ sub scan_journal_for_rbl_rejects {
 	if ($line =~ m/^--\scursor:\s(\S+)$/) {
 	    $rbl_scan_last_cursor = $1;
 	    return;
+	} elsif ($line =~ m/^-- No entries --$/) {
+	    $noentries = 1;
 	}
 
 	if ($line =~ m/\s$identifier\[\d+\]:\sNOQUEUE:\sreject:.*550 5.7.1 Service unavailable;/) {
@@ -1324,7 +1327,12 @@ sub scan_journal_for_rbl_rejects {
 	push @$cmd, "--since=@" . $rbl_scan_start_time;
     }
 
-    PVE::Tools::run_command($cmd, outfunc => $parser);
+    eval{ PVE::Tools::run_command($cmd, outfunc => $parser); };
+    my $err = $@;
+    if ($err) {
+	return if ( $err =~ m/failed: exit code 1$/ && $noentries == 1 && $rbl_count == 0 && $pregreet_count == 0);
+	die "$err\n";
+    }
 
     return ($rbl_count, $pregreet_count);
 }
-- 
2.20.1