+# Rotated log files are frequently compressed and there are a variety of
+# formats it could be compressed with. Rather than use just one that is
+# detected and hardcoded at Exim compile time, detect and use what the
+# logfile is compressed with on the fly.
+#
+# List of known compression extensions and their associated commands:
+my $compressors = {
+ gz => { cmd => 'zcat', args => '' },
+ bz2 => { cmd => 'bzcat', args => '' },
+ xz => { cmd => 'xzcat', args => '' },
+ lzma => { cmd => 'lzma', args => '-dc' }
+};
+my $csearch = 0;
+
+sub detect_compressor_bin
+ {
+ my $ext = shift();
+ my $c = $compressors->{$ext}->{cmd};
+ $compressors->{$ext}->{bin} = `which $c 2>/dev/null`;
+ chomp($compressors->{$ext}->{bin});
+ }
+
+sub detect_compressor_capable
+ {
+ my $filename = shift();
+ map { &detect_compressor_bin($_) } keys %$compressors
+ if (!$csearch);
+ $csearch = 1;
+ return undef
+ unless (grep {$filename =~ /\.(?:$_)$/} keys %$compressors);
+ # Loop through them, figure out which one it detected,
+ # and build the commandline.
+ my $cmdline = undef;
+ foreach my $ext (keys %$compressors)
+ {
+ if ($filename =~ /\.(?:$ext)$/)
+ {
+ # Just die if compressor not found; if this occurrs in the middle of
+ # two valid files with a lot of matches, error could easily be missed.
+ die("Didn't find $ext decompressor for $filename\n")
+ if ($compressors->{$ext}->{bin} eq '');
+ $cmdline = $compressors->{$ext}->{bin} ." ".
+ $compressors->{$ext}->{args};
+ last;
+ }
+ }
+ return $cmdline;
+ }
+
+sub grep_for_related {
+ my ($line,$id) = @_;
+ $id_list{$id} = 1 if $line =~ m/$related_re/;
+}
+
+sub get_related_ids {
+ my ($id) = @_;
+ push @Mids, $id unless grep /\b$id\b/, @Mids;
+ my $re = join '|', @Mids;
+ $related_re = qr/$re/;
+}