Make Porting/makerel create smaller archives with 7z and advdef

It automatically will use these to create archives ~5% smaller,
otherwise falls back to gzip and bzip2.

Also, document in Porting/release_managers_guide.pod.

1 files changed, 31 insertions, 6 deletions

diff --git a/Porting/makerel b/Porting/makerel
index 1e7ca7ce13..13bcf4a44e 100755
--- a/Porting/makerel
+++ b/Porting/makerel
@@ -171,14 +171,39 @@ exit if $opts{n};
 
 my $src = (-e $perl) ? $perl : 'perl'; # 'perl' in maint branch
 
-print "Creating and compressing the tar.gz file...\n";
-$cmd = "tar cf - $reldir | gzip --best > $reldir.tar.gz";
-system($cmd) == 0 or die "$cmd failed";
+print "Checking if you have 7z...\n";
+my $output_7z = `7z 2>&1`;
+my $have_7z = defined $output_7z && $output_7z =~ /7-Zip/;
 
-if ($opts{b}) {
-    print "Creating and compressing the tar.bz2 file...\n";
-    $cmd = "tar cf - $reldir | bzip2 > $reldir.tar.bz2";
+print "Checking if you have advdef...\n";
+my $output_advdef = `advdef --version 2>&1`;
+my $have_advdef = defined $output_advdef && $output_advdef =~ /advancecomp/;
+
+if ($have_7z) {
+    print "Creating and compressing the tar.gz file with 7z...\n";
+    $cmd = "tar cf - $reldir | 7z a -tgzip -mx9 -bd -si $reldir.tar.gz";
     system($cmd) == 0 or die "$cmd failed";
+} else {
+    print "Creating and compressing the tar.gz file...\n";
+    $cmd = "tar cf - $reldir | gzip --best > $reldir.tar.gz";
+    system($cmd) == 0 or die "$cmd failed";
+    if ($have_advdef) {
+        print "Recompressing the tar.gz file with advdef...\n";
+        $cmd = "advdef -z -4 $reldir.tar.gz";
+        system($cmd) == 0 or die "$cmd failed";
+    }
+}
+
+if ($opts{b}) {
+    if ($have_7z) {
+        print "Creating and compressing the tar.bz2 file with 7z...\n";
+        $cmd = "tar cf - $reldir | 7z a -tbzip2 -mx9 -bd -si $reldir.tar.bz2";
+        system($cmd) == 0 or die "$cmd failed";
+    } else {
+        print "Creating and compressing the tar.bz2 file...\n";
+        $cmd = "tar cf - $reldir | bzip2 > $reldir.tar.bz2";
+        system($cmd) == 0 or die "$cmd failed";
+    }
 }
 
 print "\n";