Bug#665296: autoscript in DH_Lib cannot cope with large sed one-liner

[Niels Thykier]

Hi,

I was wondering if this could be solved by allowing a "hashref" as
alternative to a sed expression.  The hashref would should map keys to
their replacements and autoscripts could then use that for making the
substitutions.
  It will not automatically fix affected tools, but it is my
understanding that only the tools in xml-core are affected.

I have attached a prototype patch that demonstrates the idea behind the
idea, though there was no test suite for autoscripts so the patch is
untested (hench the no "patch" tag).

~Niels


diff --git a/Debian/Debhelper/Dh_Lib.pm b/Debian/Debhelper/Dh_Lib.pm
index 10ae69f..5dc3ada 100644
--- a/Debian/Debhelper/Dh_Lib.pm
+++ b/Debian/Debhelper/Dh_Lib.pm
@@ -505,11 +505,15 @@ sub pkgfilename {
 # 2: script to add to
 # 3: filename of snippet
 # 4: sed to run on the snippet. Ie, s/#PACKAGE#/$PACKAGE/
+#  or a hashref mapping keys to their replacements.
+#  The key "PACKAGE" will replace "#PACKAGE#" in the snippet
+#  with the value associated with "PACKAGE".
 sub autoscript {
 	my $package=shift;
 	my $script=shift;
 	my $filename=shift;
 	my $sed=shift || "";
+	my $subst;
 
 	# This is the file we will modify.
 	my $outfile="debian/".pkgext($package)."$script.debhelper";
@@ -528,19 +532,45 @@ sub autoscript {
 			error("/usr/share/debhelper/autoscripts/$filename does not exist");
 		}
 	}
+	if ($sed && ref($sed) eq 'HASH') {
+		if (scalar(keys(%$sed)) == 0) {
+			error("Empty hash passed");
+		}
+		$subst = sub {
+			my ($input, $output) = @_;
+			my $rstr = sprintf("#(%s)#", join("|", keys(%$sed)));
+			my $regex = qr/$rstr/;
+			open(my $in, '<', $input) or error("opening $input: $!");
+			open(my $out, '>>', $output) or error("opening $output: $!");
+			while (my $line = <$in>) {
+				$line =~ s/$regex/$sed->{$1}/eg;
+				print {$out} $line;
+			}
+			close($in);
+			close($out) or error("closing $out: $!");
+		}
+	}
 
 	if (-e $outfile && ($script eq 'postrm' || $script eq 'prerm')
 	   && !compat(5)) {
 		# Add fragments to top so they run in reverse order when removing.
 		complex_doit("echo \"# Automatically added by ".basename($0)."\"> $outfile.new");
-		complex_doit("sed \"$sed\" $infile >> $outfile.new");
+		if ($subst) {
+			$subst->($infile, "$outfile.new");
+		} else {
+			complex_doit("sed \"$sed\" $infile >> $outfile.new");
+		}
 		complex_doit("echo '# End automatically added section' >> $outfile.new");
 		complex_doit("cat $outfile >> $outfile.new");
 		complex_doit("mv $outfile.new $outfile");
 	}
 	else {
 		complex_doit("echo \"# Automatically added by ".basename($0)."\">> $outfile");
-		complex_doit("sed \"$sed\" $infile >> $outfile");
+		if ($subst) {
+			$subst->($infile, $outfile);
+		} else {
+			complex_doit("sed \"$sed\" $infile >> $outfile");
+		}
 		complex_doit("echo '# End automatically added section' >> $outfile");
 	}
 }