From 190bffd846f044a13c239513f8ef1ea45ee8a1f2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Sun, 23 Jun 2013 15:18:21 +0200
Subject: [PATCH] Don't compress already-compressed files.

Fixes <https://github.com/NixOS/hydra/issues/102>.
---
 src/lib/Hydra/View/NARInfo.pm |  3 ++-
 src/lib/Hydra/View/NixNAR.pm  | 16 +++++++++++++++-
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/lib/Hydra/View/NARInfo.pm b/src/lib/Hydra/View/NARInfo.pm
index 00dd6a68..8bfd0592 100644
--- a/src/lib/Hydra/View/NARInfo.pm
+++ b/src/lib/Hydra/View/NARInfo.pm
@@ -2,6 +2,7 @@ package Hydra::View::NARInfo;
 
 use strict;
 use base qw/Catalyst::View/;
+use Hydra::View::NixNAR;
 use File::Basename;
 use Nix::Store;
 
@@ -17,7 +18,7 @@ sub process {
     my $info;
     $info .= "StorePath: $storePath\n";
     $info .= "URL: nar/" . basename $storePath. "\n";
-    $info .= "Compression: bzip2\n";
+    $info .= "Compression: " . file_compression $storePath . "\n";
     $info .= "NarHash: $narHash\n";
     $info .= "NarSize: $narSize\n";
     $info .= "References: " . join(" ", map { basename $_ } @{$refs}) . "\n";
diff --git a/src/lib/Hydra/View/NixNAR.pm b/src/lib/Hydra/View/NixNAR.pm
index af1a5367..a403b42d 100644
--- a/src/lib/Hydra/View/NixNAR.pm
+++ b/src/lib/Hydra/View/NixNAR.pm
@@ -3,16 +3,30 @@ package Hydra::View::NixNAR;
 use strict;
 use base qw/Catalyst::View/;
 
+sub file_compression {
+    my ($file) = $@_;
+
+    if /\\.(gz|bz2|xz|lz|zip)/
+	return "none";
+    else
+	return "bzip2";
+}
+
 sub process {
     my ($self, $c) = @_;
 
     my $storePath = $c->stash->{storePath};
+    my $compression = file_compression($storePath);
 
     $c->response->content_type('application/x-nix-archive'); # !!! check MIME type
+    $c->response->content_length(-s $storePath) if ($compression == "none");
 
     my $fh = new IO::Handle;
 
-    open $fh, "nix-store --dump '$storePath' | bzip2 |";
+    if ($compression == "none")
+	open $fh, "nix-store --dump '$storePath' |";
+    else
+	open $fh, "nix-store --dump '$storePath' | bzip2 |";
 
     $c->response->body($fh);