From 3e09ac0c10c95bb24a08af62393b4f761e2743d0 Mon Sep 17 00:00:00 2001
From: Eric Wong <normalperson@yhbt.net>
Date: Sat, 24 Aug 2013 09:54:45 +0000
Subject: initial commit

---
 lib/dtas/replaygain.rb | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 lib/dtas/replaygain.rb

(limited to 'lib/dtas/replaygain.rb')

diff --git a/lib/dtas/replaygain.rb b/lib/dtas/replaygain.rb
new file mode 100644
index 0000000..e049b8d
--- /dev/null
+++ b/lib/dtas/replaygain.rb
@@ -0,0 +1,42 @@
+# -*- encoding: binary -*-
+# :stopdoc:
+# Copyright (C) 2013, Eric Wong <normalperson@yhbt.net>
+# License: GPLv3 or later (https://www.gnu.org/licenses/gpl-3.0.txt)
+#
+# Represents ReplayGain metadata for a DTAS::Source
+# cleanup/validate values to prevent malicious files from making us
+# run arbitrary commands
+# *_peak values are 0..inf (1.0 being full scale, but >1 is possible
+# *_gain values are specified in dB
+
+class DTAS::ReplayGain
+  ATTRS = %w(reference_loudness track_gain album_gain track_peak album_peak)
+  ATTRS.each { |a| attr_reader a }
+
+  def check_gain(val)
+    /([+-]?\d+(?:\.\d+)?)/ =~ val ? $1 : nil
+  end
+
+  def check_float(val)
+    /(\d+(?:\.\d+)?)/ =~ val ? $1 : nil
+  end
+
+  def initialize(comments)
+    comments or return
+
+    # the replaygain standard specifies 89.0 dB, but maybe some apps are
+    # different...
+    @reference_loudness =
+              check_gain(comments["REPLAYGAIN_REFERENCE_LOUDNESS"]) || "89.0"
+
+    @track_gain = check_gain(comments["REPLAYGAIN_TRACK_GAIN"])
+    @album_gain = check_gain(comments["REPLAYGAIN_ALBUM_GAIN"])
+    @track_peak = check_float(comments["REPLAYGAIN_TRACK_PEAK"])
+    @album_peak = check_float(comments["REPLAYGAIN_ALBUM_PEAK"])
+  end
+
+  def self.new(comments)
+    tmp = super
+    tmp.track_gain ? tmp : nil
+  end
+end
-- 
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