From 160837b900524e11e2ce66e3f6dcc3dcd5e0255c Mon Sep 17 00:00:00 2001
From: Cole Helbling <cole.e.helbling@gmail.com>
Date: Sat, 20 Apr 2019 09:12:30 -0700
Subject: [PATCH] Ensure no NULL tags are set

Because `mpd_song_get_tag` from libmpdclient can return NULL, verify the
value of tag is valid. Otherwise, set a default string of "N/A". Also
adds configuration to specify what this default string should be.
---
 include/modules/mpd.hpp |  1 +
 resources/config        |  1 +
 src/modules/mpd.cpp     | 21 ++++++++++++++++-----
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/include/modules/mpd.hpp b/include/modules/mpd.hpp
index b3134f4..0574d8d 100644
--- a/include/modules/mpd.hpp
+++ b/include/modules/mpd.hpp
@@ -15,6 +15,7 @@ class MPD : public ALabel {
 
  private:
   std::thread periodic_updater();
+  std::string getTag(mpd_tag_type type, unsigned idx = 0);
   void        setLabel();
   std::string getStateIcon();
   std::string getOptionIcon(std::string optionName, bool activated);
diff --git a/resources/config b/resources/config
index 0fcb712..b2d8cc0 100644
--- a/resources/config
+++ b/resources/config
@@ -30,6 +30,7 @@
         "format": "{stateIcon} {consumeIcon}{randomIcon}{repeatIcon}{singleIcon}{artist} - {album} - {title} ({elapsedTime:%M:%S}/{totalTime:%M:%S}) ",
         "format-disconnected": "Disconnected ",
         "format-stopped": "{consumeIcon}{randomIcon}{repeatIcon}{singleIcon}Stopped ",
+        "unknown-tag": "N/A",
         "interval": 2,
         "consume-icons": {
             "on": " "
diff --git a/src/modules/mpd.cpp b/src/modules/mpd.cpp
index bd9b095..1c43982 100644
--- a/src/modules/mpd.cpp
+++ b/src/modules/mpd.cpp
@@ -75,6 +75,17 @@ std::thread waybar::modules::MPD::periodic_updater() {
   });
 }
 
+std::string waybar::modules::MPD::getTag(mpd_tag_type type, unsigned idx) {
+  std::string result = config_["unknown-tag"].isString() ? config_["unknown-tag"].asString() : "N/A";
+  const char* tag = mpd_song_get_tag(song_.get(), type, idx);
+
+  // mpd_song_get_tag can return NULL, so make sure it's valid before setting
+  if (tag)
+    result = tag;
+
+  return result;
+}
+
 void waybar::modules::MPD::setLabel() {
   if (connection_ == nullptr) {
     label_.get_style_context()->add_class("disconnected");
@@ -123,11 +134,11 @@ void waybar::modules::MPD::setLabel() {
 
     stateIcon = getStateIcon();
 
-    artist = mpd_song_get_tag(song_.get(), MPD_TAG_ARTIST, 0);
-    album_artist = mpd_song_get_tag(song_.get(), MPD_TAG_ALBUM_ARTIST, 0);
-    album = mpd_song_get_tag(song_.get(), MPD_TAG_ALBUM, 0);
-    title = mpd_song_get_tag(song_.get(), MPD_TAG_TITLE, 0);
-    date = mpd_song_get_tag(song_.get(), MPD_TAG_DATE, 0);
+    artist = getTag(MPD_TAG_ARTIST);
+    album_artist = getTag(MPD_TAG_ALBUM_ARTIST);
+    album = getTag(MPD_TAG_ALBUM);
+    title = getTag(MPD_TAG_TITLE);
+    date = getTag(MPD_TAG_DATE);
     elapsedTime = std::chrono::seconds(mpd_status_get_elapsed_time(status_.get()));
     totalTime = std::chrono::seconds(mpd_status_get_total_time(status_.get()));
   }