Better behaviour if config fails to load.

Create a default config if any exception is thrown by ::read, and
tell the UI so that it can pop up a message to say what has happened.

4 files changed, 31 insertions, 9 deletions

diff --git a/ChangeLog b/ChangeLog
index efe48eca2..2e05ac7f0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2016-07-14  Carl Hetherington  <cth@carlh.net>
+
+	* Use default configuration if the config.xml failed to load;
+	may help with #917.
+
 2016-07-12  Carl Hetherington  <cth@carlh.net>
 
 	* Version 2.9.2 released.
diff --git a/src/lib/config.cc b/src/lib/config.cc
index c483734f8..c6c6cac8b 100644
--- a/src/lib/config.cc
+++ b/src/lib/config.cc
@@ -59,6 +59,7 @@ using boost::optional;
 using boost::algorithm::trim;
 
 Config* Config::_instance = 0;
+boost::signals2::signal<void ()> Config::FailedToLoad;
 
 /** Construct default configuration */
 Config::Config ()
@@ -143,16 +144,8 @@ Config::create_certificate_chain ()
 
 void
 Config::read ()
+try
 {
-	if (!have_existing ("config.xml")) {
-		/* Make a new set of signing certificates and key */
-		_signer_chain = create_certificate_chain ();
-		/* And similar for decryption of KDMs */
-		_decryption_chain = create_certificate_chain ();
-		write ();
-		return;
-	}
-
 	cxml::Document f ("Config");
 	f.read_file (path ("config.xml"));
 	optional<string> c;
@@ -305,6 +298,19 @@ Config::read ()
 		read_cinemas (f);
 	}
 }
+catch (...) {
+	if (have_existing ("config.xml")) {
+		/* We have a config file but it didn't load */
+		FailedToLoad ();
+	}
+	set_defaults ();
+	/* Make a new set of signing certificates and key */
+	_signer_chain = create_certificate_chain ();
+	/* And similar for decryption of KDMs */
+	_decryption_chain = create_certificate_chain ();
+	write ();
+}
+
 
 /** @return Filename to write configuration to */
 boost::filesystem::path
diff --git a/src/lib/config.h b/src/lib/config.h
index feaac8390..61c6bfa69 100644
--- a/src/lib/config.h
+++ b/src/lib/config.h
@@ -483,6 +483,10 @@ public:
 
 	void changed (Property p = OTHER);
 	boost::signals2::signal<void (Property)> Changed;
+	/** Emitted if ::read() failed on an existing Config file.  There is nothing
+	    a listener can do about it: this is just for information.
+	*/
+	static boost::signals2::signal<void ()> FailedToLoad;
 
 	void write () const;
 
diff --git a/src/tools/dcpomatic.cc b/src/tools/dcpomatic.cc
index f31464282..88310ad3e 100644
--- a/src/tools/dcpomatic.cc
+++ b/src/tools/dcpomatic.cc
@@ -1006,6 +1006,8 @@ private:
 	{
 		wxInitAllImageHandlers ();
 
+		Config::FailedToLoad.connect (boost::bind (&App::config_failed_to_load, this));
+
 		wxSplashScreen* splash = 0;
 		try {
 			if (!Config::have_existing ("config.xml")) {
@@ -1175,6 +1177,11 @@ private:
 		}
 	}
 
+	void config_failed_to_load ()
+	{
+		message_dialog (_frame, _("The existing configuration failed to load.  Default values will be used instead.  These may take a short time to create."));
+	}
+
 	DOMFrame* _frame;
 	shared_ptr<wxTimer> _timer;
 	string _film_to_load;