From 034fb89db3a39529bc1c38b9f83947cf2ad53114 Mon Sep 17 00:00:00 2001
From: Florent Rougon <f.rougon@free.fr>
Date: Mon, 15 May 2017 11:06:47 +0200
Subject: [PATCH] Abort with a clear error message for invalid uses of --config
 inside a config file

The options.cxx code is not ready to handle recursive use of --config
(for config files). Instead of failing in an ugly way, abort with a
clear error message in such situations. See discussion at
<https://sourceforge.net/p/flightgear/mailman/message/35838852/>.

Note: it *is* possible to load XML PropertyList files from config files,
      so --config is not entirely "banned" from config files.

+ add missing include
---
 src/Main/options.cxx | 17 +++++++++++++----
 src/Main/options.hxx |  6 ++++--
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/src/Main/options.cxx b/src/Main/options.cxx
index 4f3120f90..5a97e20b2 100644
--- a/src/Main/options.cxx
+++ b/src/Main/options.cxx
@@ -39,6 +39,7 @@
 #include <cstdlib>      // atof(), atoi()
 #include <cstring>      // strcmp()
 #include <algorithm>
+#include <map>
 
 #include <iostream>
 #include <string>
@@ -2020,7 +2021,7 @@ void Options::init(int argc, char **argv, const SGPath& appDataPath)
         continue;
       }
 
-      int result = parseOption(argv[i]);
+      int result = parseOption(argv[i], /* fromConfigFile */ false);
       processArgResult(result);
     } else {
     // XML properties file
@@ -2231,7 +2232,7 @@ void Options::readConfig(const SGPath& path)
         break;
     line = line.substr( 0, i );
 
-    if ( parseOption( line ) == FG_OPTIONS_ERROR ) {
+    if ( parseOption(line, /* fromConfigFile */ true) == FG_OPTIONS_ERROR ) {
       cerr << endl << "Config file parse error: " << path << " '"
       << line << "'" << endl;
 	    p->showHelp = true;
@@ -2242,7 +2243,7 @@ void Options::readConfig(const SGPath& path)
   p->insertGroupMarker(); // each config file is a group
 }
 
-int Options::parseOption(const string& s)
+int Options::parseOption(const string& s, bool fromConfigFile)
 {
   if ((s == "--help") || (s=="-h")) {
     return FG_OPTIONS_HELP;
@@ -2276,7 +2277,15 @@ int Options::parseOption(const string& s)
     SGPath path = s.substr(9);
     if (path.extension() == "xml") {
         p->propertyFiles.push_back(path);
-    } else {
+    } else if (fromConfigFile) {
+      flightgear::fatalMessageBoxThenExit(
+        "FlightGear",
+        "Invalid use of the --config option.",
+        "Sorry, it is currently not supported to load a configuration file "
+        "using --config from another configuration file.\n\n"
+        "Note: this does not apply to loading of XML PropertyList files "
+        "with --config.");
+    } else {                // the --config option comes from the command line
         p->configFiles.push_back(path);
     }
 
diff --git a/src/Main/options.hxx b/src/Main/options.hxx
index ad8d848bf..ee3434a99 100644
--- a/src/Main/options.hxx
+++ b/src/Main/options.hxx
@@ -171,8 +171,10 @@ private:
   // paths, etc. to stdout in JSON format, using the UTF-8 encoding.
   void printJSONReport() const;
 
-  int parseOption(const std::string& s);
-  
+  // The 'fromConfigFile' parameter indicates whether the option comes from a
+  // config file or directly from the command line.
+  int parseOption(const std::string& s, bool fromConfigFile);
+
   void processArgResult(int result);
 
     /**