Fix DATADIR compile option

-DDATADIR used to have no effect. Now it adds a directory to the data
search path.
Also changes the system-wide data directories (/usr/share,
/usr/local/share, /Users/Shared/OpenXcom) to only be searched if
XDG_DATA_DIRS is unset or empty.

CMakeLists.txt

@@ -19,7 +19,7 @@ option ( ENABLE_CLANG_ANALYSIS "When building with clang, enable the static anal
 option ( CHECK_CCACHE "Check if ccache is installed and use it" OFF )
 set ( MSVC_WARNING_LEVEL 3 CACHE STRING "Visual Studio warning levels" )
 option ( FORCE_INSTALL_DATA_TO_BIN "Force installation of data to binary directory" OFF )
-set ( DATADIR "" CACHE STRING "Where to place datafiles" )
+set ( DATADIR "" CACHE STRING "Where to search for datafiles" /)
 set ( OPENXCOM_VERSION_STRING "" CACHE STRING "Version string (after x.x)" )
 
 if ( CHECK_CCACHE )

README.md

@@ -104,6 +104,7 @@ User and Config folder:
 
 Data folders:
 - C:\Documents and Settings\\\<user\>\My Documents\OpenXcom\data (Windows 2000/XP)
+- DATADIR build flag
 - C:\Users\\\<user\>\Documents\OpenXcom\data (Windows Vista/7/8)
 - \<game directory\>
 - . (the current directory)
@@ -119,8 +120,9 @@ User and Config folder:
 Data folders:
 - $XDG\_DATA\_HOME/openxcom (if $XDG\_DATA\_HOME is defined)
 - $HOME/Library/Application Support/OpenXcom (if $XDG\_DATA\_HOME is not defined)
+- DATADIR build flag
 - $XDG\_DATA\_DIRS/openxcom (for each directory in $XDG\_DATA\_DIRS if $XDG\_DATA\_DIRS is defined)
-- /Users/Shared/OpenXcom
+- /Users/Shared/OpenXcom (if $XDG\_DATA\_DIRS is not defined or is empty)
 - . (the current directory)
 
 ### Linux
@@ -138,9 +140,11 @@ Config folder:
 Data folders:
 - $XDG\_DATA\_HOME/openxcom (if $XDG\_DATA\_HOME is defined)
 - $HOME/.local/share/openxcom (if $XDG\_DATA\_HOME is not defined)
+- DATADIR build flag
 - $XDG\_DATA\_DIRS/openxcom (for each directory in $XDG\_DATA\_DIRS if $XDG\_DATA\_DIRS is defined)
-- /usr/local/share/openxcom
-- /usr/share/openxcom
+- /usr/local/share/openxcom (if $XDG\_DATA\_DIRS is not defined or is empty)
+- /usr/share/openxcom (if $XDG\_DATA\_DIRS is not defined or is empty)
+- the directory data files were installed to
 - . (the current directory)
 
 ## Configuration

src/CMakeLists.txt

@@ -431,9 +431,12 @@ set ( openxcom_src ${root_src} ${basescape_src} ${battlescape_src} ${engine_src}
 set ( install_dest RUNTIME )
 set ( set_exec_path ON )
 set ( install_dest_dir bin )
+if ( NOT "${DATADIR}" STREQUAL "" )
+  add_definitions( -DDATADIR="${DATADIR}" )
+endif ()
 if ( UNIX AND NOT APPLE )
   set ( data_install_dir "${CMAKE_INSTALL_FULL_DATADIR}/openxcom" )
-  add_definitions( -DDATADIR="${data_install_dir}/" )
+  add_definitions( -DINSTALLDIR="${data_install_dir}/" )
 endif ()
 if ( APPLE )
   set ( sdl_src "${MACOS_SDLMAIN_M_PATH}" )
@@ -460,7 +463,7 @@ if ( APPLE )
     endif ()
   else ()
     set ( data_install_dir "${CMAKE_INSTALL_FULL_DATADIR}/openxcom" )
-    add_definitions( -DDATADIR="${data_install_dir}/" )
+    add_definitions( -DINSTALLDIR="${data_install_dir}/" )
   endif ()
 endif ()
 if ( set_exec_path )

src/Engine/CrossPlatform.cpp

@@ -173,7 +173,10 @@ std::vector<std::string> findDataFolders()
 		PathAppendA(path, "OpenXcom\\");
 		list.push_back(path);
 	}
-
+#ifdef DATADIR
+	snprintf(path, MAX_PATH, "%s\\", DATADIR);
+	list.push_back(path);
+#endif
 	// Get binary directory
 	if (GetModuleFileNameA(NULL, path, MAX_PATH) != 0)
 	{
@@ -210,9 +213,12 @@ std::vector<std::string> findDataFolders()
 #endif
  	}
  	list.push_back(path);
-
+#ifdef DATADIR
+	snprintp(path, MAXPATHLEN, "%s/" DATADIR);
+	list.push_back(path);
+#endif
 	// Get global data folders
-	if (char const *const xdg_data_dirs = getenv("XDG_DATA_DIRS"))
+	if (char const *const xdg_data_dirs = getenv("XDG_DATA_DIRS") && *xdg_data_dirs)
 	{
 		char xdg_data_dirs_copy[strlen(xdg_data_dirs)+1];
 		strcpy(xdg_data_dirs_copy, xdg_data_dirs);
@@ -224,16 +230,17 @@ std::vector<std::string> findDataFolders()
 			dir = strtok(0, ":");
 		}
 	}
+	else
+	{
 #ifdef __APPLE__
 	list.push_back("/Users/Shared/OpenXcom/");
 #else
 	list.push_back("/usr/local/share/openxcom/");
 	list.push_back("/usr/share/openxcom/");
-#ifdef DATADIR
-	snprintf(path, MAXPATHLEN, "%s/", DATADIR);
-	list.push_back(path);
 #endif
-
+#ifdef INSTALLDIR
+	snprintf(path, MAXPATHLEN, "%s", INSTALLDIR);
+	list.push_back(path);
 #endif
 	// Get working directory
 	list.push_back("./");