Different approach, patch in default ini search path

README.md

@@ -30,6 +30,9 @@ An explanation for some of the options included in the `org.mamedev.MAME.yaml' m
 
 Currently these are the patches applied:
 
+`inipath.patch` default ini paths include the home '~/.mame' directory and two relative paths '.' and 'ini'.  The relative paths are not helpful inside the sandbox, and the '~/.mame' contents shouldn't be overwritten with each new MAME release.  Instead the default ini search path is patched to '$HOME/.mame;/app/share/mame/ini'.  This will allow a default base ini in '/app/share/mame/ini/mame.ini' and can be overridden in '~/.mame/mame.ini'.
+
 `ldopts.patch` enables an option for the linker to strip debug symbols.
 
 `use-system-lib-flac.patch` works around FORTIFY_SOURCE compiler option that causes errors in the included libflac.
+

inipath.patch

@@ -0,0 +1,13 @@
+diff --git a/src/osd/sdl/sdlmain.cpp b/src/osd/sdl/sdlmain.cpp
+index f238c7bd..dd6f2e4f 100644
+--- a/src/osd/sdl/sdlmain.cpp
++++ b/src/osd/sdl/sdlmain.cpp
+@@ -58,7 +58,7 @@
+ #elif defined(SDLMAME_MACOSX)
+ 	#define INI_PATH "$HOME/Library/Application Support/APP_NAME;$HOME/.APP_NAME;.;ini"
+ #else
+-	#define INI_PATH "$HOME/.APP_NAME;.;ini"
++	#define INI_PATH "$HOME/.APP_NAME;/app/share/APP_NAME/ini"
+ #endif // MACOSX
+ #endif // INI_PATH
+ 

mame.ini

@@ -0,0 +1,33 @@
+#
+# CORE SEARCH PATH OPTIONS
+#
+homepath                  $HOME/.mame
+rompath                   /app/share/mame/roms
+hashpath                  /app/share/mame/hash
+samplepath                /app/share/mame/samples
+artpath                   /app/share/mame/artwork
+ctrlrpath                 /app/share/mame/ctrlr
+inipath                   $HOME/.mame;/app/share/mame/ini
+fontpath                  /app/bin/
+cheatpath                 /app/share/mame/cheat
+crosshairpath             /app/share/mame/crosshair
+pluginspath               /app/share/mame/plugins
+languagepath              /app/share/mame/language
+swpath                    /app/share/mame/software
+
+#
+# CORE OUTPUT DIRECTORY OPTIONS
+#
+cfg_directory             $HOME/.mame/cfg
+nvram_directory           $HOME/.mame/nvram
+input_directory           $HOME/.mame/inp
+state_directory           $HOME/.mame/sta
+snapshot_directory        $HOME/.mame/snap
+diff_directory            $HOME/.mame/diff
+comment_directory         $HOME/.mame/comments
+share_directory           $HOME/.mame/share
+
+#
+# OSD VIDEO OPTIONS
+#
+video                     opengl

org.mamedev.MAME.yaml

@@ -39,6 +39,7 @@ modules:
       - cp -r hash/ ${FLATPAK_DEST}/share/mame/
       - cp -r hlsl/ ${FLATPAK_DEST}/share/mame/
       - cp -r ini/ ${FLATPAK_DEST}/share/mame/
+      - install -Dm 0644 mame.ini ${FLATPAK_DEST}/share/mame/ini/mame.ini
       - cp -r language/ ${FLATPAK_DEST}/share/mame/
       - cp -r plugins/ ${FLATPAK_DEST}/share/mame/
       - cp -r roms/ ${FLATPAK_DEST}/share/mame/
@@ -53,7 +54,11 @@ modules:
         path: org.mamedev.MAME.desktop
       - type: file
         path: org.mamedev.MAME.metainfo.xml
+      - type: file
+        path: mame.ini
       - type: patch
-        path: use-system-lib-flac.patch
+        path: inipath.patch
       - type: patch
         path: ldopts.patch
+      - type: patch
+        path: use-system-lib-flac.patch