fix: read RetroArch's config under XDG_CONFIG_HOME

Native RetroArch on Linux keeps retroarch.cfg under $XDG_CONFIG_HOME/retroarch when the variable is set, and falls back to ~/.retroarch.cfg (file_path_special.c fill_pathname_application_data, configuration.c open_default_config_file at e98e1da0). Detection read ~/.config/retroarch only.

install.ps1

@@ -16,7 +16,7 @@
     # and Invoke-WebRequest throws on a cut transfer before the hash is read:
     # the site's build rewrites this line there (scripts/sitebootstrap.py).
     $mismatchAdvice = "The download was most likely cut short: try again. Within minutes of an update of this project the two files can come from caches of different ages. Waiting five minutes settles that."
-    $defaultInstallSha256 = "34fd006cc0456c61b9a621e52f35cee6d3fd55ff14bbc6cea207ddc7bc57d858"
+    $defaultInstallSha256 = "f48287847612b616bcaf607bd50207353bef5648e650a732c2d9595a64726ab0"
     $maximumInstallerBytes = 2MB
     $installerExit = 0
     $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }

install.py

@@ -291,7 +291,6 @@ def _os_default_dests(os_type: str) -> dict[str, Path]:
     the command line but not found must not land in ~/bios, which none of
     them reads.
     """
-    home = Path.home()
     if os_type == "windows":
         return {
             # RetroArch's system directory defaults to <exe folder>\system
@@ -307,13 +306,13 @@ def _os_default_dests(os_type: str) -> dict[str, Path]:
         # RetroArch may be the Linux one inside the distribution, while RetroBat
         # only exists on the Windows side, reached through /mnt/c.
         return {
-            "retroarch": home / ".config" / "retroarch" / "system",
+            "retroarch": _unix_retroarch_base() / "system",
             "retrobat": _host_path("C:/RetroBat/bios"),
         }
     if os_type == "darwin":
         return {"retroarch": _macos_retroarch_base() / "system"}
     return {
-        "retroarch": home / ".config" / "retroarch" / "system",
+        "retroarch": _unix_retroarch_base() / "system",
     }
 
 
@@ -1385,6 +1384,17 @@ def _macos_retroarch_base() -> Path:
     return Path.home() / "Documents" / "RetroArch"
 
 
+def _unix_retroarch_base() -> Path:
+    """RetroArch's base folder on Linux: $XDG_CONFIG_HOME/retroarch when the
+    variable is set, else ~/.config/retroarch (fill_pathname_application_data
+    in file_path_special.c, frontend_unix_get_env in platform_unix.c). The
+    code tests only that the variable exists, so an empty one counts."""
+    xdg = os.environ.get("XDG_CONFIG_HOME")
+    if xdg is not None:
+        return Path(xdg) / "retroarch"
+    return Path.home() / ".config" / "retroarch"
+
+
 # System directory -> the retroarch.cfg it was read from and the directory
 # ':' expands to there, for finding the cores of the same installation.
 _RETROARCH_CONFIGS: dict[Path, tuple[Path, Path]] = {}
@@ -2773,11 +2783,16 @@ def detect_platforms(os_type: str) -> list[tuple[str, Path]]:
         if ra_dir:
             found.append(("retroarch", ra_dir))
 
-        # RetroArch native
-        native_cfg = home / ".config" / "retroarch" / "retroarch.cfg"
-        ra_dir = _parse_retroarch_system_dir(native_cfg)
-        if ra_dir:
-            found.append(("retroarch", ra_dir))
+        # RetroArch native: the config under its base folder, then
+        # ~/.retroarch.cfg when that one is missing (open_default_config_file
+        # in configuration.c). Either way the system folder defaults to the
+        # base folder's.
+        native_base = _unix_retroarch_base()
+        for native_cfg in (native_base / "retroarch.cfg", home / ".retroarch.cfg"):
+            ra_dir = _parse_retroarch_system_dir(native_cfg, native_base)
+            if ra_dir:
+                found.append(("retroarch", ra_dir))
+                break
 
     if os_type == "darwin":
         # open_default_config_file reads <Application Support>/RetroArch/config

install.sh

@@ -23,7 +23,7 @@ DEFAULT_INSTALL_URL="https://raw.githubusercontent.com/Abdess/retrobios/main/ins
 # curl or wget stop on a cut transfer before the hash is read: the site's
 # build rewrites this line there (scripts/sitebootstrap.py).
 MISMATCH_ADVICE="The download was most likely cut short: try again. Within minutes of an update of this project the two files can come from caches of different ages. Waiting five minutes settles that."
-DEFAULT_INSTALL_SHA256="34fd006cc0456c61b9a621e52f35cee6d3fd55ff14bbc6cea207ddc7bc57d858"
+DEFAULT_INSTALL_SHA256="f48287847612b616bcaf607bd50207353bef5648e650a732c2d9595a64726ab0"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {

install/launchers/index.json

@@ -27,8 +27,8 @@
         {
           "dest": "roms/ports/retrobios/install.py",
           "repo_path": "install.py",
-          "size": 1103111,
-          "sha256": "34fd006cc0456c61b9a621e52f35cee6d3fd55ff14bbc6cea207ddc7bc57d858",
+          "size": 1103894,
+          "sha256": "f48287847612b616bcaf607bd50207353bef5648e650a732c2d9595a64726ab0",
           "executable": false
         },
         {
@@ -71,8 +71,8 @@
     "muos": {
       "archive": {
         "dest": "ARCHIVE/RetroBIOS.muxapp",
-        "size": 1156738,
-        "sha256": "35c0920008baadca997d0f778e99ce46d702bbe3d3f0d33104d7158422b292aa"
+        "size": 1157521,
+        "sha256": "0f9b070334a530a0ed5a6b6b773928d92f5a08aa0d0af18fde7b6cb4a16e731d"
       },
       "members": [
         {
@@ -92,8 +92,8 @@
         {
           "name": "RetroBIOS/install.py",
           "repo_path": "install.py",
-          "size": 1103111,
-          "sha256": "34fd006cc0456c61b9a621e52f35cee6d3fd55ff14bbc6cea207ddc7bc57d858",
+          "size": 1103894,
+          "sha256": "f48287847612b616bcaf607bd50207353bef5648e650a732c2d9595a64726ab0",
           "executable": false
         },
         {
@@ -166,8 +166,8 @@
         {
           "dest": ".config/modules/retrobios/install.py",
           "repo_path": "install.py",
-          "size": 1103111,
-          "sha256": "34fd006cc0456c61b9a621e52f35cee6d3fd55ff14bbc6cea207ddc7bc57d858",
+          "size": 1103894,
+          "sha256": "f48287847612b616bcaf607bd50207353bef5648e650a732c2d9595a64726ab0",
           "executable": false
         },
         {

install/retroarch.json

@@ -21,12 +21,24 @@
       "config": "$HOME/snap/retroarch/current/.config/retroarch/retroarch.cfg",
       "parse_key": "system_directory"
     },
+    {
+      "os": "linux",
+      "method": "config_file",
+      "config": "$XDG_CONFIG_HOME/retroarch/retroarch.cfg",
+      "parse_key": "system_directory"
+    },
     {
       "os": "linux",
       "method": "config_file",
       "config": "$HOME/.config/retroarch/retroarch.cfg",
       "parse_key": "system_directory"
     },
+    {
+      "os": "linux",
+      "method": "config_file",
+      "config": "$HOME/.retroarch.cfg",
+      "parse_key": "system_directory"
+    },
     {
       "os": "darwin",
       "method": "config_file",

platforms/_registry.yml

@@ -219,10 +219,23 @@ platforms:
         method: config_file
         config: $HOME/snap/retroarch/current/.config/retroarch/retroarch.cfg
         parse_key: system_directory
+      # Native: $XDG_CONFIG_HOME/retroarch when the variable is set, else
+      # $HOME/.config/retroarch, then $HOME/.retroarch.cfg when that file is
+      # missing (file_path_special.c fill_pathname_application_data,
+      # configuration.c open_default_config_file). A value left at default
+      # is the system folder of the first of the two folders.
+      - os: linux
+        method: config_file
+        config: $XDG_CONFIG_HOME/retroarch/retroarch.cfg
+        parse_key: system_directory
       - os: linux
         method: config_file
         config: $HOME/.config/retroarch/retroarch.cfg
         parse_key: system_directory
+      - os: linux
+        method: config_file
+        config: $HOME/.retroarch.cfg
+        parse_key: system_directory
       # configuration.c reads <Application Support>/RetroArch/config, and a value
       # left at default is ~/Documents/RetroArch/system (platform_darwin.m).
       # Older builds kept the file one level up.

tests/test_install.py

@@ -2646,6 +2646,52 @@ class RetroArchWhereItReallyLives(unittest.TestCase):
             self.assertIn(("retroarch", support / "system"), found)
 
 
+class LinuxRetroArchFollowsXdgConfigHome(unittest.TestCase):
+    """RetroArch on Linux keeps its config under $XDG_CONFIG_HOME/retroarch
+    when the variable is set, then falls back to ~/.retroarch.cfg
+    (file_path_special.c fill_pathname_application_data, configuration.c
+    open_default_config_file). Only ~/.config/retroarch was read: a home
+    with its own XDG layout detected nothing."""
+
+    def _env(self) -> tuple[Path, Path]:
+        home = Path(_tempdir(self))
+        xdg = Path(_tempdir(self))
+        patcher = unittest.mock.patch.dict(os.environ, {"HOME": str(home)}, clear=True)
+        patcher.start()
+        self.addCleanup(patcher.stop)
+        return home, xdg
+
+    def test_the_config_under_xdg_config_home_is_read(self):
+        home, xdg = self._env()
+        (xdg / "retroarch").mkdir()
+        (xdg / "retroarch" / "retroarch.cfg").write_text('system_directory = "/srv/bios"\n')
+        # A config under ~/.config is not the one this RetroArch opens.
+        (home / ".config" / "retroarch").mkdir(parents=True)
+        (home / ".config" / "retroarch" / "retroarch.cfg").write_text(
+            'system_directory = "/elsewhere"\n')
+        os.environ["XDG_CONFIG_HOME"] = str(xdg)
+        found = install.detect_platforms("linux")
+        self.assertIn(("retroarch", Path("/srv/bios")), found)
+        self.assertNotIn(("retroarch", Path("/elsewhere")), found)
+        self.assertEqual(install._os_default_dests("linux")["retroarch"],
+                         xdg / "retroarch" / "system")
+
+    def test_home_retroarch_cfg_is_the_fallback(self):
+        home, xdg = self._env()
+        os.environ["XDG_CONFIG_HOME"] = str(xdg)
+        (home / ".retroarch.cfg").write_text('system_directory = "default"\n')
+        found = install.detect_platforms("linux")
+        self.assertIn(("retroarch", xdg / "retroarch" / "system"), found)
+
+    def test_without_the_variable_the_folder_is_under_dot_config(self):
+        home, _ = self._env()
+        (home / ".config" / "retroarch").mkdir(parents=True)
+        (home / ".config" / "retroarch" / "retroarch.cfg").write_text(
+            'system_directory = "default"\n')
+        found = install.detect_platforms("linux")
+        self.assertIn(("retroarch", home / ".config" / "retroarch" / "system"), found)
+
+
 class NoPythonNamesThisSystemsCommand(unittest.TestCase):
     """Without Python the bootstrap said `sudo apt install python3` on every
     system: Termux has no sudo and installs with `pkg install python`, and