fix: find RetroArch in Steam libraries and ES-DE

The installer looked for retroarch.exe in C:\RetroArch-Win64 and
Program Files\RetroArch only, so a RetroArch under Program Files\
RetroArch-Win64, in a Steam library on another drive, or in an
installed ES-DE's Emulators folder went undetected. All three are
searched; Steam libraries come from Steam's own library list.

install.ps1

@@ -8,7 +8,7 @@ param(
 
 $ErrorActionPreference = "Stop"
 $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-$defaultInstallSha256 = "973e116ab59e233cd4fe5ebb77d4973bc06013b22b6388e80d12fa1d61fb0c73"
+$defaultInstallSha256 = "bfc3a2127689147e8a5f729a9ed668608f06dbd3b14ca6e768cdf2a7f90d5d32"
 $maximumInstallerBytes = 2MB
 $installerExit = 0
 $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }

install.py

@@ -457,14 +457,51 @@ def _retroarch_cfg_dir(
     return None
 
 
+def _steam_libraries() -> list[Path]:
+    """Every Steam library, the default one first.
+
+    Steam lists the others in steamapps/libraryfolders.vdf, each as a
+    "path" line; a RetroArch installed on D:/SteamLibrary was not found
+    when only Program Files was searched.
+    """
+    roots: list[Path] = []
+    for var in ("ProgramFiles(x86)", "ProgramFiles"):
+        base = os.environ.get(var, "")
+        if base and (Path(base) / "Steam").is_dir():
+            roots.append(Path(base) / "Steam")
+    libraries = list(roots)
+    for root in roots:
+        vdf = root / "steamapps" / "libraryfolders.vdf"
+        try:
+            text = vdf.read_text(encoding="utf-8", errors="replace")
+        except OSError:
+            continue
+        for raw in re.findall(r'"path"\s+"([^"]+)"', text):
+            library = Path(raw.replace("\\\\", "\\"))
+            if library not in libraries:
+                libraries.append(library)
+    return libraries
+
+
 def _windows_retroarch_dirs() -> list[Path]:
-    """Folders holding retroarch.exe where the installer and the archive put
-    it: C:/RetroArch-Win64 by default, C:/RetroArch for 32-bit builds."""
+    """Folders holding retroarch.exe where its installers put it.
+
+    C:/RetroArch-Win64 by default, C:/RetroArch for 32-bit builds, the same
+    names under Program Files, every Steam library, and the Emulators folder
+    of an installed ES-DE (es_find_rules.xml lists all of them).
+    """
     candidates = [Path("C:/RetroArch-Win64"), Path("C:/RetroArch")]
     for var in ("ProgramFiles", "ProgramFiles(x86)"):
         root = os.environ.get(var, "")
         if root:
-            candidates.append(Path(root) / "RetroArch")
+            candidates += [Path(root) / "RetroArch-Win64", Path(root) / "RetroArch"]
+            candidates += [
+                Path(root) / "ES-DE" / "Emulators" / name
+                for name in ("RetroArch-Win64", "RetroArch")
+            ]
+    candidates += [
+        library / "steamapps" / "common" / "RetroArch" for library in _steam_libraries()
+    ]
     return [folder for folder in candidates if (folder / "retroarch.exe").is_file()]
 
 

install.sh

@@ -18,7 +18,7 @@ esac
 TEMP_INSTALLER=""
 TEMP_DIRECTORY=""
 DEFAULT_INSTALL_URL="https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-DEFAULT_INSTALL_SHA256="973e116ab59e233cd4fe5ebb77d4973bc06013b22b6388e80d12fa1d61fb0c73"
+DEFAULT_INSTALL_SHA256="bfc3a2127689147e8a5f729a9ed668608f06dbd3b14ca6e768cdf2a7f90d5d32"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {

tests/test_install.py

@@ -970,6 +970,49 @@ class DetectionFollowsTheRegistry(unittest.TestCase):
         self.assertEqual(found, [("emudeck", home / "elsewhere" / "bios")])
 
 
+class RetroArchIsFoundWhereWindowsInstallsPutIt(unittest.TestCase):
+    """Program Files\\RetroArch-Win64, a Steam library on another drive and
+    an installed ES-DE's Emulators folder all held a RetroArch the one-liner
+    reported as "no supported platform detected"."""
+
+    def _env(self, program_files: Path) -> None:
+        patcher = unittest.mock.patch.dict(
+            os.environ, {"ProgramFiles": str(program_files), "ProgramFiles(x86)": ""}
+        )
+        patcher.start()
+        self.addCleanup(patcher.stop)
+
+    @staticmethod
+    def _exe(folder: Path) -> Path:
+        folder.mkdir(parents=True)
+        (folder / "retroarch.exe").write_bytes(b"MZ")
+        return folder
+
+    def test_program_files_win64(self):
+        program_files = Path(_tempdir(self))
+        self._env(program_files)
+        found = self._exe(program_files / "RetroArch-Win64")
+        self.assertIn(found, install._windows_retroarch_dirs())
+
+    def test_a_steam_library_on_another_drive(self):
+        program_files = Path(_tempdir(self))
+        library = Path(_tempdir(self))
+        steamapps = program_files / "Steam" / "steamapps"
+        steamapps.mkdir(parents=True)
+        (steamapps / "libraryfolders.vdf").write_text(
+            '"libraryfolders"\n{\n\t"1"\n\t{\n\t\t"path"\t\t"' + str(library) + '"\n\t}\n}\n'
+        )
+        self._env(program_files)
+        found = self._exe(library / "steamapps" / "common" / "RetroArch")
+        self.assertIn(found, install._windows_retroarch_dirs())
+
+    def test_an_installed_es_de(self):
+        program_files = Path(_tempdir(self))
+        self._env(program_files)
+        found = self._exe(program_files / "ES-DE" / "Emulators" / "RetroArch-Win64")
+        self.assertIn(found, install._windows_retroarch_dirs())
+
+
 class InstallerStaysOnPython38AndTheStdlib(unittest.TestCase):
     """install.py runs where the bootstraps let it run: Python 3.8, stdlib only.