feat: find RetroBat through the folder it records

RetroBat.exe writes its folder to HKCU\SOFTWARE\RetroBat
LatestKnownInstallPath on every start (retrobat-executable 702da66a,
Program.cs:57 and 99, RegistryTools.cs:15-50). Only C:\RetroBat and the
profile folder were looked at, so an install on D: was missed and a forced
--platform retrobat wrote into C:\RetroBat\bios. The value is read
through winreg, or reg.exe under WSL, before the fixed folders.

install.ps1

@@ -11,7 +11,7 @@
 
     $ErrorActionPreference = "Stop"
     $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-    $defaultInstallSha256 = "caec72e5ebd146509e3b1fabc7d8d4c5c921567592d6d1581df6e5cc50f3e96f"
+    $defaultInstallSha256 = "f05f862fcebc16e99d692a20a09163665828ea0383643fcc96a41b11d77fcff7"
     $maximumInstallerBytes = 2MB
     $installerExit = 0
     $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }

install.py

@@ -1092,6 +1092,64 @@ def _detect_by_executable(os_type: str, found: list[tuple[str, Path]]) -> None:
             found.append((platform_name, newest.parent / subdir))
 
 
+# The registry's registry rules: (os, platform, key, value, BIOS folder under
+# the folder the value names). RetroBat.exe writes its own folder there on
+# every start (retrobat-executable 702da66a, RetroBat/RetroBat/Program.cs:57
+# and 99, RegistryTools.cs:15-50), wherever it was installed. The path rules
+# only knew C:\RetroBat and the profile folder.
+_REGISTRY_RULES: tuple[tuple[str, str, str, str, str], ...] = (
+    ("windows", "retrobat", "HKCU\\SOFTWARE\\RetroBat", "LatestKnownInstallPath", "bios"),
+)
+
+
+def _read_registry(key: str, value: str) -> str | None:
+    """A string value of the Windows registry, read natively or, under WSL,
+    through reg.exe. None when the key, the value or the means is missing."""
+    if os.name == "nt":
+        import winreg  # noqa: PLC0415
+
+        hive, _, subkey = key.partition("\\")
+        roots = {"HKCU": winreg.HKEY_CURRENT_USER, "HKLM": winreg.HKEY_LOCAL_MACHINE}
+        try:
+            with winreg.OpenKey(roots[hive], subkey) as handle:
+                data, _kind = winreg.QueryValueEx(handle, value)
+        except (OSError, KeyError):
+            return None
+        return data.strip() if isinstance(data, str) and data.strip() else None
+    if not _WSL["active"]:
+        return None
+    try:
+        result = subprocess.run(
+            ["reg.exe", "query", key, "/v", value],
+            capture_output=True, text=True, errors="replace", timeout=10,
+            stdin=subprocess.DEVNULL, cwd="/mnt/c" if Path("/mnt/c").is_dir() else None,
+        )
+    except (OSError, subprocess.SubprocessError):
+        return None
+    match = re.search(
+        rf"^\s*{re.escape(value)}\s+REG_(?:EXPAND_)?SZ\s+(.+?)\s*$", result.stdout, re.M
+    )
+    return match.group(1) if match else None
+
+
+def _detect_by_registry(os_type: str, found: list[tuple[str, Path]]) -> None:
+    """Add a platform whose own program names its folder in the registry.
+
+    A folder since moved or removed is passed over, so the path rules still
+    get their turn.
+    """
+    systems = ("windows",) if os_type in ("windows", "wsl") else ()
+    for rule_os, platform_name, key, value, subdir in _REGISTRY_RULES:
+        if rule_os not in systems or any(name == platform_name for name, _ in found):
+            continue
+        folder = _read_registry(key, value)
+        if not folder:
+            continue
+        base = _host_path(folder.rstrip("\\/") or folder)
+        if base.is_dir():
+            found.append((platform_name, base / subdir))
+
+
 def _detect_by_path(os_type: str, found: list[tuple[str, Path]]) -> None:
     """Add what a registry path rule finds, for a platform not found yet."""
     systems = ("linux", "windows") if os_type == "wsl" else (os_type,)
@@ -1239,6 +1297,7 @@ def detect_platforms(os_type: str) -> list[tuple[str, Path]]:
             found.append(("bizhawk", bizhawk))
 
     _detect_by_executable(os_type, found)
+    _detect_by_registry(os_type, found)
     _detect_by_path(os_type, found)
     return found
 

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="caec72e5ebd146509e3b1fabc7d8d4c5c921567592d6d1581df6e5cc50f3e96f"
+DEFAULT_INSTALL_SHA256="f05f862fcebc16e99d692a20a09163665828ea0383643fcc96a41b11d77fcff7"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {

platforms/_registry.yml

@@ -351,6 +351,14 @@ platforms:
     target_source: null
     install:
       detect:
+      # RetroBat.exe writes its own folder there on every start, wherever it
+      # was installed (retrobat-executable 702da66a,
+      # RetroBat/RetroBat/Program.cs:57 and 99, RegistryTools.cs:15-50).
+      - os: windows
+        method: registry
+        key: 'HKCU\SOFTWARE\RetroBat'
+        value: LatestKnownInstallPath
+        bios_subdir: bios
       # installer.iss: DefaultDirName=C:\RetroBat, the first place to look.
       - os: windows
         method: path_exists

tests/test_install.py

@@ -3800,5 +3800,52 @@ class ANetworkFailureNamesTheNetwork(unittest.TestCase):
         self.assertNotIn("being written to", text)
 
 
+class RetroBatIsFoundWhereItSaysItIs(unittest.TestCase):
+    """RetroBat on D:\\RetroBat was not detected, and --platform retrobat
+    wrote 7.6 GB into C:\\RetroBat\\bios, a folder it does not read.
+    RetroBat.exe writes its folder to the registry on every start."""
+
+    def test_the_table_is_the_registry(self):
+        import yaml  # noqa: PLC0415
+
+        registry = yaml.safe_load((REPO_ROOT / "platforms" / "_registry.yml").read_text())
+        rules = {
+            (rule["os"], name, rule["key"], rule["value"], rule["bios_subdir"])
+            for name, entry in registry["platforms"].items()
+            for rule in (entry.get("install") or {}).get("detect", [])
+            if rule["method"] == "registry"
+        }
+        self.assertEqual(set(install._REGISTRY_RULES), rules)
+
+    def test_the_registry_folder_wins_over_the_default(self):
+        folder = Path(_tempdir(self))
+        with unittest.mock.patch.object(install, "_read_registry",
+                                        return_value=str(folder) + "\\"):
+            found: list = []
+            install._detect_by_registry("windows", found)
+        self.assertEqual(found, [("retrobat", folder / "bios")])
+
+    def test_a_folder_since_removed_is_passed_over(self):
+        gone = Path(_tempdir(self)) / "moved"
+        with unittest.mock.patch.object(install, "_read_registry", return_value=str(gone)):
+            found: list = []
+            install._detect_by_registry("windows", found)
+        self.assertEqual(found, [])
+
+    def test_wsl_reads_it_through_reg_exe(self):
+        output = ("\nHKEY_CURRENT_USER\\SOFTWARE\\RetroBat\n"
+                  "    LatestKnownInstallPath    REG_SZ    D:\\Games\\RetroBat\\\n\n")
+        with unittest.mock.patch.dict(install._WSL, {"active": True, "root": "/mnt"}), \
+                unittest.mock.patch.object(install.os, "name", "posix"), \
+                unittest.mock.patch.object(
+                    install.subprocess, "run",
+                    return_value=SimpleNamespace(stdout=output, returncode=0)) as run:
+            value = install._read_registry("HKCU\\SOFTWARE\\RetroBat", "LatestKnownInstallPath")
+            self.assertEqual(value, "D:\\Games\\RetroBat\\")
+            self.assertEqual(install._host_path(value.rstrip("\\")),
+                             Path("/mnt/d/Games/RetroBat"))
+        self.assertEqual(run.call_args[0][0][:2], ["reg.exe", "query"])
+
+
 if __name__ == "__main__":
     unittest.main()

wiki/installer.md

@@ -318,6 +318,7 @@ WSL does not pass them. A forced `--platform retrobat` falls back to
 
 | Evidence | Platform | BIOS directory |
 |----------|----------|----------------|
+| `HKCU\SOFTWARE\RetroBat` `LatestKnownInstallPath`, which `RetroBat.exe` writes on every start (read through `reg.exe` under WSL) | RetroBat | that folder + `\bios`, before the fixed folders above |
 | `~/.config/EmuDeck/settings.sh` | EmuDeck | `emulationPath` + `/bios` |
 | `%APPDATA%\EmuDeck\settings.ps1` | EmuDeck | `$emulationPath` + `\bios` |
 | `~/.var/app/net.retrodeck.retrodeck/config/retrodeck/retrodeck.json` | RetroDECK | `paths.rd_home_path`, falling back to the pre-migration `retrodeck.cfg` and its `rdhome` |