feat: name Android BIOS folders out of reach

DraStic keeps its BIOS in its private data and Flycast in Android/data,
which Termux cannot write on Android 11 and later. An installed one is now
named with the files not copied, and a writable Flycast folder is a
standalone copy target.

install.ps1

@@ -11,7 +11,7 @@
 
     $ErrorActionPreference = "Stop"
     $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-    $defaultInstallSha256 = "956eba5f9d01138abda5550973810ccdc1138daa54c9065bf3f04cc0ba051468"
+    $defaultInstallSha256 = "6ae8bdd7bbe9a0c3e6cb2d92947bb4e135e38d6446d206ae30b988a045eaa536"
     $maximumInstallerBytes = 2MB
     $installerExit = 0
     $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }

install.py

@@ -1199,6 +1199,46 @@ def _detect_android() -> list[tuple[str, Path]]:
     return found
 
 
+# Android emulators that keep their BIOS outside RetroArch's folder:
+# (name, package, folder, files read there). DraStic keeps it in its private
+# data (GammaOS Next 14 bb28e71d, gammaos/setup.sh:345-363 extracts it to
+# /data/data/com.dsemu.drastic/files/DraStic/system), which no other app
+# writes without root. Flycast reads <home>/data/ (flycast a9bd1c74,
+# shell/android-studio/flycast/src/main/jni/src/Android.cpp:143-159), its
+# home being Android/data/com.flycast.emulator/files, which Android 11 and
+# later keep from other apps.
+ANDROID_APP_DATA = Path("/data/data")
+_ANDROID_APP_FOLDERS = (
+    ("DraStic", "com.dsemu.drastic", "/data/data/com.dsemu.drastic/files/DraStic/system",
+     ("nds_bios_arm7.bin", "nds_bios_arm9.bin", "nds_firmware.bin")),
+    ("Flycast", "com.flycast.emulator",
+     "$STORAGE/Android/data/com.flycast.emulator/files/data",
+     ("dc_boot.bin", "dc_nvmem.bin")),
+)
+
+
+def android_unreachable_folders() -> list[str]:
+    """A line for each Android emulator installed here whose BIOS folder
+    this shell cannot write, said instead of skipping it in silence.
+
+    An app's private folder can be tested for existence by any app, so the
+    emulator is known to be installed even where its folder is out of reach.
+    """
+    lines = []
+    storage = str(_android_storage_root())
+    for name, package, folder, files in _ANDROID_APP_FOLDERS:
+        target = Path(folder.replace("$STORAGE", storage, 1))
+        if folder.startswith("/data/data/"):
+            target = ANDROID_APP_DATA / Path(folder).relative_to("/data/data")
+        if not (ANDROID_APP_DATA / package).exists() and not target.exists():
+            continue
+        if target.is_dir() and os.access(target, os.W_OK):
+            continue
+        lines.append(f"{name} is installed, but this shell cannot write its BIOS folder "
+                     f"{target} without root: {', '.join(files)} are not copied there.")
+    return lines
+
+
 def _lnk_target(lnk_path: Path, exe_name: str) -> Path | None:
     """Read the target path of a Windows shortcut.
 
@@ -1539,6 +1579,8 @@ def detect_platforms(os_type: str) -> list[tuple[str, Path]]:
 
     if os_type == "android":
         found.extend(_detect_android())
+        for line in android_unreachable_folders():
+            print(line, file=sys.stderr)
 
     if os_type in ("linux", "wsl"):
         found.extend(_detect_embedded())

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="956eba5f9d01138abda5550973810ccdc1138daa54c9065bf3f04cc0ba051468"
+DEFAULT_INSTALL_SHA256="6ae8bdd7bbe9a0c3e6cb2d92947bb4e135e38d6446d206ae30b988a045eaa536"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {

platforms/_registry.yml

@@ -158,6 +158,10 @@ _standalone_copies: &standalone_copies
       # shell/apple/emulator-osx/emulator-osx/osx-main.mm:83-101 (flycast 6bb0fc3e).
       darwin:
       - $HOME/Library/Application Support/Flycast/data
+      # <home>/data/ (shell/android-studio/flycast/src/main/jni/src/Android.cpp:
+      # 143-159, flycast a9bd1c74), writable from Termux up to Android 10.
+      android:
+      - $EXTERNAL_STORAGE/Android/data/com.flycast.emulator/files/data
   - file: dc/dc_nvmem.bin
     targets:
       linux:
@@ -168,6 +172,10 @@ _standalone_copies: &standalone_copies
       # shell/apple/emulator-osx/emulator-osx/osx-main.mm:83-101 (flycast 6bb0fc3e).
       darwin:
       - $HOME/Library/Application Support/Flycast/data
+      # <home>/data/ (shell/android-studio/flycast/src/main/jni/src/Android.cpp:
+      # 143-159, flycast a9bd1c74), writable from Termux up to Android 10.
+      android:
+      - $EXTERNAL_STORAGE/Android/data/com.flycast.emulator/files/data
 
 platforms:
   retroarch:

tests/test_install.py

@@ -2724,6 +2724,57 @@ class AndroidCitationsNameTheRelease(unittest.TestCase):
             self.assertNotIn("2836-2851", text)
 
 
+class AndroidEmulatorsOutOfReachAreSaid(unittest.TestCase):
+    """DraStic keeps its BIOS in its private data and Flycast in
+    Android/data, which Termux cannot write on Android 11 and later: both
+    were skipped without a word."""
+
+    def _lines(self, make) -> list[str]:
+        root = Path(_tempdir(self))
+        app_data, storage = root / "data", root / "storage"
+        app_data.mkdir()
+        make(app_data, storage)
+        with unittest.mock.patch.object(install, "ANDROID_APP_DATA", app_data), \
+                unittest.mock.patch.dict(os.environ, {"EXTERNAL_STORAGE": str(storage)}):
+            return install.android_unreachable_folders()
+
+    def test_nothing_installed_says_nothing(self):
+        self.assertEqual(self._lines(lambda data, storage: None), [])
+
+    def test_an_installed_drastic_is_named(self):
+        lines = self._lines(lambda data, storage: (data / "com.dsemu.drastic").mkdir())
+        self.assertEqual(len(lines), 1)
+        self.assertIn("DraStic is installed", lines[0])
+        self.assertIn("nds_bios_arm7.bin", lines[0])
+
+    def test_flycast_out_of_reach_is_named(self):
+        lines = self._lines(lambda data, storage: (data / "com.flycast.emulator").mkdir())
+        self.assertEqual(len(lines), 1)
+        self.assertIn("Flycast is installed", lines[0])
+        self.assertIn("dc_boot.bin", lines[0])
+
+    def test_a_writable_flycast_folder_is_a_copy_target(self):
+        def make(data, storage):
+            (data / "com.flycast.emulator").mkdir()
+            (storage / "Android/data/com.flycast.emulator/files/data").mkdir(parents=True)
+        self.assertEqual(self._lines(make), [])
+        import yaml  # noqa: PLC0415
+
+        registry = yaml.safe_load((REPO_ROOT / "platforms" / "_registry.yml").read_text())
+        copies = {entry.get("file"): entry for entry in registry["_standalone_copies"]}
+        self.assertEqual(copies["dc/dc_boot.bin"]["targets"]["android"],
+                         ["$EXTERNAL_STORAGE/Android/data/com.flycast.emulator/files/data"])
+
+    def test_detection_prints_them(self):
+        err = io.StringIO()
+        with unittest.mock.patch.object(install, "_detect_android", return_value=[]), \
+                unittest.mock.patch.object(install, "android_unreachable_folders",
+                                           return_value=["DraStic is installed, but"]), \
+                contextlib.redirect_stderr(err):
+            install.detect_platforms("android")
+        self.assertIn("DraStic is installed", err.getvalue())
+
+
 class TheBoardTheSystemNamesIsTheTarget(unittest.TestCase):
     """Batocera, Recalbox and ROCKNIX each write the board they were built
     for, but the installer read none of them, so a Batocera RPi4 installed

wiki/installer.md

@@ -504,7 +504,16 @@ left at `default` resolves against `<shared storage>/RetroArch`, where the
 directory also sits when no config has been written yet
 (`platform_unix.c:1670-1697`).
 
-Under scoped storage those two config paths are unreadable from Termux on
+Two Android emulators keep their BIOS elsewhere. DraStic reads
+`/data/data/com.dsemu.drastic/files/DraStic/system`, private to the app, and
+Flycast reads `Android/data/com.flycast.emulator/files/data` in shared
+storage, which Android 11 and later keep from other apps. No app can write
+the first without root, and Termux cannot write the second on Android 11 and
+later. When either emulator is installed and its folder is out of reach, the
+run names it and the files that are not copied. Where the Flycast folder is
+writable (Android 10 and earlier), it is a standalone copy target.
+
+Under scoped storage the two RetroArch config paths are unreadable from Termux on
 Android 11 and later, so on current devices the shared directory is what
 answers. Running `termux-setup-storage` once is what makes it reachable: