fix: say why detection cannot look, then go on

HOME kept across su without - made every detection probe raise PermissionError, and the run and the interface ended on a traceback. Detection now finds nothing there, says which folder this user cannot open and how to go on, on the first screen too.

install.ps1

@@ -11,7 +11,7 @@
 
     $ErrorActionPreference = "Stop"
     $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-    $defaultInstallSha256 = "bf5fd291aeffd7759153f2cfc168ef153a8806e20d708b00e5287fdd63036b20"
+    $defaultInstallSha256 = "04070f071adf988291854cf4ad8fb6e7a34f8044cfbcb710ba660863c2c6b19e"
     $maximumInstallerBytes = 2MB
     $installerExit = 0
     $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }

install.py

@@ -1922,6 +1922,36 @@ def launchbox_bios_dirs(root: Path) -> dict[str, Path]:
     return dirs
 
 
+_DETECTION_REFUSED: list[str] = []
+
+
+def _detection_guarded(detect: Callable[..., list]) -> Callable[..., list]:
+    """Detection that finds nothing, and says why once, where this user
+    cannot look.
+
+    HOME kept across `su` without `-`: every probe of a config under it
+    raised PermissionError, and the run ended on a traceback before its
+    first line. A named --dest still installs.
+    """
+    def guarded(*args: object, **kwargs: object) -> list:
+        try:
+            return detect(*args, **kwargs)
+        except PermissionError as exc:
+            closed = closed_folder(Path(exc.filename)) if exc.filename else None
+            folder, why = closed or (Path(str(exc.filename or "")), exc.strerror or str(exc))
+            words = (f"Could not look for setups: this user cannot open {folder} ({why}). "
+                     "Run as its owner (su - or sudo -H), or name the BIOS folder "
+                     "with --dest.")
+            if words not in _DETECTION_REFUSED:
+                _DETECTION_REFUSED.append(words)
+                print(f"  {screen_text(words)}", file=sys.stderr)
+            return []
+    guarded.__doc__ = detect.__doc__
+    guarded.__name__ = detect.__name__
+    return guarded
+
+
+@_detection_guarded
 def detect_frontends(os_type: str, home: Path | None = None) -> list[str]:
     """Detect frontends that reference emulators without owning a BIOS dir.
 
@@ -2072,6 +2102,7 @@ def _detect_by_path(os_type: str, found: list[tuple[str, Path]]) -> None:
             found.append((platform_name, _rule_path(bios or path)))
 
 
+@_detection_guarded
 def detect_platforms(os_type: str) -> list[tuple[str, Path]]:
     """Detect installed emulator platforms and their BIOS directories."""
     found: list[tuple[str, Path]] = []
@@ -11838,8 +11869,9 @@ def _view_setup(state: TuiState, width: int, height: int) -> tuple:
     after = ([f"BIOS folder: {state.setups[focus.value][1]}"]
              if focus.action == "setup" else [])
     before = ["Found on this machine:" if state.setups else "Nothing was found here."]
+    status = [state.status] if state.status else []
     return ("Where do you play?",
-            _compose(state, width, height, before, rows, after + state.notes),
+            _compose(state, width, height, before, rows, after + status + state.notes),
             ("A/Enter Continue", "B/Esc Quit", "? Help"))
 
 
@@ -11853,6 +11885,7 @@ def _view_platforms(state: TuiState, width: int, height: int) -> tuple:
         before = ["Choose the setup that will use the BIOS files."]
     needle = state.filters.get("platforms", "")
     after = [f"No setup matches '{needle}'."] if len(rows) == 1 and needle else []
+    after += [state.status] if state.status else []
     return (title, _compose(state, width, height, before, rows, after),
             ("A/Enter Choose", "B/Esc Back", "/ Filter", "? Help"))
 
@@ -12576,6 +12609,9 @@ def tui_start(
             found = detect_platforms(os_type)
             frontends = detect_frontends(os_type)
             cards = [(card_system(mount), mount) for mount in _mounted_cards()]
+        if _DETECTION_REFUSED:
+            # Said on the normal screen before this one covered it.
+            state.status = _DETECTION_REFUSED[0]
         state.setups = [(name, path, _setup_label(name, path)) for name, path in found]
         # On the device itself its own card is the system found, by its
         # own path (muOS reads /run/muos/storage/bios, a bind of MUOS/bios).

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="bf5fd291aeffd7759153f2cfc168ef153a8806e20d708b00e5287fdd63036b20"
+DEFAULT_INSTALL_SHA256="04070f071adf988291854cf4ad8fb6e7a34f8044cfbcb710ba660863c2c6b19e"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {

tests/test_handheld_launchers.py

@@ -1218,7 +1218,9 @@ class ThePortMasterPort(unittest.TestCase):
         """The launcher keyed on the words without install.py's prefix, and
         its fake printed them the same way: the test passed, the device
         still waited 300 s."""
-        line = f"RetroBIOS: {install.TUI_IDLE_WORDS}"
+        state = install.TuiState(os_type="linux", home=Path.home())
+        state.idle_closed = True
+        line = install._farewell_lines(state)[0]
         tui = (REPO_ROOT / "ports" / "shared" / "tui.txt").read_text(encoding="utf-8")
         self.assertIn(f'= "{line}" ]', tui)
         self.assertIn(f'print("{line}", file=sys.stderr)', FAKE_INSTALL)

tests/test_install_experience.py

@@ -633,6 +633,39 @@ class ADetectedFolderUnderAClosedOne(unittest.TestCase):
         self.assertEqual(len(kinds), 2)
 
 
+class AHomeThisUserCannotOpen(unittest.TestCase):
+    """HOME kept across `su` without `-`: detection stat'ed files under it
+    and ended the run on a PermissionError traceback before any line."""
+
+    @unittest.skipIf(os.name == "nt" or os.geteuid() == 0,
+                     "a folder without search permission is POSIX")
+    def test_detection_says_so_and_the_run_goes_on(self):
+        with FakeRepository() as repo:
+            home = repo.root / "home"
+            home.mkdir()
+            env = {**repo.env(), "HOME": str(home), "RETROBIOS_OS": "linux"}
+            runs = {}
+            os.chmod(home, 0o000)
+            try:
+                for name, extra in (("named", ["--platform", "retroarch", "--dest",
+                                               str(repo.dest)]),
+                                    ("detected", [])):
+                    runs[name] = subprocess.run(
+                        [sys.executable, str(REPO_ROOT / "install.py"), "--check",
+                         "--no-input", *extra],
+                        env=env, capture_output=True, text=True, timeout=60,
+                        stdin=subprocess.DEVNULL)
+            finally:
+                os.chmod(home, 0o755)
+        for name, proc in runs.items():
+            with self.subTest(run=name):
+                self.assertNotIn("Traceback", proc.stderr)
+        # A named folder needs no detection and is checked.
+        self.assertIn("0/5 present", runs["named"].stdout)
+        self.assertIn(f"Could not look for setups: this user cannot open {home}",
+                      runs["detected"].stderr)
+
+
 class OutputToAFileAsksNothing(unittest.TestCase):
     """`install.py > log.txt` at a terminal: the menu went into the file
     and the run waited on an answer to a prompt nobody could see."""

tests/test_install_tui.py

@@ -2930,6 +2930,20 @@ class AFolderThisUserCannotOpen(unittest.TestCase):
         self.assertIn(f"This user cannot open {install._short_path(self.lock, state.home)} "
                       "(Permission denied)", self.said(state))
 
+    def test_a_home_it_cannot_open_is_said_on_the_first_screen(self):
+        """HOME kept across su without -: detection raised PermissionError
+        before the first screen."""
+        home = self.lock.parent / "home"
+        home.mkdir()
+        os.chmod(home, 0o000)
+        self.addCleanup(os.chmod, home, 0o755)
+        install._DETECTION_REFUSED.clear()
+        self.addCleanup(install._DETECTION_REFUSED.clear)
+        with mock.patch.dict(os.environ, {"HOME": str(home)}), \
+                mock.patch.object(install, "_mounted_cards", return_value=[]):
+            state, _effects = install.tui_start(_args(), "linux")
+        self.assertIn("Could not look for setups: this user cannot open", self.said(state))
+
     def test_the_nearest_folder_stops_above_it(self):
         self.assertEqual(install._nearest_folder(self.dest / "deeper"), self.lock)
 

wiki/installer.md

@@ -1086,7 +1086,7 @@ Each launcher tells the interface which buttons reach it, in
 A launcher with no mapper at all (a keyboard) leaves it unset.
 A launcher can also set `RETROBIOS_IDLE_EXIT` to a number of seconds: when
 no button has reached the interface since it opened, and nothing has run for
-that long, it closes with `No button pressed, closing.` and exit status 0.
+that long, it closes with `RetroBIOS: No button pressed, closing.` and exit status 0.
 Closed on an error or a result screen, it prints that screen's words after
 the line and exits with its code (1 for `No internet: offline mode`), so
 the launcher can tell an error from a close with nothing to report.