Require backend ACK before sending initial input

thonny/plugins/cpython_backend/cp_launcher.py

@@ -9,6 +9,7 @@
 I could also do python -c "from backend import MainCPythonBackend: MainCPythonBackend().mainloop()",
 but looks like this gives relative __file__-s on imported modules.)
 """
+from thonny.running import PROCESS_ACK
 
 # NB! This module can be also imported (when querying its path for uploading)
 if __name__ == "__main__":
@@ -39,6 +40,7 @@
 
     thonny.prepare_thonny_user_dir()
     thonny.configure_backend_logging()
+    print(PROCESS_ACK)
 
     target_cwd = sys.argv[1]
     report_time("Before constructing backend")

thonny/plugins/cpython_ssh/cps_back.py

@@ -23,6 +23,7 @@
     MessageFromBackend,
     serialize_message,
 )
+from thonny.running import PROCESS_ACK
 
 logger = getLogger("thonny.plugins.cpython_ssh.cps_back")
 
@@ -194,6 +195,7 @@ def _upload_main_backend(self):
 
 if __name__ == "__main__":
     thonny.configure_backend_logging()
+    print(PROCESS_ACK)
     args = ast.literal_eval(sys.argv[1])
     backend = SshCPythonBackend(**args)
     backend.mainloop()

thonny/plugins/ev3/ev3_back.py

@@ -5,6 +5,7 @@
 
 import thonny
 from thonny.plugins.micropython.os_mp_backend import SshUnixMicroPythonBackend
+from thonny.running import PROCESS_ACK
 
 logger = getLogger("thonny.plugins.ev3.ev3_back")
 
@@ -19,6 +20,7 @@ def _get_sys_path_for_analysis(self) -> Optional[List[str]]:
 if __name__ == "__main__":
     THONNY_USER_DIR = os.environ["THONNY_USER_DIR"]
     thonny.configure_backend_logging()
+    print(PROCESS_ACK)
 
     import ast
 

thonny/plugins/micropython/bare_metal_backend.py

@@ -44,6 +44,7 @@
     RAW_SUBMIT_MODE,
 )
 from thonny.plugins.micropython.webrepl_connection import WebReplConnection
+from thonny.running import PROCESS_ACK
 
 RAW_PASTE_COMMAND = b"\x05A\x01"
 RAW_PASTE_CONFIRMATION = b"R\x01"
@@ -1716,6 +1717,7 @@ class RawPasteNotSupportedError(RuntimeError):
 
 def launch_bare_metal_backend(backend_class: Callable[..., BareMetalMicroPythonBackend]) -> None:
     thonny.configure_backend_logging()
+    print(PROCESS_ACK)
 
     import ast
 

thonny/plugins/micropython/os_mp_backend.py

@@ -26,6 +26,7 @@
     ends_overlap,
 )
 from thonny.plugins.micropython.mp_common import PASTE_SUBMIT_MODE
+from thonny.running import PROCESS_ACK
 
 # Can't use __name__, because it will be "__main__"
 logger = getLogger("thonny.plugins.micropython.os_mp_backend")
@@ -383,6 +384,7 @@ def _create_pipkin_adapter(self):
 if __name__ == "__main__":
     THONNY_USER_DIR = os.environ["THONNY_USER_DIR"]
     thonny.configure_backend_logging()
+    print(PROCESS_ACK)
 
     import ast
 

thonny/running.py

@@ -74,6 +74,8 @@
 from thonny.ui_utils import select_sequence, show_dialog
 from thonny.workdlg import WorkDialog
 
+PROCESS_ACK = "OK"
+
 logger = getLogger(__name__)
 
 WINDOWS_EXE = "python.exe"
@@ -1058,17 +1060,30 @@ def _start_background_process(self, clean=None, extra_args=[]):
             encoding="utf-8",
         )
 
-        self._send_initial_input()
+        # read success acknowledgement
+        ack = self._proc.stdout.readline()
 
         # setup asynchronous output listeners
         Thread(target=self._listen_stdout, args=(self._proc.stdout,), daemon=True).start()
         Thread(target=self._listen_stderr, args=(self._proc.stderr,), daemon=True).start()
 
+        # only attempt initial input if process started nicely,
+        # otherwise can't read the error from stderr
+        if ack.strip() == PROCESS_ACK:
+            self._send_initial_input()
+        else:
+            get_shell().print_error(
+                f"INTERNAL ERROR, got {ack!r} instead of {PROCESS_ACK!r}\n---\n"
+            )
+
     def _send_initial_input(self) -> None:
+        # Used for sending data sending for startup, which can't be send by other means
+        # (e.g. don't want the password to end up in logs)
+
         pass
 
     def _get_launch_cwd(self):
-        return self.get_cwd() if self.uses_local_filesystem() else None
+        return get_workbench().get_local_cwd()
 
     def _get_launcher_with_args(self):
         raise NotImplementedError()