python: propagate signals to remage-cpp

python/remage/cli.py

@@ -1,11 +1,52 @@
 from __future__ import annotations
 
+import signal
 import subprocess
 import sys
 
 from .cpp_config import REMAGE_CPP_EXE_PATH
 
 
-def remage_cli():
-    result = subprocess.run([REMAGE_CPP_EXE_PATH] + sys.argv[1:], check=False)
-    sys.exit(result.returncode)
+def _run_remage_cpp() -> int:
+    """run the remage-cpp executable and return the exit code as seen in bash."""
+    # reuse our own argv[0] to have helpful help messages.
+    proc = subprocess.Popen(sys.argv, executable=REMAGE_CPP_EXE_PATH)
+
+    # propagate signals to the C++ executable.
+    def new_signal_handler(sig: int, _):
+        proc.send_signal(sig)
+
+    signals = [
+        signal.SIGHUP,
+        signal.SIGINT,
+        signal.SIGQUIT,
+        signal.SIGTERM,
+        signal.SIGTSTP,  # SIGSTOP cannot be caught, and will do nothing...
+        signal.SIGCONT,
+        signal.SIGUSR1,
+        signal.SIGUSR2,
+        signal.SIGWINCH,
+    ]
+
+    old_signal_handlers = [signal.signal(sig, new_signal_handler) for sig in signals]
+
+    # wait for C++ executable to finish.
+    proc.wait()
+
+    # restore signal handlers again, before running more python code.
+    for sig, handler in zip(signals, old_signal_handlers):
+        signal.signal(sig, handler)
+
+    return 128 - proc.returncode if proc.returncode < 0 else proc.returncode
+
+
+def remage_cli() -> None:
+    ec = _run_remage_cpp()
+    if ec not in [0, 2]:
+        # remage had an error (::fatal -> ec==134 (SIGABRT); ::error -> ec==1)
+        # ec==2 is just a warning, continue in the execution flow.
+        sys.exit(ec)
+
+    # TODO: further post-processing
+
+    sys.exit(ec)