Add filtering mechanism for executable prefix application

launch/launch/actions/execute_process.py

@@ -18,6 +18,7 @@
 import io
 import os
 import platform
+import re
 import shlex
 import signal
 import threading
@@ -187,7 +188,10 @@ def __init__(
             'emulate_tty' configuration does not represent a boolean.
         :param: prefix a set of commands/arguments to preceed the cmd, used for
             things like gdb/valgrind and defaults to the LaunchConfiguration
-            called 'launch-prefix'
+            called 'launch-prefix'. Note that a non-default prefix provided in
+            a launch file will override the prefix provided via the `launch-prefix`
+            launch configuration regardless of whether the `launch-prefix-filter` launch
+            configuration is provided.
         :param: output configuration for process output logging. Defaults to 'log'
             i.e. log both stdout and stderr to launch main log file and stderr to
             the screen.
@@ -230,6 +234,9 @@ def __init__(
         self.__prefix = normalize_to_list_of_substitutions(
             LaunchConfiguration('launch-prefix', default='') if prefix is None else prefix
         )
+        self.__prefix_filter = normalize_to_list_of_substitutions(
+            LaunchConfiguration('launch-prefix-filter', default='')
+        ) if prefix is None else None
         self.__output = os.environ.get('OVERRIDE_LAUNCH_PROCESS_OUTPUT', output)
         self.__output_format = output_format
 
@@ -681,7 +688,16 @@ def __expand_substitutions(self, context):
         cmd = [perform_substitutions(context, x) for x in self.__cmd]
         name = os.path.basename(cmd[0]) if self.__name is None \
             else perform_substitutions(context, self.__name)
-        cmd = shlex.split(perform_substitutions(context, self.__prefix)) + cmd
+
+        # Perform filtering for prefix application
+        should_apply_prefix = True  # by default
+        if self.__prefix_filter is not None:  # no prefix given on construction
+            prefix_filter = perform_substitutions(context, self.__prefix_filter)
+            # Apply if filter regex matches (empty regex matches all strings)
+            should_apply_prefix = re.match(prefix_filter, os.path.basename(cmd[0]))
+        if should_apply_prefix:
+            cmd = shlex.split(perform_substitutions(context, self.__prefix)) + cmd
+
         with _global_process_counter_lock:
             global _global_process_counter
             _global_process_counter += 1

launch/test/launch/test_execute_process.py

@@ -14,13 +14,16 @@
 
 """Tests for the ExecuteProcess Action."""
 
+import asyncio
 import os
 import platform
 import signal
 import sys
 
+from launch import LaunchContext
 from launch import LaunchDescription
 from launch import LaunchService
+from launch.actions import SetLaunchConfiguration
 from launch.actions.emit_event import EmitEvent
 from launch.actions.execute_process import ExecuteProcess
 from launch.actions.opaque_function import OpaqueFunction
@@ -168,3 +171,60 @@ def generate_launch_description():
     ls.include_launch_description(generate_launch_description())
     assert 0 == ls.run()
     assert expected_called_count == on_exit_callback.called_count
+
+
+def test_execute_process_prefix_filter_match():
+    lc = LaunchContext()
+    lc._set_asyncio_loop(asyncio.get_event_loop())
+    SetLaunchConfiguration('launch-prefix', 'time').visit(lc)
+    assert len(lc.launch_configurations) == 1
+    SetLaunchConfiguration(
+        'launch-prefix-filter',
+        f'{os.path.basename(sys.executable)}').visit(lc)
+    assert len(lc.launch_configurations) == 2
+
+    test_process = ExecuteProcess(
+        cmd=[sys.executable, '-c', "print('action')"],
+        output='screen'
+    )
+
+    test_process.execute(lc)
+    assert 'time' in test_process.process_details['cmd']
+
+
+def test_execute_process_prefix_filter_no_match():
+    lc = LaunchContext()
+    lc._set_asyncio_loop(asyncio.get_event_loop())
+    SetLaunchConfiguration('launch-prefix', 'time').visit(lc)
+    assert len(lc.launch_configurations) == 1
+    SetLaunchConfiguration(
+        'launch-prefix-filter', 'no-match').visit(lc)
+    assert len(lc.launch_configurations) == 2
+
+    test_process = ExecuteProcess(
+        cmd=[sys.executable, '-c', "print('action')"],
+        output='screen'
+    )
+
+    test_process.execute(lc)
+    assert 'time' not in test_process.process_details['cmd']
+
+
+def test_execute_process_prefix_filter_override_in_launch_file():
+    lc = LaunchContext()
+    lc._set_asyncio_loop(asyncio.get_event_loop())
+    SetLaunchConfiguration('launch-prefix', 'time').visit(lc)
+    assert len(lc.launch_configurations) == 1
+    SetLaunchConfiguration(
+        'launch-prefix-filter', 'no-match').visit(lc)
+    assert len(lc.launch_configurations) == 2
+
+    test_process = ExecuteProcess(
+        prefix='echo',
+        cmd=[sys.executable, '-c', "print('action')"],
+        output='screen'
+    )
+
+    test_process.execute(lc)
+    assert 'echo' in test_process.process_details['cmd'] and \
+        'time' not in test_process.process_details['cmd']