feat: add subprocess module with cmd and shell

These helper functions makes it easy to run arbitrary commands on the
user config file.

wmcompanion/utils/subprocess.py

@@ -0,0 +1,52 @@
+# Copyright (c) 2022 Daniel Pereira
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import asyncio
+from logging import getLogger
+
+logger = getLogger(__name__)
+
+async def cmd(cmd: str, *args: list[str], env: dict = None, output_encoding: str = "utf-8"):
+    """
+    Run a command in the existing thread event loop and return its return code and outputs.
+    """
+    proc = await asyncio.create_subprocess_exec(
+        cmd, *args, env=env,
+        stdout=asyncio.subprocess.PIPE,
+        stderr=asyncio.subprocess.PIPE,
+    )
+
+    stdout, stderr = await proc.communicate()
+
+    if proc.returncode != 0:
+        stderr_str = stderr.decode(output_encoding).strip()
+        logger.warn(f"Process '{cmd}' returned {proc.returncode}: {stderr_str}")
+
+    return dict(
+        rc=proc.returncode,
+        stderr=stderr.decode(output_encoding),
+        stdout=stdout.decode(output_encoding),
+    )
+
+async def shell(cmd: str, env: dict = None, output_encoding: str = "utf-8"):
+    """
+    Run a shell command in the existing thread event loop and return its return code and outputs.
+    """
+    proc = await asyncio.create_subprocess_shell(
+        cmd, env=env,
+        stdout=asyncio.subprocess.PIPE,
+        stderr=asyncio.subprocess.PIPE,
+    )
+
+    stdout, stderr = await proc.communicate()
+
+    if proc.returncode != 0:
+        stderr_str = stderr.decode(output_encoding).strip()
+        logger.warn(f"Shell command '{cmd}' returned {proc.returncode}: {stderr_str}")
+
+    return dict(
+        rc=proc.returncode,
+        stderr=stderr.decode(output_encoding),
+        stdout=stdout.decode(output_encoding),
+    )