Add in this file that I forgot.

commandrunner.py

@@ -0,0 +1,53 @@
+#!/usr/bin/env python3
+
+# Copyright 2014 Jussi Pakkanen
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""This program is a wrapper to run external commands. It determines
+what to run, sets up the environment and executes the command."""
+
+import sys, os, subprocess, shutil
+
+def run_command(source_dir, build_dir, subdir, command, arguments):
+    env = {'MESON_SOURCE_ROOT' : source_dir,
+           'MESON_BUILD_ROOT' : build_dir,
+           'MESON_SUBDIR' : subdir
+        }
+    cwd = os.path.join(source_dir, subdir)
+    child_env = os.environ.copy()
+    child_env.update(env)
+
+    # Is the command an executable in path?
+    exe = shutil.which(command)
+    if exe is not None:
+        command_array = [exe] + arguments
+        return subprocess.Popen(command_array, env=child_env, cwd=cwd)
+    # No? Maybe it is a script in the source tree.
+    fullpath = os.path.join(source_dir, subdir, command)
+    command_array = [fullpath] + arguments
+    try:
+        return subprocess.Popen(command_array,env=child_env, cwd=cwd)
+    except FileNotFoundError:
+        print('Could not execute command "%s".' % command)
+        sys.exit(1)
+
+if __name__ == '__main__':
+    if len(sys.argv) < 5:
+        print(sys.argv[0], '<source dir> <build dir> <subdir> <command> [arguments]')
+    src_dir = sys.argv[1]
+    build_dir = sys.argv[2]
+    subdir = sys.argv[3]
+    command = sys.argv[4]
+    arguments = sys.argv[5:]
+    sys.exit(run_command(src_dir, build_dir, subdir, command, arguments).returncode)