1 files changed, 155 insertions, 0 deletions
diff --git a/python/mozbuild/mozbuild/action/file_generate.py b/python/mozbuild/mozbuild/action/file_generate.py
new file mode 100644
index 0000000000..98dec4e359
--- /dev/null
+++ b/python/mozbuild/mozbuild/action/file_generate.py
@@ -0,0 +1,155 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Given a Python script and arguments describing the output file, and
+# the arguments that can be used to generate the output file, call the
+# script's |main| method with appropriate arguments.
+
+import argparse
+import importlib.util
+import os
+import sys
+import traceback
+
+import buildconfig
+import six
+
+from mozbuild.action.util import log_build_task
+from mozbuild.makeutil import Makefile
+from mozbuild.pythonutil import iter_modules_in_path
+from mozbuild.util import FileAvoidWrite
+
+
+def main(argv):
+    parser = argparse.ArgumentParser(
+        "Generate a file from a Python script", add_help=False
+    )
+    parser.add_argument(
+        "--locale", metavar="locale", type=six.text_type, help="The locale in use."
+    )
+    parser.add_argument(
+        "python_script",
+        metavar="python-script",
+        type=six.text_type,
+        help="The Python script to run",
+    )
+    parser.add_argument(
+        "method_name",
+        metavar="method-name",
+        type=six.text_type,
+        help="The method of the script to invoke",
+    )
+    parser.add_argument(
+        "output_file",
+        metavar="output-file",
+        type=six.text_type,
+        help="The file to generate",
+    )
+    parser.add_argument(
+        "dep_file",
+        metavar="dep-file",
+        type=six.text_type,
+        help="File to write any additional make dependencies to",
+    )
+    parser.add_argument(
+        "dep_target",
+        metavar="dep-target",
+        type=six.text_type,
+        help="Make target to use in the dependencies file",
+    )
+    parser.add_argument(
+        "additional_arguments",
+        metavar="arg",
+        nargs=argparse.REMAINDER,
+        help="Additional arguments to the script's main() method",
+    )
+
+    args = parser.parse_args(argv)
+
+    kwargs = {}
+    if args.locale:
+        kwargs["locale"] = args.locale
+    script = args.python_script
+    # Permit the script to import modules from the same directory in which it
+    # resides.  The justification for doing this is that if we were invoking
+    # the script as:
+    #
+    #    python script arg1...
+    #
+    # then importing modules from the script's directory would come for free.
+    # Since we're invoking the script in a roundabout way, we provide this
+    # bit of convenience.
+    sys.path.append(os.path.dirname(script))
+    spec = importlib.util.spec_from_file_location("script", script)
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    method = args.method_name
+    if not hasattr(module, method):
+        print(
+            'Error: script "{0}" is missing a {1} method'.format(script, method),
+            file=sys.stderr,
+        )
+        return 1
+
+    ret = 1
+    try:
+        with FileAvoidWrite(args.output_file, readmode="rb") as output:
+            try:
+                ret = module.__dict__[method](
+                    output, *args.additional_arguments, **kwargs
+                )
+            except Exception:
+                # Ensure that we don't overwrite the file if the script failed.
+                output.avoid_writing_to_file()
+                raise
+
+            # The following values indicate a statement of success:
+            #  - a set() (see below)
+            #  - 0
+            #  - False
+            #  - None
+            #
+            # Everything else is an error (so scripts can conveniently |return
+            # 1| or similar). If a set is returned, the elements of the set
+            # indicate additional dependencies that will be listed in the deps
+            # file. Python module imports are automatically included as
+            # dependencies.
+            if isinstance(ret, set):
+                deps = set(six.ensure_text(s) for s in ret)
+                # The script succeeded, so reset |ret| to indicate that.
+                ret = None
+            else:
+                deps = set()
+
+            # Only write out the dependencies if the script was successful
+            if not ret:
+                # Add dependencies on any python modules that were imported by
+                # the script.
+                deps |= set(
+                    six.ensure_text(s)
+                    for s in iter_modules_in_path(
+                        buildconfig.topsrcdir, buildconfig.topobjdir
+                    )
+                )
+                # Add dependencies on any buildconfig items that were accessed
+                # by the script.
+                deps |= set(six.ensure_text(s) for s in buildconfig.get_dependencies())
+
+                mk = Makefile()
+                mk.create_rule([args.dep_target]).add_dependencies(deps)
+                with FileAvoidWrite(args.dep_file) as dep_file:
+                    mk.dump(dep_file)
+            else:
+                # Ensure that we don't overwrite the file if the script failed.
+                output.avoid_writing_to_file()
+
+    except IOError as e:
+        print('Error opening file "{0}"'.format(e.filename), file=sys.stderr)
+        traceback.print_exc()
+        return 1
+    return ret
+
+
+if __name__ == "__main__":
+    sys.exit(log_build_task(main, sys.argv[1:]))