[libcxx][lit] Add a new executor to collect test binaries

[ldionne]

Summary

I originally added this executor for the old test format to the CHERI fork
of libc++ to gather all test binaries in one directory. This change is a
simple port of the executor to the new format.

This is mostly useful for debugging and performing analysis on the compiled
binaries or copying them in bulk to a remote server. Using this executor
also helped me discover the bug fixed in https://reviews.llvm.org/D84040.

[• wash]

EDIT: Disregard my intention comment, Louis tells me that the setup for executors has changed a bit since we last pulled from trunk, and now they're all scripts like this. This looks fine, once the question I've asked below are resolved.

libcxx/utils/copy_files.py

22

Slight preference for this to be --codesign-identity, not --codesign_identity, to be consistent with the other ones.

[• wash]

libcxx/utils/copy_files.py

41

Can we use a Python file API to validate that both of these directories exist and are writeable?

44

Why is this using subprocess instead of using a Python API for file copying? Using an actual file copy API would allow this script to remain platform independent and may help us handle errors better. For example, my org would love to use an executor like this on Windows.

[ldionne]

[Github PR Transition Cleanup]

Please reopen as a Github PR if you still want to move forward with this.

libcxx/utils/copy_files.py

+#!/usr/bin/env python3
+#===----------------------------------------------------------------------===##
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+#===----------------------------------------------------------------------===##
+
+"""copy_files.py is a utility for collecting test binaries (possibly with code signing) in a given directory."""
+
+import argparse
+import os
+import subprocess
+import sys
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--execdir', type=str, required=True)
+    parser.add_argument('--output-dir', type=str, required=True)
+    parser.add_argument('--codesign_identity', type=str, required=False, default=None)
+    parser.add_argument('--env', type=str, nargs='*', required=False, default=dict())
+    (args, remaining) = parser.parse_known_args(sys.argv[1:])
+
+    if len(remaining) < 2:
+        sys.stderr.write('Missing actual commands to run')
+        exit(1)
+    commandLine = remaining[1:] # Skip the '--'
+
+    # Do any necessary codesigning.
+    if args.codesign_identity:
+        exe = commandLine[0]
+        rc = subprocess.call(['xcrun', 'codesign', '-f', '-s', args.codesign_identity, exe], env={})
+        if rc != 0:
+            sys.stderr.write('Failed to codesign: ' + exe)
+            return rc
+
+    # Copy the executable to the output directory
+    target_dir = args.output_dir
+    print("Copying", args.execdir, "to", target_dir, flush=True)
+    if not os.path.isdir(target_dir):
+        os.makedirs(target_dir)
+    subprocess.check_call(["cp", "-av", args.execdir, target_dir])
+
+if __name__ == '__main__':
+    exit(main())