rust: Add version scripts and symbol exports

This allows Rust modules to define a version_script for shared library
variants.

This requires using a wrapper for the linker (clang++) to intercept
the flags which rustc emits.

This also adds the ability to export additional symbols in addition
to those exported by rustc by default, e.g. whole_static_library
symbols.

Bug: 314309643
Test: New Soong tests pass.
Test: m
Test: m <simple version script module>
Test: m <simple extra symbols module>

Change-Id: I93c9552e5e1181df4663d194c4df4b7053553dd4

1 files changed, 57 insertions, 0 deletions

diff --git a/scripts/rustc_linker.py b/scripts/rustc_linker.py
new file mode 100755
index 000000000..3f60708e2
--- /dev/null
+++ b/scripts/rustc_linker.py
@@ -0,0 +1,57 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2024 The Android Open Source Project
+#
+# 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 script is used as a replacement for the Rust linker to allow fine-grained
+control over the what gets emitted to the linker.
+"""
+
+import os
+import shutil
+import subprocess
+import sys
+import argparse
+
+replacementVersionScript = None
+
+argparser = argparse.ArgumentParser()
+argparser.add_argument('--android-clang-bin', required=True)
+args = argparser.parse_known_args()
+clang_args = [args[0].android_clang_bin] + args[1]
+
+for i, arg in enumerate(clang_args):
+   if arg.startswith('-Wl,--android-version-script='):
+      replacementVersionScript = arg.split("=")[1]
+      del clang_args[i]
+      break
+
+if replacementVersionScript:
+   versionScriptFound = False
+   for i, arg in enumerate(clang_args):
+      if arg.startswith('-Wl,--version-script='):
+         clang_args[i] ='-Wl,--version-script=' + replacementVersionScript
+         versionScriptFound = True
+         break
+
+   if not versionScriptFound:
+       # If rustc did not emit a version script, just append the arg
+       clang_args.append('-Wl,--version-script=' + replacementVersionScript)
+try:
+   subprocess.run(clang_args, encoding='utf-8', check=True)
+except subprocess.CalledProcessError as e:
+   sys.exit(-1)
+