rules/stripped_cc_common.bzl

"""
Copyright (C) 2021 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.
"""

"""A macro to handle shared library stripping."""

load("@rules_cc//examples:experimental_cc_shared_library.bzl", "CcSharedLibraryInfo", "cc_shared_library")
load("@rules_cc//cc:find_cc_toolchain.bzl", "find_cpp_toolchain")

# Keep this consistent with soong/cc/strip.go#NeedsStrip.
def needs_strip(attrs):
    force_disable = attrs.none
    force_enable = attrs.all or attrs.keep_symbols or attrs.keep_symbols_and_debug_frame
    return force_enable and not force_disable

# Keep this consistent with soong/cc/strip.go#strip and soong/cc/builder.go#transformStrip.
def get_strip_args(attrs):
    strip_args = []
    keep_symbols_list = attrs.keep_symbols_list
    keep_mini_debug_info = False
    if attrs.keep_symbols:
        strip_args += ["--keep-symbols"]
    elif attrs.keep_symbols_and_debug_frame:
        strip_args += ["--keep-symbols-and-debug-frame"]
    elif len(keep_symbols_list) > 0:
        strip_args += ["-k" + ",".join(keep_symbols_list)]
    elif not attrs.all:
        strip_args += ["--keep-mini-debug-info"]
        keep_mini_debug_info = True

    if not keep_mini_debug_info:
        strip_args += ["--add-gnu-debuglink"]

    return strip_args

# https://cs.android.com/android/platform/superproject/+/master:build/soong/cc/builder.go;l=131-146;drc=master
def _stripped_impl(ctx, prefix = "", extension = ""):
    out_file = ctx.actions.declare_file(prefix + ctx.attr.name + extension)
    if not needs_strip(ctx.attr):
      ctx.actions.symlink(
          output = out_file,
          target_file = ctx.files.src[0],
      )
      return out_file
    cc_toolchain = find_cpp_toolchain(ctx)
    d_file = ctx.actions.declare_file(ctx.attr.name + ".d")
    ctx.actions.run(
        env = {
            "CREATE_MINIDEBUGINFO": ctx.executable._create_minidebuginfo.path,
            "XZ": ctx.executable._xz.path,
            "CLANG_BIN": ctx.executable._ar.dirname,
        },
        inputs = ctx.files.src,
        tools = [
            ctx.executable._ar,
            ctx.executable._create_minidebuginfo,
            ctx.executable._objcopy,
            ctx.executable._readelf,
            ctx.executable._strip,
            ctx.executable._strip_script,
            ctx.executable._xz,
        ],
        outputs = [out_file, d_file],
        executable = ctx.executable._strip_script,
        arguments = get_strip_args(ctx.attr) + [
            "-i",
            ctx.files.src[0].path,
            "-o",
            out_file.path,
            "-d",
            d_file.path,
        ],
    )
    return out_file

common_attrs = {
    "keep_symbols": attr.bool(default = False),
    "keep_symbols_and_debug_frame": attr.bool(default = False),
    "all": attr.bool(default = False),
    "none": attr.bool(default = False),
    "keep_symbols_list": attr.string_list(default = []),
    "_xz": attr.label(
        cfg = "host",
        executable = True,
        allow_single_file = True,
        default = "//prebuilts/build-tools:linux-x86/bin/xz",
    ),
    "_create_minidebuginfo": attr.label(
        cfg = "host",
        executable = True,
        allow_single_file = True,
        default = "//prebuilts/build-tools:linux-x86/bin/create_minidebuginfo",
    ),
    "_strip_script": attr.label(
        cfg = "host",
        executable = True,
        allow_single_file = True,
        default = "//build/soong/scripts:strip.sh",
    ),
    "_ar": attr.label(
        cfg = "host",
        executable = True,
        allow_single_file = True,
        default = "//prebuilts/clang/host/linux-x86:llvm-ar",
    ),
    "_strip": attr.label(
        cfg = "host",
        executable = True,
        allow_single_file = True,
        default = "//prebuilts/clang/host/linux-x86:llvm-strip",
    ),
    "_readelf": attr.label(
        cfg = "host",
        executable = True,
        allow_single_file = True,
        default = "//prebuilts/clang/host/linux-x86:llvm-readelf",
    ),
    "_objcopy": attr.label(
        cfg = "host",
        executable = True,
        allow_single_file = True,
        default = "//prebuilts/clang/host/linux-x86:llvm-objcopy",
    ),
    "_cc_toolchain": attr.label(
        default = Label("@local_config_cc//:toolchain"),
        providers = [cc_common.CcToolchainInfo],
    ),
}

def _stripped_shared_library_impl(ctx):
    out_file = _stripped_impl(ctx, "lib", ".so")

    return [
        DefaultInfo(files = depset([out_file])),
        ctx.attr.src[CcSharedLibraryInfo],
    ]

stripped_shared_library = rule(
    implementation = _stripped_shared_library_impl,
    attrs = dict(
        common_attrs,
        src = attr.label(mandatory = True,  allow_single_file = True, providers = [CcSharedLibraryInfo]),
    ),
    toolchains = ["@bazel_tools//tools/cpp:toolchain_type"],
)

# A marker provider to distinguish a cc_binary from everything else that exports
# a CcInfo.
StrippedCcBinaryInfo = provider()

def _stripped_binary_impl(ctx):
    common_providers = [
        ctx.attr.src[CcInfo],
        ctx.attr.src[InstrumentedFilesInfo],
        ctx.attr.src[DebugPackageInfo],
        ctx.attr.src[OutputGroupInfo],
        StrippedCcBinaryInfo(), # a marker for dependents
    ]

    out_file = _stripped_impl(ctx)

    return [
        DefaultInfo(
            files = depset([out_file]),
            executable = out_file,
        ),
    ] + common_providers

stripped_binary = rule(
    implementation = _stripped_binary_impl,
    attrs = dict(
        common_attrs,
        src = attr.label(mandatory = True, allow_single_file = True, providers = [CcInfo]),
    ),
    toolchains = ["@bazel_tools//tools/cpp:toolchain_type"],
)