kleaf/update_source_file.bzl

# Copyright (C) 2022 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.

"""Upon `bazel run`, updates a source file."""

load("//build/kernel/kleaf/impl:hermetic_toolchain.bzl", "hermetic_toolchain")

def _update_source_file_impl(ctx):
    # --copy-links because src is a symlink inside the sandbox. We need to copy
    # the referent.
    # --no-perms because generated files usually have exec bit set, which
    # we don't want in source files.
    hermetic_tools = hermetic_toolchain.get(ctx)
    script = hermetic_tools.setup + """
        rsync --copy-links --no-perms --times {src} $(readlink -m {dst})
    """.format(
        src = ctx.file.src.short_path,
        dst = ctx.file.dst.short_path,
    )

    ctx.actions.write(
        content = script,
        output = ctx.outputs.executable,
        is_executable = True,
    )
    runfiles = [
        ctx.file.src,
        ctx.file.dst,
    ]
    return [DefaultInfo(runfiles = ctx.runfiles(
        files = runfiles,
        transitive_files = depset(
            transitive = [hermetic_tools.deps] + [target.files for target in ctx.attr.deps],
        ),
    ))]

update_source_file = rule(
    implementation = _update_source_file_impl,
    attrs = {
        "src": attr.label(allow_single_file = True),
        "dst": attr.label(allow_single_file = True),
        "deps": attr.label_list(
            allow_files = True,
            doc = """Additional files to depend on. You may add targets here to ensure these targets
                are built before updating the source file. This can be useful if you want to
                exercise additional checks.""",
        ),
    },
    executable = True,
    toolchains = [hermetic_toolchain.type],
)