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grpc/bazel/protobuf.bzl

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# Copyright 2021 The gRPC Authors
#
# 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.
"""Utility functions for generating protobuf code."""
load("@rules_proto//proto:defs.bzl", "ProtoInfo")
_PROTO_EXTENSION = ".proto"
_VIRTUAL_IMPORTS = "/_virtual_imports/"
_WELL_KNOWN_PROTOS_BASE = [
"any_proto",
"api_proto",
"compiler_plugin_proto",
"descriptor_proto",
"duration_proto",
"empty_proto",
"field_mask_proto",
"source_context_proto",
"struct_proto",
"timestamp_proto",
"type_proto",
"wrappers_proto",
]
def well_known_proto_libs():
return ["@com_google_protobuf//:" + b for b in _WELL_KNOWN_PROTOS_BASE]
def is_well_known(label):
# Bazel surfaces labels as their undelying identity, even if they are referenced
# via aliases. Bazel also does not currently provide a way to find the real label
# underlying an alias. So the implementation detail that the WKTs present at the
# top level of the protobuf repo are actually backed by targets in the
# //src/google/protobuf package leaks through here.
# We include both the alias path and the underlying path to be resilient to
# reversions of this change as well as for continuing compatiblity with repos
# that happen to pull in older versions of protobuf.
all_wkt_targets = (["@com_google_protobuf//:" + b for b in _WELL_KNOWN_PROTOS_BASE] +
["@com_google_protobuf//src/google/protobuf:" + b for b in _WELL_KNOWN_PROTOS_BASE])
return label in all_wkt_targets
def get_proto_root(workspace_root):
"""Gets the root protobuf directory.
Args:
workspace_root: context.label.workspace_root
Returns:
The directory relative to which generated include paths should be.
"""
if workspace_root:
return "/{}".format(workspace_root)
else:
return ""
def _strip_proto_extension(proto_filename):
if not proto_filename.endswith(_PROTO_EXTENSION):
fail('"{}" does not end with "{}"'.format(
proto_filename,
_PROTO_EXTENSION,
))
return proto_filename[:-len(_PROTO_EXTENSION)]
def proto_path_to_generated_filename(proto_path, fmt_str):
"""Calculates the name of a generated file for a protobuf path.
For example, "examples/protos/helloworld.proto" might map to
"helloworld.pb.h".
Args:
proto_path: The path to the .proto file.
fmt_str: A format string used to calculate the generated filename. For
example, "{}.pb.h" might be used to calculate a C++ header filename.
Returns:
The generated filename.
"""
return fmt_str.format(_strip_proto_extension(proto_path))
def get_include_directory(source_file):
"""Returns the include directory path for the source_file.
All of the include statements within the given source_file are calculated
relative to the directory returned by this method.
The returned directory path can be used as the "--proto_path=" argument
value.
Args:
source_file: A proto file.
Returns:
The include directory path for the source_file.
"""
directory = source_file.path
prefix_len = 0
if is_in_virtual_imports(source_file):
root, relative = source_file.path.split(_VIRTUAL_IMPORTS, 2)
result = root + _VIRTUAL_IMPORTS + relative.split("/", 1)[0]
return result
if not source_file.is_source and directory.startswith(source_file.root.path):
prefix_len = len(source_file.root.path) + 1
if directory.startswith("external", prefix_len):
external_separator = directory.find("/", prefix_len)
repository_separator = directory.find("/", external_separator + 1)
return directory[:repository_separator]
else:
return source_file.root.path if source_file.root.path else "."
def get_plugin_args(
plugin,
flags,
dir_out,
generate_mocks,
plugin_name = "PLUGIN"):
"""Returns arguments configuring protoc to use a plugin for a language.
Args:
plugin: An executable file to run as the protoc plugin.
flags: The plugin flags to be passed to protoc.
dir_out: The output directory for the plugin.
generate_mocks: A bool indicating whether to generate mocks.
plugin_name: A name of the plugin, it is required to be unique when there
are more than one plugin used in a single protoc command.
Returns:
A list of protoc arguments configuring the plugin.
"""
augmented_flags = list(flags)
if generate_mocks:
augmented_flags.append("generate_mock_code=true")
augmented_dir_out = dir_out
if augmented_flags:
augmented_dir_out = ",".join(augmented_flags) + ":" + dir_out
return [
"--plugin=protoc-gen-{plugin_name}={plugin_path}".format(
plugin_name = plugin_name,
plugin_path = plugin.path,
),
"--{plugin_name}_out={dir_out}".format(
plugin_name = plugin_name,
dir_out = augmented_dir_out,
),
]
def _make_prefix(label):
"""Returns the directory prefix for a label.
@repo//foo/bar:sub/dir/file.proto => 'external/repo/foo/bar/'
//foo/bar:sub/dir/file.proto => 'foo/bar/'
//:sub/dir/file.proto => ''
That is, the prefix can be removed from a file's full path to
obtain the file's relative location within the package's effective
directory."""
wsr = label.workspace_root
pkg = label.package
if not wsr and not pkg:
return ""
elif not wsr:
return pkg + "/"
elif not pkg:
return wsr + "/"
else:
return wsr + "/" + pkg + "/"
def get_staged_proto_file(label, context, source_file):
"""Copies a proto file to the appropriate location if necessary.
Args:
label: The label of the rule using the .proto file.
context: The ctx object for the rule or aspect.
source_file: The original .proto file.
Returns:
The original proto file OR a new file in the staged location.
"""
if source_file.dirname == label.package or \
is_in_virtual_imports(source_file):
# Current target and source_file are in same package
return source_file
else:
# Current target and source_file are in different packages (most
# probably even in different repositories)
prefix = _make_prefix(source_file.owner)
copied_proto = context.actions.declare_file(source_file.path[len(prefix):])
context.actions.run_shell(
inputs = [source_file],
outputs = [copied_proto],
command = "cp {} {}".format(source_file.path, copied_proto.path),
mnemonic = "CopySourceProto",
)
return copied_proto
def protos_from_context(context):
"""Copies proto files to the appropriate location.
Args:
context: The ctx object for the rule.
Returns:
A list of the protos.
"""
protos = []
for src in context.attr.deps:
for file in src[ProtoInfo].direct_sources:
protos.append(get_staged_proto_file(context.label, context, file))
return protos
def includes_from_deps(deps):
"""Get includes from rule dependencies."""
return [
file
for src in deps
for file in src[ProtoInfo].transitive_imports.to_list()
]
def get_proto_arguments(protos, genfiles_dir_path):
"""Get the protoc arguments specifying which protos to compile.
Args:
protos: The protob files to supply.
genfiles_dir_path: The path to the genfiles directory.
Returns:
The arguments to supply to protoc.
"""
arguments = []
for proto in protos:
strip_prefix_len = 0
if is_in_virtual_imports(proto):
incl_directory = get_include_directory(proto)
if proto.path.startswith(incl_directory):
strip_prefix_len = len(incl_directory) + 1
elif proto.path.startswith(genfiles_dir_path):
strip_prefix_len = len(genfiles_dir_path) + 1
arguments.append(proto.path[strip_prefix_len:])
return arguments
def declare_out_files(protos, context, generated_file_format):
"""Declares and returns the files to be generated.
Args:
protos: A list of files. The protos to declare.
context: The context object.
generated_file_format: A format string. Will be passed to
proto_path_to_generated_filename to generate the filename of each
generated file.
Returns:
A list of file providers.
"""
out_file_paths = []
for proto in protos:
if not is_in_virtual_imports(proto):
prefix = _make_prefix(proto.owner)
full_prefix = context.genfiles_dir.path + "/" + prefix
if proto.path.startswith(full_prefix):
out_file_paths.append(proto.path[len(full_prefix):])
elif proto.path.startswith(prefix):
out_file_paths.append(proto.path[len(prefix):])
else:
out_file_paths.append(proto.path[proto.path.index(_VIRTUAL_IMPORTS) + 1:])
return [
context.actions.declare_file(
proto_path_to_generated_filename(
out_file_path,
generated_file_format,
),
)
for out_file_path in out_file_paths
]
def get_out_dir(protos, context):
"""Returns the value to supply to the --<lang>_out= protoc flag.
The result is based on the input source proto files and current context.
Args:
protos: A list of protos to be used as source files in protoc command
context: A ctx object for the rule.
Returns:
The value of --<lang>_out= argument.
"""
at_least_one_virtual = 0
for proto in protos:
if is_in_virtual_imports(proto):
at_least_one_virtual = True
elif at_least_one_virtual:
fail("Proto sources must be either all virtual imports or all real")
if at_least_one_virtual:
out_dir = get_include_directory(protos[0])
ws_root = protos[0].owner.workspace_root
prefix = "/" + _make_prefix(protos[0].owner) + _VIRTUAL_IMPORTS[1:]
return struct(
path = out_dir,
import_path = out_dir[out_dir.find(prefix) + 1:],
)
out_dir = context.genfiles_dir.path
ws_root = context.label.workspace_root
if ws_root:
out_dir = out_dir + "/" + ws_root
return struct(path = out_dir, import_path = None)
def is_in_virtual_imports(source_file, virtual_folder = _VIRTUAL_IMPORTS):
"""Determines if source_file is virtual.
A file is virtual if placed in the _virtual_imports subdirectory. The
output of all proto_library targets which use import_prefix and/or
strip_import_prefix arguments is placed under _virtual_imports directory.
Args:
source_file: A proto file.
virtual_folder: The virtual folder name (is set to "_virtual_imports"
by default)
Returns:
True if source_file is located under _virtual_imports, False otherwise.
"""
return not source_file.is_source and virtual_folder in source_file.path
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