platform_build_soong/android/bazel.go

// Copyright 2021 Google Inc. All rights reserved.
//
// 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.

package android

import (
	"fmt"
	"io/ioutil"
	"path/filepath"
	"strings"

	"github.com/google/blueprint"
	"github.com/google/blueprint/proptools"
)

type bazelModuleProperties struct {
	// The label of the Bazel target replacing this Soong module. When run in conversion mode, this
	// will import the handcrafted build target into the autogenerated file. Note: this may result in
	// a conflict due to duplicate targets if bp2build_available is also set.
	Label *string

	// If true, bp2build will generate the converted Bazel target for this module. Note: this may
	// cause a conflict due to the duplicate targets if label is also set.
	Bp2build_available bool
}

// Properties contains common module properties for Bazel migration purposes.
type properties struct {
	// In USE_BAZEL_ANALYSIS=1 mode, this represents the Bazel target replacing
	// this Soong module.
	Bazel_module bazelModuleProperties
}

// BazelModuleBase contains the property structs with metadata for modules which can be converted to
// Bazel.
type BazelModuleBase struct {
	bazelProperties properties
}

// Bazelable is specifies the interface for modules that can be converted to Bazel.
type Bazelable interface {
	bazelProps() *properties
	HasHandcraftedLabel() bool
	HandcraftedLabel() string
	GetBazelLabel(ctx BazelConversionPathContext, module blueprint.Module) string
	ConvertWithBp2build() bool
	GetBazelBuildFileContents(c Config, path, name string) (string, error)
	ConvertedToBazel() bool
}

// BazelModule is a lightweight wrapper interface around Module for Bazel-convertible modules.
type BazelModule interface {
	Module
	Bazelable
}

// InitBazelModule is a wrapper function that decorates a BazelModule with Bazel-conversion
// properties.
func InitBazelModule(module BazelModule) {
	module.AddProperties(module.bazelProps())
}

// bazelProps returns the Bazel properties for the given BazelModuleBase.
func (b *BazelModuleBase) bazelProps() *properties {
	return &b.bazelProperties
}

// HasHandcraftedLabel returns whether this module has a handcrafted Bazel label.
func (b *BazelModuleBase) HasHandcraftedLabel() bool {
	return b.bazelProperties.Bazel_module.Label != nil
}

// HandcraftedLabel returns the handcrafted label for this module, or empty string if there is none
func (b *BazelModuleBase) HandcraftedLabel() string {
	return proptools.String(b.bazelProperties.Bazel_module.Label)
}

// GetBazelLabel returns the Bazel label for the given BazelModuleBase.
func (b *BazelModuleBase) GetBazelLabel(ctx BazelConversionPathContext, module blueprint.Module) string {
	if b.HasHandcraftedLabel() {
		return b.HandcraftedLabel()
	}
	if b.ConvertWithBp2build() {
		return bp2buildModuleLabel(ctx, module)
	}
	return "" // no label for unconverted module
}

// ConvertWithBp2build returns whether the given BazelModuleBase should be converted with bp2build.
func (b *BazelModuleBase) ConvertWithBp2build() bool {
	return b.bazelProperties.Bazel_module.Bp2build_available
}

// GetBazelBuildFileContents returns the file contents of a hand-crafted BUILD file if available or
// an error if there are errors reading the file.
// TODO(b/181575318): currently we append the whole BUILD file, let's change that to do
// something more targeted based on the rule type and target.
func (b *BazelModuleBase) GetBazelBuildFileContents(c Config, path, name string) (string, error) {
	if !strings.Contains(b.HandcraftedLabel(), path) {
		return "", fmt.Errorf("%q not found in bazel_module.label %q", path, b.HandcraftedLabel())
	}
	name = filepath.Join(path, name)
	f, err := c.fs.Open(name)
	if err != nil {
		return "", err
	}
	defer f.Close()

	data, err := ioutil.ReadAll(f)
	if err != nil {
		return "", err
	}
	return string(data[:]), nil
}

// ConvertedToBazel returns whether this module has been converted to Bazel, whether automatically
// or manually
func (b *BazelModuleBase) ConvertedToBazel() bool {
	return b.ConvertWithBp2build() || b.HasHandcraftedLabel()
}