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- // 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.
- package android
- import (
- "strings"
- "github.com/google/blueprint"
- )
- // Provides support for interacting with the `deapexer` module to which a `prebuilt_apex` module
- // will delegate the work to export files from a prebuilt '.apex` file.
- //
- // The actual processing that is done is quite convoluted but it is all about combining information
- // from multiple different sources in order to allow a prebuilt module to use a file extracted from
- // an apex file. As follows:
- //
- // 1. A prebuilt module, e.g. prebuilt_bootclasspath_fragment or java_import needs to use a file
- // from a prebuilt_apex/apex_set. It knows the path of the file within the apex but does not know
- // where the apex file is or what apex to use.
- //
- // 2. The connection between the prebuilt module and the prebuilt_apex/apex_set is created through
- // use of an exported_... property on the latter. That causes four things to occur:
- // a. A `deapexer` mopdule is created by the prebuilt_apex/apex_set to extract files from the
- // apex file.
- // b. A dependency is added from the prebuilt_apex/apex_set modules onto the prebuilt modules
- // listed in those properties.
- // c. An APEX variant is created for each of those prebuilt modules.
- // d. A dependency is added from the prebuilt modules to the `deapexer` module.
- //
- // 3. The prebuilt_apex/apex_set modules do not know which files are available in the apex file.
- // That information could be specified on the prebuilt_apex/apex_set modules but without
- // automated generation of those modules it would be expensive to maintain. So, instead they
- // obtain that information from the prebuilt modules. They do not know what files are actually in
- // the apex file either but they know what files they need from it. So, the
- // prebuilt_apex/apex_set modules obtain the files that should be in the apex file from those
- // modules and then pass those onto the `deapexer` module.
- //
- // 4. The `deapexer` module's ninja rule extracts all the files from the apex file into an output
- // directory and checks that all the expected files are there. The expected files are declared as
- // the outputs of the ninja rule so they are available to other modules.
- //
- // 5. The prebuilt modules then retrieve the paths to the files that they needed from the `deapexer`
- // module.
- //
- // The files that are passed to `deapexer` and those that are passed back have a unique identifier
- // that links them together. e.g. If the `deapexer` is passed something like this:
- // javalib/core-libart.jar -> javalib/core-libart.jar
- // it will return something like this:
- // javalib/core-libart.jar -> out/soong/.....deapexer.../javalib/core-libart.jar
- //
- // The reason why the `deapexer` module is separate from the prebuilt_apex/apex_set is to avoid
- // cycles. e.g.
- // prebuilt_apex "com.android.art" depends upon java_import "core-libart":
- // This is so it can create an APEX variant of the latter and obtain information about the
- // files that it needs from the apex file.
- // java_import "core-libart" depends upon `deapexer` module:
- // This is so it can retrieve the paths to the files it needs.
- // The information exported by the `deapexer` module, access it using `DeapxerInfoProvider`.
- type DeapexerInfo struct {
- apexModuleName string
- // map from the name of an exported file from a prebuilt_apex to the path to that file. The
- // exported file name is the apex relative path, e.g. javalib/core-libart.jar.
- //
- // See Prebuilt.ApexInfoMutator for more information.
- exports map[string]WritablePath
- }
- // ApexModuleName returns the name of the APEX module that provided the info.
- func (i DeapexerInfo) ApexModuleName() string {
- return i.apexModuleName
- }
- // PrebuiltExportPath provides the path, or nil if not available, of a file exported from the
- // prebuilt_apex that created this ApexInfo.
- //
- // The exported file is identified by the apex relative path, e.g. "javalib/core-libart.jar".
- //
- // See apex/deapexer.go for more information.
- func (i DeapexerInfo) PrebuiltExportPath(apexRelativePath string) WritablePath {
- path := i.exports[apexRelativePath]
- return path
- }
- // Provider that can be used from within the `GenerateAndroidBuildActions` of a module that depends
- // on a `deapexer` module to retrieve its `DeapexerInfo`.
- var DeapexerProvider = blueprint.NewProvider(DeapexerInfo{})
- // NewDeapexerInfo creates and initializes a DeapexerInfo that is suitable
- // for use with a prebuilt_apex module.
- //
- // See apex/deapexer.go for more information.
- func NewDeapexerInfo(apexModuleName string, exports map[string]WritablePath) DeapexerInfo {
- return DeapexerInfo{
- apexModuleName: apexModuleName,
- exports: exports,
- }
- }
- type deapexerTagStruct struct {
- blueprint.BaseDependencyTag
- }
- // Mark this tag so dependencies that use it are excluded from APEX contents.
- func (t deapexerTagStruct) ExcludeFromApexContents() {}
- var _ ExcludeFromApexContentsTag = DeapexerTag
- // A tag that is used for dependencies on the `deapexer` module.
- var DeapexerTag = deapexerTagStruct{}
- // RequiredFilesFromPrebuiltApex must be implemented by modules that require files to be exported
- // from a prebuilt_apex/apex_set.
- type RequiredFilesFromPrebuiltApex interface {
- // RequiredFilesFromPrebuiltApex returns a list of the file paths (relative to the root of the
- // APEX's contents) that the implementing module requires from within a prebuilt .apex file.
- //
- // For each file path this will cause the file to be extracted out of the prebuilt .apex file, and
- // the path to the extracted file will be stored in the DeapexerInfo using the APEX relative file
- // path as the key, The path can then be retrieved using the PrebuiltExportPath(key) method.
- RequiredFilesFromPrebuiltApex(ctx BaseModuleContext) []string
- }
- // Marker interface that identifies dependencies on modules that may require files from a prebuilt
- // apex.
- type RequiresFilesFromPrebuiltApexTag interface {
- blueprint.DependencyTag
- // Method that differentiates this interface from others.
- RequiresFilesFromPrebuiltApex()
- }
- // FindDeapexerProviderForModule searches through the direct dependencies of the current context
- // module for a DeapexerTag dependency and returns its DeapexerInfo. If a single nonambiguous
- // deapexer module isn't found then errors are reported with ctx.ModuleErrorf and nil is returned.
- func FindDeapexerProviderForModule(ctx ModuleContext) *DeapexerInfo {
- var di *DeapexerInfo
- ctx.VisitDirectDepsWithTag(DeapexerTag, func(m Module) {
- c := ctx.OtherModuleProvider(m, DeapexerProvider).(DeapexerInfo)
- p := &c
- if di != nil {
- // If two DeapexerInfo providers have been found then check if they are
- // equivalent. If they are then use the selected one, otherwise fail.
- if selected := equivalentDeapexerInfoProviders(di, p); selected != nil {
- di = selected
- return
- }
- ctx.ModuleErrorf("Multiple installable prebuilt APEXes provide ambiguous deapexers: %s and %s",
- di.ApexModuleName(), p.ApexModuleName())
- }
- di = p
- })
- if di != nil {
- return di
- }
- ai := ctx.Provider(ApexInfoProvider).(ApexInfo)
- ctx.ModuleErrorf("No prebuilt APEX provides a deapexer module for APEX variant %s", ai.ApexVariationName)
- return nil
- }
- // removeCompressedApexSuffix removes the _compressed suffix from the name if present.
- func removeCompressedApexSuffix(name string) string {
- return strings.TrimSuffix(name, "_compressed")
- }
- // equivalentDeapexerInfoProviders checks to make sure that the two DeapexerInfo structures are
- // equivalent.
- //
- // At the moment <x> and <x>_compressed APEXes are treated as being equivalent.
- //
- // If they are not equivalent then this returns nil, otherwise, this returns the DeapexerInfo that
- // should be used by the build, which is always the uncompressed one. That ensures that the behavior
- // of the build is not dependent on which prebuilt APEX is visited first.
- func equivalentDeapexerInfoProviders(p1 *DeapexerInfo, p2 *DeapexerInfo) *DeapexerInfo {
- n1 := removeCompressedApexSuffix(p1.ApexModuleName())
- n2 := removeCompressedApexSuffix(p2.ApexModuleName())
- // If the names don't match then they are not equivalent.
- if n1 != n2 {
- return nil
- }
- // Select the uncompressed APEX.
- if n1 == removeCompressedApexSuffix(n1) {
- return p1
- } else {
- return p2
- }
- }
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