1// Copyright (C) 2021 The Android Open Source Project
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15package apex
16
17import (
18	"strings"
19
20	"android/soong/android"
21)
22
23// Contains 'deapexer' a private module type used by 'prebuilt_apex' to make dex files contained
24// within a .apex file referenced by `prebuilt_apex` available for use by their associated
25// `java_import` modules.
26//
27// An 'apex' module references `java_library` modules from which .dex files are obtained that are
28// stored in the resulting `.apex` file. The resulting `.apex` file is then made available as a
29// prebuilt by referencing it from a `prebuilt_apex`. For each such `java_library` that is used by
30// modules outside the `.apex` file a `java_import` prebuilt is made available referencing a jar
31// that contains the Java classes.
32//
33// When building a Java module type, e.g. `java_module` or `android_app` against such prebuilts the
34// `java_import` provides the classes jar  (jar containing `.class` files) against which the
35// module's `.java` files are compiled. That classes jar usually contains only stub classes. The
36// resulting classes jar is converted into a dex jar (jar containing `.dex` files). Then if
37// necessary the dex jar is further processed by `dexpreopt` to produce an optimized form of the
38// library specific to the current Android version. This process requires access to implementation
39// dex jars for each `java_import`. The `java_import` will obtain the implementation dex jar from
40// the `.apex` file in the associated `prebuilt_apex`.
41//
42// This is intentionally not registered by name as it is not intended to be used from within an
43// `Android.bp` file.
44
45// DeapexerProperties specifies the properties supported by the deapexer module.
46//
47// As these are never intended to be supplied in a .bp file they use a different naming convention
48// to make it clear that they are different.
49type DeapexerProperties struct {
50	// List of common modules that may need access to files exported by this module.
51	//
52	// A common module in this sense is one that is not arch specific but uses a common variant for
53	// all architectures, e.g. java.
54	CommonModules []string
55
56	// List of modules that use an embedded .prof to guide optimization of the equivalent dexpreopt artifact
57	// This is a subset of CommonModules
58	DexpreoptProfileGuidedModules []string
59
60	// List of files exported from the .apex file by this module
61	//
62	// Each entry is a path from the apex root, e.g. javalib/core-libart.jar.
63	ExportedFiles []string
64}
65
66type SelectedApexProperties struct {
67	// The path to the apex selected for use by this module.
68	//
69	// Is tagged as `android:"path"` because it will usually contain a string of the form ":<module>"
70	// and is tagged as "`blueprint:"mutate"` because it is only initialized in a LoadHook not an
71	// Android.bp file.
72	Selected_apex *string `android:"path" blueprint:"mutated"`
73}
74
75type Deapexer struct {
76	android.ModuleBase
77
78	properties             DeapexerProperties
79	selectedApexProperties SelectedApexProperties
80
81	inputApex android.Path
82}
83
84// Returns the name of the deapexer module corresponding to an APEX module with the given name.
85func deapexerModuleName(apexModuleName string) string {
86	return apexModuleName + ".deapexer"
87}
88
89// Returns the name of the APEX module corresponding to an deapexer module with
90// the given name. This reverses deapexerModuleName.
91func apexModuleName(deapexerModuleName string) string {
92	return strings.TrimSuffix(deapexerModuleName, ".deapexer")
93}
94
95func privateDeapexerFactory() android.Module {
96	module := &Deapexer{}
97	module.AddProperties(&module.properties, &module.selectedApexProperties)
98	android.InitAndroidMultiTargetsArchModule(module, android.DeviceSupported, android.MultilibCommon)
99	return module
100}
101
102func (p *Deapexer) DepsMutator(ctx android.BottomUpMutatorContext) {
103	// Add dependencies from the java modules to which this exports files from the `.apex` file onto
104	// this module so that they can access the `DeapexerInfo` object that this provides.
105	// TODO: b/308174306 - Once all the mainline modules have been flagged, drop this dependency edge
106	for _, lib := range p.properties.CommonModules {
107		dep := prebuiltApexExportedModuleName(ctx, lib)
108		ctx.AddReverseDependency(ctx.Module(), android.DeapexerTag, dep)
109	}
110}
111
112func (p *Deapexer) GenerateAndroidBuildActions(ctx android.ModuleContext) {
113	p.inputApex = android.OptionalPathForModuleSrc(ctx, p.selectedApexProperties.Selected_apex).Path()
114
115	// Create and remember the directory into which the .apex file's contents will be unpacked.
116	deapexerOutput := android.PathForModuleOut(ctx, "deapexer")
117
118	exports := make(map[string]android.WritablePath)
119
120	// Create mappings from apex relative path to the extracted file's path.
121	exportedPaths := make(android.Paths, 0, len(exports))
122	for _, path := range p.properties.ExportedFiles {
123		// Populate the exports that this makes available.
124		extractedPath := deapexerOutput.Join(ctx, path)
125		exports[path] = extractedPath
126		exportedPaths = append(exportedPaths, extractedPath)
127	}
128
129	// If the prebuilt_apex exports any files then create a build rule that unpacks the apex using
130	// deapexer and verifies that all the required files were created. Also, make the mapping from
131	// apex relative path to extracted file path available for other modules.
132	if len(exports) > 0 {
133		// Make the information available for other modules.
134		di := android.NewDeapexerInfo(apexModuleName(ctx.ModuleName()), exports, p.properties.CommonModules)
135		di.AddDexpreoptProfileGuidedExportedModuleNames(p.properties.DexpreoptProfileGuidedModules...)
136		android.SetProvider(ctx, android.DeapexerProvider, di)
137
138		// Create a sorted list of the files that this exports.
139		exportedPaths = android.SortedUniquePaths(exportedPaths)
140
141		// The apex needs to export some files so create a ninja rule to unpack the apex and check that
142		// the required files are present.
143		builder := android.NewRuleBuilder(pctx, ctx)
144		command := builder.Command()
145		command.
146			Tool(android.PathForSource(ctx, "build/soong/scripts/unpack-prebuilt-apex.sh")).
147			BuiltTool("deapexer").
148			BuiltTool("debugfs").
149			BuiltTool("fsck.erofs").
150			Input(p.inputApex).
151			Text(deapexerOutput.String())
152		for _, p := range exportedPaths {
153			command.Output(p.(android.WritablePath))
154		}
155		builder.Build("deapexer", "deapex "+apexModuleName(ctx.ModuleName()))
156	}
157}
158