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1// Copyright 2016 Google Inc. All rights reserved.
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 android
16
17import "github.com/google/blueprint"
18
19// This file implements common functionality for handling modules that may exist as prebuilts,
20// source, or both.
21
22type prebuiltDependencyTag struct {
23	blueprint.BaseDependencyTag
24}
25
26var prebuiltDepTag prebuiltDependencyTag
27
28type Prebuilt struct {
29	Properties struct {
30		Srcs []string `android:"arch_variant"`
31		// When prefer is set to true the prebuilt will be used instead of any source module with
32		// a matching name.
33		Prefer bool `android:"arch_variant"`
34
35		SourceExists bool `blueprint:"mutated"`
36		UsePrebuilt  bool `blueprint:"mutated"`
37	}
38	module Module
39}
40
41func (p *Prebuilt) Name(name string) string {
42	return "prebuilt_" + name
43}
44
45func (p *Prebuilt) Path(ctx ModuleContext) Path {
46	if len(p.Properties.Srcs) == 0 {
47		ctx.PropertyErrorf("srcs", "missing prebuilt source file")
48		return nil
49	}
50
51	if len(p.Properties.Srcs) > 1 {
52		ctx.PropertyErrorf("srcs", "multiple prebuilt source files")
53		return nil
54	}
55
56	return PathForModuleSrc(ctx, p.Properties.Srcs[0])
57}
58
59type PrebuiltInterface interface {
60	Module
61	Prebuilt() *Prebuilt
62}
63
64// prebuiltMutator ensures that there is always a module with an undecorated name, and marks
65// prebuilt modules that have both a prebuilt and a source module.
66func prebuiltMutator(ctx BottomUpMutatorContext) {
67	if m, ok := ctx.Module().(PrebuiltInterface); ok && m.Prebuilt() != nil {
68		p := m.Prebuilt()
69		name := m.base().BaseModuleName()
70		if ctx.OtherModuleExists(name) {
71			ctx.AddReverseDependency(ctx.Module(), prebuiltDepTag, name)
72			p.Properties.SourceExists = true
73		} else {
74			ctx.Rename(name)
75		}
76	}
77}
78
79// PrebuiltSelectModuleMutator marks prebuilts that are used, either overriding source modules or
80// because the source module doesn't exist.  It also disables installing overridden source modules.
81func PrebuiltSelectModuleMutator(ctx TopDownMutatorContext) {
82	if m, ok := ctx.Module().(PrebuiltInterface); ok && m.Prebuilt() != nil {
83		p := m.Prebuilt()
84		if !p.Properties.SourceExists {
85			p.Properties.UsePrebuilt = p.usePrebuilt(ctx, nil)
86		}
87	} else if s, ok := ctx.Module().(Module); ok {
88		ctx.VisitDirectDeps(func(m blueprint.Module) {
89			if ctx.OtherModuleDependencyTag(m) == prebuiltDepTag {
90				p := m.(PrebuiltInterface).Prebuilt()
91				if p.usePrebuilt(ctx, s) {
92					p.Properties.UsePrebuilt = true
93					s.SkipInstall()
94				}
95			}
96		})
97	}
98}
99
100// PrebuiltReplaceMutator replaces dependencies on the source module with dependencies on the
101// prebuilt when both modules exist and the prebuilt should be used.  When the prebuilt should not
102// be used, disable installing it.
103func PrebuiltReplaceMutator(ctx BottomUpMutatorContext) {
104	if m, ok := ctx.Module().(PrebuiltInterface); ok && m.Prebuilt() != nil {
105		p := m.Prebuilt()
106		name := m.base().BaseModuleName()
107		if p.Properties.UsePrebuilt {
108			if p.Properties.SourceExists {
109				ctx.ReplaceDependencies(name)
110			}
111		} else {
112			m.SkipInstall()
113		}
114	}
115}
116
117// usePrebuilt returns true if a prebuilt should be used instead of the source module.  The prebuilt
118// will be used if it is marked "prefer" or if the source module is disabled.
119func (p *Prebuilt) usePrebuilt(ctx TopDownMutatorContext, source Module) bool {
120	if len(p.Properties.Srcs) == 0 {
121		return false
122	}
123
124	// TODO: use p.Properties.Name and ctx.ModuleDir to override preference
125	if p.Properties.Prefer {
126		return true
127	}
128
129	return source == nil || !source.Enabled()
130}
131