1// Copyright 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 snapshot
16
17import (
18	"encoding/json"
19	"path/filepath"
20
21	"android/soong/android"
22)
23
24// The host_snapshot module creates a snapshot of host tools to be used
25// in a minimal source tree.   In order to create the host_snapshot the
26// user must explicitly list the modules to be included.  The
27// host-fake-snapshot, defined in this file, is a utility to help determine
28// which host modules are being used in the minimal source tree.
29//
30// The host-fake-snapshot is designed to run in a full source tree and
31// will result in a snapshot that contains an empty file for each host
32// tool found in the tree.  The fake snapshot is only used to determine
33// the host modules that the minimal source tree depends on, hence the
34// snapshot uses an empty file for each module and saves on having to
35// actually build any tool to generate the snapshot.  The fake snapshot
36// is compatible with an actual host_snapshot and is installed into a
37// minimal source tree via the development/vendor_snapshot/update.py
38// script.
39//
40// After generating the fake snapshot and installing into the minimal
41// source tree, the dependent modules are determined via the
42// development/vendor_snapshot/update.py script (see script for more
43// information).  These modules are then used to define the actual
44// host_snapshot to be used.  This is a similar process to the other
45// snapshots (vendor, recovery,...)
46//
47// Example
48//
49// Full source tree:
50//   1/ Generate fake host snapshot
51//
52// Minimal source tree:
53//   2/ Install the fake host snapshot
54//   3/ List the host modules used from the snapshot
55//   4/ Remove fake host snapshot
56//
57// Full source tree:
58//   4/ Create host_snapshot with modules identified in step 3
59//
60// Minimal source tree:
61//   5/ Install host snapshot
62//   6/ Build
63//
64// The host-fake-snapshot is a singleton module, that will be built
65// if HOST_FAKE_SNAPSHOT_ENABLE=true.
66
67func init() {
68	registerHostSnapshotComponents(android.InitRegistrationContext)
69}
70
71// Add prebuilt information to snapshot data
72type hostSnapshotFakeJsonFlags struct {
73	SnapshotJsonFlags
74	Prebuilt bool `json:",omitempty"`
75}
76
77func registerHostSnapshotComponents(ctx android.RegistrationContext) {
78	ctx.RegisterParallelSingletonType("host-fake-snapshot", HostToolsFakeAndroidSingleton)
79}
80
81type hostFakeSingleton struct {
82	snapshotDir string
83	zipFile     android.OptionalPath
84}
85
86func (c *hostFakeSingleton) init() {
87	c.snapshotDir = "host-fake-snapshot"
88
89}
90func HostToolsFakeAndroidSingleton() android.Singleton {
91	singleton := &hostFakeSingleton{}
92	singleton.init()
93	return singleton
94}
95
96func (c *hostFakeSingleton) GenerateBuildActions(ctx android.SingletonContext) {
97	if !ctx.DeviceConfig().HostFakeSnapshotEnabled() {
98		return
99	}
100	// Find all host binary modules add 'fake' versions to snapshot
101	var outputs android.Paths
102	seen := make(map[string]bool)
103	var jsonData []hostSnapshotFakeJsonFlags
104	prebuilts := make(map[string]bool)
105
106	ctx.VisitAllModules(func(module android.Module) {
107		if module.Target().Os != ctx.Config().BuildOSTarget.Os {
108			return
109		}
110		if module.Target().Arch.ArchType != ctx.Config().BuildOSTarget.Arch.ArchType {
111			return
112		}
113
114		if android.IsModulePrebuilt(module) {
115			// Add non-prebuilt module name to map of prebuilts
116			prebuilts[android.RemoveOptionalPrebuiltPrefix(module.Name())] = true
117			return
118		}
119		if !module.Enabled(ctx) || module.IsHideFromMake() {
120			return
121		}
122		apexInfo, _ := android.SingletonModuleProvider(ctx, module, android.ApexInfoProvider)
123		if !apexInfo.IsForPlatform() {
124			return
125		}
126		path := hostToolPath(module)
127		if path.Valid() && path.String() != "" {
128			outFile := filepath.Join(c.snapshotDir, path.String())
129			if !seen[outFile] {
130				seen[outFile] = true
131				outputs = append(outputs, WriteStringToFileRule(ctx, "", outFile))
132				jsonData = append(jsonData, hostSnapshotFakeJsonFlags{*hostJsonDesc(module), false})
133			}
134		}
135	})
136	// Update any module prebuilt information
137	for idx, _ := range jsonData {
138		if _, ok := prebuilts[jsonData[idx].ModuleName]; ok {
139			// Prebuilt exists for this module
140			jsonData[idx].Prebuilt = true
141		}
142	}
143	marsh, err := json.Marshal(jsonData)
144	if err != nil {
145		ctx.Errorf("host fake snapshot json marshal failure: %#v", err)
146		return
147	}
148	outputs = append(outputs, WriteStringToFileRule(ctx, string(marsh), filepath.Join(c.snapshotDir, "host_snapshot.json")))
149	c.zipFile = zipSnapshot(ctx, c.snapshotDir, c.snapshotDir, outputs)
150
151}
152func (c *hostFakeSingleton) MakeVars(ctx android.MakeVarsContext) {
153	if !c.zipFile.Valid() {
154		return
155	}
156	ctx.Phony(
157		"host-fake-snapshot",
158		c.zipFile.Path())
159
160	ctx.DistForGoal(
161		"host-fake-snapshot",
162		c.zipFile.Path())
163
164}
165