Add apex_available to control the availablity of a module to APEXes

apex_available property controls the availability of a module to APEXes.
For example, `apex_available: ["myapex", "otherapex"]` makes the module
available only to the two APEXes: myapex and otherapex, and nothing
else, even to the platform.

If the module is intended to be available to any APEX, then a pseudo
name "//apex_available:anyapex" can be used.

If the module is intended to be available to the platform, then another
pseudo name "//apex_available:platform" is used.

For now, if unspecified, this property defaults to ["//apex_available:platform",
"//apex_available:anyapex"], which means the module is available to everybody.
This will be reduced to ["//apex_available:platform"], when marking for
apex_available for existing modules are finished.

Bug: 139870423
Bug: 128708192
Test: m
Change-Id: Id4b233c3056c7858f984cbf9427cfac4118b2682

android/apex.go

@@ -78,12 +78,23 @@ type ApexModule interface {
 
 	// Return the no_apex property
 	NoApex() bool
+
+	// Tests if this module is available for the specified APEX or ":platform"
+	AvailableFor(what string) bool
 }
 
 type ApexProperties struct {
 	// Whether this module should not be part of any APEX. Default is false.
+	// TODO(b/128708192): remove this as this is equal to apex_available: [":platform"]
 	No_apex *bool
 
+	// Availability of this module in APEXes. Only the listed APEXes can include this module.
+	// "//apex_available:anyapex" is a pseudo APEX name that matches to any APEX.
+	// "//apex_available:platform" refers to non-APEX partitions like "system.img".
+	// Default is ["//apex_available:platform", "//apex_available:anyapex"].
+	// TODO(b/128708192) change the default to ["//apex_available:platform"]
+	Apex_available []string
+
 	// Name of the apex variant that this module is mutated into
 	ApexName string `blueprint:"mutated"`
 }
@@ -136,15 +147,46 @@ func (m *ApexModuleBase) NoApex() bool {
 	return proptools.Bool(m.ApexProperties.No_apex)
 }
 
+const (
+	availableToPlatform = "//apex_available:platform"
+	availableToAnyApex  = "//apex_available:anyapex"
+)
+
+func (m *ApexModuleBase) AvailableFor(what string) bool {
+	if len(m.ApexProperties.Apex_available) == 0 {
+		// apex_available defaults to ["//apex_available:platform", "//apex_available:anyapex"],
+		// which means 'available to everybody'.
+		return true
+	}
+	return InList(what, m.ApexProperties.Apex_available) ||
+		(what != availableToPlatform && InList(availableToAnyApex, m.ApexProperties.Apex_available))
+}
+
+func (m *ApexModuleBase) checkApexAvailableProperty(mctx BaseModuleContext) {
+	for _, n := range m.ApexProperties.Apex_available {
+		if n == availableToPlatform || n == availableToAnyApex {
+			continue
+		}
+		if !mctx.OtherModuleExists(n) {
+			mctx.PropertyErrorf("apex_available", "%q is not a valid module name", n)
+		}
+	}
+}
+
 func (m *ApexModuleBase) CreateApexVariations(mctx BottomUpMutatorContext) []blueprint.Module {
 	if len(m.apexVariations) > 0 {
+		m.checkApexAvailableProperty(mctx)
 		sort.Strings(m.apexVariations)
-		variations := []string{""} // Original variation for platform
+		variations := []string{}
+		availableForPlatform := m.AvailableFor(availableToPlatform)
+		if availableForPlatform {
+			variations = append(variations, "") // Original variation for platform
+		}
 		variations = append(variations, m.apexVariations...)
 
 		modules := mctx.CreateVariations(variations...)
 		for i, m := range modules {
-			if i == 0 {
+			if availableForPlatform && i == 0 {
 				continue
 			}
 			m.(ApexModule).setApexName(variations[i])

apex/apex.go

@@ -1215,6 +1215,16 @@ func (a *apexBundle) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 		}
 	}
 
+	// check apex_available requirements
+	for _, fi := range filesInfo {
+		if am, ok := fi.module.(android.ApexModule); ok {
+			if !am.AvailableFor(ctx.ModuleName()) {
+				ctx.ModuleErrorf("requires %q that is not available for the APEX", fi.module.Name())
+				return
+			}
+		}
+	}
+
 	// prepend the name of this APEX to the module names. These names will be the names of
 	// modules that will be defined if the APEX is flattened.
 	for i := range filesInfo {

apex/apex_test.go

@@ -2422,6 +2422,158 @@ func TestApexWithApps(t *testing.T) {
 
 }
 
+func TestApexAvailable(t *testing.T) {
+	// libfoo is not available to myapex, but only to otherapex
+	testApexError(t, "requires \"libfoo\" that is not available for the APEX", `
+	apex {
+		name: "myapex",
+		key: "myapex.key",
+		native_shared_libs: ["libfoo"],
+	}
+
+	apex_key {
+		name: "myapex.key",
+		public_key: "testkey.avbpubkey",
+		private_key: "testkey.pem",
+	}
+
+	apex {
+		name: "otherapex",
+		key: "otherapex.key",
+		native_shared_libs: ["libfoo"],
+	}
+
+	apex_key {
+		name: "otherapex.key",
+		public_key: "testkey.avbpubkey",
+		private_key: "testkey.pem",
+	}
+
+	cc_library {
+		name: "libfoo",
+		stl: "none",
+		system_shared_libs: [],
+		apex_available: ["otherapex"],
+	}`)
+
+	// libbar is an indirect dep
+	testApexError(t, "requires \"libbar\" that is not available for the APEX", `
+	apex {
+		name: "myapex",
+		key: "myapex.key",
+		native_shared_libs: ["libfoo"],
+	}
+
+	apex_key {
+		name: "myapex.key",
+		public_key: "testkey.avbpubkey",
+		private_key: "testkey.pem",
+	}
+
+	apex {
+		name: "otherapex",
+		key: "otherapex.key",
+		native_shared_libs: ["libfoo"],
+	}
+
+	apex_key {
+		name: "otherapex.key",
+		public_key: "testkey.avbpubkey",
+		private_key: "testkey.pem",
+	}
+
+	cc_library {
+		name: "libfoo",
+		stl: "none",
+		shared_libs: ["libbar"],
+		system_shared_libs: [],
+		apex_available: ["myapex", "otherapex"],
+	}
+
+	cc_library {
+		name: "libbar",
+		stl: "none",
+		system_shared_libs: [],
+		apex_available: ["otherapex"],
+	}`)
+
+	testApexError(t, "\"otherapex\" is not a valid module name", `
+	apex {
+		name: "myapex",
+		key: "myapex.key",
+		native_shared_libs: ["libfoo"],
+	}
+
+	apex_key {
+		name: "myapex.key",
+		public_key: "testkey.avbpubkey",
+		private_key: "testkey.pem",
+	}
+
+	cc_library {
+		name: "libfoo",
+		stl: "none",
+		system_shared_libs: [],
+		apex_available: ["otherapex"],
+	}`)
+
+	ctx, _ := testApex(t, `
+	apex {
+		name: "myapex",
+		key: "myapex.key",
+		native_shared_libs: ["libfoo", "libbar"],
+	}
+
+	apex_key {
+		name: "myapex.key",
+		public_key: "testkey.avbpubkey",
+		private_key: "testkey.pem",
+	}
+
+	cc_library {
+		name: "libfoo",
+		stl: "none",
+		system_shared_libs: [],
+		apex_available: ["myapex"],
+	}
+
+	cc_library {
+		name: "libbar",
+		stl: "none",
+		system_shared_libs: [],
+		apex_available: ["//apex_available:anyapex"],
+	}`)
+
+	// check that libfoo and libbar are created only for myapex, but not for the platform
+	ensureListContains(t, ctx.ModuleVariantsForTests("libfoo"), "android_arm64_armv8-a_core_shared_myapex")
+	ensureListNotContains(t, ctx.ModuleVariantsForTests("libfoo"), "android_arm64_armv8-a_core_shared")
+	ensureListContains(t, ctx.ModuleVariantsForTests("libbar"), "android_arm64_armv8-a_core_shared_myapex")
+	ensureListNotContains(t, ctx.ModuleVariantsForTests("libbar"), "android_arm64_armv8-a_core_shared")
+
+	ctx, _ = testApex(t, `
+	apex {
+		name: "myapex",
+		key: "myapex.key",
+	}
+
+	apex_key {
+		name: "myapex.key",
+		public_key: "testkey.avbpubkey",
+		private_key: "testkey.pem",
+	}
+
+	cc_library {
+		name: "libfoo",
+		stl: "none",
+		system_shared_libs: [],
+		apex_available: ["//apex_available:platform"],
+	}`)
+
+	// check that libfoo is created only for the platform
+	ensureListNotContains(t, ctx.ModuleVariantsForTests("libfoo"), "android_arm64_armv8-a_core_shared_myapex")
+	ensureListContains(t, ctx.ModuleVariantsForTests("libfoo"), "android_arm64_armv8-a_core_shared")
+}
+
 func TestMain(m *testing.M) {
 	run := func() int {
 		setUp()