Enforce stub libraries should have a single apex_available

If a library contributes to an API surface, it will have only a single
copy on device. Therefore, we should disallow installation to muliple
apexes/platform.

There are some exceptions to this rule today, and they have been relaxed
using allowlists.

Bug: 277651159
Test: go test ./apex
Change-Id: Ice3023ecd28412a2610d8b98628cb727b58c5c3b

apex/apex_test.go

@@ -3131,10 +3131,7 @@ func TestStaticLinking(t *testing.T) {
 			stubs: {
 				versions: ["1", "2", "3"],
 			},
-			apex_available: [
-				"//apex_available:platform",
-				"myapex",
-			],
+			apex_available: ["myapex"],
 		}
 
 		cc_binary {
@@ -4134,7 +4131,7 @@ func TestDependenciesInApexManifest(t *testing.T) {
 		apex {
 			name: "myapex_selfcontained",
 			key: "myapex.key",
-			native_shared_libs: ["lib_dep", "libfoo"],
+			native_shared_libs: ["lib_dep_on_bar", "libbar"],
 			compile_multilib: "both",
 			file_contexts: ":myapex-file_contexts",
 			updatable: false,
@@ -4167,6 +4164,18 @@ func TestDependenciesInApexManifest(t *testing.T) {
 			],
 		}
 
+		cc_library {
+			name: "lib_dep_on_bar",
+			srcs: ["mylib.cpp"],
+			shared_libs: ["libbar"],
+			system_shared_libs: [],
+			stl: "none",
+			apex_available: [
+				"myapex_selfcontained",
+			],
+		}
+
+
 		cc_library {
 			name: "libfoo",
 			srcs: ["mytest.cpp"],
@@ -4177,9 +4186,22 @@ func TestDependenciesInApexManifest(t *testing.T) {
 			stl: "none",
 			apex_available: [
 				"myapex_provider",
+			],
+		}
+
+		cc_library {
+			name: "libbar",
+			srcs: ["mytest.cpp"],
+			stubs: {
+				versions: ["1"],
+			},
+			system_shared_libs: [],
+			stl: "none",
+			apex_available: [
 				"myapex_selfcontained",
 			],
 		}
+
 	`)
 
 	var apexManifestRule android.TestingBuildParams
@@ -4206,7 +4228,7 @@ func TestDependenciesInApexManifest(t *testing.T) {
 	apexManifestRule = ctx.ModuleForTests("myapex_selfcontained", "android_common_myapex_selfcontained_image").Rule("apexManifestRule")
 	provideNativeLibs = names(apexManifestRule.Args["provideNativeLibs"])
 	requireNativeLibs = names(apexManifestRule.Args["requireNativeLibs"])
-	ensureListContains(t, provideNativeLibs, "libfoo.so")
+	ensureListContains(t, provideNativeLibs, "libbar.so")
 	ensureListEmpty(t, requireNativeLibs)
 }
 
@@ -8488,14 +8510,14 @@ func TestTestForForLibInOtherApex(t *testing.T) {
 		apex {
 			name: "com.android.art",
 			key: "myapex.key",
-			native_shared_libs: ["mylib"],
+			native_shared_libs: ["libnativebridge"],
 			updatable: false,
 		}
 
 		apex {
 			name: "com.android.art.debug",
 			key: "myapex.key",
-			native_shared_libs: ["mylib", "mytestlib"],
+			native_shared_libs: ["libnativebridge", "libnativebrdige_test"],
 			updatable: false,
 		}
 
@@ -8506,8 +8528,8 @@ func TestTestForForLibInOtherApex(t *testing.T) {
 		}
 
 		cc_library {
-			name: "mylib",
-			srcs: ["mylib.cpp"],
+			name: "libnativebridge",
+			srcs: ["libnativebridge.cpp"],
 			system_shared_libs: [],
 			stl: "none",
 			stubs: {
@@ -8517,10 +8539,10 @@ func TestTestForForLibInOtherApex(t *testing.T) {
 		}
 
 		cc_library {
-			name: "mytestlib",
+			name: "libnativebrdige_test",
 			srcs: ["mylib.cpp"],
 			system_shared_libs: [],
-			shared_libs: ["mylib"],
+			shared_libs: ["libnativebridge"],
 			stl: "none",
 			apex_available: ["com.android.art.debug"],
 			test_for: ["com.android.art"],
@@ -10192,3 +10214,77 @@ func TestCannedFsConfig_HasCustomConfig(t *testing.T) {
 	// Ensure that canned_fs_config has "cat my_config" at the end
 	ensureContains(t, cmd, `( echo '/ 1000 1000 0755'; echo '/apex_manifest.json 1000 1000 0644'; echo '/apex_manifest.pb 1000 1000 0644'; cat my_config ) >`)
 }
+
+func TestStubLibrariesMultipleApexViolation(t *testing.T) {
+	testCases := []struct {
+		desc          string
+		hasStubs      bool
+		apexAvailable string
+		expectedError string
+	}{
+		{
+			desc:          "non-stub library can have multiple apex_available",
+			hasStubs:      false,
+			apexAvailable: `["myapex", "otherapex"]`,
+		},
+		{
+			desc:          "stub library should not be available to anyapex",
+			hasStubs:      true,
+			apexAvailable: `["//apex_available:anyapex"]`,
+			expectedError: "Stub libraries should have a single apex_available.*anyapex",
+		},
+		{
+			desc:          "stub library should not be available to multiple apexes",
+			hasStubs:      true,
+			apexAvailable: `["myapex", "otherapex"]`,
+			expectedError: "Stub libraries should have a single apex_available.*myapex.*otherapex",
+		},
+		{
+			desc:          "stub library can be available to a core apex and a test apex",
+			hasStubs:      true,
+			apexAvailable: `["myapex", "test_myapex"]`,
+		},
+	}
+	bpTemplate := `
+		cc_library {
+			name: "libfoo",
+			%v
+			apex_available: %v,
+		}
+		apex {
+			name: "myapex",
+			key: "apex.key",
+			updatable: false,
+			native_shared_libs: ["libfoo"],
+		}
+		apex {
+			name: "otherapex",
+			key: "apex.key",
+			updatable: false,
+		}
+		apex_test {
+			name: "test_myapex",
+			key: "apex.key",
+			updatable: false,
+			native_shared_libs: ["libfoo"],
+		}
+		apex_key {
+			name: "apex.key",
+		}
+	`
+	for _, tc := range testCases {
+		stubs := ""
+		if tc.hasStubs {
+			stubs = `stubs: {symbol_file: "libfoo.map.txt"},`
+		}
+		bp := fmt.Sprintf(bpTemplate, stubs, tc.apexAvailable)
+		mockFsFixturePreparer := android.FixtureModifyMockFS(func(fs android.MockFS) {
+			fs["system/sepolicy/apex/test_myapex-file_contexts"] = nil
+		})
+		if tc.expectedError == "" {
+			testApex(t, bp, mockFsFixturePreparer)
+		} else {
+			testApexError(t, tc.expectedError, bp, mockFsFixturePreparer)
+		}
+	}
+}

cc/cc.go

@@ -1987,6 +1987,56 @@ func moduleContextFromAndroidModuleContext(actx android.ModuleContext, c *Module
 	return ctx
 }
 
+// TODO (b/277651159): Remove this allowlist
+var (
+	skipStubLibraryMultipleApexViolation = map[string]bool{
+		"libclang_rt.asan":   true,
+		"libclang_rt.hwasan": true,
+		// runtime apex
+		"libc":          true,
+		"libc_hwasan":   true,
+		"libdl_android": true,
+		"libm":          true,
+		"libdl":         true,
+		// art apex
+		"libandroidio":    true,
+		"libdexfile":      true,
+		"libnativebridge": true,
+		"libnativehelper": true,
+		"libnativeloader": true,
+		"libsigchain":     true,
+	}
+)
+
+// Returns true if a stub library could be installed in multiple apexes
+func (c *Module) stubLibraryMultipleApexViolation(ctx android.ModuleContext) bool {
+	// If this is not an apex variant, no check necessary
+	if !c.InAnyApex() {
+		return false
+	}
+	// If this is not a stub library, no check necessary
+	if !c.HasStubsVariants() {
+		return false
+	}
+	// Skip the allowlist
+	// Use BaseModuleName so that this matches prebuilts.
+	if _, exists := skipStubLibraryMultipleApexViolation[c.BaseModuleName()]; exists {
+		return false
+	}
+
+	_, aaWithoutTestApexes, _ := android.ListSetDifference(c.ApexAvailable(), c.TestApexes())
+	// Stub libraries should not have more than one apex_available
+	if len(aaWithoutTestApexes) > 1 {
+		return true
+	}
+	// Stub libraries should not use the wildcard
+	if aaWithoutTestApexes[0] == android.AvailableToAnyApex {
+		return true
+	}
+	// Default: no violation
+	return false
+}
+
 func (c *Module) GenerateAndroidBuildActions(actx android.ModuleContext) {
 	// Handle the case of a test module split by `test_per_src` mutator.
 	//
@@ -2013,6 +2063,10 @@ func (c *Module) GenerateAndroidBuildActions(actx android.ModuleContext) {
 		return
 	}
 
+	if c.stubLibraryMultipleApexViolation(actx) {
+		actx.PropertyErrorf("apex_available",
+			"Stub libraries should have a single apex_available (test apexes excluded). Got %v", c.ApexAvailable())
+	}
 	if c.Properties.Clang != nil && *c.Properties.Clang == false {
 		ctx.PropertyErrorf("clang", "false (GCC) is no longer supported")
 	} else if c.Properties.Clang != nil && !ctx.DeviceConfig().BuildBrokenClangProperty() {