Pass --sdk-extensions-{root,info} to metalava

Teach soong to pass metalava the two new command line arguments
--sdk-extensions-root <dir> and --sdk-extensions-info <file> when
generating the API levels file (--generate-api-levels api-versions.xml).

The directory hierarcy in a droiddoc_exported_dir module has special
meaning, e.g. extensions/1/public/*-stubs.jar are the mainline module
stubs containing the public API for SdkExt version 1. Update the logic
where the directories are scanned for android.jar files to locate the
SDK extension jars (extensions/<int>/public/*-stubs.jar).

Also introduce a new field on droidstubs properties
(Extensions_info_file) to set the value of --sdk-extensions-info.

Note: if Extensions_info_file is not set, neither
--sdk-extensions-root or --sdk-extensions-info will be passed to
metalava.

Bug: 228828986
Test: go test -run TestDroidstubsWithSdkExtensions ./java
Test: m sdk dist && grep -e from= -e module= out/dist/data/api-versions.xml # needs APIs to be listed in the info file
Change-Id: I682e34d328fc93d3eded8565ffee40961307901a

java/droidstubs.go

@@ -17,6 +17,7 @@ package java
 import (
 	"fmt"
 	"path/filepath"
+	"regexp"
 	"strings"
 
 	"github.com/google/blueprint/proptools"
@@ -142,6 +143,10 @@ type DroidstubsProperties struct {
 	// if set to true, collect the values used by the Dev tools and
 	// write them in files packaged with the SDK. Defaults to false.
 	Write_sdk_values *bool
+
+	// path or filegroup to file defining extension an SDK name <-> numerical ID mapping and
+	// what APIs exist in which SDKs; passed to metalava via --sdk-extensions-info
+	Extensions_info_file *string `android:"path"`
 }
 
 // Used by xsd_config
@@ -398,9 +403,20 @@ func (d *Droidstubs) apiLevelsGenerationFlags(ctx android.ModuleContext, cmd *an
 	filename := proptools.StringDefault(d.properties.Api_levels_jar_filename, "android.jar")
 
 	var dirs []string
+	var extensions_dir string
 	ctx.VisitDirectDepsWithTag(metalavaAPILevelsAnnotationsDirTag, func(m android.Module) {
 		if t, ok := m.(*ExportedDroiddocDir); ok {
+			extRegex := regexp.MustCompile(t.dir.String() + `/extensions/[0-9]+/public/.*\.jar`)
+
+			// Grab the first extensions_dir and we find while scanning ExportedDroiddocDir.deps;
+			// ideally this should be read from prebuiltApis.properties.Extensions_*
 			for _, dep := range t.deps {
+				if extRegex.MatchString(dep.String()) && d.properties.Extensions_info_file != nil {
+					if extensions_dir == "" {
+						extensions_dir = t.dir.String() + "/extensions"
+					}
+					cmd.Implicit(dep)
+				}
 				if dep.Base() == filename {
 					cmd.Implicit(dep)
 				}
@@ -445,6 +461,16 @@ func (d *Droidstubs) apiLevelsGenerationFlags(ctx android.ModuleContext, cmd *an
 			cmd.FlagWithArg("--android-jar-pattern ", fmt.Sprintf("%s/%%/%s/%s", dir, sdkDir, filename))
 		}
 	}
+
+	if d.properties.Extensions_info_file != nil {
+		if extensions_dir == "" {
+			ctx.ModuleErrorf("extensions_info_file set, but no SDK extension dirs found")
+		}
+		info_file := android.PathForModuleSrc(ctx, *d.properties.Extensions_info_file)
+		cmd.Implicit(info_file)
+		cmd.FlagWithArg("--sdk-extensions-root ", extensions_dir)
+		cmd.FlagWithArg("--sdk-extensions-info ", info_file.String())
+	}
 }
 
 func metalavaUseRbe(ctx android.ModuleContext) bool {

java/droidstubs_test.go

@@ -259,3 +259,33 @@ func checkSystemModulesUseByDroidstubs(t *testing.T, ctx *android.TestContext, m
 		t.Errorf("inputs of %q must be []string{%q}, but was %#v.", moduleName, systemJar, systemJars)
 	}
 }
+
+func TestDroidstubsWithSdkExtensions(t *testing.T) {
+	ctx, _ := testJavaWithFS(t, `
+		droiddoc_exported_dir {
+			name: "sdk-dir",
+			path: "sdk",
+		}
+
+		droidstubs {
+			name: "baz-stubs",
+			api_levels_annotations_dirs: ["sdk-dir"],
+			api_levels_annotations_enabled: true,
+			extensions_info_file: ":info-file",
+		}
+
+		filegroup {
+			name: "info-file",
+			srcs: ["sdk/extensions/info.txt"],
+		}
+		`,
+		map[string][]byte{
+			"sdk/extensions/1/public/some-mainline-module-stubs.jar": nil,
+			"sdk/extensions/info.txt":                                nil,
+		})
+	m := ctx.ModuleForTests("baz-stubs", "android_common")
+	manifest := m.Output("metalava.sbox.textproto")
+	cmdline := String(android.RuleBuilderSboxProtoForTests(t, manifest).Commands[0].Command)
+	android.AssertStringDoesContain(t, "sdk-extensions-root present", cmdline, "--sdk-extensions-root sdk/extensions")
+	android.AssertStringDoesContain(t, "sdk-extensions-info present", cmdline, "--sdk-extensions-info sdk/extensions/info.txt")
+}