all: modernize handling of Android SDK and NDK paths

This change removes Gomobile's dependency on ANDROID_HOME and
ANDROID_NDK_HOME.  Setting ANDROID_HOME is generally optional,
and ANDROID_NDK_HOME is deprecated.

This change also increases the minimum API version to 16, as
all SDKs that supported API 15 are now deprecated.

Fixes golang/go#52470

Change-Id: I546365774a089e5d7ae1be0a538efd72741d92ac
Reviewed-on: https://go-review.googlesource.com/c/mobile/+/401574
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Daniel Skinner <[email protected]>
Reviewed-by: Suzy Mueller <[email protected]>
Reviewed-by: Hajime Hoshi <[email protected]>
Reviewed-by: Hyang-Ah Hana Kim <[email protected]>
Run-TryBot: Hyang-Ah Hana Kim <[email protected]>

Author: Ben Schwartz

bind/java/seq_test.go

@@ -17,6 +17,7 @@ import (
 	"testing"
 
 	"golang.org/x/mobile/internal/importers/java"
+	"golang.org/x/mobile/internal/sdkpath"
 )
 
 var gomobileBin string
@@ -98,8 +99,8 @@ func TestJavaSeqBench(t *testing.T) {
 // runTest runs the Android java test class specified with javaCls. If javaPkg is
 // set, it is passed with the -javapkg flag to gomobile. The pkgNames lists the Go
 // packages to bind for the test.
-// This requires the gradle command in PATH and
-// the Android SDK whose path is available through ANDROID_HOME environment variable.
+// This requires the gradle command to be in PATH and the Android SDK to be
+// installed.
 func runTest(t *testing.T, pkgNames []string, javaPkg, javaCls string) {
 	if gomobileBin == "" {
 		t.Skipf("no gomobile on %s", runtime.GOOS)
@@ -108,8 +109,8 @@ func runTest(t *testing.T, pkgNames []string, javaPkg, javaCls string) {
 	if err != nil {
 		t.Skip("command gradle not found, skipping")
 	}
-	if sdk := os.Getenv("ANDROID_HOME"); sdk == "" {
-		t.Skip("ANDROID_HOME environment var not set, skipping")
+	if _, err := sdkpath.AndroidHome(); err != nil {
+		t.Skip("Android SDK not found, skipping")
 	}
 
 	cwd, err := os.Getwd()

cmd/gomobile/bind.go

@@ -16,6 +16,7 @@ import (
 	"path/filepath"
 	"strings"
 
+	"golang.org/x/mobile/internal/sdkpath"
 	"golang.org/x/mod/modfile"
 	"golang.org/x/tools/go/packages"
 )
@@ -42,9 +43,10 @@ example, in Android Studio (1.2+), an AAR file can be imported using
 the module import wizard (File > New > New Module > Import .JAR or
 .AAR package), and setting it as a new dependency
 (File > Project Structure > Dependencies).  This requires 'javac'
-(version 1.7+) and Android SDK (API level 15 or newer) to build the
-library for Android. The environment variable ANDROID_HOME must be set
-to the path to Android SDK. Use the -javapkg flag to specify the Java
+(version 1.7+) and Android SDK (API level 16 or newer) to build the
+library for Android. The ANDROID_HOME and ANDROID_NDK_HOME environment
+variables can be used to specify the Android SDK and NDK if they are
+not in the default locations. Use the -javapkg flag to specify the Java
 package prefix for the generated classes.
 
 By default, -target=android builds shared libraries for all supported
@@ -85,7 +87,7 @@ func runBind(cmd *command) error {
 		if bindPrefix != "" {
 			return fmt.Errorf("-prefix is supported only for Apple targets")
 		}
-		if _, err := ndkRoot(); err != nil {
+		if _, err := ndkRoot(targets[0]); err != nil {
 			return err
 		}
 	} else {
@@ -156,7 +158,7 @@ func bootClasspath() (string, error) {
 	if bindBootClasspath != "" {
 		return bindBootClasspath, nil
 	}
-	apiPath, err := androidAPIPath()
+	apiPath, err := sdkpath.AndroidAPIPath(buildAndroidAPI)
 	if err != nil {
 		return "", err
 	}

cmd/gomobile/bind_androidapp.go

@@ -12,15 +12,15 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
-	"strconv"
 	"strings"
 
+	"golang.org/x/mobile/internal/sdkpath"
 	"golang.org/x/tools/go/packages"
 )
 
 func goAndroidBind(gobind string, pkgs []*packages.Package, targets []targetInfo) error {
-	if sdkDir := os.Getenv("ANDROID_HOME"); sdkDir == "" {
-		return fmt.Errorf("this command requires ANDROID_HOME environment variable (path to the Android SDK)")
+	if _, err := sdkpath.AndroidHome(); err != nil {
+		return fmt.Errorf("this command requires the Android SDK to be installed: %w", err)
 	}
 
 	// Run gobind to generate the bindings
@@ -270,7 +270,7 @@ func buildAAR(srcDir, androidDir string, pkgs []*packages.Package, targets []tar
 
 const (
 	javacTargetVer = "1.7"
-	minAndroidAPI  = 15
+	minAndroidAPI  = 16
 )
 
 func buildJar(w io.Writer, srcDir string) error {
@@ -370,46 +370,3 @@ func writeJar(w io.Writer, dir string) error {
 	}
 	return jarw.Close()
 }
-
-// androidAPIPath returns an android SDK platform directory under ANDROID_HOME.
-// If there are multiple platforms that satisfy the minimum version requirement
-// androidAPIPath returns the latest one among them.
-func androidAPIPath() (string, error) {
-	sdk := os.Getenv("ANDROID_HOME")
-	if sdk == "" {
-		return "", fmt.Errorf("ANDROID_HOME environment var is not set")
-	}
-	sdkDir, err := os.Open(filepath.Join(sdk, "platforms"))
-	if err != nil {
-		return "", fmt.Errorf("failed to find android SDK platform: %v", err)
-	}
-	defer sdkDir.Close()
-	fis, err := sdkDir.Readdir(-1)
-	if err != nil {
-		return "", fmt.Errorf("failed to find android SDK platform (API level: %d): %v", buildAndroidAPI, err)
-	}
-
-	var apiPath string
-	var apiVer int
-	for _, fi := range fis {
-		name := fi.Name()
-		if !strings.HasPrefix(name, "android-") {
-			continue
-		}
-		n, err := strconv.Atoi(name[len("android-"):])
-		if err != nil || n < buildAndroidAPI {
-			continue
-		}
-		p := filepath.Join(sdkDir.Name(), name)
-		_, err = os.Stat(filepath.Join(p, "android.jar"))
-		if err == nil && apiVer < n {
-			apiPath = p
-			apiVer = n
-		}
-	}
-	if apiVer == 0 {
-		return "", fmt.Errorf("failed to find android SDK platform (API level: %d) in %s",
-			buildAndroidAPI, sdkDir.Name())
-	}
-	return apiPath, nil
-}

cmd/gomobile/bind_test.go

@@ -14,18 +14,22 @@ import (
 	"strings"
 	"testing"
 	"text/template"
+
+	"golang.org/x/mobile/internal/sdkpath"
 )
 
 func TestBindAndroid(t *testing.T) {
-	androidHome := os.Getenv("ANDROID_HOME")
-	if androidHome == "" {
-		t.Skip("ANDROID_HOME not found, skipping bind")
-	}
-	platform, err := androidAPIPath()
+	platform, err := sdkpath.AndroidAPIPath(minAndroidAPI)
 	if err != nil {
-		t.Skip("No android API platform found in $ANDROID_HOME, skipping bind")
+		t.Skip("No compatible Android API platform found, skipping bind")
 	}
-	platform = strings.Replace(platform, androidHome, "$ANDROID_HOME", -1)
+	// platform is a path like "/path/to/Android/sdk/platforms/android-32"
+	components := strings.Split(platform, string(filepath.Separator))
+	if len(components) < 2 {
+		t.Fatalf("API path is too short: %s", platform)
+	}
+	components = components[len(components)-2:]
+	platformRel := filepath.Join("$ANDROID_HOME", components[0], components[1])
 
 	defer func() {
 		xout = os.Stderr
@@ -77,7 +81,7 @@ func TestBindAndroid(t *testing.T) {
 			JavaPkg         string
 		}{
 			outputData:      output,
-			AndroidPlatform: platform,
+			AndroidPlatform: platformRel,
 			JavaPkg:         tc.javaPkg,
 		}
 
@@ -273,12 +277,8 @@ func TestBindWithGoModules(t *testing.T) {
 		t.Run(target, func(t *testing.T) {
 			switch target {
 			case "android":
-				androidHome := os.Getenv("ANDROID_HOME")
-				if androidHome == "" {
-					t.Skip("ANDROID_HOME not found, skipping bind")
-				}
-				if _, err := androidAPIPath(); err != nil {
-					t.Skip("No android API platform found in $ANDROID_HOME, skipping bind")
+				if _, err := sdkpath.AndroidAPIPath(minAndroidAPI); err != nil {
+					t.Skip("No compatible Android API platform found, skipping bind")
 				}
 			case "ios":
 				if !xcodeAvailable() {

cmd/gomobile/build.go

@@ -17,6 +17,7 @@ import (
 	"strconv"
 	"strings"
 
+	"golang.org/x/mobile/internal/sdkpath"
 	"golang.org/x/tools/go/packages"
 )
 
@@ -60,7 +61,7 @@ Flag -iosversion sets the minimal version of the iOS SDK to compile against.
 The default version is 13.0.
 
 Flag -androidapi sets the Android API version to compile against.
-The default and minimum is 15.
+The default and minimum is 16.
 
 The -bundleid flag is required for -target ios and sets the bundle ID to use
 with the app.
@@ -215,7 +216,7 @@ func printcmd(format string, args ...interface{}) {
 	if tmpdir != "" {
 		cmd = strings.Replace(cmd, tmpdir, "$WORK", -1)
 	}
-	if androidHome := os.Getenv("ANDROID_HOME"); androidHome != "" {
+	if androidHome, err := sdkpath.AndroidHome(); err == nil {
 		cmd = strings.Replace(cmd, androidHome, "$ANDROID_HOME", -1)
 	}
 	if gomobilepath != "" {

cmd/gomobile/build_androidapp.go

@@ -25,7 +25,7 @@ import (
 )
 
 func goAndroidBuild(pkg *packages.Package, targets []targetInfo) (map[string]bool, error) {
-	ndkRoot, err := ndkRoot()
+	ndkRoot, err := ndkRoot(targets...)
 	if err != nil {
 		return nil, err
 	}

cmd/gomobile/build_test.go

@@ -14,6 +14,8 @@ import (
 	"strings"
 	"testing"
 	"text/template"
+
+	"golang.org/x/mobile/internal/sdkpath"
 )
 
 func TestRFC1034Label(t *testing.T) {
@@ -228,12 +230,8 @@ func TestBuildWithGoModules(t *testing.T) {
 		t.Run(target, func(t *testing.T) {
 			switch target {
 			case "android":
-				androidHome := os.Getenv("ANDROID_HOME")
-				if androidHome == "" {
-					t.Skip("ANDROID_HOME not found, skipping bind")
-				}
-				if _, err := androidAPIPath(); err != nil {
-					t.Skip("No android API platform found in $ANDROID_HOME, skipping bind")
+				if _, err := sdkpath.AndroidAPIPath(minAndroidAPI); err != nil {
+					t.Skip("No compatible android API platform found, skipping bind")
 				}
 			case "ios":
 				if !xcodeAvailable() {