cmd/gomobile: replace stripped NDK with external NDK

Gomobile has up until now used stripped NDKs hosted by Google. This
arrangement adds maintenance overhead and blocks the use of custom
NDKs or custom API levels. Also, as noted in issue 16211, the stripped
NDK is no longer tiny because Gomobile supports more platforms.

This CL removed the code for generating and packaging stripped NDKs and
adds support for using external NDKs to the gomobile tool.

gomobile init will now use the NDK installed by the Android SDK manager,
if present, or a user specified NDK if the -ndk flag is given. If no
NDK was found or specified, Android initialization is skipped. gomobile
will instruct the user to run init with a valid NDK if bind or build is
invoked without Android initialization.

gomobile init will also attempt to build OpenAL for Android if the -openal
flag specifies a source directory. It needs cmake and, on Windows, nmake
installed. If gomobile build is run on an app that requires
golang.org/x/mobile/exp/audio/al and OpenAL wasn't built by init, the user
is instructed to do so.

Tested on Linux, macOS, Windows.

Fixes golang/go#16211
Fixes golang/go#18522

Change-Id: Ia38f6e43e671a207dad562678c65225b426e7e3e
Reviewed-on: https://go-review.googlesource.com/35173
Reviewed-by: David Crawshaw <crawshaw@golang.org>
diff --git a/cmd/gomobile/bind.go b/cmd/gomobile/bind.go
index 2c70f92..8888e3b 100644
--- a/cmd/gomobile/bind.go
+++ b/cmd/gomobile/bind.go
@@ -6,6 +6,7 @@
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"go/ast"
 	"go/build"
@@ -102,6 +103,10 @@
 		return fmt.Errorf("-prefix is supported only for ios target")
 	}
 
+	if ctx.GOOS == "android" && ndkRoot == "" {
+		return errors.New("no Android NDK path is set. Please run gomobile init with the ndk-bundle installed through the Android SDK manager or with the -ndk flag set.")
+	}
+
 	var pkgs []*build.Package
 	switch len(args) {
 	case 0:
diff --git a/cmd/gomobile/bind_test.go b/cmd/gomobile/bind_test.go
index de12951..d2f4d1c 100644
--- a/cmd/gomobile/bind_test.go
+++ b/cmd/gomobile/bind_test.go
@@ -37,6 +37,7 @@
 	buildX = true
 	buildO = "asset.aar"
 	buildTarget = "android"
+	ndkRoot = "/NDK"
 
 	tests := []struct {
 		javaPkg    string
@@ -106,7 +107,7 @@
 mkdir -p $WORK/gomobile_bind
 mkdir -p $WORK/gomobile_bind
 mkdir -p $WORK/gen/src/Java
-GOOS=android GOARCH=arm CC=$GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-clang CXX=$GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-clang++ CGO_CFLAGS=-target armv7a-none-linux-androideabi --sysroot $GOMOBILE/android-{{.NDK}}/arm/sysroot CGO_CPPFLAGS=-target armv7a-none-linux-androideabi --sysroot $GOMOBILE/android-{{.NDK}}/arm/sysroot CGO_LDFLAGS=-target armv7a-none-linux-androideabi --sysroot $GOMOBILE/android-{{.NDK}}/arm/sysroot CGO_ENABLED=1 GOARM=7 GOPATH=$WORK/gen:$GOPATH go install -pkgdir=$GOMOBILE/pkg_android_arm -x golang.org/x/mobile/asset
+GOOS=android GOARCH=arm CC=/NDK/toolchains/llvm/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/clang{{.EXE}} CXX=/NDK/toolchains/llvm/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/clang++{{.EXE}} CGO_CFLAGS=-target armv7a-none-linux-androideabi --sysroot /NDK/platforms/android-15/arch-arm -gcc-toolchain /NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/{{.GOOS}}-{{.NDKARCH}} -I$GOMOBILE/include CGO_CPPFLAGS=-target armv7a-none-linux-androideabi --sysroot /NDK/platforms/android-15/arch-arm -gcc-toolchain /NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/{{.GOOS}}-{{.NDKARCH}} -I$GOMOBILE/include CGO_LDFLAGS=-target armv7a-none-linux-androideabi --sysroot /NDK/platforms/android-15/arch-arm -gcc-toolchain /NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/{{.GOOS}}-{{.NDKARCH}} -L/NDK/platforms/android-15/arch-arm/usr/lib -L$GOMOBILE/lib/arm CGO_ENABLED=1 GOARM=7 GOPATH=$WORK/gen:$GOPATH go install -pkgdir=$GOMOBILE/pkg_android_arm -x golang.org/x/mobile/asset
 rm -r -f "$WORK/fakegopath"
 mkdir -p $WORK/fakegopath/pkg
 cp $GOMOBILE/pkg_android_arm/golang.org/x/mobile/asset.a $WORK/fakegopath/pkg/android_arm/golang.org/x/mobile/asset.a
@@ -134,7 +135,7 @@
 cp $GOPATH/src/golang.org/x/mobile/bind/seq.go.support $WORK/gomobile_bind/seq.go
 mkdir -p $WORK/gomobile_bind
 mkdir -p $WORK/android/src/main/java/go
-GOOS=android GOARCH=arm CC=$GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-clang{{.EXE}} CXX=$GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-clang++{{.EXE}} CGO_CFLAGS=-target armv7a-none-linux-androideabi --sysroot $GOMOBILE/android-{{.NDK}}/arm/sysroot CGO_CPPFLAGS=-target armv7a-none-linux-androideabi --sysroot $GOMOBILE/android-{{.NDK}}/arm/sysroot CGO_LDFLAGS=-target armv7a-none-linux-androideabi --sysroot $GOMOBILE/android-{{.NDK}}/arm/sysroot CGO_ENABLED=1 GOARM=7 GOPATH=$WORK/gen:$GOPATH go build -pkgdir=$GOMOBILE/pkg_android_arm -x -buildmode=c-shared -o=$WORK/android/src/main/jniLibs/armeabi-v7a/libgojni.so $WORK/androidlib/main.go
+GOOS=android GOARCH=arm CC=/NDK/toolchains/llvm/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/clang{{.EXE}} CXX=/NDK/toolchains/llvm/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/clang++{{.EXE}} CGO_CFLAGS=-target armv7a-none-linux-androideabi --sysroot /NDK/platforms/android-15/arch-arm -gcc-toolchain /NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/{{.GOOS}}-{{.NDKARCH}} -I$GOMOBILE/include CGO_CPPFLAGS=-target armv7a-none-linux-androideabi --sysroot /NDK/platforms/android-15/arch-arm -gcc-toolchain /NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/{{.GOOS}}-{{.NDKARCH}} -I$GOMOBILE/include CGO_LDFLAGS=-target armv7a-none-linux-androideabi --sysroot /NDK/platforms/android-15/arch-arm -gcc-toolchain /NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/{{.GOOS}}-{{.NDKARCH}} -L/NDK/platforms/android-15/arch-arm/usr/lib -L$GOMOBILE/lib/arm CGO_ENABLED=1 GOARM=7 GOPATH=$WORK/gen:$GOPATH go build -pkgdir=$GOMOBILE/pkg_android_arm -x -buildmode=c-shared -o=$WORK/android/src/main/jniLibs/armeabi-v7a/libgojni.so $WORK/androidlib/main.go
 rm $WORK/android/src/main/java/go/Seq.java
 ln -s $GOPATH/src/golang.org/x/mobile/bind/java/Seq.java $WORK/android/src/main/java/go/Seq.java
 rm $WORK/android/src/main/java/go/LoadJNI.java
diff --git a/cmd/gomobile/build_androidapp.go b/cmd/gomobile/build_androidapp.go
index 3136d7d..8d261f3 100644
--- a/cmd/gomobile/build_androidapp.go
+++ b/cmd/gomobile/build_androidapp.go
@@ -22,6 +22,9 @@
 )
 
 func goAndroidBuild(pkg *build.Package, androidArchs []string) (map[string]bool, error) {
+	if ndkRoot == "" {
+		return nil, errors.New("no Android NDK path is set. Please run gomobile init with the ndk-bundle installed through the Android SDK manager or with the -ndk flag set.")
+	}
 	appName := path.Base(pkg.ImportPath)
 	libName := androidPkgName(appName)
 	manifestPath := filepath.Join(pkg.Dir, "AndroidManifest.xml")
@@ -170,13 +173,11 @@
 		toolchain := ndk.Toolchain(arch)
 		if nmpkgs[arch]["golang.org/x/mobile/exp/audio/al"] {
 			dst := "lib/" + toolchain.abi + "/libopenal.so"
-			src := dst
-			if arch == "arm" {
-				src = "lib/armeabi/libopenal.so"
-			} else if arch == "arm64" {
-				src = "lib/arm64/libopenal.so"
+			src := filepath.Join(gomobilepath, dst)
+			if _, err := os.Stat(src); err != nil {
+				return nil, errors.New("the Android requires the golang.org/x/mobile/exp/audio/al, but the OpenAL libraries was not found. Please run gomobile init with the -openal flag pointing to an OpenAL source directory.")
 			}
-			if err := apkwWriteFile(dst, filepath.Join(ndk.Root(), "openal/"+src)); err != nil {
+			if err := apkwWriteFile(dst, src); err != nil {
 				return nil, err
 			}
 		}
diff --git a/cmd/gomobile/build_test.go b/cmd/gomobile/build_test.go
index 1234c7a..569441e 100644
--- a/cmd/gomobile/build_test.go
+++ b/cmd/gomobile/build_test.go
@@ -76,6 +76,7 @@
 	buildX = true
 	buildO = "basic.apk"
 	buildTarget = "android"
+	ndkRoot = "/NDK"
 	gopath = filepath.ToSlash(filepath.SplitList(os.Getenv("GOPATH"))[0])
 	if goos == "windows" {
 		os.Setenv("HOMEDRIVE", "C:")
@@ -100,7 +101,7 @@
 var androidBuildTmpl = template.Must(template.New("output").Parse(`GOMOBILE={{.GOPATH}}/pkg/gomobile
 WORK=$WORK
 mkdir -p $WORK/lib/armeabi-v7a
-GOOS=android GOARCH=arm CC=$GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-clang{{.EXE}} CXX=$GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-clang++{{.EXE}} CGO_CFLAGS=-target armv7a-none-linux-androideabi --sysroot $GOMOBILE/android-{{.NDK}}/arm/sysroot CGO_CPPFLAGS=-target armv7a-none-linux-androideabi --sysroot $GOMOBILE/android-{{.NDK}}/arm/sysroot CGO_LDFLAGS=-target armv7a-none-linux-androideabi --sysroot $GOMOBILE/android-{{.NDK}}/arm/sysroot CGO_ENABLED=1 GOARM=7 go build -pkgdir=$GOMOBILE/pkg_android_arm -tags tag1 -x -buildmode=c-shared -o $WORK/lib/armeabi-v7a/libbasic.so golang.org/x/mobile/example/basic
+GOOS=android GOARCH=arm CC=/NDK/toolchains/llvm/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/clang{{.EXE}} CXX=/NDK/toolchains/llvm/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/clang++{{.EXE}} CGO_CFLAGS=-target armv7a-none-linux-androideabi --sysroot /NDK/platforms/android-15/arch-arm -gcc-toolchain /NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/{{.GOOS}}-{{.NDKARCH}} -I$GOMOBILE/include CGO_CPPFLAGS=-target armv7a-none-linux-androideabi --sysroot /NDK/platforms/android-15/arch-arm -gcc-toolchain /NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/{{.GOOS}}-{{.NDKARCH}} -I$GOMOBILE/include CGO_LDFLAGS=-target armv7a-none-linux-androideabi --sysroot /NDK/platforms/android-15/arch-arm -gcc-toolchain /NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/{{.GOOS}}-{{.NDKARCH}} -L/NDK/platforms/android-15/arch-arm/usr/lib -L$GOMOBILE/lib/arm CGO_ENABLED=1 GOARM=7 go build -pkgdir=$GOMOBILE/pkg_android_arm -tags tag1 -x -buildmode=c-shared -o $WORK/lib/armeabi-v7a/libbasic.so golang.org/x/mobile/example/basic
 `))
 
 func TestParseBuildTargetFlag(t *testing.T) {
diff --git a/cmd/gomobile/doc.go b/cmd/gomobile/doc.go
index fb17b6a..5405a13 100644
--- a/cmd/gomobile/doc.go
+++ b/cmd/gomobile/doc.go
@@ -123,15 +123,20 @@
 
 	gomobile init [-u]
 
-Init installs the Android C++ compiler toolchain and builds copies
-of the Go standard library for mobile devices.
+Init builds copies of the Go standard library for mobile devices. If ANDROID_HOME
+is set and the Android NDK is available, Android support is built. If on Darwin
+and the Xcode command line utilities are installed, iOS support is built.
 
-When first run, it downloads part of the Android NDK.
-The toolchain is installed in $GOPATH/pkg/gomobile.
+The toolchains are installed in $GOPATH/pkg/gomobile.
 
-The -u option forces download and installation of the new toolchain
-even when the toolchain exists.
+Init use the Android NDK installed by the Android SDK manager by default. Use the
+-ndk flag to specify a custom location for the NDK.
 
+If the -openal flag is specified, init also builds an Android version of OpenAL
+from the source directory given. OpenAL enables support for gomobile build and
+install with mobile apps using the golang.org/x/mobile/exp/audio/al package.
+It needs cmake and, on Windows, nmake installed. If cmake is installed through
+the Android SDK manager, init will use that.
 
 Compile android APK and install on device
 
diff --git a/cmd/gomobile/env.go b/cmd/gomobile/env.go
index 89395d1..fbddaba 100644
--- a/cmd/gomobile/env.go
+++ b/cmd/gomobile/env.go
@@ -26,6 +26,10 @@
 
 	androidArmNM string
 	darwinArmNM  string
+
+	ndkRoot string
+
+	archs = []string{"arm", "arm64", "386", "amd64"}
 )
 
 func buildEnvInit() (cleanup func(), err error) {
@@ -38,10 +42,6 @@
 		}
 	}
 
-	if err := envInit(); err != nil {
-		return nil, err
-	}
-
 	if buildX {
 		fmt.Fprintln(xout, "GOMOBILE="+gomobilepath)
 	}
@@ -51,6 +51,27 @@
 	if gomobilepath == "" {
 		return nil, errors.New("toolchain not installed, run `gomobile init`")
 	}
+
+	// Read the NDK root path stored by gomobile init -ndk, if any.
+	if !buildN {
+		root, err := ioutil.ReadFile(filepath.Join(gomobilepath, "android_ndk_root"))
+		if err != nil && !os.IsNotExist(err) {
+			return nil, err
+		}
+		ndkRoot = string(root)
+		if ndkRoot != "" {
+			if _, err := os.Stat(filepath.Join(ndkRoot, "toolchains")); err != nil {
+				if os.IsNotExist(err) {
+					return nil, fmt.Errorf("The ndk path %q doesn't exist. Please re-run gomobile with the ndk-bundle install through the Android SDK manager or with the -ndk flag set.", ndkRoot)
+				}
+				return nil, err
+			}
+		}
+	}
+	if err := envInit(); err != nil {
+		return nil, err
+	}
+
 	cleanupFn := func() {
 		if buildWork {
 			fmt.Printf("WORK=%s\n", tmpdir)
@@ -92,34 +113,39 @@
 
 	// Setup the cross-compiler environments.
 
-	androidEnv = make(map[string][]string)
-	for arch, toolchain := range ndk {
-		if goVersion < toolchain.minGoVer {
-			continue
-		}
+	if ndkRoot != "" {
+		androidEnv = make(map[string][]string)
+		for arch, toolchain := range ndk {
+			if goVersion < toolchain.minGoVer {
+				continue
+			}
 
-		// Emulate the flags in the clang wrapper scripts generated
-		// by make_standalone_toolchain.py
-		s := strings.SplitN(toolchain.toolPrefix, "-", 3)
-		a, os, env := s[0], s[1], s[2]
-		if a == "arm" {
-			a = "armv7a"
-		}
-		target := strings.Join([]string{a, "none", os, env}, "-")
-		sysroot := filepath.Join(ndk.Root(), toolchain.arch, "sysroot")
-		flags := fmt.Sprintf("-target %s --sysroot %s", target, sysroot)
-		androidEnv[arch] = []string{
-			"GOOS=android",
-			"GOARCH=" + arch,
-			"CC=" + toolchain.Path("clang"),
-			"CXX=" + toolchain.Path("clang++"),
-			"CGO_CFLAGS=" + flags,
-			"CGO_CPPFLAGS=" + flags,
-			"CGO_LDFLAGS=" + flags,
-			"CGO_ENABLED=1",
-		}
-		if arch == "arm" {
-			androidEnv[arch] = append(androidEnv[arch], "GOARM=7")
+			// Emulate the flags in the clang wrapper scripts generated
+			// by make_standalone_toolchain.py
+			s := strings.SplitN(toolchain.toolPrefix, "-", 3)
+			a, os, env := s[0], s[1], s[2]
+			if a == "arm" {
+				a = "armv7a"
+			}
+			target := strings.Join([]string{a, "none", os, env}, "-")
+			sysroot := filepath.Join(ndkRoot, "platforms", toolchain.platform, "arch-"+toolchain.arch)
+			gcctoolchain := filepath.Join(ndkRoot, "toolchains", toolchain.gcc, "prebuilt", archNDK())
+			flags := fmt.Sprintf("-target %s --sysroot %s -gcc-toolchain %s", target, sysroot, gcctoolchain)
+			cflags := fmt.Sprintf("%s -I%s/include", flags, gomobilepath)
+			ldflags := fmt.Sprintf("%s -L%s/usr/lib -L%s/lib/%s", flags, sysroot, gomobilepath, arch)
+			androidEnv[arch] = []string{
+				"GOOS=android",
+				"GOARCH=" + arch,
+				"CC=" + toolchain.Path("clang"),
+				"CXX=" + toolchain.Path("clang++"),
+				"CGO_CFLAGS=" + cflags,
+				"CGO_CPPFLAGS=" + cflags,
+				"CGO_LDFLAGS=" + ldflags,
+				"CGO_ENABLED=1",
+			}
+			if arch == "arm" {
+				androidEnv[arch] = append(androidEnv[arch], "GOARM=7")
+			}
 		}
 	}
 
@@ -264,6 +290,23 @@
 	return gomobilepath + "/pkg_" + getenv(env, "GOOS") + "_" + getenv(env, "GOARCH")
 }
 
+func archNDK() string {
+	if runtime.GOOS == "windows" && runtime.GOARCH == "386" {
+		return "windows"
+	} else {
+		var arch string
+		switch runtime.GOARCH {
+		case "386":
+			arch = "x86"
+		case "amd64":
+			arch = "x86_64"
+		default:
+			panic("unsupported GOARCH: " + runtime.GOARCH)
+		}
+		return runtime.GOOS + "-" + arch
+	}
+}
+
 type ndkToolchain struct {
 	arch       string
 	abi        string
@@ -274,18 +317,24 @@
 }
 
 func (tc *ndkToolchain) Path(toolName string) string {
+	// The nm tool is located in the GCC directory structure.
+	isUtil := toolName == "nm"
 	if goos == "windows" {
 		toolName += ".exe"
 	}
-	return filepath.Join(ndk.Root(), tc.arch, "bin", tc.toolPrefix+"-"+toolName)
+	path := filepath.Join(ndkRoot, "toolchains")
+	if isUtil {
+		toolName = tc.toolPrefix + "-" + toolName
+		path = filepath.Join(path, tc.gcc)
+	} else {
+		path = filepath.Join(path, "llvm")
+	}
+	path = filepath.Join(path, "prebuilt")
+	return filepath.Join(path, archNDK(), "bin", toolName)
 }
 
 type ndkConfig map[string]ndkToolchain // map: GOOS->androidConfig.
 
-func (nc ndkConfig) Root() string {
-	return filepath.Join(gomobilepath, "android-"+ndkVersion)
-}
-
 func (nc ndkConfig) Toolchain(arch string) ndkToolchain {
 	tc, ok := nc[arch]
 	if !ok || tc.minGoVer > goVersion {
@@ -294,7 +343,6 @@
 	return tc
 }
 
-// TODO: share this with release.go
 var ndk = ndkConfig{
 	"arm": {
 		arch:       "arm",
diff --git a/cmd/gomobile/hashes.go b/cmd/gomobile/hashes.go
deleted file mode 100644
index f2fec62..0000000
--- a/cmd/gomobile/hashes.go
+++ /dev/null
@@ -1,19 +0,0 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package main
-
-// Hashes were computed with 'go run release.go'
-
-var fetchHashes = map[string]string{
-	"android-ndk-r12b-darwin-x86_64.zip":            "2bdef9143a2c7680fcb7c9fd54fe85013d591f106aea43831eba5e13e10db77e",
-	"gomobile-ndk-r12b-darwin-x86_64.tar.gz":        "2c4365d033fc3c9e1fbeeb6c2773f75116a0c76000ebf0dab7290506ba9acb07",
-	"android-ndk-r12b-linux-x86_64.zip":             "eafae2d614e5475a3bcfd7c5f201db5b963cc1290ee3e8ae791ff0c66757781e",
-	"gomobile-ndk-r12b-linux-x86_64.tar.gz":         "3eaeb237f89fa7ca44dbc760085a79a1efe9c6e830f3bedf68e5473bbd716fed",
-	"android-ndk-r12b-windows-x86.zip":              "4b3b522775858bdf4e5e8f7365e06fdabb9913fb7b9f45d7010232f8271fb42c",
-	"gomobile-ndk-r12b-windows-x86.tar.gz":          "2108256dac7fe7499c139915672c0f68eca1bcfe3d9660b1ef0f9c3e776459ee",
-	"android-ndk-r12b-windows-x86_64.zip":           "a201b9dad71802464823dcfc77f61445ec1bbd8a29baa154d0a6ed84f50298ae",
-	"gomobile-ndk-r12b-windows-x86_64.tar.gz":       "558b124266add3bced8591596911862fdf7949f689a79f612c3f9e48ef8a2199",
-	"gomobile-openal-soft-1.16.0.1-ndk-r12b.tar.gz": "848307aa48311a2d4f6cd05661724b121c8f8663d616dfc8c573f9e5d926cf1d",
-}
diff --git a/cmd/gomobile/init.go b/cmd/gomobile/init.go
index 769d61e..5b8a5e0 100644
--- a/cmd/gomobile/init.go
+++ b/cmd/gomobile/init.go
@@ -5,34 +5,19 @@
 package main
 
 import (
-	"archive/tar"
 	"bytes"
-	"compress/gzip"
-	"crypto/sha256"
-	"encoding/hex"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
-	"net/http"
 	"os"
 	"os/exec"
-	"path"
 	"path/filepath"
 	"runtime"
 	"strings"
 	"time"
 )
 
-// useStrippedNDK determines whether the init subcommand fetches the clang
-// toolchain from the original Android NDK, or from the stripped-down NDK
-// hosted specifically for the gomobile tool.
-//
-// There is a significant size different (400MB compared to 30MB).
-var useStrippedNDK = true
-
-const ndkVersion = "ndk-r12b"
-const openALVersion = "openal-soft-1.16.0.1-" + ndkVersion
-
 var (
 	goos    = runtime.GOOS
 	goarch  = runtime.GOARCH
@@ -54,23 +39,26 @@
 	run:   runInit,
 	Name:  "init",
 	Usage: "[-u]",
-	Short: "install android compiler toolchain",
+	Short: "install mobile compiler toolchain",
 	Long: `
-Init installs the Android C++ compiler toolchain and builds copies
-of the Go standard library for mobile devices.
-
-When first run, it downloads part of the Android NDK.
-The toolchain is installed in $GOPATH/pkg/gomobile.
-
-The -u option forces download and installation of the new toolchain
-even when the toolchain exists.
+Init builds copies of the Go standard library for mobile devices.
+It uses Xcode, if available, to build for iOS and uses the Android
+NDK from the ndk-bundle SDK package or from the -ndk flag, to build
+for Android.
+If a OpenAL source directory is specified with -openal, init will
+also build an Android version of OpenAL for use with gomobile build
+and gomobile install.
 `,
 }
 
-var initU bool // -u
+var (
+	initNDK    string // -ndk
+	initOpenAL string // -openal
+)
 
 func init() {
-	cmdInit.flag.BoolVar(&initU, "u", false, "force toolchain download")
+	cmdInit.flag.StringVar(&initNDK, "ndk", "", "Android NDK path")
+	cmdInit.flag.StringVar(&initOpenAL, "openal", "", "OpenAL source path")
 }
 
 func runInit(cmd *command) error {
@@ -84,9 +72,9 @@
 	if buildX || buildN {
 		fmt.Fprintln(xout, "GOMOBILE="+gomobilepath)
 	}
-	removeGomobilepkg()
+	removeAll(gomobilepath)
 
-	if err := mkdir(ndk.Root()); err != nil {
+	if err := mkdir(gomobilepath); err != nil {
 		return err
 	}
 
@@ -110,17 +98,49 @@
 		removeAll(tmpdir)
 	}()
 
+	if buildN {
+		initNDK = "$NDK_PATH"
+		initOpenAL = "$OPENAL_PATH"
+	} else {
+		toolsDir := filepath.Join("prebuilt", archNDK(), "bin")
+		// Try the ndk-bundle SDK package package, if installed.
+		if initNDK == "" {
+			if sdkHome := os.Getenv("ANDROID_HOME"); sdkHome != "" {
+				path := filepath.Join(sdkHome, "ndk-bundle")
+				if st, err := os.Stat(filepath.Join(path, toolsDir)); err == nil && st.IsDir() {
+					initNDK = path
+				}
+			}
+		}
+		if initNDK != "" {
+			var err error
+			if initNDK, err = filepath.Abs(initNDK); err != nil {
+				return err
+			}
+			// Check if the platform directory contains a known subdirectory.
+			if _, err := os.Stat(filepath.Join(initNDK, toolsDir)); err != nil {
+				if os.IsNotExist(err) {
+					return fmt.Errorf("%q does not point to an Android NDK.", initNDK)
+				}
+				return err
+			}
+			ndkFile := filepath.Join(gomobilepath, "android_ndk_root")
+			if err := ioutil.WriteFile(ndkFile, []byte(initNDK), 0644); err != nil {
+				return err
+			}
+		}
+		if initOpenAL != "" {
+			var err error
+			if initOpenAL, err = filepath.Abs(initOpenAL); err != nil {
+				return err
+			}
+		}
+	}
+	ndkRoot = initNDK
 	if err := envInit(); err != nil {
 		return err
 	}
 
-	if err := fetchNDK(); err != nil {
-		return err
-	}
-	if err := fetchOpenAL(); err != nil {
-		return err
-	}
-
 	if runtime.GOOS == "darwin" {
 		// Install common x/mobile packages for local development.
 		// These are often slow to compile (due to cgo) and easy to forget.
@@ -154,6 +174,10 @@
 		return err
 	}
 
+	if err := installOpenAL(gomobilepath); err != nil {
+		return err
+	}
+
 	if buildX || buildN {
 		printcmd("go version > %s", verpath)
 	}
@@ -169,6 +193,121 @@
 	return nil
 }
 
+func installOpenAL(gomobilepath string) error {
+	if ndkRoot == "" || initOpenAL == "" {
+		return nil
+	}
+	sdkRoot := os.Getenv("ANDROID_HOME")
+	if sdkRoot == "" {
+		return nil
+	}
+	var cmake string
+	if buildN {
+		cmake = "cmake"
+	} else {
+		var err error
+		cmake, err = exec.LookPath("cmake")
+		if err != nil {
+			cmakePath := filepath.Join(sdkRoot, "cmake")
+			cmakeDir, err := os.Open(cmakePath)
+			if err != nil {
+				if os.IsNotExist(err) {
+					// Skip OpenAL install if the cmake package is not installed.
+					return errors.New("cmake was not found in the PATH. Please install it through the Android SDK manager.")
+				}
+				return err
+			}
+			defer cmakeDir.Close()
+			// There might be multiple versions of CMake installed. Use any one for now.
+			cmakeVers, err := cmakeDir.Readdirnames(1)
+			if err != nil || len(cmakeVers) == 0 {
+				return errors.New("cmake was not found in the PATH. Please install it through the Android SDK manager.")
+			}
+			cmake = filepath.Join(cmakePath, cmakeVers[0], "bin", "cmake")
+		}
+	}
+	var alTmpDir string
+	if buildN {
+		alTmpDir = filepath.Join(gomobilepath, "work")
+	} else {
+		var err error
+		alTmpDir, err = ioutil.TempDir(gomobilepath, "openal-release-")
+		if err != nil {
+			return err
+		}
+		defer removeAll(alTmpDir)
+	}
+
+	for _, f := range []string{"include/AL/al.h", "include/AL/alc.h"} {
+		dst := filepath.Join(gomobilepath, f)
+		src := filepath.Join(initOpenAL, f)
+		if err := copyFile(dst, src); err != nil {
+			return err
+		}
+	}
+
+	toolsDir := filepath.Join(ndkRoot, "prebuilt", archNDK(), "bin")
+	py27 := filepath.Join(toolsDir, "python2.7")
+	var make string
+	if !buildN && runtime.GOOS == "windows" {
+		var err error
+		make, err = exec.LookPath("nmake")
+		if err != nil {
+			return nil
+		}
+	} else {
+		make = filepath.Join(toolsDir, "make")
+	}
+	for _, arch := range archs {
+		t := ndk[arch]
+		abi := t.arch
+		if abi == "arm" {
+			abi = "armeabi"
+		}
+		// Split android-XX to get the api version.
+		platform := strings.SplitN(t.platform, "-", 2)
+		api := platform[1]
+		buildDir := alTmpDir + "/build/" + abi
+		toolchain := buildDir + "/toolchain"
+		// standalone ndk toolchains make openal-soft's build config easier.
+		cmd := exec.Command(py27,
+			"build/tools/make_standalone_toolchain.py",
+			"--arch="+t.arch,
+			"--api="+api,
+			"--install-dir="+toolchain)
+		cmd.Dir = ndkRoot
+		if err := runCmd(cmd); err != nil {
+			return err
+		}
+
+		cmd = exec.Command(cmake,
+			initOpenAL,
+			"-DCMAKE_TOOLCHAIN_FILE="+initOpenAL+"/XCompile-Android.txt",
+			"-DHOST="+t.toolPrefix)
+		cmd.Dir = buildDir
+		orgPath := os.Getenv("PATH")
+		if !buildN {
+			cmd.Env = []string{"PATH=" + toolchain + "/bin" + string(os.PathListSeparator) + orgPath}
+		}
+		if err := runCmd(cmd); err != nil {
+			return err
+		}
+
+		cmd = exec.Command(make)
+		cmd.Dir = buildDir
+		if err := runCmd(cmd); err != nil {
+			return err
+		}
+
+		dst := filepath.Join(gomobilepath, "lib", t.abi, "libopenal.so")
+		src := filepath.Join(alTmpDir, "build", abi, "libopenal.so")
+		if err := copyFile(dst, src); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 var commonPkgs = []string{
 	"golang.org/x/mobile/gl",
 	"golang.org/x/mobile/app",
@@ -225,44 +364,6 @@
 	return runCmd(cmd)
 }
 
-func removeGomobilepkg() {
-	dir, err := os.Open(gomobilepath)
-	if err != nil {
-		return
-	}
-	names, err := dir.Readdirnames(-1)
-	if err != nil {
-		return
-	}
-	for _, name := range names {
-		if name == "dl" {
-			continue
-		}
-		removeAll(filepath.Join(gomobilepath, name))
-	}
-}
-
-func move(dst, src string, names ...string) error {
-	for _, name := range names {
-		srcf := filepath.Join(src, name)
-		dstf := filepath.Join(dst, name)
-		if buildX || buildN {
-			printcmd("mv %s %s", srcf, dstf)
-		}
-		if buildN {
-			continue
-		}
-		if goos == "windows" {
-			// os.Rename fails if dstf already exists.
-			removeAll(dstf)
-		}
-		if err := os.Rename(srcf, dstf); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
 func mkdir(dir string) error {
 	if buildX || buildN {
 		printcmd("mkdir -p %s", dir)
@@ -296,280 +397,6 @@
 	return os.Remove(name)
 }
 
-func fetchOpenAL() error {
-	url := "https://dl.google.com/go/mobile/gomobile-" + openALVersion + ".tar.gz"
-	archive, err := fetch(url)
-	if err != nil {
-		return err
-	}
-	if err := extract("openal", archive); err != nil {
-		return err
-	}
-	if goos == "windows" {
-		resetReadOnlyFlagAll(filepath.Join(tmpdir, "openal"))
-	}
-	ndkroot := ndk.Root()
-	src := filepath.Join(tmpdir, "openal/include/AL")
-	for arch := range androidEnv {
-		toolchain := ndk.Toolchain(arch)
-		dst := filepath.Join(ndkroot, toolchain.arch+"/sysroot/usr/include/AL")
-		if buildX || buildN {
-			printcmd("cp -r %s %s", src, dst)
-		}
-		if buildN {
-			continue
-		}
-		if err := doCopyAll(dst, src); err != nil {
-			return err
-		}
-	}
-	libDst := filepath.Join(ndkroot, "openal")
-	libSrc := filepath.Join(tmpdir, "openal")
-	if err := mkdir(libDst); err != nil {
-		return nil
-	}
-	if err := move(libDst, libSrc, "lib"); err != nil {
-		return err
-	}
-	return nil
-}
-
-func extract(dst, src string) error {
-	if buildX || buildN {
-		printcmd("tar xfz %s", src)
-	}
-	if buildN {
-		return nil
-	}
-	tf, err := os.Open(src)
-	if err != nil {
-		return err
-	}
-	defer tf.Close()
-	zr, err := gzip.NewReader(tf)
-	if err != nil {
-		return err
-	}
-	tr := tar.NewReader(zr)
-	for {
-		hdr, err := tr.Next()
-		if err == io.EOF {
-			break
-		}
-		if err != nil {
-			return err
-		}
-		dst := filepath.Join(tmpdir, dst+"/"+hdr.Name)
-		if hdr.Typeflag == tar.TypeSymlink {
-			if err := symlink(hdr.Linkname, dst); err != nil {
-				return err
-			}
-			continue
-		}
-		if err := os.MkdirAll(filepath.Dir(dst), 0755); err != nil {
-			return err
-		}
-		f, err := os.OpenFile(dst, os.O_CREATE|os.O_EXCL|os.O_WRONLY, os.FileMode(hdr.Mode)&0777)
-		if err != nil {
-			return err
-		}
-		if _, err := io.Copy(f, tr); err != nil {
-			return err
-		}
-		if err := f.Close(); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func fetchNDK() error {
-	if useStrippedNDK {
-		if err := fetchStrippedNDK(); err != nil {
-			return err
-		}
-	} else {
-		if err := fetchFullNDK(); err != nil {
-			return err
-		}
-	}
-	if goos == "windows" {
-		resetReadOnlyFlagAll(filepath.Join(tmpdir, "android-"+ndkVersion))
-	}
-
-	// Copy the cross compiling clang and clang++ compilers
-	llvmsrc := filepath.Join(tmpdir, fmt.Sprintf(
-		"android-%s/toolchains/llvm/prebuilt", ndkVersion))
-	if goos == "windows" && ndkarch == "x86" {
-		llvmsrc = filepath.Join(llvmsrc, "windows")
-	} else {
-		llvmsrc = filepath.Join(llvmsrc, goos+"-"+ndkarch)
-	}
-	llvmdst := filepath.Join(ndk.Root(), "llvm")
-	if err := mkdir(llvmdst); err != nil {
-		return err
-	}
-	if err := move(llvmdst, llvmsrc, "lib64", "bin"); err != nil {
-		return err
-	}
-
-	for arch := range androidEnv {
-		toolchain := ndk.Toolchain(arch)
-		dst := filepath.Join(ndk.Root(), toolchain.arch)
-		dstSysroot := filepath.Join(dst, "sysroot")
-		if err := mkdir(dstSysroot); err != nil {
-			return err
-		}
-
-		srcSysroot := filepath.Join(tmpdir, fmt.Sprintf(
-			"android-%s/platforms/%s/arch-%s", ndkVersion, toolchain.platform, toolchain.arch))
-		if err := move(dstSysroot, srcSysroot, "usr"); err != nil {
-			return err
-		}
-
-		ndkpath := filepath.Join(tmpdir, fmt.Sprintf(
-			"android-%s/toolchains/%s/prebuilt", ndkVersion, toolchain.gcc))
-		if goos == "windows" && ndkarch == "x86" {
-			ndkpath = filepath.Join(ndkpath, "windows")
-		} else {
-			ndkpath = filepath.Join(ndkpath, goos+"-"+ndkarch)
-		}
-		if err := move(dst, ndkpath, "bin", "lib"); err != nil {
-			return err
-		}
-
-		linkpath := filepath.Join(dst, toolchain.toolPrefix+"/bin")
-		if err := mkdir(linkpath); err != nil {
-			return err
-		}
-
-		for _, name := range []string{"ld", "as", "nm"} {
-			if goos == "windows" {
-				name += ".exe"
-			}
-			if err := symlink(filepath.Join(dst, "bin", toolchain.toolPrefix+"-"+name), filepath.Join(linkpath, name)); err != nil {
-				return err
-			}
-		}
-		for _, toname := range []string{"clang", "clang++"} {
-			fromname := toname
-			if goos == "windows" {
-				if goarch == "386" {
-					if toname == "clang++" {
-						// there is no 32-bit version of clang++
-						continue
-					}
-					fromname += "_32"
-				}
-				fromname += ".exe"
-				toname += ".exe"
-			}
-			if err := symlink(filepath.Join(llvmdst, "bin", fromname), filepath.Join(dst, "bin", toolchain.toolPrefix+"-"+toname)); err != nil {
-				return err
-			}
-		}
-		if err := symlink(filepath.Join(llvmdst, "lib64"), filepath.Join(dst, "lib64")); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func fetchStrippedNDK() error {
-	url := "https://dl.google.com/go/mobile/gomobile-" + ndkVersion + "-" + goos + "-" + ndkarch + ".tar.gz"
-	archive, err := fetch(url)
-	if err != nil {
-		return err
-	}
-	return extract("", archive)
-}
-
-func fetchFullNDK() error {
-	url := "https://dl.google.com/android/repository/android-" + ndkVersion + "-" + goos + "-" + ndkarch + ".zip"
-	archive, err := fetch(url)
-	if err != nil {
-		return err
-	}
-	var inflate *exec.Cmd
-	if goos != "windows" {
-		inflate = exec.Command("unzip", archive)
-	} else {
-		inflate = exec.Command("unzip.exe", archive)
-	}
-	inflate.Dir = tmpdir
-	return runCmd(inflate)
-}
-
-// fetch reads a URL into $GOPATH/pkg/gomobile/dl and returns the path
-// to the downloaded file. Downloading is skipped if the file is
-// already present.
-func fetch(url string) (dst string, err error) {
-	if err := mkdir(filepath.Join(gomobilepath, "dl")); err != nil {
-		return "", err
-	}
-	name := path.Base(url)
-	dst = filepath.Join(gomobilepath, "dl", name)
-
-	// Use what's in the cache if force update is not required.
-	if !initU {
-		if buildX {
-			printcmd("stat %s", dst)
-		}
-		if _, err = os.Stat(dst); err == nil {
-			return dst, nil
-		}
-	}
-	if buildX {
-		printcmd("curl -o%s %s", dst, url)
-	}
-	if buildN {
-		return dst, nil
-	}
-
-	if buildV {
-		fmt.Fprintf(os.Stderr, "Downloading %s.\n", url)
-	}
-
-	f, err := ioutil.TempFile(tmpdir, "partial-"+name)
-	if err != nil {
-		return "", err
-	}
-	defer func() {
-		if err != nil {
-			f.Close()
-			os.Remove(f.Name())
-		}
-	}()
-	hashw := sha256.New()
-
-	resp, err := http.Get(url)
-	if err != nil {
-		return "", err
-	}
-	if resp.StatusCode != http.StatusOK {
-		err = fmt.Errorf("error fetching %v, status: %v", url, resp.Status)
-	} else {
-		_, err = io.Copy(io.MultiWriter(hashw, f), resp.Body)
-	}
-	if err2 := resp.Body.Close(); err == nil {
-		err = err2
-	}
-	if err != nil {
-		return "", err
-	}
-	if err = f.Close(); err != nil {
-		return "", err
-	}
-	hash := hex.EncodeToString(hashw.Sum(nil))
-	if fetchHashes[name] != hash {
-		return "", fmt.Errorf("sha256 for %q: %v, want %v. Try 'gomobile clean'", name, hash, fetchHashes[name])
-	}
-	if err = os.Rename(f.Name(), dst); err != nil {
-		return "", err
-	}
-	return dst, nil
-}
-
 func doCopyAll(dst, src string) error {
 	return filepath.Walk(src, func(path string, info os.FileInfo, errin error) (err error) {
 		if errin != nil {
diff --git a/cmd/gomobile/init_test.go b/cmd/gomobile/init_test.go
index cdb6024..43384ce 100644
--- a/cmd/gomobile/init_test.go
+++ b/cmd/gomobile/init_test.go
@@ -22,13 +22,11 @@
 		xout = os.Stderr
 		buildN = false
 		buildX = false
-		initU = false
 		os.Setenv("GOPATH", gopathorig)
 	}()
 	xout = buf
 	buildN = true
 	buildX = true
-	initU = true
 
 	// Test that first GOPATH element is chosen correctly.
 	gopath = "/GOPATH1"
@@ -75,7 +73,6 @@
 }
 
 type outputData struct {
-	NDK       string
 	GOOS      string
 	GOARCH    string
 	GOPATH    string
@@ -88,7 +85,6 @@
 
 func defaultOutputData() outputData {
 	data := outputData{
-		NDK:       ndkVersion,
 		GOOS:      goos,
 		GOARCH:    goarch,
 		GOPATH:    gopath,
@@ -104,38 +100,40 @@
 }
 
 var initTmpl = template.Must(template.New("output").Parse(`GOMOBILE={{.GOPATH}}/pkg/gomobile
-mkdir -p $GOMOBILE/android-{{.NDK}}
-WORK={{.GOPATH}}/pkg/gomobile/work
-mkdir -p $GOMOBILE/dl
-curl -o$GOMOBILE/dl/gomobile-{{.NDK}}-{{.GOOS}}-{{.NDKARCH}}.tar.gz https://dl.google.com/go/mobile/gomobile-{{.NDK}}-{{.GOOS}}-{{.NDKARCH}}.tar.gz
-tar xfz $GOMOBILE/dl/gomobile-{{.NDK}}-{{.GOOS}}-{{.NDKARCH}}.tar.gz
-mkdir -p $GOMOBILE/android-{{.NDK}}/llvm
-mv $WORK/android-{{.NDK}}/toolchains/llvm/prebuilt/{{.GOOS}}-{{.NDKARCH}}/lib64 $GOMOBILE/android-{{.NDK}}/llvm/lib64
-mv $WORK/android-{{.NDK}}/toolchains/llvm/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin $GOMOBILE/android-{{.NDK}}/llvm/bin
-mkdir -p $GOMOBILE/android-{{.NDK}}/arm/sysroot
-mv $WORK/android-{{.NDK}}/platforms/android-15/arch-arm/usr $GOMOBILE/android-{{.NDK}}/arm/sysroot/usr
-mv $WORK/android-{{.NDK}}/toolchains/arm-linux-androideabi-4.9/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin $GOMOBILE/android-{{.NDK}}/arm/bin
-mv $WORK/android-{{.NDK}}/toolchains/arm-linux-androideabi-4.9/prebuilt/{{.GOOS}}-{{.NDKARCH}}/lib $GOMOBILE/android-{{.NDK}}/arm/lib
-mkdir -p $GOMOBILE/android-{{.NDK}}/arm/arm-linux-androideabi/bin
-ln -s $GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-ld{{.EXE}} $GOMOBILE/android-{{.NDK}}/arm/arm-linux-androideabi/bin/ld{{.EXE}}
-ln -s $GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-as{{.EXE}} $GOMOBILE/android-{{.NDK}}/arm/arm-linux-androideabi/bin/as{{.EXE}}
-ln -s $GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-nm{{.EXE}} $GOMOBILE/android-{{.NDK}}/arm/arm-linux-androideabi/bin/nm{{.EXE}}
-ln -s $GOMOBILE/android-{{.NDK}}/llvm/bin/clang $GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-clang
-ln -s $GOMOBILE/android-{{.NDK}}/llvm/bin/clang++ $GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-clang++
-ln -s $GOMOBILE/android-{{.NDK}}/llvm/lib64 $GOMOBILE/android-{{.NDK}}/arm/lib64
-mkdir -p $GOMOBILE/dl
-curl -o$GOMOBILE/dl/gomobile-openal-soft-1.16.0.1-{{.NDK}}.tar.gz https://dl.google.com/go/mobile/gomobile-openal-soft-1.16.0.1-{{.NDK}}.tar.gz
-tar xfz $GOMOBILE/dl/gomobile-openal-soft-1.16.0.1-{{.NDK}}.tar.gz
-cp -r $WORK/openal/include/AL $GOMOBILE/android-{{.NDK}}/arm/sysroot/usr/include/AL
-mkdir -p $GOMOBILE/android-{{.NDK}}/openal
-mv $WORK/openal/lib $GOMOBILE/android-{{.NDK}}/openal/lib{{if eq .GOOS "darwin"}}
+rm -r -f "$GOMOBILE"
+mkdir -p $GOMOBILE
+WORK={{.GOPATH}}/pkg/gomobile/work{{if eq .GOOS "darwin"}}
 go install -x golang.org/x/mobile/gl
 go install -x golang.org/x/mobile/app
 go install -x golang.org/x/mobile/exp/app/debug{{end}}
-GOOS=android GOARCH=arm CC=$GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-clang{{.EXE}} CXX=$GOMOBILE/android-{{.NDK}}/arm/bin/arm-linux-androideabi-clang++{{.EXE}} CGO_CFLAGS=-target armv7a-none-linux-androideabi --sysroot $GOMOBILE/android-{{.NDK}}/arm/sysroot CGO_CPPFLAGS=-target armv7a-none-linux-androideabi --sysroot $GOMOBILE/android-{{.NDK}}/arm/sysroot CGO_LDFLAGS=-target armv7a-none-linux-androideabi --sysroot $GOMOBILE/android-{{.NDK}}/arm/sysroot CGO_ENABLED=1 GOARM=7 go install -pkgdir=$GOMOBILE/pkg_android_arm -x std
+GOOS=android GOARCH=arm CC=$NDK_PATH/toolchains/llvm/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/clang{{.EXE}} CXX=$NDK_PATH/toolchains/llvm/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/clang++{{.EXE}} CGO_CFLAGS=-target armv7a-none-linux-androideabi --sysroot $NDK_PATH/platforms/android-15/arch-arm -gcc-toolchain $NDK_PATH/toolchains/arm-linux-androideabi-4.9/prebuilt/{{.GOOS}}-{{.NDKARCH}} -I$GOMOBILE/include CGO_CPPFLAGS=-target armv7a-none-linux-androideabi --sysroot $NDK_PATH/platforms/android-15/arch-arm -gcc-toolchain $NDK_PATH/toolchains/arm-linux-androideabi-4.9/prebuilt/{{.GOOS}}-{{.NDKARCH}} -I$GOMOBILE/include CGO_LDFLAGS=-target armv7a-none-linux-androideabi --sysroot $NDK_PATH/platforms/android-15/arch-arm -gcc-toolchain $NDK_PATH/toolchains/arm-linux-androideabi-4.9/prebuilt/{{.GOOS}}-{{.NDKARCH}} -L$NDK_PATH/platforms/android-15/arch-arm/usr/lib -L$GOMOBILE/lib/arm CGO_ENABLED=1 GOARM=7 go install -pkgdir=$GOMOBILE/pkg_android_arm -x std
 {{if eq .GOOS "darwin"}}GOOS=darwin GOARCH=arm GOARM=7 CC=clang-iphoneos CXX=clang-iphoneos CGO_CFLAGS=-isysroot=iphoneos -miphoneos-version-min=6.1 -arch armv7 CGO_LDFLAGS=-isysroot=iphoneos -miphoneos-version-min=6.1 -arch armv7 CGO_ENABLED=1 go install -pkgdir=$GOMOBILE/pkg_darwin_arm -x std
 GOOS=darwin GOARCH=arm64 CC=clang-iphoneos CXX=clang-iphoneos CGO_CFLAGS=-isysroot=iphoneos -miphoneos-version-min=6.1 -arch arm64 CGO_LDFLAGS=-isysroot=iphoneos -miphoneos-version-min=6.1 -arch arm64 CGO_ENABLED=1 go install -pkgdir=$GOMOBILE/pkg_darwin_arm64 -x std
 GOOS=darwin GOARCH=amd64 CC=clang-iphonesimulator CXX=clang-iphonesimulator CGO_CFLAGS=-isysroot=iphonesimulator -mios-simulator-version-min=6.1 -arch x86_64 CGO_LDFLAGS=-isysroot=iphonesimulator -mios-simulator-version-min=6.1 -arch x86_64 CGO_ENABLED=1 go install -tags=ios -pkgdir=$GOMOBILE/pkg_darwin_amd64 -x std
-{{end}}go version > $GOMOBILE/version
+{{end}}cp $OPENAL_PATH/include/AL/al.h $GOMOBILE/include/AL/al.h
+mkdir -p $GOMOBILE/include/AL
+cp $OPENAL_PATH/include/AL/alc.h $GOMOBILE/include/AL/alc.h
+mkdir -p $GOMOBILE/include/AL
+PWD=$NDK_PATH $NDK_PATH/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/python2.7 build/tools/make_standalone_toolchain.py --arch=arm --api=15 --install-dir=$WORK/build/armeabi/toolchain
+PWD=$WORK/build/armeabi cmake $OPENAL_PATH -DCMAKE_TOOLCHAIN_FILE=$OPENAL_PATH/XCompile-Android.txt -DHOST=arm-linux-androideabi
+PWD=$WORK/build/armeabi $NDK_PATH/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/make
+cp $WORK/build/armeabi/libopenal.so $GOMOBILE/lib/armeabi-v7a/libopenal.so
+mkdir -p $GOMOBILE/lib/armeabi-v7a
+PWD=$NDK_PATH $NDK_PATH/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/python2.7 build/tools/make_standalone_toolchain.py --arch=arm64 --api=21 --install-dir=$WORK/build/arm64/toolchain
+PWD=$WORK/build/arm64 cmake $OPENAL_PATH -DCMAKE_TOOLCHAIN_FILE=$OPENAL_PATH/XCompile-Android.txt -DHOST=aarch64-linux-android
+PWD=$WORK/build/arm64 $NDK_PATH/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/make
+cp $WORK/build/arm64/libopenal.so $GOMOBILE/lib/arm64-v8a/libopenal.so
+mkdir -p $GOMOBILE/lib/arm64-v8a
+PWD=$NDK_PATH $NDK_PATH/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/python2.7 build/tools/make_standalone_toolchain.py --arch=x86 --api=15 --install-dir=$WORK/build/x86/toolchain
+PWD=$WORK/build/x86 cmake $OPENAL_PATH -DCMAKE_TOOLCHAIN_FILE=$OPENAL_PATH/XCompile-Android.txt -DHOST=i686-linux-android
+PWD=$WORK/build/x86 $NDK_PATH/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/make
+cp $WORK/build/x86/libopenal.so $GOMOBILE/lib/x86/libopenal.so
+mkdir -p $GOMOBILE/lib/x86
+PWD=$NDK_PATH $NDK_PATH/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/python2.7 build/tools/make_standalone_toolchain.py --arch=x86_64 --api=21 --install-dir=$WORK/build/x86_64/toolchain
+PWD=$WORK/build/x86_64 cmake $OPENAL_PATH -DCMAKE_TOOLCHAIN_FILE=$OPENAL_PATH/XCompile-Android.txt -DHOST=x86_64-linux-android
+PWD=$WORK/build/x86_64 $NDK_PATH/prebuilt/{{.GOOS}}-{{.NDKARCH}}/bin/make
+cp $WORK/build/x86_64/libopenal.so $GOMOBILE/lib/x86_64/libopenal.so
+mkdir -p $GOMOBILE/lib/x86_64
+go version > $GOMOBILE/version
 rm -r -f "$WORK"
 `))
diff --git a/cmd/gomobile/release.go b/cmd/gomobile/release.go
deleted file mode 100644
index 589a124..0000000
--- a/cmd/gomobile/release.go
+++ /dev/null
@@ -1,489 +0,0 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//+build ignore
-
-// Release is a tool for building the NDK tarballs hosted on dl.google.com.
-//
-// The Go toolchain only needs the gcc compiler and headers, which are ~10MB.
-// The entire NDK is ~400MB. Building smaller toolchain binaries reduces the
-// run time of gomobile init significantly.
-package main
-
-import (
-	"archive/tar"
-	"bufio"
-	"compress/gzip"
-	"crypto/sha256"
-	"encoding/hex"
-	"flag"
-	"fmt"
-	"hash"
-	"io"
-	"io/ioutil"
-	"log"
-	"net/http"
-	"os"
-	"os/exec"
-	"path/filepath"
-	"runtime"
-	"strconv"
-)
-
-const ndkVersion = "ndk-r12b"
-
-type version struct {
-	os   string
-	arch string
-}
-
-var hosts = []version{
-	{"darwin", "x86_64"},
-	{"linux", "x86_64"},
-	{"windows", "x86"},
-	{"windows", "x86_64"},
-}
-
-type target struct {
-	arch       string
-	platform   int
-	gcc        string
-	toolPrefix string
-}
-
-var targets = []target{
-	{"arm", 15, "arm-linux-androideabi-4.9", "arm-linux-androideabi"},
-	{"arm64", 21, "aarch64-linux-android-4.9", "aarch64-linux-android"},
-	{"x86", 15, "x86-4.9", "i686-linux-android"},
-	{"x86_64", 21, "x86_64-4.9", "x86_64-linux-android"},
-}
-
-var (
-	ndkdir = flag.String("ndkdir", "", "Directory for the downloaded NDKs for caching")
-	tmpdir string
-)
-
-func main() {
-	flag.Parse()
-	var err error
-	tmpdir, err = ioutil.TempDir("", "gomobile-release-")
-	if err != nil {
-		log.Panic(err)
-	}
-	defer os.RemoveAll(tmpdir)
-
-	fmt.Println("var fetchHashes = map[string]string{")
-	for _, host := range hosts {
-		if err := mkpkg(host); err != nil {
-			log.Panic(err)
-		}
-	}
-	if err := mkALPkg(); err != nil {
-		log.Panic(err)
-	}
-
-	fmt.Println("}")
-}
-
-func run(dir, path string, args ...string) error {
-	cmd := exec.Command(path, args...)
-	cmd.Dir = dir
-	buf, err := cmd.CombinedOutput()
-	if err != nil {
-		fmt.Printf("%s\n", buf)
-	}
-	return err
-}
-
-func mkALPkg() (err error) {
-	ndkPath, _, err := fetchNDK(version{os: hostOS, arch: hostArch})
-	if err != nil {
-		return err
-	}
-	ndkRoot := tmpdir + "/android-" + ndkVersion
-	if err := inflate(tmpdir, ndkPath); err != nil {
-		return err
-	}
-
-	alTmpDir, err := ioutil.TempDir("", "openal-release-")
-	if err != nil {
-		return err
-	}
-	defer os.RemoveAll(alTmpDir)
-
-	if err := run(alTmpDir, "git", "clone", "-v", "git://repo.or.cz/openal-soft.git", alTmpDir); err != nil {
-		return err
-	}
-	// TODO: use more recent revision?
-	if err := run(alTmpDir, "git", "checkout", "19f79be57b8e768f44710b6d26017bc1f8c8fbda"); err != nil {
-		return err
-	}
-
-	files := map[string]string{
-		"include/AL/al.h":  "include/AL/al.h",
-		"include/AL/alc.h": "include/AL/alc.h",
-		"COPYING":          "include/AL/COPYING",
-	}
-
-	for _, t := range targets {
-		abi := t.arch
-		if abi == "arm" {
-			abi = "armeabi"
-		}
-		buildDir := alTmpDir + "/build/" + abi
-		toolchain := buildDir + "/toolchain"
-		// standalone ndk toolchains make openal-soft's build config easier.
-		if err := run(ndkRoot, "env",
-			"build/tools/make_standalone_toolchain.py",
-			"--arch="+t.arch,
-			"--api="+strconv.Itoa(t.platform),
-			"--install-dir="+toolchain); err != nil {
-			return fmt.Errorf("make_standalone_toolchain.py failed: %v", err)
-		}
-
-		orgPath := os.Getenv("PATH")
-		os.Setenv("PATH", toolchain+"/bin"+string(os.PathListSeparator)+orgPath)
-		if err := run(buildDir, "cmake",
-			"../../",
-			"-DCMAKE_TOOLCHAIN_FILE=../../XCompile-Android.txt",
-			"-DHOST="+t.toolPrefix); err != nil {
-			return fmt.Errorf("cmake failed: %v", err)
-		}
-		os.Setenv("PATH", orgPath)
-
-		if err := run(buildDir, "make"); err != nil {
-			return fmt.Errorf("make failed: %v", err)
-		}
-
-		files["build/"+abi+"/libopenal.so"] = "lib/" + abi + "/libopenal.so"
-	}
-
-	// Build the tarball.
-	aw := newArchiveWriter("gomobile-openal-soft-1.16.0.1-" + ndkVersion + ".tar.gz")
-	defer func() {
-		err2 := aw.Close()
-		if err == nil {
-			err = err2
-		}
-	}()
-
-	for src, dst := range files {
-		f, err := os.Open(filepath.Join(alTmpDir, src))
-		if err != nil {
-			return err
-		}
-		fi, err := f.Stat()
-		if err != nil {
-			return err
-		}
-		aw.WriteHeader(&tar.Header{
-			Name: dst,
-			Mode: int64(fi.Mode()),
-			Size: fi.Size(),
-		})
-		io.Copy(aw, f)
-		f.Close()
-	}
-	return nil
-}
-
-func fetchNDK(host version) (binPath, url string, err error) {
-	ndkName := "android-" + ndkVersion + "-" + host.os + "-" + host.arch + ".zip"
-
-	url = "https://dl.google.com/android/repository/" + ndkName
-	binPath = *ndkdir
-	if binPath == "" {
-		binPath = tmpdir
-	}
-	binPath += "/" + ndkName
-
-	if _, err := os.Stat(binPath); err == nil {
-		log.Printf("\t%q: using cached NDK\n", ndkName)
-		return binPath, url, nil
-	}
-
-	log.Printf("%s\n", url)
-	binHash, err := fetch(binPath, url)
-	if err != nil {
-		return "", "", err
-	}
-
-	fmt.Printf("\t%q: %q,\n", ndkName, binHash)
-	return binPath, url, nil
-}
-
-func mkpkg(host version) error {
-	binPath, url, err := fetchNDK(host)
-	if err != nil {
-		return err
-	}
-
-	src := tmpdir + "/" + host.os + "-" + host.arch + "-src"
-	dst := tmpdir + "/" + host.os + "-" + host.arch + "-dst"
-	defer os.RemoveAll(src)
-	defer os.RemoveAll(dst)
-
-	if err := os.Mkdir(src, 0755); err != nil {
-		return err
-	}
-
-	if err := inflate(src, binPath); err != nil {
-		return err
-	}
-
-	// The NDK is unpacked into tmpdir/linux-x86_64-src/android-{{ndkVersion}}.
-	// Move the files we want into tmpdir/linux-x86_64-dst/android-{{ndkVersion}}.
-	// We preserve the same file layout to make the full NDK interchangable
-	// with the cut down file.
-	for _, t := range targets {
-		usr := fmt.Sprintf("android-%s/platforms/android-%d/arch-%s/usr/", ndkVersion, t.platform, t.arch)
-		gcc := fmt.Sprintf("android-%s/toolchains/%s/prebuilt/", ndkVersion, t.gcc)
-
-		if host.os == "windows" && host.arch == "x86" {
-			gcc += "windows"
-		} else {
-			gcc += host.os + "-" + host.arch
-		}
-
-		if err := os.MkdirAll(dst+"/"+usr, 0755); err != nil {
-			return err
-		}
-		if err := os.MkdirAll(dst+"/"+gcc+"/bin", 0755); err != nil {
-			return err
-		}
-
-		subdirs := []string{"include", "lib"}
-		switch t.arch {
-		case "x86_64":
-			subdirs = append(subdirs, "lib64", "libx32")
-		}
-		if err := move(dst+"/"+usr, src+"/"+usr, subdirs...); err != nil {
-			return err
-		}
-
-		if err := move(dst+"/"+gcc, src+"/"+gcc, "lib", "COPYING", "COPYING.LIB"); err != nil {
-			return err
-		}
-		for _, exe := range []string{"as", "ld", "nm"} {
-			if host.os == "windows" {
-				exe += ".exe"
-			}
-			if err := move(dst+"/"+gcc+"/bin", src+"/"+gcc+"/bin", t.toolPrefix+"-"+exe); err != nil {
-				return err
-			}
-		}
-	}
-
-	// Copy the LLVM clang and clang++ compilers
-	llvm := fmt.Sprintf("android-%s/toolchains/llvm/prebuilt/", ndkVersion)
-
-	if host.os == "windows" && host.arch == "x86" {
-		llvm += "windows"
-	} else {
-		llvm += host.os + "-" + host.arch
-	}
-
-	if err := os.MkdirAll(dst+"/"+llvm, 0755); err != nil {
-		return err
-	}
-
-	if err := move(dst+"/"+llvm, src+"/"+llvm, "bin", "lib64", "NOTICE"); err != nil {
-		return err
-	}
-
-	// Build the tarball.
-	aw := newArchiveWriter("gomobile-" + ndkVersion + "-" + host.os + "-" + host.arch + ".tar.gz")
-	defer func() {
-		err2 := aw.Close()
-		if err == nil {
-			err = err2
-		}
-	}()
-
-	readme := "Stripped down copy of:\n\n\t" + url + "\n\nGenerated by golang.org/x/mobile/cmd/gomobile/release.go."
-	aw.WriteHeader(&tar.Header{
-		Name: "README",
-		Mode: 0644,
-		Size: int64(len(readme)),
-	})
-	io.WriteString(aw, readme)
-
-	return filepath.Walk(dst, func(path string, fi os.FileInfo, err error) error {
-		defer func() {
-			if err != nil {
-				err = fmt.Errorf("%s: %v", path, err)
-			}
-		}()
-		if err != nil {
-			return err
-		}
-		if path == dst {
-			return nil
-		}
-		name := path[len(dst)+1:]
-		if fi.IsDir() {
-			return nil
-		}
-		if fi.Mode()&os.ModeSymlink != 0 {
-			dst, err := os.Readlink(path)
-			if err != nil {
-				log.Printf("bad symlink: %s", name)
-				return nil
-			}
-			aw.WriteHeader(&tar.Header{
-				Name:     name,
-				Linkname: dst,
-				Typeflag: tar.TypeSymlink,
-			})
-			return nil
-		}
-		aw.WriteHeader(&tar.Header{
-			Name: name,
-			Mode: int64(fi.Mode()),
-			Size: fi.Size(),
-		})
-		f, err := os.Open(path)
-		if err != nil {
-			return err
-		}
-		io.Copy(aw, f)
-		f.Close()
-		return nil
-	})
-}
-
-func fetch(dst, url string) (string, error) {
-	f, err := os.OpenFile(dst, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0755)
-	if err != nil {
-		return "", err
-	}
-	resp, err := http.Get(url)
-	if err != nil {
-		return "", err
-	}
-	if sc := resp.StatusCode; sc != http.StatusOK {
-		return "", fmt.Errorf("invalid HTTP status %d", sc)
-	}
-	hashw := sha256.New()
-	_, err = io.Copy(io.MultiWriter(hashw, f), resp.Body)
-	err2 := resp.Body.Close()
-	err3 := f.Close()
-	if err != nil {
-		return "", err
-	}
-	if err2 != nil {
-		return "", err2
-	}
-	if err3 != nil {
-		return "", err3
-	}
-	return hex.EncodeToString(hashw.Sum(nil)), nil
-}
-
-func inflate(dst, path string) error {
-	unzip := "unzip"
-	cmd := exec.Command(unzip, path)
-	cmd.Dir = dst
-	out, err := cmd.CombinedOutput()
-	if err != nil {
-		os.Stderr.Write(out)
-		return err
-	}
-	return nil
-}
-
-func move(dst, src string, names ...string) error {
-	for _, name := range names {
-		if err := os.Rename(src+"/"+name, dst+"/"+name); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-// archiveWriter writes a .tar.gz archive and prints its SHA256 to stdout.
-// If any error occurs, it continues as a no-op until Close, when it is reported.
-type archiveWriter struct {
-	name  string
-	hashw hash.Hash
-	f     *os.File
-	zw    *gzip.Writer
-	bw    *bufio.Writer
-	tw    *tar.Writer
-	err   error
-}
-
-func (aw *archiveWriter) WriteHeader(h *tar.Header) {
-	if aw.err != nil {
-		return
-	}
-	aw.err = aw.tw.WriteHeader(h)
-}
-
-func (aw *archiveWriter) Write(b []byte) (n int, err error) {
-	if aw.err != nil {
-		return len(b), nil
-	}
-	n, aw.err = aw.tw.Write(b)
-	return n, nil
-}
-
-func (aw *archiveWriter) Close() (err error) {
-	err = aw.tw.Close()
-	if aw.err == nil {
-		aw.err = err
-	}
-	err = aw.zw.Close()
-	if aw.err == nil {
-		aw.err = err
-	}
-	err = aw.bw.Flush()
-	if aw.err == nil {
-		aw.err = err
-	}
-	err = aw.f.Close()
-	if aw.err == nil {
-		aw.err = err
-	}
-	if aw.err != nil {
-		return aw.err
-	}
-	hash := hex.EncodeToString(aw.hashw.Sum(nil))
-	fmt.Printf("\t%q: %q,\n", aw.name, hash)
-	return nil
-}
-
-func newArchiveWriter(name string) *archiveWriter {
-	aw := &archiveWriter{name: name}
-	aw.f, aw.err = os.Create(name)
-	if aw.err != nil {
-		return aw
-	}
-	aw.hashw = sha256.New()
-	aw.bw = bufio.NewWriter(io.MultiWriter(aw.f, aw.hashw))
-	aw.zw, aw.err = gzip.NewWriterLevel(aw.bw, gzip.BestCompression)
-	if aw.err != nil {
-		return aw
-	}
-	aw.tw = tar.NewWriter(aw.zw)
-	return aw
-}
-
-var hostOS, hostArch string
-
-func init() {
-	switch runtime.GOOS {
-	case "linux", "darwin":
-		hostOS = runtime.GOOS
-	}
-	switch runtime.GOARCH {
-	case "386":
-		hostArch = "x86"
-	case "amd64":
-		hostArch = "x86_64"
-	}
-	if hostOS == "" || hostArch == "" {
-		panic(fmt.Sprintf("cannot run release from OS/Arch: %s/%s", hostOS, hostArch))
-	}
-}