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// 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
import (
"bytes"
"encoding/json"
"errors"
"fmt"
"io"
"io/ioutil"
"os"
"os/exec"
"path/filepath"
"strings"
"golang.org/x/mod/modfile"
"golang.org/x/tools/go/packages"
)
var cmdBind = &command{
run: runBind,
Name: "bind",
Usage: "[-target android|" + strings.Join(applePlatforms, "|") + "] [-bootclasspath <path>] [-classpath <path>] [-o output] [build flags] [package]",
Short: "build a library for Android and iOS",
Long: `
Bind generates language bindings for the package named by the import
path, and compiles a library for the named target system.
The -target flag takes either android (the default), or one or more
comma-delimited Apple platforms (` + strings.Join(applePlatforms, ", ") + `).
For -target android, the bind command produces an AAR (Android ARchive)
file that archives the precompiled Java API stub classes, the compiled
shared libraries, and all asset files in the /assets subdirectory under
the package directory. The output is named '<package_name>.aar' by
default. This AAR file is commonly used for binary distribution of an
Android library project and most Android IDEs support AAR import. For
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
package prefix for the generated classes.
By default, -target=android builds shared libraries for all supported
instruction sets (arm, arm64, 386, amd64). A subset of instruction sets
can be selected by specifying target type with the architecture name. E.g.,
-target=android/arm,android/386.
For Apple -target platforms, gomobile must be run on an OS X machine with
Xcode installed. The generated Objective-C types can be prefixed with the
-prefix flag.
For -target android, the -bootclasspath and -classpath flags are used to
control the bootstrap classpath and the classpath for Go wrappers to Java
classes.
The -v flag provides verbose output, including the list of packages built.
The build flags -a, -n, -x, -gcflags, -ldflags, -tags, -trimpath, and -work
are shared with the build command. For documentation, see 'go help build'.
`,
}
func runBind(cmd *command) error {
cleanup, err := buildEnvInit()
if err != nil {
return err
}
defer cleanup()
args := cmd.flag.Args()
targets, err := parseBuildTarget(buildTarget)
if err != nil {
return fmt.Errorf(`invalid -target=%q: %v`, buildTarget, err)
}
if isAndroidPlatform(targets[0].platform) {
if bindPrefix != "" {
return fmt.Errorf("-prefix is supported only for Apple targets")
}
if _, err := ndkRoot(); err != nil {
return err
}
} else {
if bindJavaPkg != "" {
return fmt.Errorf("-javapkg is supported only for android target")
}
}
var gobind string
if !buildN {
gobind, err = exec.LookPath("gobind")
if err != nil {
return errors.New("gobind was not found. Please run gomobile init before trying again")
}
} else {
gobind = "gobind"
}
if len(args) == 0 {
args = append(args, ".")
}
// TODO(ydnar): this should work, unless build tags affect loading a single package.
// Should we try to import packages with different build tags per platform?
pkgs, err := packages.Load(packagesConfig(targets[0]), args...)
if err != nil {
return err
}
// check if any of the package is main
for _, pkg := range pkgs {
if pkg.Name == "main" {
return fmt.Errorf(`binding "main" package (%s) is not supported`, pkg.PkgPath)
}
}
switch {
case isAndroidPlatform(targets[0].platform):
return goAndroidBind(gobind, pkgs, targets)
case isApplePlatform(targets[0].platform):
if !xcodeAvailable() {
return fmt.Errorf("-target=%q requires Xcode", buildTarget)
}
return goAppleBind(gobind, pkgs, targets)
default:
return fmt.Errorf(`invalid -target=%q`, buildTarget)
}
}
var (
bindPrefix string // -prefix
bindJavaPkg string // -javapkg
bindClasspath string // -classpath
bindBootClasspath string // -bootclasspath
)
func init() {
// bind command specific commands.
cmdBind.flag.StringVar(&bindJavaPkg, "javapkg", "",
"specifies custom Java package path prefix. Valid only with -target=android.")
cmdBind.flag.StringVar(&bindPrefix, "prefix", "",
"custom Objective-C name prefix. Valid only with -target=ios.")
cmdBind.flag.StringVar(&bindClasspath, "classpath", "", "The classpath for imported Java classes. Valid only with -target=android.")
cmdBind.flag.StringVar(&bindBootClasspath, "bootclasspath", "", "The bootstrap classpath for imported Java classes. Valid only with -target=android.")
}
func bootClasspath() (string, error) {
if bindBootClasspath != "" {
return bindBootClasspath, nil
}
apiPath, err := androidAPIPath()
if err != nil {
return "", err
}
return filepath.Join(apiPath, "android.jar"), nil
}
func copyFile(dst, src string) error {
if buildX {
printcmd("cp %s %s", src, dst)
}
return writeFile(dst, func(w io.Writer) error {
if buildN {
return nil
}
f, err := os.Open(src)
if err != nil {
return err
}
defer f.Close()
if _, err := io.Copy(w, f); err != nil {
return fmt.Errorf("cp %s %s failed: %v", src, dst, err)
}
return nil
})
}
func writeFile(filename string, generate func(io.Writer) error) error {
if buildV {
fmt.Fprintf(os.Stderr, "write %s\n", filename)
}
if err := mkdir(filepath.Dir(filename)); err != nil {
return err
}
if buildN {
return generate(ioutil.Discard)
}
f, err := os.Create(filename)
if err != nil {
return err
}
defer func() {
if cerr := f.Close(); err == nil {
err = cerr
}
}()
return generate(f)
}
func packagesConfig(t targetInfo) *packages.Config {
config := &packages.Config{}
// Add CGO_ENABLED=1 explicitly since Cgo is disabled when GOOS is different from host OS.
config.Env = append(os.Environ(), "GOARCH="+t.arch, "GOOS="+platformOS(t.platform), "CGO_ENABLED=1")
tags := append(buildTags[:], platformTags(t.platform)...)
if len(tags) > 0 {
config.BuildFlags = []string{"-tags=" + strings.Join(tags, ",")}
}
return config
}
// getModuleVersions returns a module information at the directory src.
func getModuleVersions(targetPlatform string, targetArch string, src string) (*modfile.File, error) {
cmd := exec.Command("go", "list")
cmd.Env = append(os.Environ(), "GOOS="+platformOS(targetPlatform), "GOARCH="+targetArch)
tags := append(buildTags[:], platformTags(targetPlatform)...)
// TODO(hyangah): probably we don't need to add all the dependencies.
cmd.Args = append(cmd.Args, "-m", "-json", "-tags="+strings.Join(tags, ","), "all")
cmd.Dir = src
output, err := cmd.Output()
if err != nil {
// Module information is not available at src.
return nil, nil
}
type Module struct {
Main bool
Path string
Version string
Dir string
Replace *Module
}
f := &modfile.File{}
f.AddModuleStmt("gobind")
e := json.NewDecoder(bytes.NewReader(output))
for {
var mod *Module
err := e.Decode(&mod)
if err != nil && err != io.EOF {
return nil, err
}
if mod != nil {
if mod.Replace != nil {
p, v := mod.Replace.Path, mod.Replace.Version
if modfile.IsDirectoryPath(p) {
// replaced by a local directory
p = mod.Replace.Dir
}
f.AddReplace(mod.Path, mod.Version, p, v)
} else {
// When the version part is empty, the module is local and mod.Dir represents the location.
if v := mod.Version; v == "" {
f.AddReplace(mod.Path, mod.Version, mod.Dir, "")
} else {
f.AddRequire(mod.Path, v)
}
}
}
if err == io.EOF {
break
}
}
return f, nil
}
// writeGoMod writes go.mod file at $WORK/src when Go modules are used.
func writeGoMod(dir, targetPlatform, targetArch string) error {
m, err := areGoModulesUsed()
if err != nil {
return err
}
// If Go modules are not used, go.mod should not be created because the dependencies might not be compatible with Go modules.
if !m {
return nil
}
return writeFile(filepath.Join(dir, "src", "go.mod"), func(w io.Writer) error {
f, err := getModuleVersions(targetPlatform, targetArch, ".")
if err != nil {
return err
}
if f == nil {
return nil
}
bs, err := f.Format()
if err != nil {
return err
}
if _, err := w.Write(bs); err != nil {
return err
}
return nil
})
}
func areGoModulesUsed() (bool, error) {
out, err := exec.Command("go", "env", "GOMOD").Output()
if err != nil {
return false, err
}
outstr := strings.TrimSpace(string(out))
if outstr == "" {
return false, nil
}
return true, nil
}