add AndroidNDKBuild

.gitignore

@@ -4,6 +4,7 @@
 *.so
 *.dylib
 BaiduPCS-Go
+cmd/AndroidNDKBuild/AndroidNDKBuild
 
 # Test binary, build with `go test -c`
 *.test

cmd/AndroidNDKBuild/main.go

@@ -0,0 +1,120 @@
+// go build -ldflags "-X main.APILevel=15 -X main.Arch=x86_64"
+// env ANDROID_API_LEVEL NDK ANDROID_NDK_ROOT GOARCH
+
+package main
+
+import (
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+)
+
+var (
+	// NDKPath path to Android NDK
+	NDKPath string
+	// APILevel Android api level
+	APILevel string
+	// Arch arch
+	Arch string
+)
+
+func getNDKPath() string {
+	ndkPath, ok := os.LookupEnv("NDK")
+	if ok {
+		return ndkPath
+	}
+	ndkPath, ok = os.LookupEnv("ANDROID_NDK_ROOT")
+	if ok {
+		return ndkPath
+	}
+	ndkPath, ok = os.LookupEnv("ANDROID_NDK_DIR")
+	if ok {
+		return ndkPath
+	}
+	return ""
+}
+
+func getAPILevel() string {
+	apiLevelStr, ok := os.LookupEnv("ANDROID_API_LEVEL")
+	if ok {
+		return apiLevelStr
+	}
+	return "21"
+}
+
+func getGoarch() string {
+	arch, ok := os.LookupEnv("GOARCH")
+	if ok {
+		return arch
+	}
+
+	return runtime.GOARCH
+}
+
+func getArch() string {
+	goarch := getGoarch()
+	switch goarch {
+	case "386":
+		return "x86"
+	case "amd64":
+		return "x86_64"
+	case "arm":
+		return "arm"
+	case "arm64":
+		return "aarch64"
+	}
+	return goarch
+}
+
+func getPlatformsArch() string {
+	goarch := getGoarch()
+	switch goarch {
+	case "386":
+		return "x86"
+	case "amd64":
+		return "x86_64"
+	}
+	return goarch
+}
+
+func main() {
+	if NDKPath == "" {
+		NDKPath = getNDKPath()
+	}
+	if APILevel == "" {
+		APILevel = getAPILevel()
+	}
+	if Arch == "" {
+		Arch = getArch()
+	}
+
+	lastPattern := "*-gcc"
+	if runtime.GOOS == "windows" {
+		lastPattern += ".exe"
+	}
+
+	gccPaths, err := filepath.Glob(filepath.Join(NDKPath, "toolchains", getArch()+"-*", "prebuilt", runtime.GOOS+"-*", "bin", lastPattern))
+	checkErr(err)
+	if len(gccPaths) == 0 {
+		panic("no match gcc")
+	}
+
+	args := make([]string, len(os.Args))
+	copy(args, os.Args)
+	args[0] = "--sysroot=" + NDKPath + "/platforms/android-" + APILevel + "/arch-" + getPlatformsArch()
+
+	gccExec := exec.Command(gccPaths[0], args...)
+	gccExec.Stdout = os.Stdout
+	gccExec.Stderr = os.Stderr
+
+	gccExec.Run()
+
+	return
+}
+
+func checkErr(err error) {
+	if err != nil {
+		panic(err)
+	}
+}