build.go

// +build ignore

package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"runtime"
	"strconv"
	"strings"
	"time"
)

var (
	versionRe  = regexp.MustCompile(`-[0-9]{1,3}-g[0-9a-f]{5,10}`)
	goarch     string
	goos       string
	version    string = "v1"
	race       bool
	workingDir string
)

const minGoVersion = 1.3

func main() {
	log.SetOutput(os.Stdout)
	log.SetFlags(0)

	ensureGoPath()
	readVersionFromPackageJson()

	log.Printf("Version: %s\n", version)

	flag.StringVar(&goarch, "goarch", runtime.GOARCH, "GOARCH")
	flag.StringVar(&goos, "goos", runtime.GOOS, "GOOS")
	flag.BoolVar(&race, "race", race, "Use race detector")
	flag.Parse()

	if flag.NArg() == 0 {
		log.Println("Usage: go run build.go build")
		return
	}

	workingDir, _ = os.Getwd()

	for _, cmd := range flag.Args() {
		switch cmd {
		case "setup":
			setup()

		case "build":
			clean()
			build("bin/oem-image-installer", "./src/", []string{})

		case "clean":
			clean()

		default:
			log.Fatalf("Unknown command %q", cmd)
		}
	}
}

func readVersionFromPackageJson() {
	reader, err := os.Open("package.json")
	if err != nil {
		log.Fatal("Failed to open package.json")
		return
	}
	defer reader.Close()

	jsonObj := map[string]interface{}{}
	jsonParser := json.NewDecoder(reader)

	if err := jsonParser.Decode(&jsonObj); err != nil {
		log.Fatal("Failed to decode package.json")
	}

	version = jsonObj["version"].(string)
}

func ensureGoPath() {
	if os.Getenv("GOPATH") == "" {
		cwd, err := os.Getwd()
		if err != nil {
			log.Fatal(err)
		}
		gopath := filepath.Clean(filepath.Join(cwd, "../../../../"))
		log.Println("GOPATH is", gopath)
		os.Setenv("GOPATH", gopath)
	}
}

func setup() {
	runPrint("go", "get", "-v", "launchpad.net/godeps")
	runPrint("godeps", "-t", "-u", "dependencies.tsv")
}

func build(binaryName, pkg string, tags []string) {
	args := []string{"build", "-ldflags", ldflags()}
	if len(tags) > 0 {
		args = append(args, "-tags", strings.Join(tags, ","))
	}
	if race {
		args = append(args, "-race")
	}

	args = append(args, "-o", binaryName)
	args = append(args, pkg)
	setBuildEnv()

	runPrint("go", "version")
	runPrint("go", args...)
}

func ldflags() string {
	var b bytes.Buffer
	b.WriteString("-w")
	b.WriteString(fmt.Sprintf(" -X main.version=%s", version))
	b.WriteString(fmt.Sprintf(" -X main.commit=%s", getGitSha()))
	b.WriteString(fmt.Sprintf(" -X main.commitstamp=%d", commitStamp()))
	return b.String()
}

func clean() {
}

func setBuildEnv() {
	os.Setenv("GOOS", goos)
	if strings.HasPrefix(goarch, "armv") {
		os.Setenv("GOARCH", "arm")
		os.Setenv("GOARM", goarch[4:])
	} else {
		os.Setenv("GOARCH", goarch)
	}
	if goarch == "386" {
		os.Setenv("GO386", "387")
	}
	log.Println("GOPATH=" + os.Getenv("GOPATH"))
}

func getGitSha() string {
	v, err := runError("git", "describe", "--always", "--dirty")
	if err != nil {
		return "unknown-dev"
	}
	v = versionRe.ReplaceAllFunc(v, func(s []byte) []byte {
		s[0] = '+'
		return s
	})
	return string(v)
}

func commitStamp() int64 {
	bs, err := runError("git", "show", "-s", "--format=%ct")
	if err != nil {
		return time.Now().Unix()
	}
	s, _ := strconv.ParseInt(string(bs), 10, 64)
	return s
}

func run(cmd string, args ...string) []byte {
	bs, err := runError(cmd, args...)
	if err != nil {
		log.Println(cmd, strings.Join(args, " "))
		log.Println(string(bs))
		log.Fatal(err)
	}
	return bytes.TrimSpace(bs)
}

func runError(cmd string, args ...string) ([]byte, error) {
	ecmd := exec.Command(cmd, args...)
	bs, err := ecmd.CombinedOutput()
	if err != nil {
		return nil, err
	}

	return bytes.TrimSpace(bs), nil
}

func runPrint(cmd string, args ...string) {
	log.Println(cmd, strings.Join(args, " "))
	ecmd := exec.Command(cmd, args...)
	ecmd.Stdout = os.Stdout
	ecmd.Stderr = os.Stderr
	err := ecmd.Run()
	if err != nil {
		log.Fatal(err)
	}
}