Adding upstream version 1.2.3.

Signed-off-by: Daniel Baumann <daniel@debian.org>

cmd/go-get-release/main.go

@@ -0,0 +1,132 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"github.com/rhysd/go-github-selfupdate/selfupdate"
+	"go/build"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+var version = "1.0.0"
+
+func usage() {
+	fmt.Fprintln(os.Stderr, `Usage: go-get-release [flags] {package}
+
+  go-get-release is like "go get", but it downloads the latest release from
+  GitHub. {package} must start with "github.com/".
+
+Flags:`)
+	flag.PrintDefaults()
+}
+
+func getCommand(pkg string) string {
+	_, cmd := filepath.Split(pkg)
+	if cmd == "" {
+		// When pkg path is ending with path separator, we need to split it out.
+		// i.e. github.com/rhysd/foo/cmd/bar/
+		_, cmd = filepath.Split(cmd)
+	}
+	return cmd
+}
+
+func parseSlug(pkg string) (string, bool) {
+	pkg = pkg[len("github.com/"):]
+	first := false
+	for i, r := range pkg {
+		if r == '/' {
+			if !first {
+				first = true
+			} else {
+				return pkg[:i], true
+			}
+		}
+	}
+	if first {
+		// When 'github.com/foo/bar' is specified, reaching here.
+		return pkg, true
+	}
+	return "", false
+}
+
+func installFrom(url, cmd, path string) error {
+	res, err := http.Get(url)
+	if err != nil {
+		return fmt.Errorf("Failed to download release binary from %s: %s", url, err)
+	}
+	defer res.Body.Close()
+	if res.StatusCode != 200 {
+		return fmt.Errorf("Failed to download release binary from %s: Invalid response ", url)
+	}
+	executable, err := selfupdate.UncompressCommand(res.Body, url, cmd)
+	if err != nil {
+		return fmt.Errorf("Failed to uncompress downloaded asset from %s: %s", url, err)
+	}
+	bin, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE, 0755)
+	if err != nil {
+		return err
+	}
+	if _, err := io.Copy(bin, executable); err != nil {
+		return fmt.Errorf("Failed to write binary to %s: %s", path, err)
+	}
+	return nil
+}
+
+func main() {
+	help := flag.Bool("help", false, "Show help")
+	ver := flag.Bool("version", false, "Show version")
+
+	flag.Usage = usage
+	flag.Parse()
+
+	if *ver {
+		fmt.Println(version)
+		os.Exit(0)
+	}
+
+	if *help || flag.NArg() != 1 || !strings.HasPrefix(flag.Arg(0), "github.com/") {
+		usage()
+		os.Exit(1)
+	}
+
+	slug, ok := parseSlug(flag.Arg(0))
+	if !ok {
+		usage()
+		os.Exit(1)
+	}
+
+	latest, found, err := selfupdate.DetectLatest(slug)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "Error while detecting the latest version:", err)
+		os.Exit(1)
+	}
+	if !found {
+		fmt.Fprintln(os.Stderr, "No release was found in", slug)
+		os.Exit(1)
+	}
+
+	cmd := getCommand(flag.Arg(0))
+	cmdPath := filepath.Join(build.Default.GOPATH, "bin", cmd)
+	if _, err := os.Stat(cmdPath); err != nil {
+		// When executable is not existing yet
+		if err := installFrom(latest.AssetURL, cmd, cmdPath); err != nil {
+			fmt.Fprintf(os.Stderr, "Error while installing the release binary from %s: %s\n", latest.AssetURL, err)
+			os.Exit(1)
+		}
+	} else {
+		if err := selfupdate.UpdateTo(latest.AssetURL, cmdPath); err != nil {
+			fmt.Fprintf(os.Stderr, "Error while replacing the binary with %s: %s\n", latest.AssetURL, err)
+			os.Exit(1)
+		}
+	}
+
+	fmt.Printf(`Command was updated to the latest version %s: %s
+
+Release Notes:
+%s
+`, latest.Version, cmdPath, latest.ReleaseNotes)
+}