ref: a3b6eb95a0d28eccbb0ed4502a647f9c37225b7e
dir: gover/main.go
// Copyright 2018 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.
// The gover command compiles and runs the go command from a release version.
//
// To install, run:
//
// $ go get suah.dev/gover
// $ gover download 1.14.2
//
// And then use the gover command as if it were your normal go command.
//
// To download a specific version, run "gover download VERSION".
package main
import (
"bytes"
"errors"
"fmt"
_ "embed"
"io"
"log"
"net/http"
"os"
"os/exec"
"os/user"
"path"
"path/filepath"
"runtime"
"strings"
"golang.org/x/crypto/openpgp"
"suah.dev/protect"
)
// Google Inc. (Linux Packages Signing Authority) <linux-packages-keymaster@google.com>
// RSA key 0x78BD65473CB3BD13
// Primary key fingerprint: EB4C 1BFD 4F04 2F6D DDCC EC91 7721 F63B D38B 4796
// Subkey fingerprint: 2F52 8D36 D67B 69ED F998 D857 78BD 6547 3CB3 BD13
//go:embed google.pub
var pubKey string
func main() {
log.SetFlags(0)
root, err := goroot("gover")
version := ""
if err != nil {
log.Fatalf("gover: %v", err)
}
if err := os.MkdirAll(root, 0755); err != nil {
log.Fatalf("failed to create gover directory: %v\n", err)
}
_ = protect.Pledge("stdio tty unveil rpath cpath wpath proc dns inet fattr exec")
_ = protect.Unveil("/etc", "r")
_ = protect.Unveil(root, "rwxc")
_ = protect.UnveilBlock()
if len(os.Args) == 1 {
log.Fatalf("gover: usage: gover [download|version]")
os.Exit(1)
}
if os.Args[1] == "download" {
switch len(os.Args) {
case 3:
version = os.Args[2]
if err := installVer(root, version); err != nil {
log.Fatalf("gover: %v", err)
}
default:
log.Fatalf("gover: usage: gover download [version]")
}
log.Printf("Success. You may now run 'gover %s'!", version)
os.Exit(0)
}
version = os.Args[1]
gobin := filepath.Join(root, version, "go", "bin", "go"+exe())
gorootPath := filepath.Join(root, version, "go")
if _, err := os.Stat(gobin); err != nil {
log.Fatalf("gover: not downloaded. Run 'gover download' to install to %v", root)
}
cmd := exec.Command(gobin, os.Args[2:]...)
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
newPath := filepath.Join(root, version, "go", "bin")
if p := os.Getenv("PATH"); p != "" {
newPath += string(filepath.ListSeparator) + p
}
cmd.Env = dedupEnv(caseInsensitiveEnv, append(os.Environ(), "GOROOT="+gorootPath, "PATH="+newPath))
if err := cmd.Run(); err != nil {
if _, ok := err.(*exec.ExitError); ok {
// TODO: return the same exit status maybe.
os.Exit(1)
}
log.Fatalf("gover: failed to execute %v: %v", gobin, err)
}
os.Exit(0)
}
func fetch(a, b string) (*os.File, error) {
fmt.Printf("Fetching %q\n", a)
f, err := os.Create(b)
if err != nil {
return nil, err
}
fResp, err := http.Get(a)
if err != nil {
return nil, err
}
defer fResp.Body.Close()
if _, err := io.Copy(f, fResp.Body); err != nil {
return nil, err
}
_, err = f.Seek(0, 0)
if err != nil {
return nil, err
}
return f, nil
}
func fetchify(goURL string, fp string) error {
buf := bytes.NewBufferString(pubKey)
kr, err := openpgp.ReadArmoredKeyRing(buf)
if err != nil {
return err
}
tbz, err := fetch(goURL, fp)
if err != nil {
return err
}
sig, err := fetch(goURL+".asc", fp+".asc")
if err != nil {
return err
}
defer tbz.Close()
defer sig.Close()
_, err = openpgp.CheckArmoredDetachedSignature(kr, tbz, sig)
if err != nil {
return err
}
fmt.Println("Signature OK.")
_, err = tbz.Seek(0, 0)
if err != nil {
return err
}
return Untar(tbz, path.Dir(fp))
}
func installVer(root, version string) error {
goURL := fmt.Sprintf("https://dl.google.com/go/go%s.src.tar.gz", version)
goFP := filepath.Join(root, version, fmt.Sprintf("go%s.src.tar.gz", version))
if _, err := os.Stat(filepath.Join(root, version, "go")); err != nil {
if err := os.MkdirAll(filepath.Join(root, version), 0755); err != nil {
return fmt.Errorf("failed to create source directory: %v", err)
}
err := fetchify(goURL, goFP)
if err != nil {
return fmt.Errorf("failed to verify: %v", err)
}
}
cmd := exec.Command(filepath.Join(root, version, "go", "src", makeScript()))
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
cmd.Dir = filepath.Join(root, version, "go", "src")
if runtime.GOOS == "windows" {
// Workaround make.bat not autodetecting GOROOT_BOOTSTRAP. Issue 28641.
goroot, err := exec.Command("go", "env", "GOROOT").Output()
if err != nil {
return fmt.Errorf("failed to detect an existing go installation for bootstrap: %v", err)
}
cmd.Env = append(os.Environ(), "GOROOT_BOOTSTRAP="+strings.TrimSpace(string(goroot)))
}
if err := cmd.Run(); err != nil {
return fmt.Errorf("failed to build go: %v", err)
}
return nil
}
func makeScript() string {
switch runtime.GOOS {
case "plan9":
return "make.rc"
case "windows":
return "make.bat"
default:
return "make.bash"
}
}
const caseInsensitiveEnv = runtime.GOOS == "windows"
func exe() string {
if runtime.GOOS == "windows" {
return ".exe"
}
return ""
}
func goroot(version string) (string, error) {
home, err := homedir()
if err != nil {
return "", fmt.Errorf("failed to get home directory: %v", err)
}
return filepath.Join(home, "sdk", version), nil
}
func homedir() (string, error) {
// This could be replaced with os.UserHomeDir, but it was introduced too
// recently, and we want this to work with go as packaged by Linux
// distributions. Note that user.Current is not enough as it does not
// prioritize $HOME. See also Issue 26463.
switch runtime.GOOS {
case "plan9":
if dir := os.Getenv("home"); dir != "" {
return dir, nil
}
return "", errors.New("can't find user home directory; %USERPROFILE% is empty")
case "windows":
if dir := os.Getenv("USERPROFILE"); dir != "" {
return dir, nil
}
return "", errors.New("can't find user home directory; %USERPROFILE% is empty")
default:
if dir := os.Getenv("HOME"); dir != "" {
return dir, nil
}
if u, err := user.Current(); err == nil && u.HomeDir != "" {
return u.HomeDir, nil
}
return "", errors.New("can't find user home directory; $HOME is empty")
}
}
// dedupEnv returns a copy of env with any duplicates removed, in favor of
// later values.
// Items are expected to be on the normal environment "key=value" form.
// If caseInsensitive is true, the case of keys is ignored.
//
// This function is unnecessary when the binary is
// built with Go 1.9+, but keep it around for now until Go 1.8
// is no longer seen in the wild in common distros.
//
// This is copied verbatim from golang.org/x/build/envutil.Dedup at CL 10301
// (commit a91ae26).
func dedupEnv(caseInsensitive bool, env []string) []string {
out := make([]string, 0, len(env))
saw := map[string]int{} // to index in the array
for _, kv := range env {
eq := strings.Index(kv, "=")
if eq < 1 {
out = append(out, kv)
continue
}
k := kv[:eq]
if caseInsensitive {
k = strings.ToLower(k)
}
if dupIdx, isDup := saw[k]; isDup {
out[dupIdx] = kv
} else {
saw[k] = len(out)
out = append(out, kv)
}
}
return out
}