--- /dev/null
+// Copyright 2017 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.
+
+// +build !plan9
+
+package main
+
+import (
+ "bytes"
+ "context"
+ exec "golang.org/x/sys/execabs"
+ "runtime"
+ "strings"
+)
+
+// arch contains either amd64 or 386.
+var arch = func() string {
+ cmd := exec.Command("uname", "-m") // "x86_64"
+ if runtime.GOOS == "windows" {
+ cmd = exec.Command("powershell", "-command", "(Get-WmiObject -Class Win32_ComputerSystem).SystemType") // "x64-based PC"
+ }
+
+ out, err := cmd.Output()
+ if err != nil {
+ // a sensible default?
+ return "amd64"
+ }
+ if bytes.Contains(out, []byte("64")) {
+ return "amd64"
+ }
+ return "386"
+}()
+
+func findGo(ctx context.Context, cmd string) (string, error) {
+ out, err := exec.CommandContext(ctx, cmd, "go").CombinedOutput()
+ return strings.TrimSpace(string(out)), err
+}