1// Copyright 2022 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package main
6
7import (
8	"os/exec"
9	"strings"
10)
11
12// setDir sets cmd.Dir to dir, and also adds PWD=dir to cmd's environment.
13func setDir(cmd *exec.Cmd, dir string) {
14	cmd.Dir = dir
15	if cmd.Env != nil {
16		// os/exec won't set PWD automatically.
17		setEnv(cmd, "PWD", dir)
18	}
19}
20
21// setEnv sets cmd.Env so that key = value.
22func setEnv(cmd *exec.Cmd, key, value string) {
23	cmd.Env = append(cmd.Environ(), key+"="+value)
24}
25
26// unsetEnv sets cmd.Env so that key is not present in the environment.
27func unsetEnv(cmd *exec.Cmd, key string) {
28	cmd.Env = cmd.Environ()
29
30	prefix := key + "="
31	newEnv := []string{}
32	for _, entry := range cmd.Env {
33		if strings.HasPrefix(entry, prefix) {
34			continue
35		}
36		newEnv = append(newEnv, entry)
37		// key may appear multiple times, so keep going.
38	}
39	cmd.Env = newEnv
40}
41