1 // Copyright 2010 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.
5 // +build aix darwin dragonfly freebsd hurd js,wasm linux nacl netbsd openbsd solaris
7 // Unix environment variables.
14 // envOnce guards initialization by copyenv, which populates env.
17 // envLock guards env and envs.
20 // env maps from an environment variable to its first occurrence in envs.
23 // envs is provided by the runtime. elements are expected to
24 // be of the form "key=value". An empty string means deleted
25 // (or a duplicate to be ignored).
26 envs []string = runtime_envs()
29 func runtime_envs() []string // in package runtime
31 // setenv_c and unsetenv_c are provided by the runtime but are no-ops
32 // if cgo isn't loaded.
33 func setenv_c(k, v string)
34 func unsetenv_c(k string)
37 env = make(map[string]int)
38 for i, s := range envs {
39 for j := 0; j < len(s); j++ {
42 if _, ok := env[key]; !ok {
43 env[key] = i // first mention of key
45 // Clear duplicate keys. This permits Unsetenv to
46 // safely delete only the first item without
47 // worrying about unshadowing a later one,
48 // which might be a security problem.
57 func Unsetenv(key string) error {
61 defer envLock.Unlock()
63 if i, ok := env[key]; ok {
71 func Getenv(key string) (value string, found bool) {
78 defer envLock.RUnlock()
85 for i := 0; i < len(s); i++ {
93 func Setenv(key, value string) error {
98 for i := 0; i < len(key); i++ {
99 if key[i] == '=' || key[i] == 0 {
103 for i := 0; i < len(value); i++ {
110 defer envLock.Unlock()
113 kv := key + "=" + value
118 envs = append(envs, kv)
126 envOnce.Do(copyenv) // prevent copyenv in Getenv/Setenv
129 defer envLock.Unlock()
134 env = make(map[string]int)
138 func Environ() []string {
141 defer envLock.RUnlock()
142 a := make([]string, 0, len(envs))
143 for _, env := range envs {