1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
|
// Copyright 2010 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.
//go:build aix || darwin || dragonfly || freebsd || (js && wasm) || linux || netbsd || openbsd || solaris || plan9
// Unix environment variables.
package syscall
import (
"runtime"
"sync"
)
var (
// envOnce guards initialization by copyenv, which populates env.
envOnce sync.Once
// envLock guards env and envs.
envLock sync.RWMutex
// env maps from an environment variable to its first occurrence in envs.
env map[string]int
// envs is provided by the runtime. elements are expected to
// be of the form "key=value". An empty string means deleted
// (or a duplicate to be ignored).
envs []string = runtime_envs()
)
func runtime_envs() []string // in package runtime
// setenv_c and unsetenv_c are provided by the runtime but are no-ops
// if cgo isn't loaded.
func setenv_c(k, v string)
func unsetenv_c(k string)
func copyenv() {
env = make(map[string]int)
for i, s := range envs {
for j := 0; j < len(s); j++ {
if s[j] == '=' {
key := s[:j]
if _, ok := env[key]; !ok {
env[key] = i // first mention of key
} else {
// Clear duplicate keys. This permits Unsetenv to
// safely delete only the first item without
// worrying about unshadowing a later one,
// which might be a security problem.
envs[i] = ""
}
break
}
}
}
}
func Unsetenv(key string) error {
envOnce.Do(copyenv)
envLock.Lock()
defer envLock.Unlock()
if i, ok := env[key]; ok {
envs[i] = ""
delete(env, key)
}
unsetenv_c(key)
return nil
}
func Getenv(key string) (value string, found bool) {
envOnce.Do(copyenv)
if len(key) == 0 {
return "", false
}
envLock.RLock()
defer envLock.RUnlock()
i, ok := env[key]
if !ok {
return "", false
}
s := envs[i]
for i := 0; i < len(s); i++ {
if s[i] == '=' {
return s[i+1:], true
}
}
return "", false
}
func Setenv(key, value string) error {
envOnce.Do(copyenv)
if len(key) == 0 {
return EINVAL
}
for i := 0; i < len(key); i++ {
if key[i] == '=' || key[i] == 0 {
return EINVAL
}
}
// On Plan 9, null is used as a separator, eg in $path.
if runtime.GOOS != "plan9" {
for i := 0; i < len(value); i++ {
if value[i] == 0 {
return EINVAL
}
}
}
envLock.Lock()
defer envLock.Unlock()
i, ok := env[key]
kv := key + "=" + value
if ok {
envs[i] = kv
} else {
i = len(envs)
envs = append(envs, kv)
}
env[key] = i
setenv_c(key, value)
return nil
}
func Clearenv() {
envOnce.Do(copyenv) // prevent copyenv in Getenv/Setenv
envLock.Lock()
defer envLock.Unlock()
for k := range env {
unsetenv_c(k)
}
env = make(map[string]int)
envs = []string{}
}
func Environ() []string {
envOnce.Do(copyenv)
envLock.RLock()
defer envLock.RUnlock()
a := make([]string, 0, len(envs))
for _, env := range envs {
if env != "" {
a = append(a, env)
}
}
return a
}
|
