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04dc9f2 | 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 | // 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 unix || (js && wasm) || plan9 || wasip1
// Unix environment variables.
package syscall
import (
"runtime"
"sync"
)
var (
// 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
var copyenv = sync.OnceFunc(func() {
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 {
copyenv()
envLock.Lock()
defer envLock.Unlock()
if i, ok := env[key]; ok {
envs[i] = ""
delete(env, key)
}
runtimeUnsetenv(key)
return nil
}
func Getenv(key string) (value string, found bool) {
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 {
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
runtimeSetenv(key, value)
return nil
}
func Clearenv() {
copyenv()
envLock.Lock()
defer envLock.Unlock()
runtimeClearenv(env)
env = make(map[string]int)
envs = []string{}
}
func Environ() []string {
copyenv()
envLock.RLock()
defer envLock.RUnlock()
a := make([]string, 0, len(envs))
for _, env := range envs {
if env != "" {
a = append(a, env)
}
}
return a
}
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