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// 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.
// +build darwin freebsd linux netbsd openbsd
// Unix environment variables.
package syscall
import "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".
Envs []string
)
// setenv_c is provided by the runtime, but is a no-op if cgo isn't
// loaded.
func setenv_c(k, v 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
}
break
}
}
}
}
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
}
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()
env = make(map[string]int)
Envs = []string{}
// TODO(bradfitz): pass through to C
}
func Environ() []string {
envOnce.Do(copyenv)
envLock.RLock()
defer envLock.RUnlock()
a := make([]string, len(Envs))
copy(a, Envs)
return a
}
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