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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.
// Unix environment variables.
package os
import (
"sync"
)
// ENOENV is the Error indicating that an environment variable does not exist.
var ENOENV = NewError("no such environment variable")
var env map[string]string
var once sync.Once
func copyenv() {
env = make(map[string]string)
for _, s := range Envs {
for j := 0; j < len(s); j++ {
if s[j] == '=' {
env[s[0:j]] = s[j+1:]
break
}
}
}
}
// Getenverror retrieves the value of the environment variable named by the key.
// It returns the value and an error, if any.
func Getenverror(key string) (value string, err Error) {
once.Do(copyenv)
if len(key) == 0 {
return "", EINVAL
}
v, ok := env[key]
if !ok {
return "", ENOENV
}
return v, nil
}
// Getenv retrieves the value of the environment variable named by the key.
// It returns the value, which will be empty if the variable is not present.
func Getenv(key string) string {
v, _ := Getenverror(key)
return v
}
// Setenv sets the value of the environment variable named by the key.
// It returns an Error, if any.
func Setenv(key, value string) Error {
once.Do(copyenv)
if len(key) == 0 {
return EINVAL
}
env[key] = value
return nil
}
// Clearenv deletes all environment variables.
func Clearenv() {
once.Do(copyenv) // prevent copyenv in Getenv/Setenv
env = make(map[string]string)
}
// Environ returns an array of strings representing the environment,
// in the form "key=value".
func Environ() []string {
once.Do(copyenv)
a := make([]string, len(env))
i := 0
for k, v := range env {
// check i < len(a) for safety,
// in case env is changing underfoot.
if i < len(a) {
a[i] = k + "=" + v
i++
}
}
return a[0:i]
}
// TempDir returns the default directory to use for temporary files.
func TempDir() string {
dir := Getenv("TMPDIR")
if dir == "" {
dir = "/tmp"
}
return dir
}
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