110 lines
2.2 KiB
Go
110 lines
2.2 KiB
Go
// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Unix environment variables.
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package os
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import (
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"sync"
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)
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// ENOENV is the Error indicating that an environment variable does not exist.
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var ENOENV = NewError("no such environment variable")
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var env map[string]string
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var once sync.Once
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func copyenv() {
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env = make(map[string]string)
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for _, s := range Envs {
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for j := 0; j < len(s); j++ {
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if s[j] == '=' {
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env[s[0:j]] = s[j+1:]
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break
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}
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}
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}
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}
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var envLock sync.RWMutex
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// Getenverror retrieves the value of the environment variable named by the key.
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// It returns the value and an error, if any.
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func Getenverror(key string) (value string, err Error) {
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once.Do(copyenv)
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if len(key) == 0 {
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return "", EINVAL
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}
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envLock.RLock()
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defer envLock.RUnlock()
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v, ok := env[key]
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if !ok {
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return "", ENOENV
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}
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return v, nil
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}
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// Getenv retrieves the value of the environment variable named by the key.
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// It returns the value, which will be empty if the variable is not present.
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func Getenv(key string) string {
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v, _ := Getenverror(key)
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return v
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}
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// Setenv sets the value of the environment variable named by the key.
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// It returns an Error, if any.
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func Setenv(key, value string) Error {
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once.Do(copyenv)
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if len(key) == 0 {
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return EINVAL
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}
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envLock.Lock()
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defer envLock.Unlock()
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env[key] = value
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setenv_c(key, value) // is a no-op if cgo isn't loaded
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return nil
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}
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// Clearenv deletes all environment variables.
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func Clearenv() {
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once.Do(copyenv) // prevent copyenv in Getenv/Setenv
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envLock.Lock()
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defer envLock.Unlock()
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env = make(map[string]string)
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// TODO(bradfitz): pass through to C
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}
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// Environ returns an array of strings representing the environment,
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// in the form "key=value".
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func Environ() []string {
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once.Do(copyenv)
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envLock.RLock()
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defer envLock.RUnlock()
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a := make([]string, len(env))
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i := 0
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for k, v := range env {
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a[i] = k + "=" + v
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i++
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}
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return a
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}
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// TempDir returns the default directory to use for temporary files.
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func TempDir() string {
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dir := Getenv("TMPDIR")
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if dir == "" {
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dir = "/tmp"
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}
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return dir
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}
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