129 lines
2.1 KiB
Go
129 lines
2.1 KiB
Go
// Copyright 2011 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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// Plan 9 environment variables.
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package syscall
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import (
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"errors"
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"sync"
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)
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var (
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// envOnce guards initialization by copyenv, which populates env.
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envOnce sync.Once
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// envLock guards env.
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envLock sync.RWMutex
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// env maps from an environment variable to its value.
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env map[string]string
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)
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func readenv(key string) (string, error) {
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fd, err := Open("/env/"+key, O_RDONLY)
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if err != nil {
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return "", err
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}
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defer Close(fd)
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l, _ := Seek(fd, 0, 2)
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Seek(fd, 0, 0)
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buf := make([]byte, l)
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n, err := Read(fd, buf)
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if err != nil {
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return "", err
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}
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if n > 0 && buf[n-1] == 0 {
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buf = buf[:n-1]
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}
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return string(buf), nil
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}
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func writeenv(key, value string) error {
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fd, err := Create("/env/"+key, O_RDWR, 0666)
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if err != nil {
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return err
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}
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defer Close(fd)
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_, err = Write(fd, []byte(value))
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return err
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}
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func copyenv() {
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env = make(map[string]string)
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fd, err := Open("/env", O_RDONLY)
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if err != nil {
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return
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}
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defer Close(fd)
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files, err := readdirnames(fd)
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if err != nil {
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return
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}
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for _, key := range files {
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v, err := readenv(key)
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if err != nil {
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continue
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}
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env[key] = v
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}
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}
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func Getenv(key string) (value string, found bool) {
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envOnce.Do(copyenv)
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if len(key) == 0 {
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return "", false
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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 "", false
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}
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return v, true
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}
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func Setenv(key, value string) error {
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envOnce.Do(copyenv)
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if len(key) == 0 {
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return errors.New("zero length key")
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}
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envLock.Lock()
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defer envLock.Unlock()
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err := writeenv(key, value)
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if err != nil {
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return err
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}
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env[key] = value
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return nil
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}
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func Clearenv() {
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envOnce.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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RawSyscall(SYS_RFORK, RFCENVG, 0, 0)
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}
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func Environ() []string {
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envOnce.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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