libgo/go/syscall/env_plan9.go

   1 // Copyright 2011 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // Plan 9 environment variables.
   6
   7 package syscall
   8
   9 import (
  10         "errors"
  11 )
  12
  13 var (
  14         errZeroLengthKey = errors.New("zero length key")
  15         errShortWrite    = errors.New("i/o count too small")
  16 )
  17
  18 func readenv(key string) (string, error) {
  19         fd, err := open("/env/"+key, O_RDONLY)
  20         if err != nil {
  21                 return "", err
  22         }
  23         defer Close(fd)
  24         l, _ := Seek(fd, 0, 2)
  25         Seek(fd, 0, 0)
  26         buf := make([]byte, l)
  27         n, err := Read(fd, buf)
  28         if err != nil {
  29                 return "", err
  30         }
  31         if n > 0 && buf[n-1] == 0 {
  32                 buf = buf[:n-1]
  33         }
  34         return string(buf), nil
  35 }
  36
  37 func writeenv(key, value string) error {
  38         fd, err := create("/env/"+key, O_RDWR, 0666)
  39         if err != nil {
  40                 return err
  41         }
  42         defer Close(fd)
  43         b := []byte(value)
  44         n, err := Write(fd, b)
  45         if err != nil {
  46                 return err
  47         }
  48         if n != len(b) {
  49                 return errShortWrite
  50         }
  51         return nil
  52 }
  53
  54 func Getenv(key string) (value string, found bool) {
  55         if len(key) == 0 {
  56                 return "", false
  57         }
  58         v, err := readenv(key)
  59         if err != nil {
  60                 return "", false
  61         }
  62         return v, true
  63 }
  64
  65 func Setenv(key, value string) error {
  66         if len(key) == 0 {
  67                 return errZeroLengthKey
  68         }
  69         err := writeenv(key, value)
  70         if err != nil {
  71                 return err
  72         }
  73         return nil
  74 }
  75
  76 func Clearenv() {
  77         RawSyscall(SYS_RFORK, RFCENVG, 0, 0)
  78 }
  79
  80 func Unsetenv(key string) error {
  81         if len(key) == 0 {
  82                 return errZeroLengthKey
  83         }
  84         Remove("/env/" + key)
  85         return nil
  86 }
  87
  88 func Environ() []string {
  89         fd, err := open("/env", O_RDONLY)
  90         if err != nil {
  91                 return nil
  92         }
  93         defer Close(fd)
  94         files, err := readdirnames(fd)
  95         if err != nil {
  96                 return nil
  97         }
  98         ret := make([]string, 0, len(files))
  99
 100         for _, key := range files {
 101                 v, err := readenv(key)
 102                 if err != nil {
 103                         continue
 104                 }
 105                 ret = append(ret, key+"="+v)
 106         }
 107         return ret
 108 }