libgo/go/syscall/env_windows.go

   1 // Copyright 2010 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 // Windows environment variables.
   6
   7 package syscall
   8
   9 import (
  10         "unicode/utf16"
  11         "unsafe"
  12 )
  13
  14 func Getenv(key string) (value string, found bool) {
  15         keyp, err := UTF16PtrFromString(key)
  16         if err != nil {
  17                 return "", false
  18         }
  19         n := uint32(100)
  20         for {
  21                 b := make([]uint16, n)
  22                 n, err = GetEnvironmentVariable(keyp, &b[0], uint32(len(b)))
  23                 if n == 0 && err == ERROR_ENVVAR_NOT_FOUND {
  24                         return "", false
  25                 }
  26                 if n <= uint32(len(b)) {
  27                         return string(utf16.Decode(b[:n])), true
  28                 }
  29         }
  30 }
  31
  32 func Setenv(key, value string) error {
  33         v, err := UTF16PtrFromString(value)
  34         if err != nil {
  35                 return err
  36         }
  37         keyp, err := UTF16PtrFromString(key)
  38         if err != nil {
  39                 return err
  40         }
  41         e := SetEnvironmentVariable(keyp, v)
  42         if e != nil {
  43                 return e
  44         }
  45         return nil
  46 }
  47
  48 func Unsetenv(key string) error {
  49         keyp, err := UTF16PtrFromString(key)
  50         if err != nil {
  51                 return err
  52         }
  53         return SetEnvironmentVariable(keyp, nil)
  54 }
  55
  56 func Clearenv() {
  57         for _, s := range Environ() {
  58                 // Environment variables can begin with =
  59                 // so start looking for the separator = at j=1.
  60                 // http://blogs.msdn.com/b/oldnewthing/archive/2010/05/06/10008132.aspx
  61                 for j := 1; j < len(s); j++ {
  62                         if s[j] == '=' {
  63                                 Unsetenv(s[0:j])
  64                                 break
  65                         }
  66                 }
  67         }
  68 }
  69
  70 func Environ() []string {
  71         s, e := GetEnvironmentStrings()
  72         if e != nil {
  73                 return nil
  74         }
  75         defer FreeEnvironmentStrings(s)
  76         r := make([]string, 0, 50) // Empty with room to grow.
  77         for from, i, p := 0, 0, (*[1 << 24]uint16)(unsafe.Pointer(s)); true; i++ {
  78                 if p[i] == 0 {
  79                         // empty string marks the end
  80                         if i <= from {
  81                                 break
  82                         }
  83                         r = append(r, string(utf16.Decode(p[from:i])))
  84                         from = i + 1
  85                 }
  86         }
  87         return r
  88 }