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