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 Setenv(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 } 89
