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// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Windows environment variables.
package os
import (
"syscall"
"utf16"
"unsafe"
)
// ENOENV is the Error indicating that an environment variable does not exist.
var ENOENV = NewError("no such environment variable")
// Getenverror retrieves the value of the environment variable named by the key.
// It returns the value and an error, if any.
func Getenverror(key string) (value string, err Error) {
b := make([]uint16, 100)
n, e := syscall.GetEnvironmentVariable(syscall.StringToUTF16Ptr(key), &b[0], uint32(len(b)))
if n == 0 && e == syscall.ERROR_ENVVAR_NOT_FOUND {
return "", ENOENV
}
if n > uint32(len(b)) {
b = make([]uint16, n)
n, e = syscall.GetEnvironmentVariable(syscall.StringToUTF16Ptr(key), &b[0], uint32(len(b)))
if n > uint32(len(b)) {
n = 0
}
}
if n == 0 {
return "", NewSyscallError("GetEnvironmentVariable", e)
}
return string(utf16.Decode(b[0:n])), nil
}
// Getenv retrieves the value of the environment variable named by the key.
// It returns the value, which will be empty if the variable is not present.
func Getenv(key string) string {
v, _ := Getenverror(key)
return v
}
// Setenv sets the value of the environment variable named by the key.
// It returns an Error, if any.
func Setenv(key, value string) Error {
var v *uint16
if len(value) > 0 {
v = syscall.StringToUTF16Ptr(value)
}
ok, e := syscall.SetEnvironmentVariable(syscall.StringToUTF16Ptr(key), v)
if !ok {
return NewSyscallError("SetEnvironmentVariable", e)
}
return nil
}
// Clearenv deletes all environment variables.
func Clearenv() {
for _, s := range Environ() {
// Environment variables can begin with =
// so start looking for the separator = at j=1.
// http://blogs.msdn.com/b/oldnewthing/archive/2010/05/06/10008132.aspx
for j := 1; j < len(s); j++ {
if s[j] == '=' {
Setenv(s[0:j], "")
break
}
}
}
}
// Environ returns an array of strings representing the environment,
// in the form "key=value".
func Environ() []string {
s, e := syscall.GetEnvironmentStrings()
if e != 0 {
return nil
}
defer syscall.FreeEnvironmentStrings(s)
r := make([]string, 0, 50) // Empty with room to grow.
for from, i, p := 0, 0, (*[1 << 24]uint16)(unsafe.Pointer(s)); true; i++ {
if p[i] == 0 {
// empty string marks the end
if i <= from {
break
}
r = append(r, string(utf16.Decode(p[from:i])))
from = i + 1
}
}
return r
}
// TempDir returns the default directory to use for temporary files.
func TempDir() string {
const pathSep = '\\'
dirw := make([]uint16, syscall.MAX_PATH)
n, _ := syscall.GetTempPath(uint32(len(dirw)), &dirw[0])
if n > uint32(len(dirw)) {
dirw = make([]uint16, n)
n, _ = syscall.GetTempPath(uint32(len(dirw)), &dirw[0])
if n > uint32(len(dirw)) {
n = 0
}
}
if n > 0 && dirw[n-1] == pathSep {
n--
}
return string(utf16.Decode(dirw[0:n]))
}