// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Windows environment variables.
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package syscall
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import (
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"unicode/utf16"
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"unsafe"
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)
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func Getenv(key string) (value string, found bool) {
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keyp, err := UTF16PtrFromString(key)
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if err != nil {
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return "", false
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}
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n := uint32(100)
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for {
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b := make([]uint16, n)
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n, err = GetEnvironmentVariable(keyp, &b[0], uint32(len(b)))
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if n == 0 && err == ERROR_ENVVAR_NOT_FOUND {
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return "", false
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}
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if n <= uint32(len(b)) {
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return string(utf16.Decode(b[:n])), true
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}
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}
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}
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func Setenv(key, value string) error {
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v, err := UTF16PtrFromString(value)
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if err != nil {
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return err
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}
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keyp, err := UTF16PtrFromString(key)
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if err != nil {
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return err
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}
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e := SetEnvironmentVariable(keyp, v)
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if e != nil {
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return e
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}
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return nil
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}
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func Unsetenv(key string) error {
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keyp, err := UTF16PtrFromString(key)
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if err != nil {
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return err
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}
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return SetEnvironmentVariable(keyp, nil)
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}
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func Clearenv() {
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for _, s := range Environ() {
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// Environment variables can begin with =
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// so start looking for the separator = at j=1.
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// https://blogs.msdn.com/b/oldnewthing/archive/2010/05/06/10008132.aspx
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for j := 1; j < len(s); j++ {
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if s[j] == '=' {
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Unsetenv(s[0:j])
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break
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}
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}
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}
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}
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func Environ() []string {
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s, e := GetEnvironmentStrings()
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if e != nil {
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return nil
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}
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defer FreeEnvironmentStrings(s)
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r := make([]string, 0, 50) // Empty with room to grow.
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for from, i, p := 0, 0, (*[1 << 24]uint16)(unsafe.Pointer(s)); true; i++ {
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if p[i] == 0 {
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// empty string marks the end
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if i <= from {
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break
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}
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r = append(r, string(utf16.Decode(p[from:i])))
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from = i + 1
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}
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}
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return r
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}
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