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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 syscall
import (
"unsafe"
)
func Getenv(key string) (value string, found bool) {
keyp, err := UTF16PtrFromString(key)
if err != nil {
return "", false
}
n := uint32(100)
for {
b := make([]uint16, n)
n, err = GetEnvironmentVariable(keyp, &b[0], uint32(len(b)))
if n == 0 && err == ERROR_ENVVAR_NOT_FOUND {
return "", false
}
if n <= uint32(len(b)) {
return UTF16ToString(b[:n]), true
}
}
}
func Setenv(key, value string) error {
v, err := UTF16PtrFromString(value)
if err != nil {
return err
}
keyp, err := UTF16PtrFromString(key)
if err != nil {
return err
}
e := SetEnvironmentVariable(keyp, v)
if e != nil {
return e
}
runtimeSetenv(key, value)
return nil
}
func Unsetenv(key string) error {
keyp, err := UTF16PtrFromString(key)
if err != nil {
return err
}
e := SetEnvironmentVariable(keyp, nil)
if e != nil {
return e
}
runtimeUnsetenv(key)
return nil
}
func Clearenv() {
for _, s := range Environ() {
// Environment variables can begin with =
// so start looking for the separator = at j=1.
// https://devblogs.microsoft.com/oldnewthing/20100506-00/?p=14133
for j := 1; j < len(s); j++ {
if s[j] == '=' {
Unsetenv(s[0:j])
break
}
}
}
}
func Environ() []string {
envp, e := GetEnvironmentStrings()
if e != nil {
return nil
}
defer FreeEnvironmentStrings(envp)
r := make([]string, 0, 50) // Empty with room to grow.
const size = unsafe.Sizeof(*envp)
for *envp != 0 { // environment block ends with empty string
// find NUL terminator
end := unsafe.Pointer(envp)
for *(*uint16)(end) != 0 {
end = unsafe.Add(end, size)
}
entry := unsafe.Slice(envp, (uintptr(end)-uintptr(unsafe.Pointer(envp)))/size)
r = append(r, UTF16ToString(entry))
envp = (*uint16)(unsafe.Add(end, size))
}
return r
}