| // Copyright 2020 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. |
| |
| //go:build windows |
| |
| package execenv |
| |
| import ( |
| "internal/syscall/windows" |
| "syscall" |
| "unicode/utf16" |
| "unsafe" |
| ) |
| |
| // Default will return the default environment |
| // variables based on the process attributes |
| // provided. |
| // |
| // If the process attributes contain a token, then |
| // the environment variables will be sourced from |
| // the defaults for that user token, otherwise they |
| // will be sourced from syscall.Environ(). |
| func Default(sys *syscall.SysProcAttr) (env []string, err error) { |
| if sys == nil || sys.Token == 0 { |
| return syscall.Environ(), nil |
| } |
| var block *uint16 |
| err = windows.CreateEnvironmentBlock(&block, sys.Token, false) |
| if err != nil { |
| return nil, err |
| } |
| defer windows.DestroyEnvironmentBlock(block) |
| blockp := uintptr(unsafe.Pointer(block)) |
| for { |
| |
| // find NUL terminator |
| end := unsafe.Pointer(blockp) |
| for *(*uint16)(end) != 0 { |
| end = unsafe.Pointer(uintptr(end) + 2) |
| } |
| |
| n := (uintptr(end) - uintptr(unsafe.Pointer(blockp))) / 2 |
| if n == 0 { |
| // environment block ends with empty string |
| break |
| } |
| |
| entry := (*[(1 << 30) - 1]uint16)(unsafe.Pointer(blockp))[:n:n] |
| env = append(env, string(utf16.Decode(entry))) |
| blockp += 2 * (uintptr(len(entry)) + 1) |
| } |
| return |
| } |