nonblocking_windows.mx raw

   1  // Copyright 2025 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  package windows
   6  
   7  import (
   8  	"syscall"
   9  	"unsafe"
  10  )
  11  
  12  // IsNonblock returns whether the file descriptor fd is opened
  13  // in non-blocking mode, that is, the [syscall.FILE_FLAG_OVERLAPPED] flag
  14  // was set when the file was opened.
  15  func IsNonblock(fd syscall.Handle) (nonblocking bool, err error) {
  16  	var info FILE_MODE_INFORMATION
  17  	if err := NtQueryInformationFile(syscall.Handle(fd), &IO_STATUS_BLOCK{}, unsafe.Pointer(&info), uint32(unsafe.Sizeof(info)), FileModeInformation); err != nil {
  18  		return false, err
  19  	}
  20  	return info.Mode&(FILE_SYNCHRONOUS_IO_ALERT|FILE_SYNCHRONOUS_IO_NONALERT) == 0, nil
  21  }
  22