github.com/hxx258456/ccgo@v0.0.5-0.20230213014102-48b35f46f66f/internal/syscall/unix/nonblocking.go (about)

     1  // Copyright 2018 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  //go:build dragonfly || freebsd || linux || netbsd || openbsd
     6  // +build dragonfly freebsd linux netbsd openbsd
     7  
     8  package unix
     9  
    10  import "syscall"
    11  
    12  // FcntlSyscall is the number for the fcntl system call. This is
    13  // usually SYS_FCNTL, but can be overridden to SYS_FCNTL64.
    14  var FcntlSyscall uintptr = syscall.SYS_FCNTL
    15  
    16  func IsNonblock(fd int) (nonblocking bool, err error) {
    17  	flag, _, e1 := syscall.Syscall(FcntlSyscall, uintptr(fd), uintptr(syscall.F_GETFL), 0)
    18  	if e1 != 0 {
    19  		return false, e1
    20  	}
    21  	return flag&syscall.O_NONBLOCK != 0, nil
    22  }