Source file src/internal/syscall/unix/nonblocking.go

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

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