sock_cloexec.go

     1  // Copyright 2013 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  // This file implements sysSocket for platforms that provide a fast path for
     6  // setting SetNonblock and CloseOnExec.
     7  
     8  //go:build dragonfly || freebsd || illumos || linux || netbsd || openbsd
     9  
    10  package net
    11  
    12  import (
    13  	"internal/poll"
    14  	"os"
    15  	"syscall"
    16  )
    17  
    18  // Wrapper around the socket system call that marks the returned file
    19  // descriptor as nonblocking and close-on-exec.
    20  func sysSocket(family, sotype, proto int) (int, error) {
    21  	s, err := socketFunc(family, sotype|syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC, proto)
    22  	// On Linux the SOCK_NONBLOCK and SOCK_CLOEXEC flags were
    23  	// introduced in 2.6.27 kernel and on FreeBSD both flags were
    24  	// introduced in 10 kernel. If we get an EINVAL error on Linux
    25  	// or EPROTONOSUPPORT error on FreeBSD, fall back to using
    26  	// socket without them.
    27  	switch err {
    28  	case nil:
    29  		return s, nil
    30  	default:
    31  		return -1, os.NewSyscallError("socket", err)
    32  	case syscall.EPROTONOSUPPORT, syscall.EINVAL:
    33  	}
    34  
    35  	// See ../syscall/exec_unix.go for description of ForkLock.
    36  	syscall.ForkLock.RLock()
    37  	s, err = socketFunc(family, sotype, proto)
    38  	if err == nil {
    39  		syscall.CloseOnExec(s)
    40  	}
    41  	syscall.ForkLock.RUnlock()
    42  	if err != nil {
    43  		return -1, os.NewSyscallError("socket", err)
    44  	}
    45  	if err = syscall.SetNonblock(s, true); err != nil {
    46  		poll.CloseFunc(s)
    47  		return -1, os.NewSyscallError("setnonblock", err)
    48  	}
    49  	return s, nil
    50  }
    51
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