sock_cloexec.go

Documentation: net

		 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  // +build dragonfly freebsd illumos linux netbsd openbsd
		10  
		11  package net
		12  
		13  import (
		14  	"internal/poll"
		15  	"os"
		16  	"syscall"
		17  )
		18  
		19  // Wrapper around the socket system call that marks the returned file
		20  // descriptor as nonblocking and close-on-exec.
		21  func sysSocket(family, sotype, proto int) (int, error) {
		22  	s, err := socketFunc(family, sotype|syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC, proto)
		23  	// On Linux the SOCK_NONBLOCK and SOCK_CLOEXEC flags were
		24  	// introduced in 2.6.27 kernel and on FreeBSD both flags were
		25  	// introduced in 10 kernel. If we get an EINVAL error on Linux
		26  	// or EPROTONOSUPPORT error on FreeBSD, fall back to using
		27  	// socket without them.
		28  	switch err {
		29  	case nil:
		30  		return s, nil
		31  	default:
		32  		return -1, os.NewSyscallError("socket", err)
		33  	case syscall.EPROTONOSUPPORT, syscall.EINVAL:
		34  	}
		35  
		36  	// See ../syscall/exec_unix.go for description of ForkLock.
		37  	syscall.ForkLock.RLock()
		38  	s, err = socketFunc(family, sotype, proto)
		39  	if err == nil {
		40  		syscall.CloseOnExec(s)
		41  	}
		42  	syscall.ForkLock.RUnlock()
		43  	if err != nil {
		44  		return -1, os.NewSyscallError("socket", err)
		45  	}
		46  	if err = syscall.SetNonblock(s, true); err != nil {
		47  		poll.CloseFunc(s)
		48  		return -1, os.NewSyscallError("setnonblock", err)
		49  	}
		50  	return s, nil
		51  }
		52
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