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Source file src/net/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 and accept for platforms that
     6	// provide a fast path for setting SetNonblock and CloseOnExec.
     7	
     8	// +build freebsd linux
     9	
    10	package net
    11	
    12	import (
    13		"os"
    14		"syscall"
    15	)
    16	
    17	// Wrapper around the socket system call that marks the returned file
    18	// descriptor as nonblocking and close-on-exec.
    19	func sysSocket(family, sotype, proto int) (int, error) {
    20		s, err := socketFunc(family, sotype|syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC, proto)
    21		// On Linux the SOCK_NONBLOCK and SOCK_CLOEXEC flags were
    22		// introduced in 2.6.27 kernel and on FreeBSD both flags were
    23		// introduced in 10 kernel. If we get an EINVAL error on Linux
    24		// or EPROTONOSUPPORT error on FreeBSD, fall back to using
    25		// socket without them.
    26		switch err {
    27		case nil:
    28			return s, nil
    29		default:
    30			return -1, os.NewSyscallError("socket", err)
    31		case syscall.EPROTONOSUPPORT, syscall.EINVAL:
    32		}
    33	
    34		// See ../syscall/exec_unix.go for description of ForkLock.
    35		syscall.ForkLock.RLock()
    36		s, err = socketFunc(family, sotype, proto)
    37		if err == nil {
    38			syscall.CloseOnExec(s)
    39		}
    40		syscall.ForkLock.RUnlock()
    41		if err != nil {
    42			return -1, os.NewSyscallError("socket", err)
    43		}
    44		if err = syscall.SetNonblock(s, true); err != nil {
    45			closeFunc(s)
    46			return -1, os.NewSyscallError("setnonblock", err)
    47		}
    48		return s, nil
    49	}
    50	
    51	// Wrapper around the accept system call that marks the returned file
    52	// descriptor as nonblocking and close-on-exec.
    53	func accept(s int) (int, syscall.Sockaddr, error) {
    54		ns, sa, err := accept4Func(s, syscall.SOCK_NONBLOCK|syscall.SOCK_CLOEXEC)
    55		// On Linux the accept4 system call was introduced in 2.6.28
    56		// kernel and on FreeBSD it was introduced in 10 kernel. If we
    57		// get an ENOSYS error on both Linux and FreeBSD, or EINVAL
    58		// error on Linux, fall back to using accept.
    59		switch err {
    60		case nil:
    61			return ns, sa, nil
    62		default: // errors other than the ones listed
    63			return -1, sa, os.NewSyscallError("accept4", err)
    64		case syscall.ENOSYS: // syscall missing
    65		case syscall.EINVAL: // some Linux use this instead of ENOSYS
    66		case syscall.EACCES: // some Linux use this instead of ENOSYS
    67		case syscall.EFAULT: // some Linux use this instead of ENOSYS
    68		}
    69	
    70		// See ../syscall/exec_unix.go for description of ForkLock.
    71		// It is probably okay to hold the lock across syscall.Accept
    72		// because we have put fd.sysfd into non-blocking mode.
    73		// However, a call to the File method will put it back into
    74		// blocking mode. We can't take that risk, so no use of ForkLock here.
    75		ns, sa, err = acceptFunc(s)
    76		if err == nil {
    77			syscall.CloseOnExec(ns)
    78		}
    79		if err != nil {
    80			return -1, nil, os.NewSyscallError("accept", err)
    81		}
    82		if err = syscall.SetNonblock(ns, true); err != nil {
    83			closeFunc(ns)
    84			return -1, nil, os.NewSyscallError("setnonblock", err)
    85		}
    86		return ns, sa, nil
    87	}
    88	

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