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/* Accept a connection on a socket, with specific opening flags.
Copyright (C) 2009-2019 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include <sys/socket.h>
#include <errno.h>
#include <fcntl.h>
#include "binary-io.h"
#if GNULIB_MSVC_NOTHROW
# include "msvc-nothrow.h"
#else
# include <io.h>
#endif
#ifndef SOCK_CLOEXEC
# define SOCK_CLOEXEC 0
#endif
#ifndef SOCK_NONBLOCK
# define SOCK_NONBLOCK 0
#endif
int
accept4 (int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags)
{
int fd;
#if HAVE_DECL_ACCEPT4
# undef accept4
/* Try the system call first, if it exists. (We may be running with a glibc
that has the function but with an older kernel that lacks it.) */
{
/* Cache the information whether the system call really exists. */
static int have_accept4_really; /* 0 = unknown, 1 = yes, -1 = no */
if (have_accept4_really >= 0)
{
int result = accept4 (sockfd, addr, addrlen, flags);
if (!(result < 0 && errno == ENOSYS))
{
have_accept4_really = 1;
return result;
}
have_accept4_really = -1;
}
}
#endif
/* Check the supported flags. */
if ((flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK | O_TEXT | O_BINARY)) != 0)
{
errno = EINVAL;
return -1;
}
fd = accept (sockfd, addr, addrlen);
if (fd < 0)
return -1;
#if SOCK_CLOEXEC
# if defined _WIN32 && ! defined __CYGWIN__
/* Native Windows API. */
if (flags & SOCK_CLOEXEC)
{
HANDLE curr_process = GetCurrentProcess ();
HANDLE old_handle = (HANDLE) _get_osfhandle (fd);
HANDLE new_handle;
int nfd;
if (!DuplicateHandle (curr_process, /* SourceProcessHandle */
old_handle, /* SourceHandle */
curr_process, /* TargetProcessHandle */
(PHANDLE) &new_handle, /* TargetHandle */
(DWORD) 0, /* DesiredAccess */
FALSE, /* InheritHandle */
DUPLICATE_SAME_ACCESS)) /* Options */
{
close (fd);
errno = EBADF; /* arbitrary */
return -1;
}
/* Closing fd before allocating the new fd ensures that the new fd will
have the minimum possible value. */
close (fd);
nfd = _open_osfhandle ((intptr_t) new_handle,
O_NOINHERIT | (flags & (O_TEXT | O_BINARY)));
if (nfd < 0)
{
CloseHandle (new_handle);
return -1;
}
return nfd;
}
# else
/* Unix API. */
if (flags & SOCK_CLOEXEC)
{
int fcntl_flags;
if ((fcntl_flags = fcntl (fd, F_GETFD, 0)) < 0
|| fcntl (fd, F_SETFD, fcntl_flags | FD_CLOEXEC) == -1)
{
int saved_errno = errno;
close (fd);
errno = saved_errno;
return -1;
}
}
# endif
#endif
#if SOCK_NONBLOCK
if (flags & SOCK_NONBLOCK)
{
int fcntl_flags;
if ((fcntl_flags = fcntl (fd, F_GETFL, 0)) < 0
|| fcntl (fd, F_SETFL, fcntl_flags | O_NONBLOCK) == -1)
{
int saved_errno = errno;
close (fd);
errno = saved_errno;
return -1;
}
}
#endif
#if O_BINARY
if (flags & O_BINARY)
set_binary_mode (fd, O_BINARY);
else if (flags & O_TEXT)
set_binary_mode (fd, O_TEXT);
#endif
return fd;
}
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