src/backend/port/win32/socket.c - hawq - Git at Google

 /*-------------------------------------------------------------------------
  *
  * socket.c
  *	  Microsoft Windows Win32 Socket Functions
  *
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
  *	  $PostgreSQL: pgsql/src/backend/port/win32/socket.c,v 1.22 2009/06/11 14:49:00 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */

 #include "postgres.h"

 #undef socket
 #undef accept
 #undef connect
 #undef select
 #undef recv
 #undef send

 /*
  * Blocking socket functions implemented so they listen on both
  * the socket and the signal event, required for signal handling.
  */

 /*
  * Convert the last socket error code into errno
  */
 static void
 TranslateSocketError(void)
 {
 	switch (WSAGetLastError())
 	{
 		case WSANOTINITIALISED:
 		case WSAENETDOWN:
 		case WSAEINPROGRESS:
 		case WSAEINVAL:
 		case WSAESOCKTNOSUPPORT:
 		case WSAEFAULT:
 		case WSAEINVALIDPROVIDER:
 		case WSAEINVALIDPROCTABLE:
 		case WSAEMSGSIZE:
 			errno = EINVAL;
 			break;
 		case WSAEAFNOSUPPORT:
 			errno = EAFNOSUPPORT;
 			break;
 		case WSAEMFILE:
 			errno = EMFILE;
 			break;
 		case WSAENOBUFS:
 			errno = ENOBUFS;
 			break;
 		case WSAEPROTONOSUPPORT:
 		case WSAEPROTOTYPE:
 			errno = EPROTONOSUPPORT;
 			break;
 		case WSAECONNREFUSED:
 			errno = ECONNREFUSED;
 			break;
 		case WSAEINTR:
 			errno = EINTR;
 			break;
 		case WSAENOTSOCK:
 			errno = EBADFD;
 			break;
 		case WSAEOPNOTSUPP:
 			errno = EOPNOTSUPP;
 			break;
 		case WSAEWOULDBLOCK:
 			errno = EWOULDBLOCK;
 			break;
 		case WSAEACCES:
 			errno = EACCES;
 			break;
 		case WSAENOTCONN:
 		case WSAENETRESET:
 		case WSAECONNRESET:
 		case WSAESHUTDOWN:
 		case WSAECONNABORTED:
 		case WSAEDISCON:
 			errno = ECONNREFUSED;		/* ENOTCONN? */
 			break;
 		default:
 			ereport(NOTICE,
 					(errmsg_internal("Unknown win32 socket error code: %i", WSAGetLastError())));
 			errno = EINVAL;
 	}
 }

 static int
 pgwin32_poll_signals(void)
 {
 	if (UNBLOCKED_SIGNAL_QUEUE())
 	{
 		pgwin32_dispatch_queued_signals();
 		errno = EINTR;
 		return 1;
 	}
 	return 0;
 }

 static int
 isDataGram(SOCKET s)
 {
 	int type;
 	int typelen = sizeof(type);

 	if ( getsockopt(s, SOL_SOCKET, SO_TYPE, (char*)&type, &typelen) )
 		return 1;

 	return ( type == SOCK_DGRAM ) ? 1 : 0;
 }

 int
 pgwin32_waitforsinglesocket(SOCKET s, int what, int timeout)
 {
 	static HANDLE waitevent = INVALID_HANDLE_VALUE;
 	static SOCKET current_socket = -1;
 	static int    isUDP = 0;
 	HANDLE		events[2];
 	int			r;

 	if (waitevent == INVALID_HANDLE_VALUE)
 	{
 		waitevent = CreateEvent(NULL, TRUE, FALSE, NULL);

 		if (waitevent == INVALID_HANDLE_VALUE)
 			ereport(ERROR,
 					(errmsg_internal("Failed to create socket waiting event: %i", (int) GetLastError())));
 	}
 	else if (!ResetEvent(waitevent))
 		ereport(ERROR,
 				(errmsg_internal("Failed to reset socket waiting event: %i", (int) GetLastError())));

 	/*
 	 * make sure we don't multiplex this kernel event object with a different
 	 * socket from a previous call
 	 */

 	if (current_socket != s)
 	{
 		if ( current_socket != -1 )
 			WSAEventSelect(current_socket, waitevent, 0);
 		isUDP = isDataGram(s);
 	}

 	current_socket = s;

 	if (WSAEventSelect(s, waitevent, what) == SOCKET_ERROR)
 	{
 		TranslateSocketError();
 		return 0;
 	}

 	events[0] = pgwin32_signal_event;
 	events[1] = waitevent;

 	/*
 	 * Just a workaround of unknown locking problem with writing in UDP socket
 	 * under high load: Client's pgsql backend sleeps infinitely in
 	 * WaitForMultipleObjectsEx, pgstat process sleeps in pgwin32_select().
 	 * So, we will wait with small timeout(0.1 sec) and if sockect is still
 	 * blocked, try WSASend (see comments in pgwin32_select) and wait again.
 	 */
 	if ((what & FD_WRITE) && isUDP)
 	{
 		for(;;)
 		{
 			r = WaitForMultipleObjectsEx(2, events, FALSE, 100, TRUE);

 			if ( r == WAIT_TIMEOUT )
 			{
 				char        c;
 				WSABUF      buf;
 				DWORD       sent;

 				buf.buf = &c;
 				buf.len = 0;

 				r = WSASend(s, &buf, 1, &sent, 0, NULL, NULL);
 				if (r == 0)         /* Completed - means things are fine! */
 					return 1;
 				else if ( WSAGetLastError() != WSAEWOULDBLOCK )
 				{
 					TranslateSocketError();
 					return 0;
 				}
 			}
 			else
 				break;
 		}
 	}
 	else
 		r = WaitForMultipleObjectsEx(2, events, FALSE, timeout, TRUE);

 	if (r == WAIT_OBJECT_0 || r == WAIT_IO_COMPLETION)
 	{
 		pgwin32_dispatch_queued_signals();
 		errno = EINTR;
 		return 0;
 	}
 	if (r == WAIT_OBJECT_0 + 1)
 		return 1;
 	if (r == WAIT_TIMEOUT)
 		return 0;
 	ereport(ERROR,
 			(errmsg_internal("Bad return from WaitForMultipleObjects: %i (%i)", r, (int) GetLastError())));
 	return 0;
 }

 /*
  * Create a socket, setting it to overlapped and non-blocking
  */
 SOCKET
 pgwin32_socket(int af, int type, int protocol)
 {
 	SOCKET		s;
 	unsigned long on = 1;

 	s = WSASocket(af, type, protocol, NULL, 0, WSA_FLAG_OVERLAPPED);
 	if (s == INVALID_SOCKET)
 	{
 		TranslateSocketError();
 		return INVALID_SOCKET;
 	}

 	if (ioctlsocket(s, FIONBIO, &on))
 	{
 		TranslateSocketError();
 		return INVALID_SOCKET;
 	}
 	errno = 0;

 	return s;
 }


 SOCKET
 pgwin32_accept(SOCKET s, struct sockaddr * addr, int *addrlen)
 {
 	SOCKET		rs;

 	/*
 	 * Poll for signals, but don't return with EINTR, since we don't handle
 	 * that in pqcomm.c
 	 */
 	pgwin32_poll_signals();

 	rs = WSAAccept(s, addr, addrlen, NULL, 0);
 	if (rs == INVALID_SOCKET)
 	{
 		TranslateSocketError();
 		return INVALID_SOCKET;
 	}
 	return rs;
 }


 /* No signal delivery during connect. */
 int
 pgwin32_connect(SOCKET s, const struct sockaddr * addr, int addrlen)
 {
 	int			r;

 	r = WSAConnect(s, addr, addrlen, NULL, NULL, NULL, NULL);
 	if (r == 0)
 		return 0;

 	if (WSAGetLastError() != WSAEWOULDBLOCK)
 	{
 		TranslateSocketError();
 		return -1;
 	}

 	while (pgwin32_waitforsinglesocket(s, FD_CONNECT, INFINITE) == 0)
 	{
 		/* Loop endlessly as long as we are just delivering signals */
 	}

 	return 0;
 }

 int
 pgwin32_recv(SOCKET s, char *buf, int len, int f)
 {
 	WSABUF		wbuf;
 	int			r;
 	DWORD		b;
 	DWORD		flags = f;
 	int		n;

 	if (pgwin32_poll_signals())
 		return -1;

 	wbuf.len = len;
 	wbuf.buf = buf;

 	r = WSARecv(s, &wbuf, 1, &b, &flags, NULL, NULL);
 	if (r != SOCKET_ERROR && b > 0)
 		/* Read succeeded right away */
 		return b;

 	if (r == SOCKET_ERROR &&
 		WSAGetLastError() != WSAEWOULDBLOCK)
 	{
 		TranslateSocketError();
 		return -1;
 	}

 	/* No error, zero bytes (win2000+) or error+WSAEWOULDBLOCK (<=nt4) */

 	for (n = 0; n < 5; n++)
 	{
 		if (pgwin32_waitforsinglesocket(s, FD_READ | FD_CLOSE | FD_ACCEPT,
 										INFINITE) == 0)
 			return -1; /* errno already set */

 		r = WSARecv(s, &wbuf, 1, &b, &flags, NULL, NULL);
 		if (r == SOCKET_ERROR)
 		{
 			if (WSAGetLastError() == WSAEWOULDBLOCK)
 			{
 				/*
 				 * There seem to be cases on win2k (at least) where WSARecv
 				 * can return WSAEWOULDBLOCK even when
 				 * pgwin32_waitforsinglesocket claims the socket is readable.
 				 * In this case, just sleep for a moment and try again. We try
 				 * up to 5 times - if it fails more than that it's not likely
 				 * to ever come back.
 				 */
 				pg_usleep(10000);
 				continue;
 			}
 			TranslateSocketError();
 			return -1;
 		}
 		return b;
 	}
 	ereport(NOTICE,
 		(errmsg_internal("Failed to read from ready socket (after retries)")));
 	errno = EWOULDBLOCK;
 	return -1;
 }

 int
 pgwin32_send(SOCKET s, char *buf, int len, int flags)
 {
 	WSABUF		wbuf;
 	int			r;
 	DWORD		b;

 	if (pgwin32_poll_signals())
 		return -1;

 	wbuf.len = len;
 	wbuf.buf = buf;

 	/*
 	 * Readiness of socket to send data to UDP socket may be not true: socket
 	 * can become busy again! So loop until send or error occurs.
 	 */
 	for (;;)
 	{
 		r = WSASend(s, &wbuf, 1, &b, flags, NULL, NULL);
 		if (r != SOCKET_ERROR && b > 0)
 			/* Write succeeded right away */
 			return b;

 		if (r == SOCKET_ERROR &&
 			WSAGetLastError() != WSAEWOULDBLOCK)
 		{
 			TranslateSocketError();
 			return -1;
 		}

 		/* No error, zero bytes (win2000+) or error+WSAEWOULDBLOCK (<=nt4) */

 		if (pgwin32_waitforsinglesocket(s, FD_WRITE | FD_CLOSE, INFINITE) == 0)
 			return -1;
 	}

 	return -1;
 }


 /*
  * Wait for activity on one or more sockets.
  * While waiting, allow signals to run
  *
  * NOTE! Currently does not implement exceptfds check,
  * since it is not used in postgresql!
  */
 int
 pgwin32_select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, const struct timeval * timeout)
 {
 	WSAEVENT	events[FD_SETSIZE * 2]; /* worst case is readfds totally
 										 * different from writefds, so
 										 * 2*FD_SETSIZE sockets */
 	SOCKET		sockets[FD_SETSIZE * 2];
 	int			numevents = 0;
 	int			i;
 	int			r;
 	DWORD		timeoutval = WSA_INFINITE;
 	FD_SET		outreadfds;
 	FD_SET		outwritefds;
 	int			nummatches = 0;

 	Assert(exceptfds == NULL);

 	if (pgwin32_poll_signals())
 		return -1;

 	FD_ZERO(&outreadfds);
 	FD_ZERO(&outwritefds);

 	/*
 	 * Write FDs are different in the way that it is only flagged by
 	 * WSASelectEvent() if we have tried to write to them first. So try an
 	 * empty write
 	 */
 	if (writefds)
 	{
 		for (i = 0; i < writefds->fd_count; i++)
 		{
 			char		c;
 			WSABUF		buf;
 			DWORD		sent;

 			buf.buf = &c;
 			buf.len = 0;

 			r = WSASend(writefds->fd_array[i], &buf, 1, &sent, 0, NULL, NULL);
 			if (r == 0)			/* Completed - means things are fine! */
 				FD_SET(writefds->fd_array[i], &outwritefds);

 			else
 			{					/* Not completed */
 				if (WSAGetLastError() != WSAEWOULDBLOCK)

 					/*
 					 * Not completed, and not just "would block", so an error
 					 * occured
 					 */
 					FD_SET(writefds->fd_array[i], &outwritefds);
 			}
 		}
 		if (outwritefds.fd_count > 0)
 		{
 			memcpy(writefds, &outwritefds, sizeof(fd_set));
 			if (readfds)
 				FD_ZERO(readfds);
 			return outwritefds.fd_count;
 		}
 	}


 	/* Now set up for an actual select */

 	if (timeout != NULL)
 	{
 		/* timeoutval is in milliseconds */
 		timeoutval = timeout->tv_sec * 1000 + timeout->tv_usec / 1000;
 	}

 	if (readfds != NULL)
 	{
 		for (i = 0; i < readfds->fd_count; i++)
 		{
 			events[numevents] = WSACreateEvent();
 			sockets[numevents] = readfds->fd_array[i];
 			numevents++;
 		}
 	}
 	if (writefds != NULL)
 	{
 		for (i = 0; i < writefds->fd_count; i++)
 		{
 			if (!readfds ||
 				!FD_ISSET(writefds->fd_array[i], readfds))
 			{
 				/* If the socket is not in the read list */
 				events[numevents] = WSACreateEvent();
 				sockets[numevents] = writefds->fd_array[i];
 				numevents++;
 			}
 		}
 	}

 	for (i = 0; i < numevents; i++)
 	{
 		int			flags = 0;

 		if (readfds && FD_ISSET(sockets[i], readfds))
 			flags |= FD_READ | FD_ACCEPT | FD_CLOSE;

 		if (writefds && FD_ISSET(sockets[i], writefds))
 			flags |= FD_WRITE | FD_CLOSE;

 		if (WSAEventSelect(sockets[i], events[i], flags) == SOCKET_ERROR)
 		{
 			TranslateSocketError();
 			for (i = 0; i < numevents; i++)
 				WSACloseEvent(events[i]);
 			return -1;
 		}
 	}

 	events[numevents] = pgwin32_signal_event;
 	r = WaitForMultipleObjectsEx(numevents + 1, events, FALSE, timeoutval, TRUE);
 	if (r != WAIT_TIMEOUT && r != WAIT_IO_COMPLETION && r != (WAIT_OBJECT_0 + numevents))
 	{
 		/*
 		 * We scan all events, even those not signalled, in case more than one
 		 * event has been tagged but Wait.. can only return one.
 		 */
 		WSANETWORKEVENTS resEvents;

 		for (i = 0; i < numevents; i++)
 		{
 			ZeroMemory(&resEvents, sizeof(resEvents));
 			if (WSAEnumNetworkEvents(sockets[i], events[i], &resEvents) == SOCKET_ERROR)
 				ereport(FATAL,
 						(errmsg_internal("failed to enumerate network events: %i", (int) GetLastError())));
 			/* Read activity? */
 			if (readfds && FD_ISSET(sockets[i], readfds))
 			{
 				if ((resEvents.lNetworkEvents & FD_READ) ||
 					(resEvents.lNetworkEvents & FD_ACCEPT) ||
 					(resEvents.lNetworkEvents & FD_CLOSE))
 				{
 					FD_SET(sockets[i], &outreadfds);

 					nummatches++;
 				}
 			}
 			/* Write activity? */
 			if (writefds && FD_ISSET(sockets[i], writefds))
 			{
 				if ((resEvents.lNetworkEvents & FD_WRITE) ||
 					(resEvents.lNetworkEvents & FD_CLOSE))
 				{
 					FD_SET(sockets[i], &outwritefds);

 					nummatches++;
 				}
 			}
 		}
 	}

 	/* Clean up all handles */
 	for (i = 0; i < numevents; i++)
 	{
 		WSAEventSelect(sockets[i], events[i], 0);
 		WSACloseEvent(events[i]);
 	}

 	if (r == WSA_WAIT_TIMEOUT)
 	{
 		if (readfds)
 			FD_ZERO(readfds);
 		if (writefds)
 			FD_ZERO(writefds);
 		return 0;
 	}

 	if (r == WAIT_OBJECT_0 + numevents)
 	{
 		pgwin32_dispatch_queued_signals();
 		errno = EINTR;
 		if (readfds)
 			FD_ZERO(readfds);
 		if (writefds)
 			FD_ZERO(writefds);
 		return -1;
 	}

 	/* Overwrite socket sets with our resulting values */
 	if (readfds)
 		memcpy(readfds, &outreadfds, sizeof(fd_set));
 	if (writefds)
 		memcpy(writefds, &outwritefds, sizeof(fd_set));
 	return nummatches;
 }


 /*
  * Return win32 error string, since strerror can't
  * handle winsock codes
  */
 static char wserrbuf[256];
 const char *
 pgwin32_socket_strerror(int err)
 {
 	static HANDLE handleDLL = INVALID_HANDLE_VALUE;

 	if (handleDLL == INVALID_HANDLE_VALUE)
 	{
 		handleDLL = LoadLibraryEx("netmsg.dll", NULL, DONT_RESOLVE_DLL_REFERENCES | LOAD_LIBRARY_AS_DATAFILE);
 		if (handleDLL == NULL)
 			ereport(FATAL,
 					(errmsg_internal("Failed to load netmsg.dll: %i", (int) GetLastError())));
 	}

 	ZeroMemory(&wserrbuf, sizeof(wserrbuf));
 	if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_FROM_HMODULE,
 					  handleDLL,
 					  err,
 					  MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT),
 					  wserrbuf,
 					  sizeof(wserrbuf) - 1,
 					  NULL) == 0)
 	{
 		/* Failed to get id */
 		sprintf(wserrbuf, "Unknown winsock error %i", err);
 	}
 	return wserrbuf;
 }
	/*-------------------------------------------------------------------------
	*
	* socket.c
	* Microsoft Windows Win32 Socket Functions
	*
	* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
	*
	* IDENTIFICATION
	* $PostgreSQL: pgsql/src/backend/port/win32/socket.c,v 1.22 2009/06/11 14:49:00 momjian Exp $
	*
	*-------------------------------------------------------------------------
	*/

	#include "postgres.h"

	#undef socket
	#undef accept
	#undef connect
	#undef select
	#undef recv
	#undef send

	/*
	* Blocking socket functions implemented so they listen on both
	* the socket and the signal event, required for signal handling.
	*/

	/*
	* Convert the last socket error code into errno
	*/
	static void
	TranslateSocketError(void)
	{
	switch (WSAGetLastError())
	{
	case WSANOTINITIALISED:
	case WSAENETDOWN:
	case WSAEINPROGRESS:
	case WSAEINVAL:
	case WSAESOCKTNOSUPPORT:
	case WSAEFAULT:
	case WSAEINVALIDPROVIDER:
	case WSAEINVALIDPROCTABLE:
	case WSAEMSGSIZE:
	errno = EINVAL;
	break;
	case WSAEAFNOSUPPORT:
	errno = EAFNOSUPPORT;
	break;
	case WSAEMFILE:
	errno = EMFILE;
	break;
	case WSAENOBUFS:
	errno = ENOBUFS;
	break;
	case WSAEPROTONOSUPPORT:
	case WSAEPROTOTYPE:
	errno = EPROTONOSUPPORT;
	break;
	case WSAECONNREFUSED:
	errno = ECONNREFUSED;
	break;
	case WSAEINTR:
	errno = EINTR;
	break;
	case WSAENOTSOCK:
	errno = EBADFD;
	break;
	case WSAEOPNOTSUPP:
	errno = EOPNOTSUPP;
	break;
	case WSAEWOULDBLOCK:
	errno = EWOULDBLOCK;
	break;
	case WSAEACCES:
	errno = EACCES;
	break;
	case WSAENOTCONN:
	case WSAENETRESET:
	case WSAECONNRESET:
	case WSAESHUTDOWN:
	case WSAECONNABORTED:
	case WSAEDISCON:
	errno = ECONNREFUSED; /* ENOTCONN? */
	break;
	default:
	ereport(NOTICE,
	(errmsg_internal("Unknown win32 socket error code: %i", WSAGetLastError())));
	errno = EINVAL;
	}
	}

	static int
	pgwin32_poll_signals(void)
	{
	if (UNBLOCKED_SIGNAL_QUEUE())
	{
	pgwin32_dispatch_queued_signals();
	errno = EINTR;
	return 1;
	}
	return 0;
	}

	static int
	isDataGram(SOCKET s)
	{
	int type;
	int typelen = sizeof(type);

	if ( getsockopt(s, SOL_SOCKET, SO_TYPE, (char*)&type, &typelen) )
	return 1;

	return ( type == SOCK_DGRAM ) ? 1 : 0;
	}

	int
	pgwin32_waitforsinglesocket(SOCKET s, int what, int timeout)
	{
	static HANDLE waitevent = INVALID_HANDLE_VALUE;
	static SOCKET current_socket = -1;
	static int isUDP = 0;
	HANDLE events[2];
	int r;

	if (waitevent == INVALID_HANDLE_VALUE)
	{
	waitevent = CreateEvent(NULL, TRUE, FALSE, NULL);

	if (waitevent == INVALID_HANDLE_VALUE)
	ereport(ERROR,
	(errmsg_internal("Failed to create socket waiting event: %i", (int) GetLastError())));
	}
	else if (!ResetEvent(waitevent))
	ereport(ERROR,
	(errmsg_internal("Failed to reset socket waiting event: %i", (int) GetLastError())));

	/*
	* make sure we don't multiplex this kernel event object with a different
	* socket from a previous call
	*/

	if (current_socket != s)
	{
	if ( current_socket != -1 )
	WSAEventSelect(current_socket, waitevent, 0);
	isUDP = isDataGram(s);
	}

	current_socket = s;

	if (WSAEventSelect(s, waitevent, what) == SOCKET_ERROR)
	{
	TranslateSocketError();
	return 0;
	}

	events[0] = pgwin32_signal_event;
	events[1] = waitevent;

	/*
	* Just a workaround of unknown locking problem with writing in UDP socket
	* under high load: Client's pgsql backend sleeps infinitely in
	* WaitForMultipleObjectsEx, pgstat process sleeps in pgwin32_select().
	* So, we will wait with small timeout(0.1 sec) and if sockect is still
	* blocked, try WSASend (see comments in pgwin32_select) and wait again.
	*/
	if ((what & FD_WRITE) && isUDP)
	{
	for(;;)
	{
	r = WaitForMultipleObjectsEx(2, events, FALSE, 100, TRUE);

	if ( r == WAIT_TIMEOUT )
	{
	char c;
	WSABUF buf;
	DWORD sent;

	buf.buf = &c;
	buf.len = 0;

	r = WSASend(s, &buf, 1, &sent, 0, NULL, NULL);
	if (r == 0) /* Completed - means things are fine! */
	return 1;
	else if ( WSAGetLastError() != WSAEWOULDBLOCK )
	{
	TranslateSocketError();
	return 0;
	}
	}
	else
	break;
	}
	}
	else
	r = WaitForMultipleObjectsEx(2, events, FALSE, timeout, TRUE);

	if (r == WAIT_OBJECT_0 \|\| r == WAIT_IO_COMPLETION)
	{
	pgwin32_dispatch_queued_signals();
	errno = EINTR;
	return 0;
	}
	if (r == WAIT_OBJECT_0 + 1)
	return 1;
	if (r == WAIT_TIMEOUT)
	return 0;
	ereport(ERROR,
	(errmsg_internal("Bad return from WaitForMultipleObjects: %i (%i)", r, (int) GetLastError())));
	return 0;
	}

	/*
	* Create a socket, setting it to overlapped and non-blocking
	*/
	SOCKET
	pgwin32_socket(int af, int type, int protocol)
	{
	SOCKET s;
	unsigned long on = 1;

	s = WSASocket(af, type, protocol, NULL, 0, WSA_FLAG_OVERLAPPED);
	if (s == INVALID_SOCKET)
	{
	TranslateSocketError();
	return INVALID_SOCKET;
	}

	if (ioctlsocket(s, FIONBIO, &on))
	{
	TranslateSocketError();
	return INVALID_SOCKET;
	}
	errno = 0;

	return s;
	}


	SOCKET
	pgwin32_accept(SOCKET s, struct sockaddr * addr, int *addrlen)
	{
	SOCKET rs;

	/*
	* Poll for signals, but don't return with EINTR, since we don't handle
	* that in pqcomm.c
	*/
	pgwin32_poll_signals();

	rs = WSAAccept(s, addr, addrlen, NULL, 0);
	if (rs == INVALID_SOCKET)
	{
	TranslateSocketError();
	return INVALID_SOCKET;
	}
	return rs;
	}


	/* No signal delivery during connect. */
	int
	pgwin32_connect(SOCKET s, const struct sockaddr * addr, int addrlen)
	{
	int r;

	r = WSAConnect(s, addr, addrlen, NULL, NULL, NULL, NULL);
	if (r == 0)
	return 0;

	if (WSAGetLastError() != WSAEWOULDBLOCK)
	{
	TranslateSocketError();
	return -1;
	}

	while (pgwin32_waitforsinglesocket(s, FD_CONNECT, INFINITE) == 0)
	{
	/* Loop endlessly as long as we are just delivering signals */
	}

	return 0;
	}

	int
	pgwin32_recv(SOCKET s, char *buf, int len, int f)
	{
	WSABUF wbuf;
	int r;
	DWORD b;
	DWORD flags = f;
	int n;

	if (pgwin32_poll_signals())
	return -1;

	wbuf.len = len;
	wbuf.buf = buf;

	r = WSARecv(s, &wbuf, 1, &b, &flags, NULL, NULL);
	if (r != SOCKET_ERROR && b > 0)
	/* Read succeeded right away */
	return b;

	if (r == SOCKET_ERROR &&
	WSAGetLastError() != WSAEWOULDBLOCK)
	{
	TranslateSocketError();
	return -1;
	}

	/* No error, zero bytes (win2000+) or error+WSAEWOULDBLOCK (<=nt4) */

	for (n = 0; n < 5; n++)
	{
	if (pgwin32_waitforsinglesocket(s, FD_READ \| FD_CLOSE \| FD_ACCEPT,
	INFINITE) == 0)
	return -1; /* errno already set */

	r = WSARecv(s, &wbuf, 1, &b, &flags, NULL, NULL);
	if (r == SOCKET_ERROR)
	{
	if (WSAGetLastError() == WSAEWOULDBLOCK)
	{
	/*
	* There seem to be cases on win2k (at least) where WSARecv
	* can return WSAEWOULDBLOCK even when
	* pgwin32_waitforsinglesocket claims the socket is readable.
	* In this case, just sleep for a moment and try again. We try
	* up to 5 times - if it fails more than that it's not likely
	* to ever come back.
	*/
	pg_usleep(10000);
	continue;
	}
	TranslateSocketError();
	return -1;
	}
	return b;
	}
	ereport(NOTICE,
	(errmsg_internal("Failed to read from ready socket (after retries)")));
	errno = EWOULDBLOCK;
	return -1;
	}

	int
	pgwin32_send(SOCKET s, char *buf, int len, int flags)
	{
	WSABUF wbuf;
	int r;
	DWORD b;

	if (pgwin32_poll_signals())
	return -1;

	wbuf.len = len;
	wbuf.buf = buf;

	/*
	* Readiness of socket to send data to UDP socket may be not true: socket
	* can become busy again! So loop until send or error occurs.
	*/
	for (;;)
	{
	r = WSASend(s, &wbuf, 1, &b, flags, NULL, NULL);
	if (r != SOCKET_ERROR && b > 0)
	/* Write succeeded right away */
	return b;

	if (r == SOCKET_ERROR &&
	WSAGetLastError() != WSAEWOULDBLOCK)
	{
	TranslateSocketError();
	return -1;
	}

	/* No error, zero bytes (win2000+) or error+WSAEWOULDBLOCK (<=nt4) */

	if (pgwin32_waitforsinglesocket(s, FD_WRITE \| FD_CLOSE, INFINITE) == 0)
	return -1;
	}

	return -1;
	}


	/*
	* Wait for activity on one or more sockets.
	* While waiting, allow signals to run
	*
	* NOTE! Currently does not implement exceptfds check,
	* since it is not used in postgresql!
	*/
	int
	pgwin32_select(int nfds, fd_set readfds, fd_set writefds, fd_set exceptfds, const struct timeval timeout)
	{
	WSAEVENT events[FD_SETSIZE * 2]; /* worst case is readfds totally
	* different from writefds, so
	* 2FD_SETSIZE sockets /
	SOCKET sockets[FD_SETSIZE * 2];
	int numevents = 0;
	int i;
	int r;
	DWORD timeoutval = WSA_INFINITE;
	FD_SET outreadfds;
	FD_SET outwritefds;
	int nummatches = 0;

	Assert(exceptfds == NULL);

	if (pgwin32_poll_signals())
	return -1;

	FD_ZERO(&outreadfds);
	FD_ZERO(&outwritefds);

	/*
	* Write FDs are different in the way that it is only flagged by
	* WSASelectEvent() if we have tried to write to them first. So try an
	* empty write
	*/
	if (writefds)
	{
	for (i = 0; i < writefds->fd_count; i++)
	{
	char c;
	WSABUF buf;
	DWORD sent;

	buf.buf = &c;
	buf.len = 0;

	r = WSASend(writefds->fd_array[i], &buf, 1, &sent, 0, NULL, NULL);
	if (r == 0) /* Completed - means things are fine! */
	FD_SET(writefds->fd_array[i], &outwritefds);

	else
	{ /* Not completed */
	if (WSAGetLastError() != WSAEWOULDBLOCK)

	/*
	* Not completed, and not just "would block", so an error
	* occured
	*/
	FD_SET(writefds->fd_array[i], &outwritefds);
	}
	}
	if (outwritefds.fd_count > 0)
	{
	memcpy(writefds, &outwritefds, sizeof(fd_set));
	if (readfds)
	FD_ZERO(readfds);
	return outwritefds.fd_count;
	}
	}


	/* Now set up for an actual select */

	if (timeout != NULL)
	{
	/* timeoutval is in milliseconds */
	timeoutval = timeout->tv_sec * 1000 + timeout->tv_usec / 1000;
	}

	if (readfds != NULL)
	{
	for (i = 0; i < readfds->fd_count; i++)
	{
	events[numevents] = WSACreateEvent();
	sockets[numevents] = readfds->fd_array[i];
	numevents++;
	}
	}
	if (writefds != NULL)
	{
	for (i = 0; i < writefds->fd_count; i++)
	{
	if (!readfds \|\|
	!FD_ISSET(writefds->fd_array[i], readfds))
	{
	/* If the socket is not in the read list */
	events[numevents] = WSACreateEvent();
	sockets[numevents] = writefds->fd_array[i];
	numevents++;
	}
	}
	}

	for (i = 0; i < numevents; i++)
	{
	int flags = 0;

	if (readfds && FD_ISSET(sockets[i], readfds))
	flags \|= FD_READ \| FD_ACCEPT \| FD_CLOSE;

	if (writefds && FD_ISSET(sockets[i], writefds))
	flags \|= FD_WRITE \| FD_CLOSE;

	if (WSAEventSelect(sockets[i], events[i], flags) == SOCKET_ERROR)
	{
	TranslateSocketError();
	for (i = 0; i < numevents; i++)
	WSACloseEvent(events[i]);
	return -1;
	}
	}

	events[numevents] = pgwin32_signal_event;
	r = WaitForMultipleObjectsEx(numevents + 1, events, FALSE, timeoutval, TRUE);
	if (r != WAIT_TIMEOUT && r != WAIT_IO_COMPLETION && r != (WAIT_OBJECT_0 + numevents))
	{
	/*
	* We scan all events, even those not signalled, in case more than one
	* event has been tagged but Wait.. can only return one.
	*/
	WSANETWORKEVENTS resEvents;

	for (i = 0; i < numevents; i++)
	{
	ZeroMemory(&resEvents, sizeof(resEvents));
	if (WSAEnumNetworkEvents(sockets[i], events[i], &resEvents) == SOCKET_ERROR)
	ereport(FATAL,
	(errmsg_internal("failed to enumerate network events: %i", (int) GetLastError())));
	/* Read activity? */
	if (readfds && FD_ISSET(sockets[i], readfds))
	{
	if ((resEvents.lNetworkEvents & FD_READ) \|\|
	(resEvents.lNetworkEvents & FD_ACCEPT) \|\|
	(resEvents.lNetworkEvents & FD_CLOSE))
	{
	FD_SET(sockets[i], &outreadfds);

	nummatches++;
	}
	}
	/* Write activity? */
	if (writefds && FD_ISSET(sockets[i], writefds))
	{
	if ((resEvents.lNetworkEvents & FD_WRITE) \|\|
	(resEvents.lNetworkEvents & FD_CLOSE))
	{
	FD_SET(sockets[i], &outwritefds);

	nummatches++;
	}
	}
	}
	}

	/* Clean up all handles */
	for (i = 0; i < numevents; i++)
	{
	WSAEventSelect(sockets[i], events[i], 0);
	WSACloseEvent(events[i]);
	}

	if (r == WSA_WAIT_TIMEOUT)
	{
	if (readfds)
	FD_ZERO(readfds);
	if (writefds)
	FD_ZERO(writefds);
	return 0;
	}

	if (r == WAIT_OBJECT_0 + numevents)
	{
	pgwin32_dispatch_queued_signals();
	errno = EINTR;
	if (readfds)
	FD_ZERO(readfds);
	if (writefds)
	FD_ZERO(writefds);
	return -1;
	}

	/* Overwrite socket sets with our resulting values */
	if (readfds)
	memcpy(readfds, &outreadfds, sizeof(fd_set));
	if (writefds)
	memcpy(writefds, &outwritefds, sizeof(fd_set));
	return nummatches;
	}


	/*
	* Return win32 error string, since strerror can't
	* handle winsock codes
	*/
	static char wserrbuf[256];
	const char *
	pgwin32_socket_strerror(int err)
	{
	static HANDLE handleDLL = INVALID_HANDLE_VALUE;

	if (handleDLL == INVALID_HANDLE_VALUE)
	{
	handleDLL = LoadLibraryEx("netmsg.dll", NULL, DONT_RESOLVE_DLL_REFERENCES \| LOAD_LIBRARY_AS_DATAFILE);
	if (handleDLL == NULL)
	ereport(FATAL,
	(errmsg_internal("Failed to load netmsg.dll: %i", (int) GetLastError())));
	}

	ZeroMemory(&wserrbuf, sizeof(wserrbuf));
	if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS \| FORMAT_MESSAGE_FROM_SYSTEM \| FORMAT_MESSAGE_FROM_HMODULE,
	handleDLL,
	err,
	MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT),
	wserrbuf,
	sizeof(wserrbuf) - 1,
	NULL) == 0)
	{
	/* Failed to get id */
	sprintf(wserrbuf, "Unknown winsock error %i", err);
	}
	return wserrbuf;
	}