R6.6 is the Xorg base-lineXORG-MAIN

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+/***********************************************************
+
+Copyright 1987, 1989, 1998  The Open Group
+
+Permission to use, copy, modify, distribute, and sell this software and its
+documentation for any purpose is hereby granted without fee, provided that
+the above copyright notice appear in all copies and that both that
+copyright notice and this permission notice appear in supporting
+documentation.
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+Except as contained in this notice, the name of The Open Group shall not be
+used in advertising or otherwise to promote the sale, use or other dealings
+in this Software without prior written authorization from The Open Group.
+
+
+Copyright 1987, 1989 by Digital Equipment Corporation, Maynard, Massachusetts.
+
+                        All Rights Reserved
+
+Permission to use, copy, modify, and distribute this software and its 
+documentation for any purpose and without fee is hereby granted, 
+provided that the above copyright notice appear in all copies and that
+both that copyright notice and this permission notice appear in 
+supporting documentation, and that the name of Digital not be
+used in advertising or publicity pertaining to distribution of the
+software without specific, written prior permission.  
+
+DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
+ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
+DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
+ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
+SOFTWARE.
+
+******************************************************************/
+/* $Xorg: io.c,v 1.6 2001/02/09 02:05:23 xorgcvs Exp $ */
+/*****************************************************************
+ * i/o functions
+ *
+ *   WriteToClient, ReadRequestFromClient
+ *   InsertFakeRequest, ResetCurrentRequest
+ *
+ *****************************************************************/
+
+#ifdef WIN32
+#include <X11/Xwinsock.h>
+#endif
+#include <stdio.h>
+#include <X11/Xtrans.h>
+#ifdef X_NOT_STDC_ENV
+extern int errno;
+#endif
+#include "Xmd.h"
+#include <errno.h>
+#ifndef WIN32
+#include <sys/uio.h>
+#endif
+#include "X.h"
+#define NEED_REPLIES
+#include "Xproto.h"
+#include "os.h"
+#include "Xpoll.h"
+#include "osdep.h"
+#include "opaque.h"
+#include "dixstruct.h"
+#include "misc.h"
+#ifdef LBX
+#include "lbxserve.h"
+#endif
+
+CallbackListPtr       ReplyCallback;
+CallbackListPtr       FlushCallback;
+
+/* check for both EAGAIN and EWOULDBLOCK, because some supposedly POSIX
+ * systems are broken and return EWOULDBLOCK when they should return EAGAIN
+ */
+#if defined(EAGAIN) && defined(EWOULDBLOCK)
+#define ETEST(err) (err == EAGAIN || err == EWOULDBLOCK)
+#else
+#ifdef EAGAIN
+#define ETEST(err) (err == EAGAIN)
+#else
+#define ETEST(err) (err == EWOULDBLOCK)
+#endif
+#endif
+
+extern fd_set ClientsWithInput, IgnoredClientsWithInput, AllClients;
+extern fd_set ClientsWriteBlocked;
+extern fd_set OutputPending;
+extern int ConnectionTranslation[];
+extern Bool NewOutputPending;
+extern Bool AnyClientsWriteBlocked;
+
+Bool CriticalOutputPending;
+int timesThisConnection = 0;
+ConnectionInputPtr FreeInputs = (ConnectionInputPtr)NULL;
+ConnectionOutputPtr FreeOutputs = (ConnectionOutputPtr)NULL;
+OsCommPtr AvailableInput = (OsCommPtr)NULL;
+
+#define get_req_len(req,cli) ((cli)->swapped ? \
+			      lswaps((req)->length) : (req)->length)
+
+#ifdef BIGREQS
+#include "bigreqstr.h"
+
+#define get_big_req_len(req,cli) ((cli)->swapped ? \
+				  lswapl(((xBigReq *)(req))->length) : \
+				  ((xBigReq *)(req))->length)
+#endif
+
+#define MAX_TIMES_PER         10
+
+/*
+ *   A lot of the code in this file manipulates a ConnectionInputPtr:
+ *
+ *    -----------------------------------------------
+ *   |------- bufcnt ------->|           |           |
+ *   |           |- gotnow ->|           |           |
+ *   |           |-------- needed ------>|           |
+ *   |-----------+--------- size --------+---------->|
+ *    -----------------------------------------------
+ *   ^           ^
+ *   |           |
+ *   buffer   bufptr
+ *
+ *  buffer is a pointer to the start of the buffer.
+ *  bufptr points to the start of the current request.
+ *  bufcnt counts how many bytes are in the buffer.
+ *  size is the size of the buffer in bytes.
+ *
+ *  In several of the functions, gotnow and needed are local variables
+ *  that do the following:
+ *
+ *  gotnow is the number of bytes of the request that we're
+ *  trying to read that are currently in the buffer.
+ *  Typically, gotnow = (buffer + bufcnt) - bufptr
+ *
+ *  needed = the length of the request that we're trying to
+ *  read.  Watch out: needed sometimes counts bytes and sometimes
+ *  counts CARD32's.
+ */
+
+
+/*****************************************************************
+ * ReadRequestFromClient
+ *    Returns one request in client->requestBuffer.  The request
+ *    length will be in client->req_len.  Return status is:
+ *
+ *    > 0  if  successful, specifies length in bytes of the request
+ *    = 0  if  entire request is not yet available
+ *    < 0  if  client should be terminated
+ *
+ *    The request returned must be contiguous so that it can be
+ *    cast in the dispatcher to the correct request type.  Because requests
+ *    are variable length, ReadRequestFromClient() must look at the first 4
+ *    or 8 bytes of a request to determine the length (the request length is
+ *    in the 3rd and 4th bytes of the request unless it is a Big Request
+ *    (see the Big Request Extension), in which case the 3rd and 4th bytes
+ *    are zero and the following 4 bytes are the request length.
+ *
+ *    Note: in order to make the server scheduler (WaitForSomething())
+ *    "fair", the ClientsWithInput mask is used.  This mask tells which
+ *    clients have FULL requests left in their buffers.  Clients with
+ *    partial requests require a read.  Basically, client buffers
+ *    are drained before select() is called again.  But, we can't keep
+ *    reading from a client that is sending buckets of data (or has
+ *    a partial request) because others clients need to be scheduled.
+ *****************************************************************/
+
+#define YieldControl()				\
+        { isItTimeToYield = TRUE;		\
+	  timesThisConnection = 0; }
+#define YieldControlNoInput()			\
+        { YieldControl();			\
+	  FD_CLR(fd, &ClientsWithInput); }
+#define YieldControlDeath()			\
+        { timesThisConnection = 0; }
+
+#ifdef hpux_not_tog
+#define LBX_NEED_OLD_SYMBOL_FOR_LOADABLES
+#endif
+
+#ifdef LBX
+#ifdef LBX_NEED_OLD_SYMBOL_FOR_LOADABLES
+#undef ReadRequestFromClient
+int
+ReadRequestFromClient(client)
+    ClientPtr client;
+{
+    return (*client->readRequest)(client);
+}
+#endif
+int
+StandardReadRequestFromClient(client)
+    ClientPtr client;
+#else
+int
+ReadRequestFromClient(client)
+    ClientPtr client;
+#endif
+{
+    OsCommPtr oc = (OsCommPtr)client->osPrivate;
+    register ConnectionInputPtr oci = oc->input;
+    int fd = oc->fd;
+    register unsigned int gotnow, needed;
+    int result;
+    register xReq *request;
+    Bool need_header;
+#ifdef BIGREQS
+    Bool move_header;
+#endif
+
+    /* If an input buffer was empty, either free it if it is too big
+     * or link it into our list of free input buffers.  This means that
+     * different clients can share the same input buffer (at different
+     * times).  This was done to save memory.
+     */
+
+    if (AvailableInput)
+    {
+	if (AvailableInput != oc)
+	{
+	    register ConnectionInputPtr aci = AvailableInput->input;
+	    if (aci->size > BUFWATERMARK)
+	    {
+		xfree(aci->buffer);
+		xfree(aci);
+	    }
+	    else
+	    {
+		aci->next = FreeInputs;
+		FreeInputs = aci;
+	    }
+	    AvailableInput->input = (ConnectionInputPtr)NULL;
+	}
+	AvailableInput = (OsCommPtr)NULL;
+    }
+
+    /* make sure we have an input buffer */
+
+    if (!oci)
+    {
+	if (oci = FreeInputs)
+	{
+	    FreeInputs = oci->next;
+	}
+	else if (!(oci = AllocateInputBuffer()))
+	{
+	    YieldControlDeath();
+	    return -1;
+	}
+	oc->input = oci;
+    }
+
+    /* advance to start of next request */
+
+    oci->bufptr += oci->lenLastReq;
+
+    need_header = FALSE;
+#ifdef BIGREQS
+    move_header = FALSE;
+#endif
+    gotnow = oci->bufcnt + oci->buffer - oci->bufptr;
+    if (gotnow < sizeof(xReq))
+    {
+	/* We don't have an entire xReq yet.  Can't tell how big
+	 * the request will be until we get the whole xReq.
+	 */
+	needed = sizeof(xReq);
+	need_header = TRUE;
+    }
+    else
+    {
+	/* We have a whole xReq.  We can tell how big the whole
+	 * request will be unless it is a Big Request.
+	 */
+	request = (xReq *)oci->bufptr;
+	needed = get_req_len(request, client);
+#ifdef BIGREQS
+	if (!needed && client->big_requests)
+	{
+	    /* It's a Big Request. */
+	    move_header = TRUE;
+	    if (gotnow < sizeof(xBigReq))
+	    {
+		/* Still need more data to tell just how big. */
+		needed = sizeof(xBigReq) >> 2; /* needed is in CARD32s now */
+		need_header = TRUE;
+	    }
+	    else
+		needed = get_big_req_len(request, client);
+	}
+#endif
+	client->req_len = needed;
+	needed <<= 2; /* needed is in bytes now */
+    }
+    if (gotnow < needed)
+    {
+	/* Need to read more data, either so that we can get a
+	 * complete xReq (if need_header is TRUE), a complete
+	 * xBigReq (if move_header is TRUE), or the rest of the
+	 * request (if need_header and move_header are both FALSE).
+	 */
+
+	oci->lenLastReq = 0;
+	if (needed > MAXBUFSIZE)
+	{
+	    /* request is too big for us to handle */
+	    YieldControlDeath();
+	    return -1;
+	}
+	if ((gotnow == 0) ||
+	    ((oci->bufptr - oci->buffer + needed) > oci->size))
+	{
+	    /* no data, or the request is too big to fit in the buffer */
+
+	    if ((gotnow > 0) && (oci->bufptr != oci->buffer))
+		/* save the data we've already read */
+		memmove(oci->buffer, oci->bufptr, gotnow);
+	    if (needed > oci->size)
+	    {
+		/* make buffer bigger to accomodate request */
+		char *ibuf;
+
+		ibuf = (char *)xrealloc(oci->buffer, needed);
+		if (!ibuf)
+		{
+		    YieldControlDeath();
+		    return -1;
+		}
+		oci->size = needed;
+		oci->buffer = ibuf;
+	    }
+	    oci->bufptr = oci->buffer;
+	    oci->bufcnt = gotnow;
+	}
+	/*  XXX this is a workaround.  This function is sometimes called
+	 *  after the trans_conn has been freed.  In this case trans_conn
+	 *  will be null.  Really ought to restructure things so that we
+	 *  never get here in those circumstances.
+	 */
+	if (!oc->trans_conn)
+	{
+	    /*  treat as if an error occured on the read, which is what
+	     *  used to happen
+	     */
+	    YieldControlDeath();
+	    return -1;
+	}
+#ifdef LBX
+	if (oc->proxy && oc->proxy->compHandle)
+	    result = (*oc->proxy->streamOpts.streamCompRead)(fd,
+			     (unsigned char *)oci->buffer + oci->bufcnt,
+			     oci->size - oci->bufcnt);
+	else
+#endif
+	    result = _XSERVTransRead(oc->trans_conn, oci->buffer + oci->bufcnt,
+				     oci->size - oci->bufcnt); 
+	if (result <= 0)
+	{
+	    if ((result < 0) && ETEST(errno))
+	    {
+		YieldControlNoInput();
+		return 0;
+	    }
+	    YieldControlDeath();
+	    return -1;
+	}
+	oci->bufcnt += result;
+	gotnow += result;
+	/* free up some space after huge requests */
+	if ((oci->size > BUFWATERMARK) &&
+	    (oci->bufcnt < BUFSIZE) && (needed < BUFSIZE))
+	{
+	    char *ibuf;
+
+	    ibuf = (char *)xrealloc(oci->buffer, BUFSIZE);
+	    if (ibuf)
+	    {
+		oci->size = BUFSIZE;
+		oci->buffer = ibuf;
+		oci->bufptr = ibuf + oci->bufcnt - gotnow;
+	    }
+	}
+	if (need_header && gotnow >= needed)
+	{
+	    /* We wanted an xReq, now we've gotten it. */
+	    request = (xReq *)oci->bufptr;
+	    needed = get_req_len(request, client);
+#ifdef BIGREQS
+	    if (!needed && client->big_requests)
+	    {
+		move_header = TRUE;
+		if (gotnow < sizeof(xBigReq))
+		    needed = sizeof(xBigReq) >> 2;
+		else
+		    needed = get_big_req_len(request, client);
+	    }
+#endif
+	    client->req_len = needed;
+	    needed <<= 2;
+	}
+	if (gotnow < needed)
+	{
+	    /* Still don't have enough; punt. */
+	    YieldControlNoInput();
+	    return 0;
+	}
+    }
+    if (needed == 0)
+    {
+#ifdef BIGREQS
+	if (client->big_requests)
+	    needed = sizeof(xBigReq);
+	else
+#endif
+	    needed = sizeof(xReq);
+    }
+    oci->lenLastReq = needed;
+
+    /*
+     *  Check to see if client has at least one whole request in the
+     *  buffer beyond the request we're returning to the caller.
+     *  If there is only a partial request, treat like buffer
+     *  is empty so that select() will be called again and other clients
+     *  can get into the queue.   
+     */
+
+    gotnow -= needed;
+    if (gotnow >= sizeof(xReq)) 
+    {
+	request = (xReq *)(oci->bufptr + needed);
+	if (gotnow >= (result = (get_req_len(request, client) << 2))
+#ifdef BIGREQS
+	    && (result ||
+		(client->big_requests &&
+		 (gotnow >= sizeof(xBigReq) &&
+		  gotnow >= (get_big_req_len(request, client) << 2))))
+#endif
+	    )
+	    FD_SET(fd, &ClientsWithInput);
+	else
+	    YieldControlNoInput();
+    }
+    else
+    {
+	if (!gotnow)
+	    AvailableInput = oc;
+	YieldControlNoInput();
+    }
+    if (++timesThisConnection >= MAX_TIMES_PER)
+	YieldControl();
+#ifdef BIGREQS
+    if (move_header)
+    {
+	request = (xReq *)oci->bufptr;
+	oci->bufptr += (sizeof(xBigReq) - sizeof(xReq));
+	*(xReq *)oci->bufptr = *request;
+	oci->lenLastReq -= (sizeof(xBigReq) - sizeof(xReq));
+	client->req_len -= (sizeof(xBigReq) - sizeof(xReq)) >> 2;
+    }
+#endif
+    client->requestBuffer = (pointer)oci->bufptr;
+    return needed;
+}
+
+/*****************************************************************
+ * InsertFakeRequest
+ *    Splice a consed up (possibly partial) request in as the next request.
+ *
+ **********************/
+
+Bool
+InsertFakeRequest(client, data, count)
+    ClientPtr client;
+    char *data;
+    int count;
+{
+    OsCommPtr oc = (OsCommPtr)client->osPrivate;
+    register ConnectionInputPtr oci = oc->input;
+    int fd = oc->fd;
+    register int gotnow, moveup;
+
+    if (AvailableInput)
+    {
+	if (AvailableInput != oc)
+	{
+	    register ConnectionInputPtr aci = AvailableInput->input;
+	    if (aci->size > BUFWATERMARK)
+	    {
+		xfree(aci->buffer);
+		xfree(aci);
+	    }
+	    else
+	    {
+		aci->next = FreeInputs;
+		FreeInputs = aci;
+	    }
+	    AvailableInput->input = (ConnectionInputPtr)NULL;
+	}
+	AvailableInput = (OsCommPtr)NULL;
+    }
+    if (!oci)
+    {
+	if (oci = FreeInputs)
+	    FreeInputs = oci->next;
+	else if (!(oci = AllocateInputBuffer()))
+	    return FALSE;
+	oc->input = oci;
+    }
+    oci->bufptr += oci->lenLastReq;
+    oci->lenLastReq = 0;
+    gotnow = oci->bufcnt + oci->buffer - oci->bufptr;
+    if ((gotnow + count) > oci->size)
+    {
+	char *ibuf;
+
+	ibuf = (char *)xrealloc(oci->buffer, gotnow + count);
+	if (!ibuf)
+	    return(FALSE);
+	oci->size = gotnow + count;
+	oci->buffer = ibuf;
+	oci->bufptr = ibuf + oci->bufcnt - gotnow;
+    }
+    moveup = count - (oci->bufptr - oci->buffer);
+    if (moveup > 0)
+    {
+	if (gotnow > 0)
+	    memmove(oci->bufptr + moveup, oci->bufptr, gotnow);
+	oci->bufptr += moveup;
+	oci->bufcnt += moveup;
+    }
+    memmove(oci->bufptr - count, data, count);
+    oci->bufptr -= count;
+    gotnow += count;
+    if ((gotnow >= sizeof(xReq)) &&
+	(gotnow >= (int)(get_req_len((xReq *)oci->bufptr, client) << 2)))
+	FD_SET(fd, &ClientsWithInput);
+    else
+	YieldControlNoInput();
+    return(TRUE);
+}
+
+/*****************************************************************
+ * ResetRequestFromClient
+ *    Reset to reexecute the current request, and yield.
+ *
+ **********************/
+
+ResetCurrentRequest(client)
+    ClientPtr client;
+{
+    OsCommPtr oc = (OsCommPtr)client->osPrivate;
+    register ConnectionInputPtr oci = oc->input;
+    int fd = oc->fd;
+    register xReq *request;
+    int gotnow, needed;
+#ifdef LBX
+    Bool part;
+    LbxClientPtr lbxClient = LbxClient(client);
+
+    if (lbxClient) {
+	LbxSetForBlock(lbxClient);
+	if (!oci) {
+	    AppendFakeRequest(client,
+			      client->requestBuffer, client->req_len << 2);
+	    return;
+	}
+    }
+#endif
+    if (AvailableInput == oc)
+	AvailableInput = (OsCommPtr)NULL;
+    oci->lenLastReq = 0;
+    gotnow = oci->bufcnt + oci->buffer - oci->bufptr;
+    if (gotnow < sizeof(xReq))
+    {
+	YieldControlNoInput();
+    }
+    else
+    {
+	request = (xReq *)oci->bufptr;
+	needed = get_req_len(request, client);
+#ifdef BIGREQS
+	if (!needed && client->big_requests)
+	{
+	    oci->bufptr -= sizeof(xBigReq) - sizeof(xReq);
+	    *(xReq *)oci->bufptr = *request;
+	    ((xBigReq *)oci->bufptr)->length = client->req_len;
+	    if (client->swapped)
+	    {
+		char n;
+		swapl(&((xBigReq *)oci->bufptr)->length, n);
+	    }
+	}
+#endif
+	if (gotnow >= (needed << 2))
+	{
+	    if (FD_ISSET(fd, &AllClients))
+	    {
+		FD_SET(fd, &ClientsWithInput);
+	    }
+	    else
+	    {
+		FD_SET(fd, &IgnoredClientsWithInput);
+	    }
+	    YieldControl();
+	}
+	else
+	    YieldControlNoInput();
+    }
+}
+
+
+
+/*****************************************************************
+ *  PeekNextRequest and SkipRequests were implemented to support DBE 
+ *  idioms, but can certainly be used outside of DBE.  There are two 
+ *  related macros in os.h, ReqLen and CastxReq.  See the porting 
+ *  layer document for more details.
+ *
+ **********************/
+
+
+/*****************************************************************
+ *  PeekNextRequest
+ *      lets you look ahead at the unexecuted requests in a 
+ *      client's request buffer.
+ *
+ *      Note: this implementation of PeekNextRequest ignores the
+ *      readmore parameter.
+ *
+ **********************/
+
+xReqPtr
+PeekNextRequest(req, client, readmore)
+    xReqPtr req;	/* request we're starting from */
+    ClientPtr client;	/* client whose requests we're skipping */
+    Bool readmore;	/* attempt to read more if next request isn't there? */
+{
+    register ConnectionInputPtr oci = ((OsCommPtr)client->osPrivate)->input;
+    xReqPtr pnextreq;
+    int needed, gotnow, reqlen;
+
+    if (!oci) return NULL;
+
+    if (!req)
+    {
+	/* caller wants the request after the one currently being executed */
+	pnextreq = (xReqPtr)
+	    (((CARD32 *)client->requestBuffer) + client->req_len);
+    }
+    else
+    {
+	/* caller wants the request after the one specified by req */
+	reqlen = get_req_len(req, client);
+#ifdef BIGREQS
+	if (!reqlen) reqlen = get_big_req_len(req, client);
+#endif
+	pnextreq = (xReqPtr)(((char *)req) + (reqlen << 2));
+    }
+
+    /* see how much of the next request we have available */
+
+    gotnow = oci->bufcnt - (((char *)pnextreq) - oci->buffer);
+
+    if (gotnow < sizeof(xReq))
+	return NULL;
+
+    needed = get_req_len(pnextreq, client) << 2;
+#ifdef BIGREQS
+    if (!needed)
+    {
+	/* it's a big request */
+	if (gotnow < sizeof(xBigReq))
+	    return NULL;
+	needed = get_big_req_len(pnextreq, client) << 2;
+    }
+#endif
+
+    /* if we have less than we need, return NULL */
+
+    return (gotnow < needed) ? NULL : pnextreq;
+}
+
+/*****************************************************************
+ *  SkipRequests 
+ *      lets you skip over some of the requests in a client's
+ *      request buffer.  Presumably the caller has used PeekNextRequest
+ *      to examine the requests being skipped and has performed whatever 
+ *      actions they dictate.
+ *
+ **********************/
+
+CallbackListPtr SkippedRequestsCallback = NULL;
+
+void
+SkipRequests(req, client, numskipped)
+    xReqPtr req;	/* last request being skipped */
+    ClientPtr client;   /* client whose requests we're skipping */
+    int numskipped;	/* how many requests we're skipping */
+{
+    OsCommPtr oc = (OsCommPtr)client->osPrivate;
+    register ConnectionInputPtr oci = oc->input;
+    int reqlen;
+
+    /* see if anyone wants to snoop the skipped requests */
+
+    if (SkippedRequestsCallback)
+    {
+	SkippedRequestInfoRec skipinfo;
+	skipinfo.req = req;
+	skipinfo.client = client;
+	skipinfo.numskipped = numskipped;
+	CallCallbacks(&SkippedRequestsCallback, &skipinfo);
+    }
+
+    /* adjust the sequence number */
+    client->sequence += numskipped;
+
+    /* twiddle the oci to skip over the requests */
+
+    reqlen = get_req_len(req, client);
+#ifdef BIGREQS
+    if (!reqlen) reqlen = get_big_req_len(req, client);
+#endif
+    reqlen <<= 2;
+    oci->bufptr = (char *)req;
+    oci->lenLastReq = reqlen;
+
+    /* see if any requests left in the buffer */
+
+    if ( ((char *)req + reqlen) == (oci->buffer + oci->bufcnt) )
+    {
+	/* no requests; mark input buffer as available and client
+	 * as having no input
+	 */
+	int fd = oc->fd;
+	AvailableInput = oc;
+	YieldControlNoInput();
+    }
+}
+
+
+    /* lookup table for adding padding bytes to data that is read from
+    	or written to the X socket.  */
+static int padlength[4] = {0, 3, 2, 1};
+
+ /********************
+ * FlushAllOutput()
+ *    Flush all clients with output.  However, if some client still
+ *    has input in the queue (more requests), then don't flush.  This
+ *    will prevent the output queue from being flushed every time around
+ *    the round robin queue.  Now, some say that it SHOULD be flushed
+ *    every time around, but...
+ *
+ **********************/
+
+void
+FlushAllOutput()
+{
+    register int index, base, mask;
+    OsCommPtr oc;
+    register ClientPtr client;
+    Bool newoutput = NewOutputPending;
+#ifdef WIN32
+    fd_set newOutputPending;
+#endif
+
+    if (FlushCallback)
+	CallCallbacks(&FlushCallback, NULL);
+
+    if (!newoutput)
+	return;
+
+    /*
+     * It may be that some client still has critical output pending,
+     * but he is not yet ready to receive it anyway, so we will
+     * simply wait for the select to tell us when he's ready to receive.
+     */
+    CriticalOutputPending = FALSE;
+    NewOutputPending = FALSE;
+
+#ifndef WIN32
+    for (base = 0; base < howmany(XFD_SETSIZE, NFDBITS); base++)
+    {
+	mask = OutputPending.fds_bits[ base ];
+	OutputPending.fds_bits[ base ] = 0;
+	while (mask)
+	{
+	    index = ffs(mask) - 1;
+	    mask &= ~lowbit(mask);
+	    if ((index = ConnectionTranslation[(base << 5) + index]) == 0)
+		continue;
+	    client = clients[index];
+	    if (client->clientGone)
+		continue;
+	    oc = (OsCommPtr)client->osPrivate;
+	    if (
+#ifdef LBX
+		!oc->proxy &&
+#endif
+		FD_ISSET(oc->fd, &ClientsWithInput))
+	    {
+		FD_SET(oc->fd, &OutputPending); /* set the bit again */
+		NewOutputPending = TRUE;
+	    }
+	    else
+		(void)FlushClient(client, oc, (char *)NULL, 0);
+	}
+    }
+#else  /* WIN32 */
+    FD_ZERO(&newOutputPending);
+    for (base = 0; base < XFD_SETCOUNT(&OutputPending); base++)
+    {
+	    index = XFD_FD(&OutputPending, base);
+	    if ((index = ConnectionTranslation[index]) == 0)
+		continue;
+	    client = clients[index];
+	    if (client->clientGone)
+		continue;
+	    oc = (OsCommPtr)client->osPrivate;
+	    if (
+#ifdef LBX
+		!oc->proxy &&
+#endif
+		FD_ISSET(oc->fd, &ClientsWithInput))
+	    {
+		FD_SET(oc->fd, &newOutputPending); /* set the bit again */
+		NewOutputPending = TRUE;
+	    }
+	    else
+		(void)FlushClient(client, oc, (char *)NULL, 0);
+    }
+    XFD_COPYSET(&newOutputPending, &OutputPending);
+#endif /* WIN32 */
+}
+
+void
+FlushIfCriticalOutputPending()
+{
+    if (CriticalOutputPending)
+	FlushAllOutput();
+}
+
+void
+SetCriticalOutputPending()
+{
+    CriticalOutputPending = TRUE;
+}
+
+/*****************
+ * WriteToClient
+ *    Copies buf into ClientPtr.buf if it fits (with padding), else
+ *    flushes ClientPtr.buf and buf to client.  As of this writing,
+ *    every use of WriteToClient is cast to void, and the result
+ *    is ignored.  Potentially, this could be used by requests
+ *    that are sending several chunks of data and want to break
+ *    out of a loop on error.  Thus, we will leave the type of
+ *    this routine as int.
+ *****************/
+
+int
+WriteToClient (who, count, buf)
+    ClientPtr who;
+    char *buf;
+    int count;
+{
+    OsCommPtr oc = (OsCommPtr)who->osPrivate;
+    register ConnectionOutputPtr oco = oc->output;
+    int padBytes;
+
+    if (!count)
+	return(0);
+
+    if (!oco)
+    {
+	if (oco = FreeOutputs)
+	{
+	    FreeOutputs = oco->next;
+	}
+	else if (!(oco = AllocateOutputBuffer()))
+	{
+	    if (oc->trans_conn) {
+		_XSERVTransDisconnect(oc->trans_conn);
+		_XSERVTransClose(oc->trans_conn);
+		oc->trans_conn = NULL;
+	    }
+	    MarkClientException(who);
+	    return -1;
+	}
+	oc->output = oco;
+    }
+
+    padBytes = padlength[count & 3];
+
+    if(ReplyCallback)
+    {
+        ReplyInfoRec replyinfo;
+
+	replyinfo.client = who;
+	replyinfo.replyData = buf;
+	replyinfo.dataLenBytes = count + padBytes;
+	if (who->replyBytesRemaining)
+	{ /* still sending data of an earlier reply */
+	    who->replyBytesRemaining -= count + padBytes;
+	    replyinfo.startOfReply = FALSE;
+	    replyinfo.bytesRemaining = who->replyBytesRemaining;
+	    CallCallbacks((&ReplyCallback), (pointer)&replyinfo);
+	}
+	else if (who->clientState == ClientStateRunning
+		 && buf[0] == X_Reply)
+        { /* start of new reply */
+	    CARD32 replylen;
+	    unsigned long bytesleft;
+	    char n;
+
+	    replylen = ((xGenericReply *)buf)->length;
+	    if (who->swapped)
+		swapl(&replylen, n);
+	    bytesleft = (replylen * 4) + SIZEOF(xReply) - count - padBytes;
+	    replyinfo.startOfReply = TRUE;
+	    replyinfo.bytesRemaining = who->replyBytesRemaining = bytesleft;
+	    CallCallbacks((&ReplyCallback), (pointer)&replyinfo);
+	} 	                      
+    } 
+  
+    if (oco->count + count + padBytes > oco->size)
+    {
+	FD_CLR(oc->fd, &OutputPending);
+	if(!XFD_ANYSET(&OutputPending)) {
+		CriticalOutputPending = FALSE;
+		NewOutputPending = FALSE;
+	}
+	return FlushClient(who, oc, buf, count);
+    }
+
+    NewOutputPending = TRUE;
+    FD_SET(oc->fd, &OutputPending);
+    memmove((char *)oco->buf + oco->count, buf, count);
+    oco->count += count + padBytes;
+    return(count);
+}
+
+ /********************
+ * FlushClient()
+ *    If the client isn't keeping up with us, then we try to continue
+ *    buffering the data and set the apropriate bit in ClientsWritable
+ *    (which is used by WaitFor in the select).  If the connection yields
+ *    a permanent error, or we can't allocate any more space, we then
+ *    close the connection.
+ *
+ **********************/
+
+#ifdef LBX
+#ifdef LBX_NEED_OLD_SYMBOL_FOR_LOADABLES
+#undef FlushClient
+int
+FlushClient(who, oc, extraBuf, extraCount)
+    ClientPtr who;
+    OsCommPtr oc;
+    char *extraBuf;
+    int extraCount;
+{
+    return (*oc->Flush)(who, oc, extraBuf, extraCount);
+}
+#endif
+int
+StandardFlushClient(who, oc, extraBuf, extraCount)
+#else
+int
+FlushClient(who, oc, extraBuf, extraCount)
+#endif
+    ClientPtr who;
+    OsCommPtr oc;
+    char *extraBuf;
+    int extraCount; /* do not modify... returned below */
+{
+    register ConnectionOutputPtr oco = oc->output;
+    int connection = oc->fd;
+    XtransConnInfo trans_conn = oc->trans_conn;
+    struct iovec iov[3];
+    static char padBuffer[3];
+    long written;
+    long padsize;
+    long notWritten;
+    long todo;
+
+    if (!oco)
+	return 0;
+    written = 0;
+    padsize = padlength[extraCount & 3];
+    notWritten = oco->count + extraCount + padsize;
+    todo = notWritten;
+    while (notWritten) {
+	long before = written;	/* amount of whole thing written */
+	long remain = todo;	/* amount to try this time, <= notWritten */
+	int i = 0;
+	long len;
+
+	/* You could be very general here and have "in" and "out" iovecs
+	 * and write a loop without using a macro, but what the heck.  This
+	 * translates to:
+	 *
+	 *     how much of this piece is new?
+	 *     if more new then we are trying this time, clamp
+	 *     if nothing new
+	 *         then bump down amount already written, for next piece
+	 *         else put new stuff in iovec, will need all of next piece
+	 *
+	 * Note that todo had better be at least 1 or else we'll end up
+	 * writing 0 iovecs.
+	 */
+#define InsertIOV(pointer, length) \
+	len = (length) - before; \
+	if (len > remain) \
+	    len = remain; \
+	if (len <= 0) { \
+	    before = (-len); \
+	} else { \
+	    iov[i].iov_len = len; \
+	    iov[i].iov_base = (pointer) + before; \
+	    i++; \
+	    remain -= len; \
+	    before = 0; \
+	}
+
+	InsertIOV ((char *)oco->buf, oco->count)
+	InsertIOV (extraBuf, extraCount)
+	InsertIOV (padBuffer, padsize)
+
+	errno = 0;
+	if (trans_conn && (len = _XSERVTransWritev(trans_conn, iov, i)) >= 0)
+	{
+	    written += len;
+	    notWritten -= len;
+	    todo = notWritten;
+	}
+	else if (ETEST(errno)
+#ifdef SUNSYSV /* check for another brain-damaged OS bug */
+		 || (errno == 0)
+#endif
+#ifdef EMSGSIZE /* check for another brain-damaged OS bug */
+		 || ((errno == EMSGSIZE) && (todo == 1))
+#endif
+		)
+	{
+	    /* If we've arrived here, then the client is stuffed to the gills
+	       and not ready to accept more.  Make a note of it and buffer
+	       the rest. */
+	    FD_SET(connection, &ClientsWriteBlocked);
+	    AnyClientsWriteBlocked = TRUE;
+
+	    if (written < oco->count)
+	    {
+		if (written > 0)
+		{
+		    oco->count -= written;
+		    memmove((char *)oco->buf,
+			    (char *)oco->buf + written,
+			  oco->count);
+		    written = 0;
+		}
+	    }
+	    else
+	    {
+		written -= oco->count;
+		oco->count = 0;
+	    }
+
+	    if (notWritten > oco->size)
+	    {
+		unsigned char *obuf;
+
+		obuf = (unsigned char *)xrealloc(oco->buf,
+						 notWritten + BUFSIZE);
+		if (!obuf)
+		{
+		    _XSERVTransDisconnect(oc->trans_conn);
+		    _XSERVTransClose(oc->trans_conn);
+		    oc->trans_conn = NULL;
+		    MarkClientException(who);
+		    oco->count = 0;
+		    return(-1);
+		}
+		oco->size = notWritten + BUFSIZE;
+		oco->buf = obuf;
+	    }
+
+	    /* If the amount written extended into the padBuffer, then the
+	       difference "extraCount - written" may be less than 0 */
+	    if ((len = extraCount - written) > 0)
+		memmove ((char *)oco->buf + oco->count,
+			 extraBuf + written,
+		       len);
+
+	    oco->count = notWritten; /* this will include the pad */
+	    /* return only the amount explicitly requested */
+	    return extraCount;
+	}
+#ifdef EMSGSIZE /* check for another brain-damaged OS bug */
+	else if (errno == EMSGSIZE)
+	{
+	    todo >>= 1;
+	}
+#endif
+	else
+	{
+	    if (oc->trans_conn)
+	    {
+		_XSERVTransDisconnect(oc->trans_conn);
+		_XSERVTransClose(oc->trans_conn);
+		oc->trans_conn = NULL;
+	    }
+	    MarkClientException(who);
+	    oco->count = 0;
+	    return(-1);
+	}
+    }
+
+    /* everything was flushed out */
+    oco->count = 0;
+    /* check to see if this client was write blocked */
+    if (AnyClientsWriteBlocked)
+    {
+	FD_CLR(oc->fd, &ClientsWriteBlocked);
+ 	if (! XFD_ANYSET(&ClientsWriteBlocked))
+	    AnyClientsWriteBlocked = FALSE;
+    }
+    if (oco->size > BUFWATERMARK)
+    {
+	xfree(oco->buf);
+	xfree(oco);
+    }
+    else
+    {
+	oco->next = FreeOutputs;
+	FreeOutputs = oco;
+    }
+    oc->output = (ConnectionOutputPtr)NULL;
+    return extraCount; /* return only the amount explicitly requested */
+}
+
+ConnectionInputPtr
+AllocateInputBuffer()
+{
+    register ConnectionInputPtr oci;
+
+    oci = (ConnectionInputPtr)xalloc(sizeof(ConnectionInput));
+    if (!oci)
+	return (ConnectionInputPtr)NULL;
+    oci->buffer = (char *)xalloc(BUFSIZE);
+    if (!oci->buffer)
+    {
+	xfree(oci);
+	return (ConnectionInputPtr)NULL;
+    }
+    oci->size = BUFSIZE;
+    oci->bufptr = oci->buffer;
+    oci->bufcnt = 0;
+    oci->lenLastReq = 0;
+    return oci;
+}
+
+ConnectionOutputPtr
+AllocateOutputBuffer()
+{
+    register ConnectionOutputPtr oco;
+
+    oco = (ConnectionOutputPtr)xalloc(sizeof(ConnectionOutput));
+    if (!oco)
+	return (ConnectionOutputPtr)NULL;
+    oco->buf = (unsigned char *) xalloc(BUFSIZE);
+    if (!oco->buf)
+    {
+	xfree(oco);
+	return (ConnectionOutputPtr)NULL;
+    }
+    oco->size = BUFSIZE;
+    oco->count = 0;
+#ifdef LBX
+    oco->nocompress = FALSE;
+#endif
+    return oco;
+}
+
+void
+FreeOsBuffers(oc)
+    OsCommPtr oc;
+{
+    register ConnectionInputPtr oci;
+    register ConnectionOutputPtr oco;
+
+    if (AvailableInput == oc)
+	AvailableInput = (OsCommPtr)NULL;
+    if (oci = oc->input)
+    {
+	if (FreeInputs)
+	{
+	    xfree(oci->buffer);
+	    xfree(oci);
+	}
+	else
+	{
+	    FreeInputs = oci;
+	    oci->next = (ConnectionInputPtr)NULL;
+	    oci->bufptr = oci->buffer;
+	    oci->bufcnt = 0;
+	    oci->lenLastReq = 0;
+	}
+    }
+    if (oco = oc->output)
+    {
+	if (FreeOutputs)
+	{
+	    xfree(oco->buf);
+	    xfree(oco);
+	}
+	else
+	{
+	    FreeOutputs = oco;
+	    oco->next = (ConnectionOutputPtr)NULL;
+	    oco->count = 0;
+	}
+    }
+#ifdef LBX
+    if (oci = oc->largereq) {
+	xfree(oci->buffer);
+	xfree(oci);
+    }
+#endif
+}
+
+void
+ResetOsBuffers()
+{
+    register ConnectionInputPtr oci;
+    register ConnectionOutputPtr oco;
+
+    while (oci = FreeInputs)
+    {
+	FreeInputs = oci->next;
+	xfree(oci->buffer);
+	xfree(oci);
+    }
+    while (oco = FreeOutputs)
+    {
+	FreeOutputs = oco->next;
+	xfree(oco->buf);
+	xfree(oco);
+    }
+}