io.c

远程桌面连接工具

/***********************************************************

Copyright (c) 1987, 1989  X Consortium

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

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
X CONSORTIUM 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 X Consortium 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 X Consortium.


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.

******************************************************************/
/* $XConsortium: io.c /main/72 1996/12/27 15:40:56 rws $ */
/* $XFree86: xc/programs/Xserver/os/io.c,v 3.15 1997/01/18 06:58:00 dawes 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>
#if !defined(AMOEBA) && !defined(MINIX) && !defined(__EMX__) && !defined(WIN32)
#ifndef Lynx
#include <sys/uio.h>
#else
#include <uio.h>
#endif
#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
 */
#ifndef __EMX__
#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
#else /* __EMX__  Writing to full pipes may return ENOSPC */
#define ETEST(err) (err == EAGAIN || err == EWOULDBLOCK || err == ENOSPC)
#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; }

#if defined(LBX) || defined(LBX_COMPAT)
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 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))
	    {
#if defined(SVR4) && defined(i386) && !defined(sun)
#if defined(LBX) && 0
		/*
		 * For LBX connections, we can get a valid EWOULDBLOCK
		 * There is probably a better way of distinguishing LBX
		 * connections, but this works. (DHD)
		 */
		extern int LbxRead();
		if (oc->Read == LbxRead)
#else
		if (0)
#endif
#endif
		{
		    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);
	    }