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   1 /* Copyright (C) 2001-2004 Bart Massey and Jamey Sharp.
   2  *
   3  * Permission is hereby granted, free of charge, to any person obtaining a
   4  * copy of this software and associated documentation files (the "Software"),
   5  * to deal in the Software without restriction, including without limitation
   6  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   7  * and/or sell copies of the Software, and to permit persons to whom the
   8  * Software is furnished to do so, subject to the following conditions:
   9  *
  10  * The above copyright notice and this permission notice shall be included in
  11  * all copies or substantial portions of the Software.
  12  *
  13  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  14  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  15  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  16  * AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  17  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  18  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  19  *
  20  * Except as contained in this notice, the names of the authors or their
  21  * institutions shall not be used in advertising or otherwise to promote the
  22  * sale, use or other dealings in this Software without prior written
  23  * authorization from the authors.
  24  */
  25
  26 /* Stuff that reads stuff from the server. */
  27
  28 #include <assert.h>
  29 #include <string.h>
  30 #include <stdlib.h>
  31 #include <unistd.h>
  32 #include <stdio.h>
  33 #include <errno.h>
  34
  35 #include "xcb.h"
  36 #include "xcbext.h"
  37 #include "xcbint.h"
  38 #if USE_POLL
  39 #include <poll.h>
  40 #endif
  41 #ifndef _WIN32
  42 #include <sys/select.h>
  43 #include <sys/socket.h>
  44 #endif
  45
  46 #ifdef _WIN32
  47 #include "xcb_windefs.h"
  48 #endif /* _WIN32 */
  49
  50 #define XCB_ERROR 0
  51 #define XCB_REPLY 1
  52 #define XCB_XGE_EVENT 35
  53
  54 /* required for compiling for Win32 using MinGW */
  55 #ifndef MSG_WAITALL
  56 #define MSG_WAITALL 0
  57 #endif
  58
  59 struct event_list {
  60     xcb_generic_event_t *event;
  61     struct event_list *next;
  62 };
  63
  64 struct reply_list {
  65     void *reply;
  66     struct reply_list *next;
  67 };
  68
  69 typedef struct pending_reply {
  70     uint64_t first_request;
  71     uint64_t last_request;
  72     enum workarounds workaround;
  73     int flags;
  74     struct pending_reply *next;
  75 } pending_reply;
  76
  77 typedef struct reader_list {
  78     uint64_t request;
  79     pthread_cond_t *data;
  80     struct reader_list *next;
  81 } reader_list;
  82
  83 static void remove_finished_readers(reader_list **prev_reader, uint64_t completed)
  84 {
  85     while(*prev_reader && XCB_SEQUENCE_COMPARE((*prev_reader)->request, <=, completed))
  86     {
  87         /* If you don't have what you're looking for now, you never
  88          * will. Wake up and leave me alone. */
  89         pthread_cond_signal((*prev_reader)->data);
  90         *prev_reader = (*prev_reader)->next;
  91     }
  92 }
  93
  94 static int read_packet(xcb_connection_t *c)
  95 {
  96     xcb_generic_reply_t genrep;
  97     int length = 32;
  98     int eventlength = 0; /* length after first 32 bytes for GenericEvents */
  99     void *buf;
 100     pending_reply *pend = 0;
 101     struct event_list *event;
 102
 103     /* Wait for there to be enough data for us to read a whole packet */
 104     if(c->in.queue_len < length)
 105         return 0;
 106
 107     /* Get the response type, length, and sequence number. */
 108     memcpy(&genrep, c->in.queue, sizeof(genrep));
 109
 110     /* Compute 32-bit sequence number of this packet. */
 111     if((genrep.response_type & 0x7f) != XCB_KEYMAP_NOTIFY)
 112     {
 113         uint64_t lastread = c->in.request_read;
 114         c->in.request_read = (lastread & UINT64_C(0xffffffffffff0000)) | genrep.sequence;
 115         if(XCB_SEQUENCE_COMPARE(c->in.request_read, <, lastread))
 116             c->in.request_read += 0x10000;
 117         if(XCB_SEQUENCE_COMPARE(c->in.request_read, >, c->in.request_expected))
 118             c->in.request_expected = c->in.request_read;
 119
 120         if(c->in.request_read != lastread)
 121         {
 122             if(c->in.current_reply)
 123             {
 124                 _xcb_map_put(c->in.replies, lastread, c->in.current_reply);
 125                 c->in.current_reply = 0;
 126                 c->in.current_reply_tail = &c->in.current_reply;
 127             }
 128             c->in.request_completed = c->in.request_read - 1;
 129         }
 130
 131         while(c->in.pending_replies &&
 132               c->in.pending_replies->workaround != WORKAROUND_EXTERNAL_SOCKET_OWNER &&
 133               XCB_SEQUENCE_COMPARE (c->in.pending_replies->last_request, <=, c->in.request_completed))
 134         {
 135             pending_reply *oldpend = c->in.pending_replies;
 136             c->in.pending_replies = oldpend->next;
 137             if(!oldpend->next)
 138                 c->in.pending_replies_tail = &c->in.pending_replies;
 139             free(oldpend);
 140         }
 141
 142         if(genrep.response_type == XCB_ERROR)
 143             c->in.request_completed = c->in.request_read;
 144
 145         remove_finished_readers(&c->in.readers, c->in.request_completed);
 146     }
 147
 148     if(genrep.response_type == XCB_ERROR || genrep.response_type == XCB_REPLY)
 149     {
 150         pend = c->in.pending_replies;
 151         if(pend &&
 152            !(XCB_SEQUENCE_COMPARE(pend->first_request, <=, c->in.request_read) &&
 153              (pend->workaround == WORKAROUND_EXTERNAL_SOCKET_OWNER ||
 154               XCB_SEQUENCE_COMPARE(c->in.request_read, <=, pend->last_request))))
 155             pend = 0;
 156     }
 157
 158     /* For reply packets, check that the entire packet is available. */
 159     if(genrep.response_type == XCB_REPLY)
 160     {
 161         if(pend && pend->workaround == WORKAROUND_GLX_GET_FB_CONFIGS_BUG)
 162         {
 163             uint32_t *p = (uint32_t *) c->in.queue;
 164             genrep.length = p[2] * p[3] * 2;
 165         }
 166         length += genrep.length * 4;
 167     }
 168
 169     /* XGE events may have sizes > 32 */
 170     if ((genrep.response_type & 0x7f) == XCB_XGE_EVENT)
 171         eventlength = genrep.length * 4;
 172
 173     buf = malloc(length + eventlength +
 174             (genrep.response_type == XCB_REPLY ? 0 : sizeof(uint32_t)));
 175     if(!buf)
 176     {
 177         _xcb_conn_shutdown(c);
 178         return 0;
 179     }
 180
 181     if(_xcb_in_read_block(c, buf, length) <= 0)
 182     {
 183         free(buf);
 184         return 0;
 185     }
 186
 187     /* pull in XGE event data if available, append after event struct */
 188     if (eventlength)
 189     {
 190         if(_xcb_in_read_block(c, &((xcb_generic_event_t*)buf)[1], eventlength) <= 0)
 191         {
 192             free(buf);
 193             return 0;
 194         }
 195     }
 196
 197     if(pend && (pend->flags & XCB_REQUEST_DISCARD_REPLY))
 198     {
 199         free(buf);
 200         return 1;
 201     }
 202
 203     if(genrep.response_type != XCB_REPLY)
 204         ((xcb_generic_event_t *) buf)->full_sequence = c->in.request_read;
 205
 206     /* reply, or checked error */
 207     if( genrep.response_type == XCB_REPLY ||
 208        (genrep.response_type == XCB_ERROR && pend && (pend->flags & XCB_REQUEST_CHECKED)))
 209     {
 210         struct reply_list *cur = malloc(sizeof(struct reply_list));
 211         if(!cur)
 212         {
 213             _xcb_conn_shutdown(c);
 214             free(buf);
 215             return 0;
 216         }
 217         cur->reply = buf;
 218         cur->next = 0;
 219         *c->in.current_reply_tail = cur;
 220         c->in.current_reply_tail = &cur->next;
 221         if(c->in.readers && c->in.readers->request == c->in.request_read)
 222             pthread_cond_signal(c->in.readers->data);
 223         return 1;
 224     }
 225
 226     /* event, or unchecked error */
 227     event = malloc(sizeof(struct event_list));
 228     if(!event)
 229     {
 230         _xcb_conn_shutdown(c);
 231         free(buf);
 232         return 0;
 233     }
 234     event->event = buf;
 235     event->next = 0;
 236     *c->in.events_tail = event;
 237     c->in.events_tail = &event->next;
 238     pthread_cond_signal(&c->in.event_cond);
 239     return 1; /* I have something for you... */
 240 }
 241
 242 static xcb_generic_event_t *get_event(xcb_connection_t *c)
 243 {
 244     struct event_list *cur = c->in.events;
 245     xcb_generic_event_t *ret;
 246     if(!c->in.events)
 247         return 0;
 248     ret = cur->event;
 249     c->in.events = cur->next;
 250     if(!cur->next)
 251         c->in.events_tail = &c->in.events;
 252     free(cur);
 253     return ret;
 254 }
 255
 256 static void free_reply_list(struct reply_list *head)
 257 {
 258     while(head)
 259     {
 260         struct reply_list *cur = head;
 261         head = cur->next;
 262         free(cur->reply);
 263         free(cur);
 264     }
 265 }
 266
 267 static int read_block(const int fd, void *buf, const ssize_t len)
 268 {
 269     int done = 0;
 270     while(done < len)
 271     {
 272         int ret = recv(fd, ((char *) buf) + done, len - done,MSG_WAITALL);
 273         if(ret > 0)
 274             done += ret;
 275 #ifndef _WIN32
 276         if(ret < 0 && errno == EAGAIN)
 277 #else
 278         if(ret == SOCKET_ERROR && WSAGetLastError() == WSAEWOULDBLOCK)
 279 #endif /* !_Win32 */
 280         {
 281 #if USE_POLL
 282             struct pollfd pfd;
 283             pfd.fd = fd;
 284             pfd.events = POLLIN;
 285             pfd.revents = 0;
 286             do {
 287                 ret = poll(&pfd, 1, -1);
 288             } while (ret == -1 && errno == EINTR);
 289 #else
 290             fd_set fds;
 291             FD_ZERO(&fds);
 292             FD_SET(fd, &fds);
 293
 294             /* Initializing errno here makes sure that for Win32 this loop will execute only once */
 295             errno = 0;
 296             do {
 297                 ret = select(fd + 1, &fds, 0, 0, 0);
 298             } while (ret == -1 && errno == EINTR);
 299 #endif /* USE_POLL */
 300         }
 301         if(ret <= 0)
 302             return ret;
 303     }
 304     return len;
 305 }
 306
 307 static int poll_for_reply(xcb_connection_t *c, uint64_t request, void **reply, xcb_generic_error_t **error)
 308 {
 309     struct reply_list *head;
 310
 311     /* If an error occurred when issuing the request, fail immediately. */
 312     if(!request)
 313         head = 0;
 314     /* We've read requests past the one we want, so if it has replies we have
 315      * them all and they're in the replies map. */
 316     else if(XCB_SEQUENCE_COMPARE(request, <, c->in.request_read))
 317     {
 318         head = _xcb_map_remove(c->in.replies, request);
 319         if(head && head->next)
 320             _xcb_map_put(c->in.replies, request, head->next);
 321     }
 322     /* We're currently processing the responses to the request we want, and we
 323      * have a reply ready to return. So just return it without blocking. */
 324     else if(request == c->in.request_read && c->in.current_reply)
 325     {
 326         head = c->in.current_reply;
 327         c->in.current_reply = head->next;
 328         if(!head->next)
 329             c->in.current_reply_tail = &c->in.current_reply;
 330     }
 331     /* We know this request can't have any more replies, and we've already
 332      * established it doesn't have a reply now. Don't bother blocking. */
 333     else if(request == c->in.request_completed)
 334         head = 0;
 335     /* We may have more replies on the way for this request: block until we're
 336      * sure. */
 337     else
 338         return 0;
 339
 340     if(error)
 341         *error = 0;
 342     *reply = 0;
 343
 344     if(head)
 345     {
 346         if(((xcb_generic_reply_t *) head->reply)->response_type == XCB_ERROR)
 347         {
 348             if(error)
 349                 *error = head->reply;
 350             else
 351                 free(head->reply);
 352         }
 353         else
 354             *reply = head->reply;
 355
 356         free(head);
 357     }
 358
 359     return 1;
 360 }
 361
 362 static void insert_reader(reader_list **prev_reader, reader_list *reader, uint64_t request, pthread_cond_t *cond)
 363 {
 364     while(*prev_reader && XCB_SEQUENCE_COMPARE((*prev_reader)->request, <=, request))
 365         prev_reader = &(*prev_reader)->next;
 366     reader->request = request;
 367     reader->data = cond;
 368     reader->next = *prev_reader;
 369     *prev_reader = reader;
 370 }
 371
 372 static void remove_reader(reader_list **prev_reader, reader_list *reader)
 373 {
 374     while(*prev_reader && XCB_SEQUENCE_COMPARE((*prev_reader)->request, <=, reader->request))
 375         if(*prev_reader == reader)
 376         {
 377             *prev_reader = (*prev_reader)->next;
 378             break;
 379         }
 380 }
 381
 382 static void *wait_for_reply(xcb_connection_t *c, uint64_t request, xcb_generic_error_t **e)
 383 {
 384     void *ret = 0;
 385
 386     /* If this request has not been written yet, write it. */
 387     if(c->out.return_socket || _xcb_out_flush_to(c, request))
 388     {
 389         pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
 390         reader_list reader;
 391
 392         insert_reader(&c->in.readers, &reader, request, &cond);
 393
 394         while(!poll_for_reply(c, request, &ret, e))
 395             if(!_xcb_conn_wait(c, &cond, 0, 0))
 396                 break;
 397
 398         remove_reader(&c->in.readers, &reader);
 399         pthread_cond_destroy(&cond);
 400     }
 401
 402     _xcb_in_wake_up_next_reader(c);
 403     return ret;
 404 }
 405
 406 static uint64_t widen(xcb_connection_t *c, unsigned int request)
 407 {
 408     uint64_t widened_request = (c->out.request & UINT64_C(0xffffffff00000000)) | request;
 409     if(widened_request > c->out.request)
 410         widened_request -= UINT64_C(1) << 32;
 411     return widened_request;
 412 }
 413
 414 /* Public interface */
 415
 416 void *xcb_wait_for_reply(xcb_connection_t *c, unsigned int request, xcb_generic_error_t **e)
 417 {
 418     void *ret;
 419     if(e)
 420         *e = 0;
 421     if(c->has_error)
 422         return 0;
 423
 424     pthread_mutex_lock(&c->iolock);
 425     ret = wait_for_reply(c, widen(c, request), e);
 426     pthread_mutex_unlock(&c->iolock);
 427     return ret;
 428 }
 429
 430 static void insert_pending_discard(xcb_connection_t *c, pending_reply **prev_next, uint64_t seq)
 431 {
 432     pending_reply *pend;
 433     pend = malloc(sizeof(*pend));
 434     if(!pend)
 435     {
 436         _xcb_conn_shutdown(c);
 437         return;
 438     }
 439
 440     pend->first_request = seq;
 441     pend->last_request = seq;
 442     pend->workaround = 0;
 443     pend->flags = XCB_REQUEST_DISCARD_REPLY;
 444     pend->next = *prev_next;
 445     *prev_next = pend;
 446
 447     if(!pend->next)
 448         c->in.pending_replies_tail = &pend->next;
 449 }
 450
 451 static void discard_reply(xcb_connection_t *c, uint64_t request)
 452 {
 453     void *reply;
 454     pending_reply **prev_pend;
 455
 456     /* Free any replies or errors that we've already read. Stop if
 457      * xcb_wait_for_reply would block or we've run out of replies. */
 458     while(poll_for_reply(c, request, &reply, 0) && reply)
 459         free(reply);
 460
 461     /* If we've proven there are no more responses coming, we're done. */
 462     if(XCB_SEQUENCE_COMPARE(request, <=, c->in.request_completed))
 463         return;
 464
 465     /* Walk the list of pending requests. Mark the first match for deletion. */
 466     for(prev_pend = &c->in.pending_replies; *prev_pend; prev_pend = &(*prev_pend)->next)
 467     {
 468         if(XCB_SEQUENCE_COMPARE((*prev_pend)->first_request, >, request))
 469             break;
 470
 471         if((*prev_pend)->first_request == request)
 472         {
 473             /* Pending reply found. Mark for discard: */
 474             (*prev_pend)->flags |= XCB_REQUEST_DISCARD_REPLY;
 475             return;
 476         }
 477     }
 478
 479     /* Pending reply not found (likely due to _unchecked request). Create one: */
 480     insert_pending_discard(c, prev_pend, request);
 481 }
 482
 483 void xcb_discard_reply(xcb_connection_t *c, unsigned int sequence)
 484 {
 485     if(c->has_error)
 486         return;
 487
 488     /* If an error occurred when issuing the request, fail immediately. */
 489     if(!sequence)
 490         return;
 491
 492     pthread_mutex_lock(&c->iolock);
 493     discard_reply(c, widen(c, sequence));
 494     pthread_mutex_unlock(&c->iolock);
 495 }
 496
 497 int xcb_poll_for_reply(xcb_connection_t *c, unsigned int request, void **reply, xcb_generic_error_t **error)
 498 {
 499     int ret;
 500     if(c->has_error)
 501     {
 502         *reply = 0;
 503         if(error)
 504             *error = 0;
 505         return 1; /* would not block */
 506     }
 507     assert(reply != 0);
 508     pthread_mutex_lock(&c->iolock);
 509     ret = poll_for_reply(c, widen(c, request), reply, error);
 510     pthread_mutex_unlock(&c->iolock);
 511     return ret;
 512 }
 513
 514 xcb_generic_event_t *xcb_wait_for_event(xcb_connection_t *c)
 515 {
 516     xcb_generic_event_t *ret;
 517     if(c->has_error)
 518         return 0;
 519     pthread_mutex_lock(&c->iolock);
 520     /* get_event returns 0 on empty list. */
 521     while(!(ret = get_event(c)))
 522         if(!_xcb_conn_wait(c, &c->in.event_cond, 0, 0))
 523             break;
 524
 525     _xcb_in_wake_up_next_reader(c);
 526     pthread_mutex_unlock(&c->iolock);
 527     return ret;
 528 }
 529
 530 static xcb_generic_event_t *poll_for_next_event(xcb_connection_t *c, int queued)
 531 {
 532     xcb_generic_event_t *ret = 0;
 533     if(!c->has_error)
 534     {
 535         pthread_mutex_lock(&c->iolock);
 536         /* FIXME: follow X meets Z architecture changes. */
 537         ret = get_event(c);
 538         if(!ret && !queued && _xcb_in_read(c)) /* _xcb_in_read shuts down the connection on error */
 539             ret = get_event(c);
 540         pthread_mutex_unlock(&c->iolock);
 541     }
 542     return ret;
 543 }
 544
 545 xcb_generic_event_t *xcb_poll_for_event(xcb_connection_t *c)
 546 {
 547     return poll_for_next_event(c, 0);
 548 }
 549
 550 xcb_generic_event_t *xcb_poll_for_queued_event(xcb_connection_t *c)
 551 {
 552     return poll_for_next_event(c, 1);
 553 }
 554
 555 xcb_generic_error_t *xcb_request_check(xcb_connection_t *c, xcb_void_cookie_t cookie)
 556 {
 557     uint64_t request;
 558     xcb_generic_error_t *ret = 0;
 559     void *reply;
 560     if(c->has_error)
 561         return 0;
 562     pthread_mutex_lock(&c->iolock);
 563     request = widen(c, cookie.sequence);
 564     if(XCB_SEQUENCE_COMPARE(request, >=, c->in.request_expected)
 565        && XCB_SEQUENCE_COMPARE(request, >, c->in.request_completed))
 566     {
 567         _xcb_out_send_sync(c);
 568         _xcb_out_flush_to(c, c->out.request);
 569     }
 570     reply = wait_for_reply(c, request, &ret);
 571     assert(!reply);
 572     pthread_mutex_unlock(&c->iolock);
 573     return ret;
 574 }
 575
 576 /* Private interface */
 577
 578 int _xcb_in_init(_xcb_in *in)
 579 {
 580     if(pthread_cond_init(&in->event_cond, 0))
 581         return 0;
 582     in->reading = 0;
 583
 584     in->queue_len = 0;
 585
 586     in->request_read = 0;
 587     in->request_completed = 0;
 588
 589     in->replies = _xcb_map_new();
 590     if(!in->replies)
 591         return 0;
 592
 593     in->current_reply_tail = &in->current_reply;
 594     in->events_tail = &in->events;
 595     in->pending_replies_tail = &in->pending_replies;
 596
 597     return 1;
 598 }
 599
 600 void _xcb_in_destroy(_xcb_in *in)
 601 {
 602     pthread_cond_destroy(&in->event_cond);
 603     free_reply_list(in->current_reply);
 604     _xcb_map_delete(in->replies, (void (*)(void *)) free_reply_list);
 605     while(in->events)
 606     {
 607         struct event_list *e = in->events;
 608         in->events = e->next;
 609         free(e->event);
 610         free(e);
 611     }
 612     while(in->pending_replies)
 613     {
 614         pending_reply *pend = in->pending_replies;
 615         in->pending_replies = pend->next;
 616         free(pend);
 617     }
 618 }
 619
 620 void _xcb_in_wake_up_next_reader(xcb_connection_t *c)
 621 {
 622     int pthreadret;
 623     if(c->in.readers)
 624         pthreadret = pthread_cond_signal(c->in.readers->data);
 625     else
 626         pthreadret = pthread_cond_signal(&c->in.event_cond);
 627     assert(pthreadret == 0);
 628 }
 629
 630 int _xcb_in_expect_reply(xcb_connection_t *c, uint64_t request, enum workarounds workaround, int flags)
 631 {
 632     pending_reply *pend = malloc(sizeof(pending_reply));
 633     assert(workaround != WORKAROUND_NONE || flags != 0);
 634     if(!pend)
 635     {
 636         _xcb_conn_shutdown(c);
 637         return 0;
 638     }
 639     pend->first_request = pend->last_request = request;
 640     pend->workaround = workaround;
 641     pend->flags = flags;
 642     pend->next = 0;
 643     *c->in.pending_replies_tail = pend;
 644     c->in.pending_replies_tail = &pend->next;
 645     return 1;
 646 }
 647
 648 void _xcb_in_replies_done(xcb_connection_t *c)
 649 {
 650     struct pending_reply *pend;
 651     if (c->in.pending_replies_tail != &c->in.pending_replies)
 652     {
 653         pend = container_of(c->in.pending_replies_tail, struct pending_reply, next);
 654         if(pend->workaround == WORKAROUND_EXTERNAL_SOCKET_OWNER)
 655         {
 656             pend->last_request = c->out.request;
 657             pend->workaround = WORKAROUND_NONE;
 658         }
 659     }
 660 }
 661
 662 int _xcb_in_read(xcb_connection_t *c)
 663 {
 664     int n = recv(c->fd, c->in.queue + c->in.queue_len, sizeof(c->in.queue) - c->in.queue_len,MSG_WAITALL);
 665     if(n > 0)
 666         c->in.queue_len += n;
 667     while(read_packet(c))
 668         /* empty */;
 669 #ifndef _WIN32
 670     if((n > 0) || (n < 0 && errno == EAGAIN))
 671 #else
 672     if((n > 0) || (n < 0 && WSAGetLastError() == WSAEWOULDBLOCK))
 673 #endif /* !_WIN32 */
 674         return 1;
 675     _xcb_conn_shutdown(c);
 676     return 0;
 677 }
 678
 679 int _xcb_in_read_block(xcb_connection_t *c, void *buf, int len)
 680 {
 681     int done = c->in.queue_len;
 682     if(len < done)
 683         done = len;
 684
 685     memcpy(buf, c->in.queue, done);
 686     c->in.queue_len -= done;
 687     memmove(c->in.queue, c->in.queue + done, c->in.queue_len);
 688
 689     if(len > done)
 690     {
 691         int ret = read_block(c->fd, (char *) buf + done, len - done);
 692         if(ret <= 0)
 693         {
 694             _xcb_conn_shutdown(c);
 695             return ret;
 696         }
 697     }
 698
 699     return len;
 700 }