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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 #else
  41 #include <sys/select.h>
  42 #endif
  43
  44 #define XCB_ERROR 0
  45 #define XCB_REPLY 1
  46 #define XCB_XGE_EVENT 35
  47
  48 struct event_list {
  49     xcb_generic_event_t *event;
  50     struct event_list *next;
  51 };
  52
  53 struct reply_list {
  54     void *reply;
  55     struct reply_list *next;
  56 };
  57
  58 typedef struct pending_reply {
  59     uint64_t first_request;
  60     uint64_t last_request;
  61     enum workarounds workaround;
  62     int flags;
  63     struct pending_reply *next;
  64 } pending_reply;
  65
  66 typedef struct reader_list {
  67     unsigned int request;
  68     pthread_cond_t *data;
  69     struct reader_list *next;
  70 } reader_list;
  71
  72 static void wake_up_next_reader(xcb_connection_t *c)
  73 {
  74     int pthreadret;
  75     if(c->in.readers)
  76         pthreadret = pthread_cond_signal(c->in.readers->data);
  77     else
  78         pthreadret = pthread_cond_signal(&c->in.event_cond);
  79     assert(pthreadret == 0);
  80 }
  81
  82 static int read_packet(xcb_connection_t *c)
  83 {
  84     xcb_generic_reply_t genrep;
  85     int length = 32;
  86     int eventlength = 0; /* length after first 32 bytes for GenericEvents */
  87     void *buf;
  88     pending_reply *pend = 0;
  89     struct event_list *event;
  90
  91     /* Wait for there to be enough data for us to read a whole packet */
  92     if(c->in.queue_len < length)
  93         return 0;
  94
  95     /* Get the response type, length, and sequence number. */
  96     memcpy(&genrep, c->in.queue, sizeof(genrep));
  97
  98     /* Compute 32-bit sequence number of this packet. */
  99     if((genrep.response_type & 0x7f) != XCB_KEYMAP_NOTIFY)
 100     {
 101         uint64_t lastread = c->in.request_read;
 102         c->in.request_read = (lastread & UINT64_C(0xffffffffffff0000)) | genrep.sequence;
 103         if(XCB_SEQUENCE_COMPARE(c->in.request_read, <, lastread))
 104             c->in.request_read += 0x10000;
 105         if(XCB_SEQUENCE_COMPARE(c->in.request_read, >, c->in.request_expected))
 106             c->in.request_expected = c->in.request_read;
 107
 108         if(c->in.request_read != lastread)
 109         {
 110             if(c->in.current_reply)
 111             {
 112                 _xcb_map_put(c->in.replies, lastread, c->in.current_reply);
 113                 c->in.current_reply = 0;
 114                 c->in.current_reply_tail = &c->in.current_reply;
 115             }
 116             c->in.request_completed = c->in.request_read - 1;
 117         }
 118
 119         while(c->in.pending_replies &&
 120               c->in.pending_replies->workaround != WORKAROUND_EXTERNAL_SOCKET_OWNER &&
 121               XCB_SEQUENCE_COMPARE (c->in.pending_replies->last_request, <=, c->in.request_completed))
 122         {
 123             pending_reply *oldpend = c->in.pending_replies;
 124             c->in.pending_replies = oldpend->next;
 125             if(!oldpend->next)
 126                 c->in.pending_replies_tail = &c->in.pending_replies;
 127             free(oldpend);
 128         }
 129
 130         if(genrep.response_type == XCB_ERROR)
 131             c->in.request_completed = c->in.request_read;
 132     }
 133
 134     if(genrep.response_type == XCB_ERROR || genrep.response_type == XCB_REPLY)
 135     {
 136         pend = c->in.pending_replies;
 137         if(pend &&
 138            !(XCB_SEQUENCE_COMPARE(pend->first_request, <=, c->in.request_read) &&
 139              (pend->workaround == WORKAROUND_EXTERNAL_SOCKET_OWNER ||
 140               XCB_SEQUENCE_COMPARE(c->in.request_read, <=, pend->last_request))))
 141             pend = 0;
 142     }
 143
 144     /* For reply packets, check that the entire packet is available. */
 145     if(genrep.response_type == XCB_REPLY)
 146     {
 147         if(pend && pend->workaround == WORKAROUND_GLX_GET_FB_CONFIGS_BUG)
 148         {
 149             uint32_t *p = (uint32_t *) c->in.queue;
 150             genrep.length = p[2] * p[3] * 2;
 151         }
 152         length += genrep.length * 4;
 153     }
 154
 155     /* XGE events may have sizes > 32 */
 156     if (genrep.response_type == XCB_XGE_EVENT)
 157     {
 158         eventlength = ((xcb_ge_event_t*)&genrep)->length * 4;
 159     }
 160
 161     buf = malloc(length + eventlength +
 162             (genrep.response_type == XCB_REPLY ? 0 : sizeof(uint32_t)));
 163     if(!buf)
 164     {
 165         _xcb_conn_shutdown(c);
 166         return 0;
 167     }
 168
 169     if(_xcb_in_read_block(c, buf, length) <= 0)
 170     {
 171         free(buf);
 172         return 0;
 173     }
 174
 175     /* pull in XGE event data if available, append after event struct */
 176     if (eventlength)
 177     {
 178         if(_xcb_in_read_block(c, &((xcb_generic_event_t*)buf)[1], eventlength) <= 0)
 179         {
 180             free(buf);
 181             return 0;
 182         }
 183     }
 184
 185     if(pend && (pend->flags & XCB_REQUEST_DISCARD_REPLY))
 186     {
 187         free(buf);
 188         return 1;
 189     }
 190
 191     if(genrep.response_type != XCB_REPLY)
 192         ((xcb_generic_event_t *) buf)->full_sequence = c->in.request_read;
 193
 194     /* reply, or checked error */
 195     if( genrep.response_type == XCB_REPLY ||
 196        (genrep.response_type == XCB_ERROR && pend && (pend->flags & XCB_REQUEST_CHECKED)))
 197     {
 198         reader_list *reader;
 199         struct reply_list *cur = malloc(sizeof(struct reply_list));
 200         if(!cur)
 201         {
 202             _xcb_conn_shutdown(c);
 203             free(buf);
 204             return 0;
 205         }
 206         cur->reply = buf;
 207         cur->next = 0;
 208         *c->in.current_reply_tail = cur;
 209         c->in.current_reply_tail = &cur->next;
 210         for(reader = c->in.readers;
 211             reader &&
 212             XCB_SEQUENCE_COMPARE_32(reader->request, <=, c->in.request_read);
 213             reader = reader->next)
 214         {
 215             if(XCB_SEQUENCE_COMPARE_32(reader->request, ==, c->in.request_read))
 216             {
 217                 pthread_cond_signal(reader->data);
 218                 break;
 219             }
 220         }
 221         return 1;
 222     }
 223
 224     /* event, or unchecked error */
 225     event = malloc(sizeof(struct event_list));
 226     if(!event)
 227     {
 228         _xcb_conn_shutdown(c);
 229         free(buf);
 230         return 0;
 231     }
 232     event->event = buf;
 233     event->next = 0;
 234     *c->in.events_tail = event;
 235     c->in.events_tail = &event->next;
 236     pthread_cond_signal(&c->in.event_cond);
 237     return 1; /* I have something for you... */
 238 }
 239
 240 static xcb_generic_event_t *get_event(xcb_connection_t *c)
 241 {
 242     struct event_list *cur = c->in.events;
 243     xcb_generic_event_t *ret;
 244     if(!c->in.events)
 245         return 0;
 246     ret = cur->event;
 247     c->in.events = cur->next;
 248     if(!cur->next)
 249         c->in.events_tail = &c->in.events;
 250     free(cur);
 251     return ret;
 252 }
 253
 254 static void free_reply_list(struct reply_list *head)
 255 {
 256     while(head)
 257     {
 258         struct reply_list *cur = head;
 259         head = cur->next;
 260         free(cur->reply);
 261         free(cur);
 262     }
 263 }
 264
 265 static int read_block(const int fd, void *buf, const ssize_t len)
 266 {
 267     int done = 0;
 268     while(done < len)
 269     {
 270         int ret = read(fd, ((char *) buf) + done, len - done);
 271         if(ret > 0)
 272             done += ret;
 273         if(ret < 0 && errno == EAGAIN)
 274         {
 275 #if USE_POLL
 276             struct pollfd pfd;
 277             pfd.fd = fd;
 278             pfd.events = POLLIN;
 279             pfd.revents = 0;
 280             do {
 281                 ret = poll(&pfd, 1, -1);
 282             } while (ret == -1 && errno == EINTR);
 283 #else
 284             fd_set fds;
 285             FD_ZERO(&fds);
 286             FD_SET(fd, &fds);
 287             do {
 288                 ret = select(fd + 1, &fds, 0, 0, 0);
 289             } while (ret == -1 && errno == EINTR);
 290 #endif
 291         }
 292         if(ret <= 0)
 293             return ret;
 294     }
 295     return len;
 296 }
 297
 298 static int poll_for_reply(xcb_connection_t *c, unsigned int request, void **reply, xcb_generic_error_t **error)
 299 {
 300     struct reply_list *head;
 301
 302     /* If an error occurred when issuing the request, fail immediately. */
 303     if(!request)
 304         head = 0;
 305     /* We've read requests past the one we want, so if it has replies we have
 306      * them all and they're in the replies map. */
 307     else if(XCB_SEQUENCE_COMPARE_32(request, <, c->in.request_read))
 308     {
 309         head = _xcb_map_remove(c->in.replies, request);
 310         if(head && head->next)
 311             _xcb_map_put(c->in.replies, request, head->next);
 312     }
 313     /* We're currently processing the responses to the request we want, and we
 314      * have a reply ready to return. So just return it without blocking. */
 315     else if(XCB_SEQUENCE_COMPARE_32(request, ==, c->in.request_read) && c->in.current_reply)
 316     {
 317         head = c->in.current_reply;
 318         c->in.current_reply = head->next;
 319         if(!head->next)
 320             c->in.current_reply_tail = &c->in.current_reply;
 321     }
 322     /* We know this request can't have any more replies, and we've already
 323      * established it doesn't have a reply now. Don't bother blocking. */
 324     else if(XCB_SEQUENCE_COMPARE_32(request, ==, c->in.request_completed))
 325         head = 0;
 326     /* We may have more replies on the way for this request: block until we're
 327      * sure. */
 328     else
 329         return 0;
 330
 331     if(error)
 332         *error = 0;
 333     *reply = 0;
 334
 335     if(head)
 336     {
 337         if(((xcb_generic_reply_t *) head->reply)->response_type == XCB_ERROR)
 338         {
 339             if(error)
 340                 *error = head->reply;
 341             else
 342                 free(head->reply);
 343         }
 344         else
 345             *reply = head->reply;
 346
 347         free(head);
 348     }
 349
 350     return 1;
 351 }
 352
 353 /* Public interface */
 354
 355 void *xcb_wait_for_reply(xcb_connection_t *c, unsigned int request, xcb_generic_error_t **e)
 356 {
 357     uint64_t widened_request;
 358     void *ret = 0;
 359     if(e)
 360         *e = 0;
 361     if(c->has_error)
 362         return 0;
 363
 364     pthread_mutex_lock(&c->iolock);
 365
 366     widened_request = (c->out.request & UINT64_C(0xffffffff00000000)) | request;
 367     if(widened_request > c->out.request)
 368         widened_request -= UINT64_C(1) << 32;
 369
 370     /* If this request has not been written yet, write it. */
 371     if(c->out.return_socket || _xcb_out_flush_to(c, widened_request))
 372     {
 373         pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
 374         reader_list reader;
 375         reader_list **prev_reader;
 376
 377         for(prev_reader = &c->in.readers;
 378             *prev_reader &&
 379             XCB_SEQUENCE_COMPARE_32((*prev_reader)->request, <=, request);
 380             prev_reader = &(*prev_reader)->next)
 381         {
 382             /* empty */;
 383         }
 384         reader.request = request;
 385         reader.data = &cond;
 386         reader.next = *prev_reader;
 387         *prev_reader = &reader;
 388
 389         while(!poll_for_reply(c, request, &ret, e))
 390             if(!_xcb_conn_wait(c, &cond, 0, 0))
 391                 break;
 392
 393         for(prev_reader = &c->in.readers;
 394             *prev_reader &&
 395             XCB_SEQUENCE_COMPARE_32((*prev_reader)->request, <=, request);
 396             prev_reader = &(*prev_reader)->next)
 397         {
 398             if(*prev_reader == &reader)
 399             {
 400                 *prev_reader = (*prev_reader)->next;
 401                 break;
 402             }
 403         }
 404         pthread_cond_destroy(&cond);
 405     }
 406
 407     wake_up_next_reader(c);
 408     pthread_mutex_unlock(&c->iolock);
 409     return ret;
 410 }
 411
 412 static void insert_pending_discard(xcb_connection_t *c, pending_reply **prev_next, uint64_t seq)
 413 {
 414     pending_reply *pend;
 415     pend = malloc(sizeof(*pend));
 416     if(!pend)
 417     {
 418         _xcb_conn_shutdown(c);
 419         return;
 420     }
 421
 422     pend->first_request = seq;
 423     pend->last_request = seq;
 424     pend->workaround = 0;
 425     pend->flags = XCB_REQUEST_DISCARD_REPLY;
 426     pend->next = *prev_next;
 427     *prev_next = pend;
 428
 429     if(!pend->next)
 430         c->in.pending_replies_tail = &pend->next;
 431 }
 432
 433 static void discard_reply(xcb_connection_t *c, unsigned int request)
 434 {
 435     pending_reply *pend = 0;
 436     pending_reply **prev_pend;
 437     uint64_t widened_request;
 438
 439     /* We've read requests past the one we want, so if it has replies we have
 440      * them all and they're in the replies map. */
 441     if(XCB_SEQUENCE_COMPARE_32(request, <, c->in.request_read))
 442     {
 443         struct reply_list *head;
 444         head = _xcb_map_remove(c->in.replies, request);
 445         while (head)
 446         {
 447             struct reply_list *next = head->next;
 448             free(head->reply);
 449             free(head);
 450             head = next;
 451         }
 452         return;
 453     }
 454
 455     /* We're currently processing the responses to the request we want, and we
 456      * have a reply ready to return. Free it, and mark the pend to free any further
 457      * replies. */
 458     if(XCB_SEQUENCE_COMPARE_32(request, ==, c->in.request_read) && c->in.current_reply)
 459     {
 460         struct reply_list *head;
 461         head = c->in.current_reply;
 462         c->in.current_reply = NULL;
 463         c->in.current_reply_tail = &c->in.current_reply;
 464         while (head)
 465         {
 466             struct reply_list *next = head->next;
 467             free(head->reply);
 468             free(head);
 469             head = next;
 470         }
 471
 472         pend = c->in.pending_replies;
 473         if(pend &&
 474             !(XCB_SEQUENCE_COMPARE(pend->first_request, <=, c->in.request_read) &&
 475              (pend->workaround == WORKAROUND_EXTERNAL_SOCKET_OWNER ||
 476               XCB_SEQUENCE_COMPARE(c->in.request_read, <=, pend->last_request))))
 477             pend = 0;
 478         if(pend)
 479             pend->flags |= XCB_REQUEST_DISCARD_REPLY;
 480         else
 481             insert_pending_discard(c, &c->in.pending_replies, c->in.request_read);
 482
 483         return;
 484     }
 485
 486     /* Walk the list of pending requests. Mark the first match for deletion. */
 487     for(prev_pend = &c->in.pending_replies; *prev_pend; prev_pend = &(*prev_pend)->next)
 488     {
 489         if(XCB_SEQUENCE_COMPARE_32((*prev_pend)->first_request, >, request))
 490             break;
 491
 492         if(XCB_SEQUENCE_COMPARE_32((*prev_pend)->first_request, ==, request))
 493         {
 494             /* Pending reply found. Mark for discard: */
 495             (*prev_pend)->flags |= XCB_REQUEST_DISCARD_REPLY;
 496             return;
 497         }
 498     }
 499
 500     /* Pending reply not found (likely due to _unchecked request). Create one: */
 501     widened_request = (c->out.request & UINT64_C(0xffffffff00000000)) | request;
 502     if(widened_request > c->out.request)
 503         widened_request -= UINT64_C(1) << 32;
 504
 505     insert_pending_discard(c, prev_pend, widened_request);
 506 }
 507
 508 void xcb_discard_reply(xcb_connection_t *c, unsigned int sequence)
 509 {
 510     if(c->has_error)
 511         return;
 512
 513     /* If an error occurred when issuing the request, fail immediately. */
 514     if(!sequence)
 515         return;
 516
 517     pthread_mutex_lock(&c->iolock);
 518     discard_reply(c, sequence);
 519     pthread_mutex_unlock(&c->iolock);
 520 }
 521
 522 int xcb_poll_for_reply(xcb_connection_t *c, unsigned int request, void **reply, xcb_generic_error_t **error)
 523 {
 524     int ret;
 525     if(c->has_error)
 526     {
 527         *reply = 0;
 528         if(error)
 529             *error = 0;
 530         return 1; /* would not block */
 531     }
 532     assert(reply != 0);
 533     pthread_mutex_lock(&c->iolock);
 534     ret = poll_for_reply(c, request, reply, error);
 535     pthread_mutex_unlock(&c->iolock);
 536     return ret;
 537 }
 538
 539 xcb_generic_event_t *xcb_wait_for_event(xcb_connection_t *c)
 540 {
 541     xcb_generic_event_t *ret;
 542     if(c->has_error)
 543         return 0;
 544     pthread_mutex_lock(&c->iolock);
 545     /* get_event returns 0 on empty list. */
 546     while(!(ret = get_event(c)))
 547         if(!_xcb_conn_wait(c, &c->in.event_cond, 0, 0))
 548             break;
 549
 550     wake_up_next_reader(c);
 551     pthread_mutex_unlock(&c->iolock);
 552     return ret;
 553 }
 554
 555 xcb_generic_event_t *xcb_poll_for_event(xcb_connection_t *c)
 556 {
 557     xcb_generic_event_t *ret = 0;
 558     if(!c->has_error)
 559     {
 560         pthread_mutex_lock(&c->iolock);
 561         /* FIXME: follow X meets Z architecture changes. */
 562         ret = get_event(c);
 563         if(!ret && _xcb_in_read(c)) /* _xcb_in_read shuts down the connection on error */
 564             ret = get_event(c);
 565         pthread_mutex_unlock(&c->iolock);
 566     }
 567     return ret;
 568 }
 569
 570 xcb_generic_error_t *xcb_request_check(xcb_connection_t *c, xcb_void_cookie_t cookie)
 571 {
 572     /* FIXME: this could hold the lock to avoid syncing unnecessarily, but
 573      * that would require factoring the locking out of xcb_get_input_focus,
 574      * xcb_get_input_focus_reply, and xcb_wait_for_reply. */
 575     xcb_generic_error_t *ret;
 576     void *reply;
 577     if(c->has_error)
 578         return 0;
 579     if(XCB_SEQUENCE_COMPARE_32(cookie.sequence,>,c->in.request_expected)
 580        && XCB_SEQUENCE_COMPARE_32(cookie.sequence,>,c->in.request_completed))
 581     {
 582         free(xcb_get_input_focus_reply(c, xcb_get_input_focus(c), &ret));
 583         assert(!ret);
 584     }
 585     reply = xcb_wait_for_reply(c, cookie.sequence, &ret);
 586     assert(!reply);
 587     return ret;
 588 }
 589
 590 /* Private interface */
 591
 592 int _xcb_in_init(_xcb_in *in)
 593 {
 594     if(pthread_cond_init(&in->event_cond, 0))
 595         return 0;
 596     in->reading = 0;
 597
 598     in->queue_len = 0;
 599
 600     in->request_read = 0;
 601     in->request_completed = 0;
 602
 603     in->replies = _xcb_map_new();
 604     if(!in->replies)
 605         return 0;
 606
 607     in->current_reply_tail = &in->current_reply;
 608     in->events_tail = &in->events;
 609     in->pending_replies_tail = &in->pending_replies;
 610
 611     return 1;
 612 }
 613
 614 void _xcb_in_destroy(_xcb_in *in)
 615 {
 616     pthread_cond_destroy(&in->event_cond);
 617     free_reply_list(in->current_reply);
 618     _xcb_map_delete(in->replies, (void (*)(void *)) free_reply_list);
 619     while(in->events)
 620     {
 621         struct event_list *e = in->events;
 622         in->events = e->next;
 623         free(e->event);
 624         free(e);
 625     }
 626     while(in->pending_replies)
 627     {
 628         pending_reply *pend = in->pending_replies;
 629         in->pending_replies = pend->next;
 630         free(pend);
 631     }
 632 }
 633
 634 int _xcb_in_expect_reply(xcb_connection_t *c, uint64_t request, enum workarounds workaround, int flags)
 635 {
 636     pending_reply *pend = malloc(sizeof(pending_reply));
 637     assert(workaround != WORKAROUND_NONE || flags != 0);
 638     if(!pend)
 639     {
 640         _xcb_conn_shutdown(c);
 641         return 0;
 642     }
 643     pend->first_request = pend->last_request = request;
 644     pend->workaround = workaround;
 645     pend->flags = flags;
 646     pend->next = 0;
 647     *c->in.pending_replies_tail = pend;
 648     c->in.pending_replies_tail = &pend->next;
 649     return 1;
 650 }
 651
 652 void _xcb_in_replies_done(xcb_connection_t *c)
 653 {
 654     struct pending_reply *pend;
 655     if (c->in.pending_replies_tail != &c->in.pending_replies)
 656     {
 657         pend = container_of(c->in.pending_replies_tail, struct pending_reply, next);
 658         if(pend->workaround == WORKAROUND_EXTERNAL_SOCKET_OWNER)
 659         {
 660             pend->last_request = c->out.request;
 661             pend->workaround = WORKAROUND_NONE;
 662         }
 663     }
 664 }
 665
 666 int _xcb_in_read(xcb_connection_t *c)
 667 {
 668     int n = read(c->fd, c->in.queue + c->in.queue_len, sizeof(c->in.queue) - c->in.queue_len);
 669     if(n > 0)
 670         c->in.queue_len += n;
 671     while(read_packet(c))
 672         /* empty */;
 673     if((n > 0) || (n < 0 && errno == EAGAIN))
 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 }