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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 #elif !defined _WIN32
  41 #include <sys/select.h>
  42 #include <sys/socket.h>
  43 #endif
  44
  45 #ifdef _WIN32
  46 #include "xcb_windefs.h"
  47 #endif /* _WIN32 */
  48
  49 #define XCB_ERROR 0
  50 #define XCB_REPLY 1
  51 #define XCB_XGE_EVENT 35
  52
  53 /* required for compiling for Win32 using MinGW */
  54 #ifndef MSG_WAITALL
  55 #define MSG_WAITALL 0
  56 #endif
  57
  58 struct event_list {
  59     xcb_generic_event_t *event;
  60     struct event_list *next;
  61 };
  62
  63 struct reply_list {
  64     void *reply;
  65     struct reply_list *next;
  66 };
  67
  68 typedef struct pending_reply {
  69     uint64_t first_request;
  70     uint64_t last_request;
  71     enum workarounds workaround;
  72     int flags;
  73     struct pending_reply *next;
  74 } pending_reply;
  75
  76 typedef struct reader_list {
  77     unsigned int request;
  78     pthread_cond_t *data;
  79     struct reader_list *next;
  80 } reader_list;
  81
  82 static void wake_up_next_reader(xcb_connection_t *c)
  83 {
  84     int pthreadret;
  85     if(c->in.readers)
  86         pthreadret = pthread_cond_signal(c->in.readers->data);
  87     else
  88         pthreadret = pthread_cond_signal(&c->in.event_cond);
  89     assert(pthreadret == 0);
  90 }
  91
  92 static int read_packet(xcb_connection_t *c)
  93 {
  94     xcb_generic_reply_t genrep;
  95     int length = 32;
  96     int eventlength = 0; /* length after first 32 bytes for GenericEvents */
  97     void *buf;
  98     pending_reply *pend = 0;
  99     struct event_list *event;
 100
 101     /* Wait for there to be enough data for us to read a whole packet */
 102     if(c->in.queue_len < length)
 103         return 0;
 104
 105     /* Get the response type, length, and sequence number. */
 106     memcpy(&genrep, c->in.queue, sizeof(genrep));
 107
 108     /* Compute 32-bit sequence number of this packet. */
 109     if((genrep.response_type & 0x7f) != XCB_KEYMAP_NOTIFY)
 110     {
 111         uint64_t lastread = c->in.request_read;
 112         c->in.request_read = (lastread & UINT64_C(0xffffffffffff0000)) | genrep.sequence;
 113         if(XCB_SEQUENCE_COMPARE(c->in.request_read, <, lastread))
 114             c->in.request_read += 0x10000;
 115         if(XCB_SEQUENCE_COMPARE(c->in.request_read, >, c->in.request_expected))
 116             c->in.request_expected = c->in.request_read;
 117
 118         if(c->in.request_read != lastread)
 119         {
 120             if(c->in.current_reply)
 121             {
 122                 _xcb_map_put(c->in.replies, lastread, c->in.current_reply);
 123                 c->in.current_reply = 0;
 124                 c->in.current_reply_tail = &c->in.current_reply;
 125             }
 126             c->in.request_completed = c->in.request_read - 1;
 127         }
 128
 129         while(c->in.pending_replies &&
 130               c->in.pending_replies->workaround != WORKAROUND_EXTERNAL_SOCKET_OWNER &&
 131               XCB_SEQUENCE_COMPARE (c->in.pending_replies->last_request, <=, c->in.request_completed))
 132         {
 133             pending_reply *oldpend = c->in.pending_replies;
 134             c->in.pending_replies = oldpend->next;
 135             if(!oldpend->next)
 136                 c->in.pending_replies_tail = &c->in.pending_replies;
 137             free(oldpend);
 138         }
 139
 140         if(genrep.response_type == XCB_ERROR)
 141             c->in.request_completed = c->in.request_read;
 142     }
 143
 144     if(genrep.response_type == XCB_ERROR || genrep.response_type == XCB_REPLY)
 145     {
 146         pend = c->in.pending_replies;
 147         if(pend &&
 148            !(XCB_SEQUENCE_COMPARE(pend->first_request, <=, c->in.request_read) &&
 149              (pend->workaround == WORKAROUND_EXTERNAL_SOCKET_OWNER ||
 150               XCB_SEQUENCE_COMPARE(c->in.request_read, <=, pend->last_request))))
 151             pend = 0;
 152     }
 153
 154     /* For reply packets, check that the entire packet is available. */
 155     if(genrep.response_type == XCB_REPLY)
 156     {
 157         if(pend && pend->workaround == WORKAROUND_GLX_GET_FB_CONFIGS_BUG)
 158         {
 159             uint32_t *p = (uint32_t *) c->in.queue;
 160             genrep.length = p[2] * p[3] * 2;
 161         }
 162         length += genrep.length * 4;
 163     }
 164
 165     /* XGE events may have sizes > 32 */
 166     if (genrep.response_type == XCB_XGE_EVENT)
 167     {
 168         eventlength = ((xcb_ge_event_t*)&genrep)->length * 4;
 169     }
 170
 171     buf = malloc(length + eventlength +
 172             (genrep.response_type == XCB_REPLY ? 0 : sizeof(uint32_t)));
 173     if(!buf)
 174     {
 175         _xcb_conn_shutdown(c);
 176         return 0;
 177     }
 178
 179     if(_xcb_in_read_block(c, buf, length) <= 0)
 180     {
 181         free(buf);
 182         return 0;
 183     }
 184
 185     /* pull in XGE event data if available, append after event struct */
 186     if (eventlength)
 187     {
 188         if(_xcb_in_read_block(c, &((xcb_generic_event_t*)buf)[1], eventlength) <= 0)
 189         {
 190             free(buf);
 191             return 0;
 192         }
 193     }
 194
 195     if(pend && (pend->flags & XCB_REQUEST_DISCARD_REPLY))
 196     {
 197         free(buf);
 198         return 1;
 199     }
 200
 201     if(genrep.response_type != XCB_REPLY)
 202         ((xcb_generic_event_t *) buf)->full_sequence = c->in.request_read;
 203
 204     /* reply, or checked error */
 205     if( genrep.response_type == XCB_REPLY ||
 206        (genrep.response_type == XCB_ERROR && pend && (pend->flags & XCB_REQUEST_CHECKED)))
 207     {
 208         reader_list *reader;
 209         struct reply_list *cur = malloc(sizeof(struct reply_list));
 210         if(!cur)
 211         {
 212             _xcb_conn_shutdown(c);
 213             free(buf);
 214             return 0;
 215         }
 216         cur->reply = buf;
 217         cur->next = 0;
 218         *c->in.current_reply_tail = cur;
 219         c->in.current_reply_tail = &cur->next;
 220         for(reader = c->in.readers;
 221             reader &&
 222             XCB_SEQUENCE_COMPARE_32(reader->request, <=, c->in.request_read);
 223             reader = reader->next)
 224         {
 225             if(XCB_SEQUENCE_COMPARE_32(reader->request, ==, c->in.request_read))
 226             {
 227                 pthread_cond_signal(reader->data);
 228                 break;
 229             }
 230         }
 231         return 1;
 232     }
 233
 234     /* event, or unchecked error */
 235     event = malloc(sizeof(struct event_list));
 236     if(!event)
 237     {
 238         _xcb_conn_shutdown(c);
 239         free(buf);
 240         return 0;
 241     }
 242     event->event = buf;
 243     event->next = 0;
 244     *c->in.events_tail = event;
 245     c->in.events_tail = &event->next;
 246     pthread_cond_signal(&c->in.event_cond);
 247     return 1; /* I have something for you... */
 248 }
 249
 250 static xcb_generic_event_t *get_event(xcb_connection_t *c)
 251 {
 252     struct event_list *cur = c->in.events;
 253     xcb_generic_event_t *ret;
 254     if(!c->in.events)
 255         return 0;
 256     ret = cur->event;
 257     c->in.events = cur->next;
 258     if(!cur->next)
 259         c->in.events_tail = &c->in.events;
 260     free(cur);
 261     return ret;
 262 }
 263
 264 static void free_reply_list(struct reply_list *head)
 265 {
 266     while(head)
 267     {
 268         struct reply_list *cur = head;
 269         head = cur->next;
 270         free(cur->reply);
 271         free(cur);
 272     }
 273 }
 274
 275 static int read_block(const int fd, void *buf, const ssize_t len)
 276 {
 277     int done = 0;
 278     while(done < len)
 279     {
 280         int ret = recv(fd, ((char *) buf) + done, len - done,MSG_WAITALL);
 281         if(ret > 0)
 282             done += ret;
 283 #ifndef _WIN32
 284         if(ret < 0 && errno == EAGAIN)
 285 #else
 286         if(ret == SOCKET_ERROR && WSAGetLastError() == WSAEWOULDBLOCK)
 287 #endif /* !_Win32 */
 288         {
 289 #if USE_POLL
 290             struct pollfd pfd;
 291             pfd.fd = fd;
 292             pfd.events = POLLIN;
 293             pfd.revents = 0;
 294             do {
 295                 ret = poll(&pfd, 1, -1);
 296             } while (ret == -1 && errno == EINTR);
 297 #else
 298             fd_set fds;
 299             FD_ZERO(&fds);
 300             FD_SET(fd, &fds);
 301
 302             /* Initializing errno here makes sure that for Win32 this loop will execute only once */
 303             errno = 0;
 304             do {
 305                 ret = select(fd + 1, &fds, 0, 0, 0);
 306             } while (ret == -1 && errno == EINTR);
 307 #endif /* USE_POLL */
 308         }
 309         if(ret <= 0)
 310             return ret;
 311     }
 312     return len;
 313 }
 314
 315 static int poll_for_reply(xcb_connection_t *c, unsigned int request, void **reply, xcb_generic_error_t **error)
 316 {
 317     struct reply_list *head;
 318
 319     /* If an error occurred when issuing the request, fail immediately. */
 320     if(!request)
 321         head = 0;
 322     /* We've read requests past the one we want, so if it has replies we have
 323      * them all and they're in the replies map. */
 324     else if(XCB_SEQUENCE_COMPARE_32(request, <, c->in.request_read))
 325     {
 326         head = _xcb_map_remove(c->in.replies, request);
 327         if(head && head->next)
 328             _xcb_map_put(c->in.replies, request, head->next);
 329     }
 330     /* We're currently processing the responses to the request we want, and we
 331      * have a reply ready to return. So just return it without blocking. */
 332     else if(XCB_SEQUENCE_COMPARE_32(request, ==, c->in.request_read) && c->in.current_reply)
 333     {
 334         head = c->in.current_reply;
 335         c->in.current_reply = head->next;
 336         if(!head->next)
 337             c->in.current_reply_tail = &c->in.current_reply;
 338     }
 339     /* We know this request can't have any more replies, and we've already
 340      * established it doesn't have a reply now. Don't bother blocking. */
 341     else if(XCB_SEQUENCE_COMPARE_32(request, ==, c->in.request_completed))
 342         head = 0;
 343     /* We may have more replies on the way for this request: block until we're
 344      * sure. */
 345     else
 346         return 0;
 347
 348     if(error)
 349         *error = 0;
 350     *reply = 0;
 351
 352     if(head)
 353     {
 354         if(((xcb_generic_reply_t *) head->reply)->response_type == XCB_ERROR)
 355         {
 356             if(error)
 357                 *error = head->reply;
 358             else
 359                 free(head->reply);
 360         }
 361         else
 362             *reply = head->reply;
 363
 364         free(head);
 365     }
 366
 367     return 1;
 368 }
 369
 370 /* Public interface */
 371
 372 void *xcb_wait_for_reply(xcb_connection_t *c, unsigned int request, xcb_generic_error_t **e)
 373 {
 374     uint64_t widened_request;
 375     void *ret = 0;
 376     if(e)
 377         *e = 0;
 378     if(c->has_error)
 379         return 0;
 380
 381     pthread_mutex_lock(&c->iolock);
 382
 383     widened_request = (c->out.request & UINT64_C(0xffffffff00000000)) | request;
 384     if(widened_request > c->out.request)
 385         widened_request -= UINT64_C(1) << 32;
 386
 387     /* If this request has not been written yet, write it. */
 388     if(c->out.return_socket || _xcb_out_flush_to(c, widened_request))
 389     {
 390         pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
 391         reader_list reader;
 392         reader_list **prev_reader;
 393
 394         for(prev_reader = &c->in.readers;
 395             *prev_reader &&
 396             XCB_SEQUENCE_COMPARE_32((*prev_reader)->request, <=, request);
 397             prev_reader = &(*prev_reader)->next)
 398         {
 399             /* empty */;
 400         }
 401         reader.request = request;
 402         reader.data = &cond;
 403         reader.next = *prev_reader;
 404         *prev_reader = &reader;
 405
 406         while(!poll_for_reply(c, request, &ret, e))
 407             if(!_xcb_conn_wait(c, &cond, 0, 0))
 408                 break;
 409
 410         for(prev_reader = &c->in.readers;
 411             *prev_reader &&
 412             XCB_SEQUENCE_COMPARE_32((*prev_reader)->request, <=, request);
 413             prev_reader = &(*prev_reader)->next)
 414         {
 415             if(*prev_reader == &reader)
 416             {
 417                 *prev_reader = (*prev_reader)->next;
 418                 break;
 419             }
 420         }
 421         pthread_cond_destroy(&cond);
 422     }
 423
 424     wake_up_next_reader(c);
 425     pthread_mutex_unlock(&c->iolock);
 426     return ret;
 427 }
 428
 429 static void insert_pending_discard(xcb_connection_t *c, pending_reply **prev_next, uint64_t seq)
 430 {
 431     pending_reply *pend;
 432     pend = malloc(sizeof(*pend));
 433     if(!pend)
 434     {
 435         _xcb_conn_shutdown(c);
 436         return;
 437     }
 438
 439     pend->first_request = seq;
 440     pend->last_request = seq;
 441     pend->workaround = 0;
 442     pend->flags = XCB_REQUEST_DISCARD_REPLY;
 443     pend->next = *prev_next;
 444     *prev_next = pend;
 445
 446     if(!pend->next)
 447         c->in.pending_replies_tail = &pend->next;
 448 }
 449
 450 static void discard_reply(xcb_connection_t *c, unsigned int request)
 451 {
 452     pending_reply *pend = 0;
 453     pending_reply **prev_pend;
 454     uint64_t widened_request;
 455
 456     /* We've read requests past the one we want, so if it has replies we have
 457      * them all and they're in the replies map. */
 458     if(XCB_SEQUENCE_COMPARE_32(request, <, c->in.request_read))
 459     {
 460         struct reply_list *head;
 461         head = _xcb_map_remove(c->in.replies, request);
 462         while (head)
 463         {
 464             struct reply_list *next = head->next;
 465             free(head->reply);
 466             free(head);
 467             head = next;
 468         }
 469         return;
 470     }
 471
 472     /* We're currently processing the responses to the request we want, and we
 473      * have a reply ready to return. Free it, and mark the pend to free any further
 474      * replies. */
 475     if(XCB_SEQUENCE_COMPARE_32(request, ==, c->in.request_read) && c->in.current_reply)
 476     {
 477         struct reply_list *head;
 478         head = c->in.current_reply;
 479         c->in.current_reply = NULL;
 480         c->in.current_reply_tail = &c->in.current_reply;
 481         while (head)
 482         {
 483             struct reply_list *next = head->next;
 484             free(head->reply);
 485             free(head);
 486             head = next;
 487         }
 488
 489         pend = c->in.pending_replies;
 490         if(pend &&
 491             !(XCB_SEQUENCE_COMPARE(pend->first_request, <=, c->in.request_read) &&
 492              (pend->workaround == WORKAROUND_EXTERNAL_SOCKET_OWNER ||
 493               XCB_SEQUENCE_COMPARE(c->in.request_read, <=, pend->last_request))))
 494             pend = 0;
 495         if(pend)
 496             pend->flags |= XCB_REQUEST_DISCARD_REPLY;
 497         else
 498             insert_pending_discard(c, &c->in.pending_replies, c->in.request_read);
 499
 500         return;
 501     }
 502
 503     /* Walk the list of pending requests. Mark the first match for deletion. */
 504     for(prev_pend = &c->in.pending_replies; *prev_pend; prev_pend = &(*prev_pend)->next)
 505     {
 506         if(XCB_SEQUENCE_COMPARE_32((*prev_pend)->first_request, >, request))
 507             break;
 508
 509         if(XCB_SEQUENCE_COMPARE_32((*prev_pend)->first_request, ==, request))
 510         {
 511             /* Pending reply found. Mark for discard: */
 512             (*prev_pend)->flags |= XCB_REQUEST_DISCARD_REPLY;
 513             return;
 514         }
 515     }
 516
 517     /* Pending reply not found (likely due to _unchecked request). Create one: */
 518     widened_request = (c->out.request & UINT64_C(0xffffffff00000000)) | request;
 519     if(widened_request > c->out.request)
 520         widened_request -= UINT64_C(1) << 32;
 521
 522     insert_pending_discard(c, prev_pend, widened_request);
 523 }
 524
 525 void xcb_discard_reply(xcb_connection_t *c, unsigned int sequence)
 526 {
 527     if(c->has_error)
 528         return;
 529
 530     /* If an error occurred when issuing the request, fail immediately. */
 531     if(!sequence)
 532         return;
 533
 534     pthread_mutex_lock(&c->iolock);
 535     discard_reply(c, sequence);
 536     pthread_mutex_unlock(&c->iolock);
 537 }
 538
 539 int xcb_poll_for_reply(xcb_connection_t *c, unsigned int request, void **reply, xcb_generic_error_t **error)
 540 {
 541     int ret;
 542     if(c->has_error)
 543     {
 544         *reply = 0;
 545         if(error)
 546             *error = 0;
 547         return 1; /* would not block */
 548     }
 549     assert(reply != 0);
 550     pthread_mutex_lock(&c->iolock);
 551     ret = poll_for_reply(c, request, reply, error);
 552     pthread_mutex_unlock(&c->iolock);
 553     return ret;
 554 }
 555
 556 xcb_generic_event_t *xcb_wait_for_event(xcb_connection_t *c)
 557 {
 558     xcb_generic_event_t *ret;
 559     if(c->has_error)
 560         return 0;
 561     pthread_mutex_lock(&c->iolock);
 562     /* get_event returns 0 on empty list. */
 563     while(!(ret = get_event(c)))
 564         if(!_xcb_conn_wait(c, &c->in.event_cond, 0, 0))
 565             break;
 566
 567     wake_up_next_reader(c);
 568     pthread_mutex_unlock(&c->iolock);
 569     return ret;
 570 }
 571
 572 xcb_generic_event_t *xcb_poll_for_event(xcb_connection_t *c)
 573 {
 574     xcb_generic_event_t *ret = 0;
 575     if(!c->has_error)
 576     {
 577         pthread_mutex_lock(&c->iolock);
 578         /* FIXME: follow X meets Z architecture changes. */
 579         ret = get_event(c);
 580         if(!ret && _xcb_in_read(c)) /* _xcb_in_read shuts down the connection on error */
 581             ret = get_event(c);
 582         pthread_mutex_unlock(&c->iolock);
 583     }
 584     return ret;
 585 }
 586
 587 xcb_generic_error_t *xcb_request_check(xcb_connection_t *c, xcb_void_cookie_t cookie)
 588 {
 589     /* FIXME: this could hold the lock to avoid syncing unnecessarily, but
 590      * that would require factoring the locking out of xcb_get_input_focus,
 591      * xcb_get_input_focus_reply, and xcb_wait_for_reply. */
 592     xcb_generic_error_t *ret;
 593     void *reply;
 594     if(c->has_error)
 595         return 0;
 596     if(XCB_SEQUENCE_COMPARE_32(cookie.sequence,>,c->in.request_expected)
 597        && XCB_SEQUENCE_COMPARE_32(cookie.sequence,>,c->in.request_completed))
 598     {
 599         free(xcb_get_input_focus_reply(c, xcb_get_input_focus(c), &ret));
 600         assert(!ret);
 601     }
 602     reply = xcb_wait_for_reply(c, cookie.sequence, &ret);
 603     assert(!reply);
 604     return ret;
 605 }
 606
 607 /* Private interface */
 608
 609 int _xcb_in_init(_xcb_in *in)
 610 {
 611     if(pthread_cond_init(&in->event_cond, 0))
 612         return 0;
 613     in->reading = 0;
 614
 615     in->queue_len = 0;
 616
 617     in->request_read = 0;
 618     in->request_completed = 0;
 619
 620     in->replies = _xcb_map_new();
 621     if(!in->replies)
 622         return 0;
 623
 624     in->current_reply_tail = &in->current_reply;
 625     in->events_tail = &in->events;
 626     in->pending_replies_tail = &in->pending_replies;
 627
 628     return 1;
 629 }
 630
 631 void _xcb_in_destroy(_xcb_in *in)
 632 {
 633     pthread_cond_destroy(&in->event_cond);
 634     free_reply_list(in->current_reply);
 635     _xcb_map_delete(in->replies, (void (*)(void *)) free_reply_list);
 636     while(in->events)
 637     {
 638         struct event_list *e = in->events;
 639         in->events = e->next;
 640         free(e->event);
 641         free(e);
 642     }
 643     while(in->pending_replies)
 644     {
 645         pending_reply *pend = in->pending_replies;
 646         in->pending_replies = pend->next;
 647         free(pend);
 648     }
 649 }
 650
 651 int _xcb_in_expect_reply(xcb_connection_t *c, uint64_t request, enum workarounds workaround, int flags)
 652 {
 653     pending_reply *pend = malloc(sizeof(pending_reply));
 654     assert(workaround != WORKAROUND_NONE || flags != 0);
 655     if(!pend)
 656     {
 657         _xcb_conn_shutdown(c);
 658         return 0;
 659     }
 660     pend->first_request = pend->last_request = request;
 661     pend->workaround = workaround;
 662     pend->flags = flags;
 663     pend->next = 0;
 664     *c->in.pending_replies_tail = pend;
 665     c->in.pending_replies_tail = &pend->next;
 666     return 1;
 667 }
 668
 669 void _xcb_in_replies_done(xcb_connection_t *c)
 670 {
 671     struct pending_reply *pend;
 672     if (c->in.pending_replies_tail != &c->in.pending_replies)
 673     {
 674         pend = container_of(c->in.pending_replies_tail, struct pending_reply, next);
 675         if(pend->workaround == WORKAROUND_EXTERNAL_SOCKET_OWNER)
 676         {
 677             pend->last_request = c->out.request;
 678             pend->workaround = WORKAROUND_NONE;
 679         }
 680     }
 681 }
 682
 683 int _xcb_in_read(xcb_connection_t *c)
 684 {
 685     int n = recv(c->fd, c->in.queue + c->in.queue_len, sizeof(c->in.queue) - c->in.queue_len,MSG_WAITALL);
 686     if(n > 0)
 687         c->in.queue_len += n;
 688     while(read_packet(c))
 689         /* empty */;
 690 #ifndef _WIN32
 691     if((n > 0) || (n < 0 && errno == EAGAIN))
 692 #else
 693     if((n > 0) || (n < 0 && WSAGetLastError() == WSAEWOULDBLOCK))
 694 #endif /* !_WIN32 */
 695         return 1;
 696     _xcb_conn_shutdown(c);
 697     return 0;
 698 }
 699
 700 int _xcb_in_read_block(xcb_connection_t *c, void *buf, int len)
 701 {
 702     int done = c->in.queue_len;
 703     if(len < done)
 704         done = len;
 705
 706     memcpy(buf, c->in.queue, done);
 707     c->in.queue_len -= done;
 708     memmove(c->in.queue, c->in.queue + done, c->in.queue_len);
 709
 710     if(len > done)
 711     {
 712         int ret = read_block(c->fd, (char *) buf + done, len - done);
 713         if(ret <= 0)
 714         {
 715             _xcb_conn_shutdown(c);
 716             return ret;
 717         }
 718     }
 719
 720     return len;
 721 }