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