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IABSD.fr/xenocara/lib/libX11/src/xcb_io.c
matthieu
- lib/libX11/src/xcb_io.c
-
/* Copyright (C) 2003-2006 Jamey Sharp, Josh Triplett * This file is licensed under the MIT license. See the file COPYING. */ #ifdef HAVE_CONFIG_H #include <config.h> #endif #include "Xlibint.h" #include "locking.h" #include "Xprivate.h" #include "Xxcbint.h" #include <xcb/xcbext.h> #include <assert.h> #ifdef HAVE_INTTYPES_H #include <inttypes.h> #endif #include <stdio.h> #include <stdint.h> #include <stdlib.h> #include <string.h> #include <limits.h> #ifdef HAVE_SYS_SELECT_H #include <sys/select.h> #endif #define xcb_fail_assert(_message, _var) { \ unsigned int _var = 1; \ fprintf(stderr, "[xcb] Aborting, sorry about that.\n"); \ assert(!_var); \ } #define throw_thread_fail_assert(_message, _var) { \ fprintf(stderr, "[xcb] " _message "\n"); \ fprintf(stderr, "[xcb] Most likely this is a multi-threaded client " \ "and XInitThreads has not been called\n"); \ xcb_fail_assert(_message, _var); \ } /* XXX: It would probably be most useful if we stored the last-processed * request, so we could find the offender from the message. */ #define throw_extlib_fail_assert(_message, _var) { \ fprintf(stderr, "[xcb] " _message "\n"); \ fprintf(stderr, "[xcb] This is most likely caused by a broken X " \ "extension library\n"); \ xcb_fail_assert(_message, _var); \ } static void return_socket(void *closure) { Display *dpy = closure; InternalLockDisplay(dpy, /* don't skip user locks */ 0); _XSend(dpy, NULL, 0); dpy->bufmax = dpy->buffer; UnlockDisplay(dpy); } static Bool require_socket(Display *dpy) { if(dpy->bufmax == dpy->buffer) { uint64_t sent; int flags = 0; /* if we don't own the event queue, we have to ask XCB * to set our errors aside for us. */ if(dpy->xcb->event_owner != XlibOwnsEventQueue) flags = XCB_REQUEST_CHECKED; if(!xcb_take_socket(dpy->xcb->connection, return_socket, dpy, flags, &sent)) { _XIOError(dpy); return False; } dpy->xcb->last_flushed = sent; X_DPY_SET_REQUEST(dpy, sent); dpy->bufmax = dpy->xcb->real_bufmax; } return True; } /* Call internal connection callbacks for any fds that are currently * ready to read. This function will not block unless one of the * callbacks blocks. * * This code borrowed from _XWaitForReadable. Inverse call tree: * _XRead * _XWaitForWritable * _XFlush * _XSend * _XEventsQueued * _XReadEvents * _XRead[0-9]+ * _XAllocIDs * _XReply * _XEatData * _XReadPad */ static Bool check_internal_connections(Display *dpy) { struct _XConnectionInfo *ilist; fd_set r_mask; struct timeval tv; int result; int highest_fd = -1; if(dpy->flags & XlibDisplayProcConni || !dpy->im_fd_info) return True; FD_ZERO(&r_mask); for(ilist = dpy->im_fd_info; ilist; ilist = ilist->next) { assert(ilist->fd >= 0); FD_SET(ilist->fd, &r_mask); if(ilist->fd > highest_fd) highest_fd = ilist->fd; } assert(highest_fd >= 0); tv.tv_sec = 0; tv.tv_usec = 0; result = select(highest_fd + 1, &r_mask, NULL, NULL, &tv); if(result == -1) { if(errno != EINTR) { _XIOError(dpy); return False; } return True; } for(ilist = dpy->im_fd_info; result && ilist; ilist = ilist->next) if(FD_ISSET(ilist->fd, &r_mask)) { _XProcessInternalConnection(dpy, ilist); --result; } return True; } static PendingRequest *append_pending_request(Display *dpy, uint64_t sequence) { PendingRequest *node = malloc(sizeof(PendingRequest)); assert(node); node->next = NULL; node->sequence = sequence; node->reply_waiter = 0; if(dpy->xcb->pending_requests_tail) { if (XLIB_SEQUENCE_COMPARE(dpy->xcb->pending_requests_tail->sequence, >=, node->sequence)) throw_thread_fail_assert("Unknown sequence number " "while appending request", xcb_xlib_unknown_seq_number); if (dpy->xcb->pending_requests_tail->next != NULL) throw_thread_fail_assert("Unknown request in queue " "while appending request", xcb_xlib_unknown_req_pending); dpy->xcb->pending_requests_tail->next = node; } else dpy->xcb->pending_requests = node; dpy->xcb->pending_requests_tail = node; return node; } static void dequeue_pending_request(Display *dpy, PendingRequest *req) { if (req != dpy->xcb->pending_requests) throw_thread_fail_assert("Unknown request in queue while " "dequeuing", xcb_xlib_unknown_req_in_deq); dpy->xcb->pending_requests = req->next; if(!dpy->xcb->pending_requests) { if (req != dpy->xcb->pending_requests_tail) throw_thread_fail_assert("Unknown request in queue " "while dequeuing", xcb_xlib_unknown_req_in_deq); dpy->xcb->pending_requests_tail = NULL; } else if (XLIB_SEQUENCE_COMPARE(req->sequence, >=, dpy->xcb->pending_requests->sequence)) throw_thread_fail_assert("Unknown sequence number while " "dequeuing request", xcb_xlib_threads_sequence_lost); free(req); } static int handle_error(Display *dpy, xError *err, Bool in_XReply) { _XExtension *ext; int ret_code; /* Oddly, Xlib only allows extensions to suppress errors when * those errors were seen by _XReply. */ if(in_XReply) /* * we better see if there is an extension who may * want to suppress the error. */ for(ext = dpy->ext_procs; ext; ext = ext->next) if(ext->error && (*ext->error)(dpy, err, &ext->codes, &ret_code)) return ret_code; _XError(dpy, err); return 0; } /* Widen a 32-bit sequence number into a 64bit (uint64_t) sequence number. * Treating the comparison as a 1 and shifting it avoids a conditional branch. */ static void widen(uint64_t *wide, unsigned int narrow) { uint64_t new = (*wide & ~((uint64_t)0xFFFFFFFFUL)) | narrow; *wide = new + (((uint64_t)(new < *wide)) << 32); } /* Thread-safety rules: * * At most one thread can be reading from XCB's event queue at a time. * If you are not the current event-reading thread and you need to find * out if an event is available, you must wait. * * The same rule applies for reading replies. * * A single thread cannot be both the the event-reading and the * reply-reading thread at the same time. * * We always look at both the current event and the first pending reply * to decide which to process next. * * We always process all responses in sequence-number order, which may * mean waiting for another thread (either the event_waiter or the * reply_waiter) to handle an earlier response before we can process or * return a later one. If so, we wait on the corresponding condition * variable for that thread to process the response and wake us up. */ static xcb_generic_reply_t *poll_for_event(Display *dpy, Bool queued_only) { /* Make sure the Display's sequence numbers are valid */ if (!require_socket(dpy)) return NULL; /* Precondition: This thread can safely get events from XCB. */ assert(dpy->xcb->event_owner == XlibOwnsEventQueue && !dpy->xcb->event_waiter); if(!dpy->xcb->next_event) { if(queued_only) dpy->xcb->next_event = xcb_poll_for_queued_event(dpy->xcb->connection); else dpy->xcb->next_event = xcb_poll_for_event(dpy->xcb->connection); } if(dpy->xcb->next_event) { PendingRequest *req = dpy->xcb->pending_requests; xcb_generic_event_t *event = dpy->xcb->next_event; uint64_t event_sequence = X_DPY_GET_LAST_REQUEST_READ(dpy); widen(&event_sequence, event->full_sequence); if(!req || XLIB_SEQUENCE_COMPARE(event_sequence, <, req->sequence) || (event->response_type != X_Error && event_sequence == req->sequence)) { uint64_t request = X_DPY_GET_REQUEST(dpy); if (XLIB_SEQUENCE_COMPARE(event_sequence, >, request)) { throw_thread_fail_assert("Unknown sequence " "number while " "processing queue", xcb_xlib_threads_sequence_lost); } X_DPY_SET_LAST_REQUEST_READ(dpy, event_sequence); dpy->xcb->next_event = NULL; return (xcb_generic_reply_t *) event; } } return NULL; } static xcb_generic_reply_t *poll_for_response(Display *dpy) { void *response; xcb_generic_reply_t *event; PendingRequest *req; while(1) { xcb_generic_error_t *error = NULL; uint64_t request; Bool poll_queued_only = dpy->xcb->next_response != NULL; /* Step 1: is there an event in our queue before the next * reply/error? Return that first. * * If we don't have a reply/error saved from an earlier * invocation we check incoming events too, otherwise only * the ones already queued. */ response = poll_for_event(dpy, poll_queued_only); if(response) break; /* Step 2: * Response is NULL, i.e. we have no events. * If we are not waiting for a reply or some other thread * had dibs on the next reply, exit. */ req = dpy->xcb->pending_requests; if(!req || req->reply_waiter) break; /* Step 3: * We have some response (error or reply) related to req * saved from an earlier invocation of this function. Let's * use that one. */ if(dpy->xcb->next_response) { if (((xcb_generic_reply_t*)dpy->xcb->next_response)->response_type == X_Error) { error = dpy->xcb->next_response; response = NULL; } else { response = dpy->xcb->next_response; error = NULL; } dpy->xcb->next_response = NULL; } else { /* Step 4: pull down the next response from the wire. This * should be the 99% case. * xcb_poll_for_reply64() may also pull down events that * happened before the reply. */ if(!xcb_poll_for_reply64(dpy->xcb->connection, req->sequence, &response, &error)) { /* if there is no reply/error, xcb_poll_for_reply64 * may have read events. Return that. */ response = poll_for_event(dpy, True); break; } /* Step 5: we have a new response, but we may also have some * events that happened before that response. Return those * first and save our reply/error for the next invocation. */ event = poll_for_event(dpy, True); if(event) { dpy->xcb->next_response = error ? error : response; response = event; break; } } /* Step 6: actually handle the reply/error now... */ request = X_DPY_GET_REQUEST(dpy); if(XLIB_SEQUENCE_COMPARE(req->sequence, >, request)) { throw_thread_fail_assert("Unknown sequence number " "while awaiting reply", xcb_xlib_threads_sequence_lost); } X_DPY_SET_LAST_REQUEST_READ(dpy, req->sequence); if(response) break; dequeue_pending_request(dpy, req); if(error) return (xcb_generic_reply_t *) error; } return response; } static void handle_response(Display *dpy, xcb_generic_reply_t *response, Bool in_XReply) { _XAsyncHandler *async, *next; switch(response->response_type) { case X_Reply: for(async = dpy->async_handlers; async; async = next) { next = async->next; if(async->handler(dpy, (xReply *) response, (char *) response, sizeof(xReply) + (response->length << 2), async->data)) break; } break; case X_Error: handle_error(dpy, (xError *) response, in_XReply); break; default: /* event */ /* GenericEvents may be > 32 bytes. In this case, the * event struct is trailed by the additional bytes. the * xcb_generic_event_t struct uses 4 bytes for internal * numbering, so we need to shift the trailing data to * be after the first 32 bytes. */ if(response->response_type == GenericEvent && ((xcb_ge_event_t *) response)->length) { xcb_ge_event_t *event = (xcb_ge_event_t *) response; memmove(&event->full_sequence, &event[1], event->length * 4); } _XEnq(dpy, (xEvent *) response); break; } free(response); } int _XEventsQueued(Display *dpy, int mode) { xcb_generic_reply_t *response; if(dpy->flags & XlibDisplayIOError) return 0; if(dpy->xcb->event_owner != XlibOwnsEventQueue) return 0; if(mode == QueuedAfterFlush) _XSend(dpy, NULL, 0); else if (!check_internal_connections(dpy)) return 0; /* If another thread is blocked waiting for events, then we must * let that thread pick up the next event. Since it blocked, we * can reasonably claim there are no new events right now. */ if(!dpy->xcb->event_waiter) { while((response = poll_for_response(dpy))) handle_response(dpy, response, False); if(xcb_connection_has_error(dpy->xcb->connection)) { _XIOError(dpy); return 0; } } return dpy->qlen; } /* _XReadEvents - Flush the output queue, * then read as many events as possible (but at least 1) and enqueue them */ void _XReadEvents(Display *dpy) { xcb_generic_reply_t *response; unsigned long serial; if(dpy->flags & XlibDisplayIOError) return; _XSend(dpy, NULL, 0); if(dpy->xcb->event_owner != XlibOwnsEventQueue) return; if (!check_internal_connections(dpy)) return; serial = dpy->next_event_serial_num; while(serial == dpy->next_event_serial_num || dpy->qlen == 0) { if(dpy->xcb->event_waiter) { ConditionWait(dpy, dpy->xcb->event_notify); /* Maybe the other thread got us an event. */ continue; } if(!dpy->xcb->next_event) { xcb_generic_event_t *event; dpy->xcb->event_waiter = 1; UnlockDisplay(dpy); event = xcb_wait_for_event(dpy->xcb->connection); /* It appears that classic Xlib respected user * locks when waking up after waiting for * events. However, if this thread did not have * any user locks, and another thread takes a * user lock and tries to read events, then we'd * deadlock. So we'll choose to let the thread * that got in first consume events, despite the * later thread's user locks. */ InternalLockDisplay(dpy, /* ignore user locks */ 1); dpy->xcb->event_waiter = 0; ConditionBroadcast(dpy, dpy->xcb->event_notify); if(!event) { _XIOError(dpy); return; } dpy->xcb->next_event = event; } /* We've established most of the conditions for * poll_for_response to return non-NULL. The exceptions * are connection shutdown, and finding that another * thread is waiting for the next reply we'd like to * process. */ response = poll_for_response(dpy); if(response) handle_response(dpy, response, False); else if(dpy->xcb->pending_requests->reply_waiter) { /* need braces around ConditionWait */ ConditionWait(dpy, dpy->xcb->reply_notify); } else { _XIOError(dpy); return; } } /* The preceding loop established that there is no * event_waiter--unless we just called ConditionWait because of * a reply_waiter, in which case another thread may have become * the event_waiter while we slept unlocked. */ if(!dpy->xcb->event_waiter) while((response = poll_for_response(dpy))) handle_response(dpy, response, False); if(xcb_connection_has_error(dpy->xcb->connection)) _XIOError(dpy); } /* * _XSend - Flush the buffer and send the client data. 32 bit word aligned * transmission is used, if size is not 0 mod 4, extra bytes are transmitted. * * Note that the connection must not be read from once the data currently * in the buffer has been written. */ void _XSend(Display *dpy, const char *data, long size) { static const xReq dummy_request; static char const pad[3]; struct iovec vec[3]; uint64_t requests; uint64_t dpy_request; _XExtension *ext; xcb_connection_t *c = dpy->xcb->connection; if(dpy->flags & XlibDisplayIOError) return; if(dpy->bufptr == dpy->buffer && !size) return; /* append_pending_request does not alter the dpy request number * therefore we can get it outside of the loop and the if */ dpy_request = X_DPY_GET_REQUEST(dpy); /* iff we asked XCB to set aside errors, we must pick those up * eventually. iff there are async handlers, we may have just * issued requests that will generate replies. in either case, * we need to remember to check later. */ if(dpy->xcb->event_owner != XlibOwnsEventQueue || dpy->async_handlers) { uint64_t sequence; for(sequence = dpy->xcb->last_flushed + 1; sequence <= dpy_request; ++sequence) append_pending_request(dpy, sequence); } requests = dpy_request - dpy->xcb->last_flushed; dpy->xcb->last_flushed = dpy_request; vec[0].iov_base = dpy->buffer; vec[0].iov_len = dpy->bufptr - dpy->buffer; vec[1].iov_base = (char *)data; vec[1].iov_len = size; vec[2].iov_base = (char *)pad; vec[2].iov_len = -size & 3; for(ext = dpy->flushes; ext; ext = ext->next_flush) { int i; for(i = 0; i < 3; ++i) if(vec[i].iov_len) ext->before_flush(dpy, &ext->codes, vec[i].iov_base, vec[i].iov_len); } if(xcb_writev(c, vec, 3, requests) < 0) { _XIOError(dpy); return; } dpy->bufptr = dpy->buffer; dpy->last_req = (char *) &dummy_request; if (!check_internal_connections(dpy)) return; _XSetSeqSyncFunction(dpy); } /* * _XFlush - Flush the X request buffer. If the buffer is empty, no * action is taken. */ void _XFlush(Display *dpy) { if (!require_socket(dpy)) return; _XSend(dpy, NULL, 0); _XEventsQueued(dpy, QueuedAfterReading); } static const XID inval_id = ~0UL; void _XIDHandler(Display *dpy) { if (dpy->xcb->next_xid == inval_id) _XAllocIDs(dpy, &dpy->xcb->next_xid, 1); } /* _XAllocID - resource ID allocation routine. */ XID _XAllocID(Display *dpy) { XID ret = dpy->xcb->next_xid; assert (ret != inval_id); dpy->xcb->next_xid = inval_id; _XSetPrivSyncFunction(dpy); return ret; } /* _XAllocIDs - multiple resource ID allocation routine. */ void _XAllocIDs(Display *dpy, XID *ids, int count) { int i; #ifdef XTHREADS if (dpy->lock) (*dpy->lock->user_lock_display)(dpy); UnlockDisplay(dpy); #endif for (i = 0; i < count; i++) ids[i] = xcb_generate_id(dpy->xcb->connection); #ifdef XTHREADS InternalLockDisplay(dpy, /* don't skip user locks */ 0); if (dpy->lock) (*dpy->lock->user_unlock_display)(dpy); #endif } static void _XFreeReplyData(Display *dpy, Bool force) { if(!force && dpy->xcb->reply_consumed < dpy->xcb->reply_length) return; free(dpy->xcb->reply_data); dpy->xcb->reply_data = NULL; } /* * _XReply - Wait for a reply packet and copy its contents into the * specified rep. * extra: number of 32-bit words expected after the reply * discard: should I discard data following "extra" words? */ Status _XReply(Display *dpy, xReply *rep, int extra, Bool discard) { xcb_generic_error_t *error; xcb_connection_t *c = dpy->xcb->connection; char *reply; PendingRequest *current; uint64_t dpy_request; if (dpy->xcb->reply_data) throw_extlib_fail_assert("Extra reply data still left in queue", xcb_xlib_extra_reply_data_left); if(dpy->flags & XlibDisplayIOError) return 0; _XSend(dpy, NULL, 0); dpy_request = X_DPY_GET_REQUEST(dpy); if(dpy->xcb->pending_requests_tail && dpy->xcb->pending_requests_tail->sequence == dpy_request) current = dpy->xcb->pending_requests_tail; else current = append_pending_request(dpy, dpy_request); /* Don't let any other thread get this reply. */ current->reply_waiter = 1; while(1) { PendingRequest *req = dpy->xcb->pending_requests; xcb_generic_reply_t *response; if(req != current && req->reply_waiter) { ConditionWait(dpy, dpy->xcb->reply_notify); /* Another thread got this reply. */ continue; } req->reply_waiter = 1; UnlockDisplay(dpy); response = xcb_wait_for_reply64(c, req->sequence, &error); /* Any user locks on another thread must have been taken * while we slept in xcb_wait_for_reply64. Classic Xlib * ignored those user locks in this case, so we do too. */ InternalLockDisplay(dpy, /* ignore user locks */ 1); /* We have the response we're looking for. Now, before * letting anyone else process this sequence number, we * need to process any events that should have come * earlier. */ if(dpy->xcb->event_owner == XlibOwnsEventQueue) { xcb_generic_reply_t *event; /* If some thread is already waiting for events, * it will get the first one. That thread must * process that event before we can continue. */ /* FIXME: That event might be after this reply, * and might never even come--or there might be * multiple threads trying to get events. */ while(dpy->xcb->event_waiter) { /* need braces around ConditionWait */ ConditionWait(dpy, dpy->xcb->event_notify); } while((event = poll_for_event(dpy, True))) handle_response(dpy, event, True); } req->reply_waiter = 0; ConditionBroadcast(dpy, dpy->xcb->reply_notify); dpy_request = X_DPY_GET_REQUEST(dpy); if(XLIB_SEQUENCE_COMPARE(req->sequence, >, dpy_request)) { throw_thread_fail_assert("Unknown sequence number " "while processing reply", xcb_xlib_threads_sequence_lost); } X_DPY_SET_LAST_REQUEST_READ(dpy, req->sequence); if(!response) dequeue_pending_request(dpy, req); if(req == current) { reply = (char *) response; break; } if(error) handle_response(dpy, (xcb_generic_reply_t *) error, True); else if(response) handle_response(dpy, response, True); } if (!check_internal_connections(dpy)) return 0; if(dpy->xcb->next_event && dpy->xcb->next_event->response_type == X_Error) { xcb_generic_event_t *event = dpy->xcb->next_event; uint64_t last_request_read = X_DPY_GET_LAST_REQUEST_READ(dpy); uint64_t event_sequence = last_request_read; widen(&event_sequence, event->full_sequence); if(event_sequence == last_request_read) { error = (xcb_generic_error_t *) event; dpy->xcb->next_event = NULL; } } if(error) { int ret_code; /* Xlib is evil and assumes that even errors will be * copied into rep. */ memcpy(rep, error, 32); /* do not die on "no such font", "can't allocate", "can't grab" failures */ switch(error->error_code) { case BadName: switch(error->major_code) { case X_LookupColor: case X_AllocNamedColor: free(error); return 0; } break; case BadFont: if(error->major_code == X_QueryFont) { free(error); return 0; } break; case BadAlloc: case BadAccess: free(error); return 0; } ret_code = handle_error(dpy, (xError *) error, True); free(error); return ret_code; } /* it's not an error, but we don't have a reply, so it's an I/O * error. */ if(!reply) { _XIOError(dpy); return 0; } /* there's no error and we have a reply. */ dpy->xcb->reply_data = reply; dpy->xcb->reply_consumed = sizeof(xReply) + (extra * 4); dpy->xcb->reply_length = sizeof(xReply); if(dpy->xcb->reply_data[0] == 1) dpy->xcb->reply_length += (((xcb_generic_reply_t *) dpy->xcb->reply_data)->length * 4); /* error: Xlib asks too much. give them what we can anyway. */ if(dpy->xcb->reply_length < dpy->xcb->reply_consumed) dpy->xcb->reply_consumed = dpy->xcb->reply_length; memcpy(rep, dpy->xcb->reply_data, dpy->xcb->reply_consumed); _XFreeReplyData(dpy, discard); return 1; } int _XRead(Display *dpy, char *data, long size) { assert(size >= 0); if(size == 0) return 0; if(dpy->xcb->reply_data == NULL || dpy->xcb->reply_consumed + size > dpy->xcb->reply_length) throw_extlib_fail_assert("Too much data requested from _XRead", xcb_xlib_too_much_data_requested); memcpy(data, dpy->xcb->reply_data + dpy->xcb->reply_consumed, size); dpy->xcb->reply_consumed += size; _XFreeReplyData(dpy, False); return 0; } /* * _XReadPad - Read bytes from the socket taking into account incomplete * reads. If the number of bytes is not 0 mod 4, read additional pad * bytes. */ void _XReadPad(Display *dpy, char *data, long size) { _XRead(dpy, data, size); dpy->xcb->reply_consumed += -size & 3; _XFreeReplyData(dpy, False); } /* Read and discard "n" 8-bit bytes of data */ void _XEatData(Display *dpy, unsigned long n) { dpy->xcb->reply_consumed += n; _XFreeReplyData(dpy, False); } /* * Read and discard "n" 32-bit words of data * Matches the units of the length field in X protocol replies, and provides * a single implementation of overflow checking to avoid having to replicate * those checks in every caller. */ void _XEatDataWords(Display *dpy, unsigned long n) { if (n < ((INT_MAX - dpy->xcb->reply_consumed) >> 2)) dpy->xcb->reply_consumed += (n << 2); else /* Overflow would happen, so just eat the rest of the reply */ dpy->xcb->reply_consumed = dpy->xcb->reply_length; _XFreeReplyData(dpy, False); } unsigned long _XNextRequest(Display *dpy) { /* This will update dpy->request. The assumption is that the next thing * that the application will do is make a request so there's little * overhead. */ require_socket(dpy); return NextRequest(dpy); }