xcb_io.c   [plain text]

/* Copyright (C) 2003-2006 Jamey Sharp, Josh Triplett
 * This file is licensed under the MIT license. See the file COPYING. */

#include "Xlibint.h"
#include "locking.h"
#include "Xxcbint.h"
#include <xcb/xcbext.h>
#include <xcb/xcbxlib.h>

#include <assert.h>
#include <stdlib.h>
#include <string.h>

/* 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 void 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;

	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)
			return;
		_XIOError(dpy);
	}

	for(ilist = dpy->im_fd_info; result && ilist; ilist = ilist->next)
		if(FD_ISSET(ilist->fd, &r_mask))
		{
			_XProcessInternalConnection(dpy, ilist);
			--result;
		}
}

static void condition_wait(Display *dpy, xcondition_t cv)
{
	_XPutXCBBuffer(dpy);
	xcb_xlib_unlock(dpy->xcb->connection);
	ConditionWait(dpy, cv);
	xcb_xlib_lock(dpy->xcb->connection);
	_XGetXCBBuffer(dpy);
}

static void call_handlers(Display *dpy, xcb_generic_reply_t *buf)
{
	_XAsyncHandler *async, *next;
	for(async = dpy->async_handlers; async; async = next)
	{
		next = async->next;
		if(async->handler(dpy, (xReply *) buf, (char *) buf, sizeof(xReply) + (buf->length << 2), async->data))
			return;
	}
	if(buf->response_type == 0) /* unhandled error */
	    _XError(dpy, (xError *) buf);
}

static xcb_generic_event_t * wait_or_poll_for_event(Display *dpy, int wait)
{
	xcb_connection_t *c = dpy->xcb->connection;
	xcb_generic_event_t *event;
	if(wait)
	{
		UnlockDisplay(dpy);
		event = xcb_wait_for_event(c);
		LockDisplay(dpy);
	}
	else
		event = xcb_poll_for_event(c);
	return event;
}

static void process_responses(Display *dpy, int wait_for_first_event, xcb_generic_error_t **current_error, unsigned int current_request)
{
	void *reply;
	xcb_generic_event_t *event = dpy->xcb->next_event;
	xcb_generic_error_t *error;
	xcb_connection_t *c = dpy->xcb->connection;
	if(!event && dpy->xcb->event_owner == XlibOwnsEventQueue)
		event = wait_or_poll_for_event(dpy, wait_for_first_event);

	while(1)
	{
		PendingRequest *req = dpy->xcb->pending_requests;
		assert(!(req && current_request && !XCB_SEQUENCE_COMPARE(req->sequence, <=, current_request)));
		if(event && (!req || XCB_SEQUENCE_COMPARE(event->full_sequence, <=, req->sequence)))
		{
			dpy->last_request_read = event->full_sequence;
			if(event->response_type != X_Error)
			{
				_XEnq(dpy, (xEvent *) event);
				wait_for_first_event = 0;
			}
			else if(current_error && event->full_sequence == current_request)
			{
				/* This can only occur when called from
				 * _XReply, which doesn't need a new event. */
				*current_error = (xcb_generic_error_t *) event;
				event = 0;
				break;
			}
			else
				_XError(dpy, (xError *) event);
			free(event);
			event = wait_or_poll_for_event(dpy, wait_for_first_event);
		}
		else if(req && req->waiters != -1)
		{
			if(req->sequence == current_request)
				break;
			if(!current_request && !wait_for_first_event)
				break;
			dpy->xcb->next_event = event;
			req->waiters++;
			assert(req->waiters > 0);
			condition_wait(dpy, &req->condition);
			--req->waiters;
			event = dpy->xcb->next_event;
		}
		else if(req && xcb_poll_for_reply(dpy->xcb->connection, req->sequence, &reply, &error))
		{
			unsigned int sequence = req->sequence;
			if(!reply)
			{
				dpy->xcb->pending_requests = req->next;
				if(!dpy->xcb->pending_requests)
					dpy->xcb->pending_requests_tail = &dpy->xcb->pending_requests;
				free(req);
				reply = error;
			}
			if(reply)
			{
				dpy->last_request_read = sequence;
				call_handlers(dpy, reply);
				free(reply);
			}
		}
		else
			break;
	}

	dpy->xcb->next_event = event;

	if(xcb_connection_has_error(c))
		_XIOError(dpy);

	assert_sequence_less(dpy->last_request_read, dpy->request);
	assert(!wait_for_first_event);
}

int _XEventsQueued(Display *dpy, int mode)
{
	if(dpy->flags & XlibDisplayIOError)
		return 0;
	if(dpy->xcb->event_owner != XlibOwnsEventQueue)
		return 0;

	if(mode == QueuedAfterFlush)
		_XSend(dpy, 0, 0);
	else
		check_internal_connections(dpy);
	process_responses(dpy, 0, 0, 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)
{
	if(dpy->flags & XlibDisplayIOError)
		return;
	_XSend(dpy, 0, 0);
	if(dpy->xcb->event_owner != XlibOwnsEventQueue)
		return;
	check_internal_connections(dpy);
	process_responses(dpy, 1, 0, 0);
}

/*
 * _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)
{
	xcb_connection_t *c = dpy->xcb->connection;
	if(dpy->flags & XlibDisplayIOError)
		return;

	assert(!dpy->xcb->request_extra);
	dpy->xcb->request_extra = data;
	dpy->xcb->request_extra_size = size;

	/* give dpy->buffer to XCB */
	_XPutXCBBuffer(dpy);

	if(xcb_flush(c) <= 0)
		_XIOError(dpy);

	/* get a new dpy->buffer */
	_XGetXCBBuffer(dpy);

	check_internal_connections(dpy);

	/* A straight port of XlibInt.c would call _XSetSeqSyncFunction
	 * here. However that does no good: unlike traditional Xlib,
	 * Xlib/XCB almost never calls _XFlush because _XPutXCBBuffer
	 * automatically pushes requests down into XCB, so Xlib's buffer
	 * is empty most of the time. Since setting a synchandler has no
	 * effect until after UnlockDisplay returns, we may as well do
	 * the check in _XUnlockDisplay. */
}

/*
 * _XFlush - Flush the X request buffer.  If the buffer is empty, no
 * action is taken.
 */
void _XFlush(Display *dpy)
{
	_XSend(dpy, 0, 0);

	_XEventsQueued(dpy, QueuedAfterReading);
}

static int
_XIDHandler(Display *dpy)
{
	XID next = xcb_generate_id(dpy->xcb->connection);
	LockDisplay(dpy);
	dpy->xcb->next_xid = next;
	if(dpy->flags & XlibDisplayPrivSync)
	{
		dpy->synchandler = dpy->savedsynchandler;
		dpy->flags &= ~XlibDisplayPrivSync;
	}
	UnlockDisplay(dpy);
	SyncHandle();
	return 0;
}

/* _XAllocID - resource ID allocation routine. */
XID _XAllocID(Display *dpy)
{
	XID ret = dpy->xcb->next_xid;
	dpy->xcb->next_xid = 0;

	assert(!(dpy->flags & XlibDisplayPrivSync));
	dpy->savedsynchandler = dpy->synchandler;
	dpy->flags |= XlibDisplayPrivSync;
	dpy->synchandler = _XIDHandler;
	return ret;
}

/* _XAllocIDs - multiple resource ID allocation routine. */
void _XAllocIDs(Display *dpy, XID *ids, int count)
{
	int i;
	_XPutXCBBuffer(dpy);
	for (i = 0; i < count; i++)
		ids[i] = xcb_generate_id(dpy->xcb->connection);
	_XGetXCBBuffer(dpy);
}

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 = 0;
}

static PendingRequest * insert_pending_request(Display *dpy)
{
	PendingRequest **cur = &dpy->xcb->pending_requests;
	while(*cur && XCB_SEQUENCE_COMPARE((*cur)->sequence, <, dpy->request))
		cur = &((*cur)->next);
	if(*cur && (*cur)->sequence == dpy->request)
	{
		/* Replacing an existing PendingRequest should only happen once,
		   when calling _XReply, and the replaced PendingRequest must
		   not have a condition set. */
		assert((*cur)->waiters == -1);
	}
	else
	{
		PendingRequest *node = malloc(sizeof(PendingRequest));
		assert(node);
		node->next = *cur;
		node->sequence = dpy->request;
		if(cur == dpy->xcb->pending_requests_tail)
			dpy->xcb->pending_requests_tail = &(node->next);
		*cur = node;
	}
	(*cur)->waiters = 0;
	xcondition_init(&((*cur)->condition));
	return *cur;
}

/*
 * _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;

	assert(!dpy->xcb->reply_data);

	if(dpy->flags & XlibDisplayIOError)
		return 0;

	/* Internals of UnlockDisplay done by hand here, so that we can
	   insert_pending_request *after* we _XPutXCBBuffer, but before we
	   unlock the display. */
	_XPutXCBBuffer(dpy);
	current = insert_pending_request(dpy);
	if(!dpy->lock || dpy->lock->locking_level == 0)
		xcb_xlib_unlock(dpy->xcb->connection);
	if(dpy->xcb->lock_fns.unlock_display)
		dpy->xcb->lock_fns.unlock_display(dpy);
	reply = xcb_wait_for_reply(c, current->sequence, &error);
	LockDisplay(dpy);

	check_internal_connections(dpy);
	process_responses(dpy, 0, &error, current->sequence);

	if(current->waiters)
	{ /* The ConditionBroadcast macro contains an if; braces needed here. */
		ConditionBroadcast(dpy, &current->condition);
	}
	--current->waiters;

	if(error)
	{
		_XExtension *ext;
		xError *err = (xError *) error;
		int ret_code;

		dpy->last_request_read = error->full_sequence;

		/* 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(err->errorCode)
		{
			case BadName:
				switch(err->majorCode)
				{
					case X_LookupColor:
					case X_AllocNamedColor:
						return 0;
				}
				break;
			case BadFont:
				if(err->majorCode == X_QueryFont)
					return 0;
				break;
			case BadAlloc:
			case BadAccess:
				return 0;
		}

		/* 
		 * 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, (xError *) error);
		return 0;
	}

	/* 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;
	}

	dpy->last_request_read = current->sequence;

	/* 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;
	assert(dpy->xcb->reply_data != 0);
	assert(dpy->xcb->reply_consumed + size <= dpy->xcb->reply_length);
	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);
}