[bpt/emacs.git] / src / blockinput.h

/* blockinput.h - interface to blocking complicated interrupt-driven input.
   Copyright (C) 1989, 1993, 2004 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#ifndef EMACS_BLOCKINPUT_H
#define EMACS_BLOCKINPUT_H

#include "atimer.h"

/* When Emacs is using signal-driven input, the processing of those
   input signals can get pretty hairy.  For example, when Emacs is
   running under X windows, handling an input signal can entail
   retrieving events from the X event queue, or making other X calls.

   If an input signal occurs while Emacs is in the midst of some
   non-reentrant code, and the signal processing invokes that same
   code, we lose.  For example, malloc and the Xlib functions aren't
   usually re-entrant, and both are used by the X input signal handler
   - if we try to process an input signal in the midst of executing
   any of these functions, we'll lose.

   To avoid this, we make the following requirements:

   * Everyone must evaluate BLOCK_INPUT before entering these functions,
   and then call UNBLOCK_INPUT after performing them.  Calls
   BLOCK_INPUT and UNBLOCK_INPUT may be nested.

   * Any complicated interrupt handling code should test
   interrupt_input_blocked, and put off its work until later.

   * If the interrupt handling code wishes, it may set
   interrupt_input_pending to a non-zero value.  If that flag is set
   when input becomes unblocked, UNBLOCK_INPUT will send a new SIGIO.  */

extern int interrupt_input_blocked;

/* Nonzero means an input interrupt has arrived
   during the current critical section.  */
extern int interrupt_input_pending;


/* Non-zero means asynchronous timers should be run when input is
   unblocked.  */

extern int pending_atimers;

/* Begin critical section. */
#define BLOCK_INPUT (interrupt_input_blocked++)

/* End critical section.

   If doing signal-driven input, and a signal came in when input was
   blocked, reinvoke the signal handler now to deal with it.

   We used to have two possible definitions of this macro - one for
   when SIGIO was #defined, and one for when it wasn't; when SIGIO
   wasn't #defined, we wouldn't bother to check if we should re-invoke
   the signal handler.  But that doesn't work very well; some of the
   files which use this macro don't #include the right files to get
   SIGIO.

   So, we always test interrupt_input_pending now; that's not too
   expensive, and it'll never get set if we don't need to resignal.  */

#define UNBLOCK_INPUT 				\
  do						\
    {						\
      --interrupt_input_blocked;		\
      if (interrupt_input_blocked == 0)		\
	{					\
	  if (interrupt_input_pending)		\
	    reinvoke_input_signal ();		\
	  if (pending_atimers)			\
	    do_pending_atimers ();		\
	}					\
      else if (interrupt_input_blocked < 0)	\
	abort ();				\
    }						\
  while (0)

/* Undo any number of BLOCK_INPUT calls,
   and also reinvoke any pending signal.  */

#define TOTALLY_UNBLOCK_INPUT			\
  if (interrupt_input_blocked != 0)		\
    {						\
      interrupt_input_blocked = 1;		\
      UNBLOCK_INPUT;				\
    }						\
  else

/* Undo any number of BLOCK_INPUT calls down to level LEVEL,
   and also (if the level is now 0) reinvoke any pending signal.  */

#define UNBLOCK_INPUT_TO(LEVEL)				\
  do							\
    {							\
      int oldlevel = interrupt_input_blocked;		\
      interrupt_input_blocked = (LEVEL) + 1;		\
      if (interrupt_input_blocked != oldlevel + 1)	\
        UNBLOCK_INPUT;					\
    }							\
  while (0)

#define UNBLOCK_INPUT_RESIGNAL UNBLOCK_INPUT

/* In critical section ? */
#define INPUT_BLOCKED_P (interrupt_input_blocked > 0)

/* Defined in keyboard.c */
/* Don't use a prototype here; it causes trouble in some files.  */
extern void reinvoke_input_signal ();

#endif /* EMACS_BLOCKINPUT_H */

/* arch-tag: 51a9ec86-945a-4966-8f04-2d1341250e03
   (do not change this comment) */
Commit	Line	Data
9ac0d9e0	1	/* blockinput.h - interface to blocking complicated interrupt-driven input.
a0ecb2ac	2	Copyright (C) 1989, 1993, 2004 Free Software Foundation, Inc.
33f9662a JB	3
	4	This file is part of GNU Emacs.
	5
	6	GNU Emacs is free software; you can redistribute it and/or modify
	7	it under the terms of the GNU General Public License as published by
	8	the Free Software Foundation; either version 2, or (at your option)
	9	any later version.
	10
	11	GNU Emacs is distributed in the hope that it will be useful,
	12	but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	GNU General Public License for more details.
	15
	16	You should have received a copy of the GNU General Public License
	17	along with GNU Emacs; see the file COPYING. If not, write to
3b7ad313 EN	18	the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
3b7ad313 EN	19	Boston, MA 02111-1307, USA. */
33f9662a	20
b6df5543 DL	21	#ifndef EMACS_BLOCKINPUT_H
	22	#define EMACS_BLOCKINPUT_H
	23
	24	#include "atimer.h"
33f9662a JB	25
	26	/* When Emacs is using signal-driven input, the processing of those
	27	input signals can get pretty hairy. For example, when Emacs is
	28	running under X windows, handling an input signal can entail
	29	retrieving events from the X event queue, or making other X calls.
	30
	31	If an input signal occurs while Emacs is in the midst of some
	32	non-reentrant code, and the signal processing invokes that same
	33	code, we lose. For example, malloc and the Xlib functions aren't
	34	usually re-entrant, and both are used by the X input signal handler
	35	- if we try to process an input signal in the midst of executing
	36	any of these functions, we'll lose.
	37
	38	To avoid this, we make the following requirements:
	39
	40	* Everyone must evaluate BLOCK_INPUT before entering these functions,
	41	and then call UNBLOCK_INPUT after performing them. Calls
	42	BLOCK_INPUT and UNBLOCK_INPUT may be nested.
	43
	44	* Any complicated interrupt handling code should test
177c0ea7	45	interrupt_input_blocked, and put off its work until later.
33f9662a JB	46
	47	* If the interrupt handling code wishes, it may set
	48	interrupt_input_pending to a non-zero value. If that flag is set
	49	when input becomes unblocked, UNBLOCK_INPUT will send a new SIGIO. */
	50
61836955	51	extern int interrupt_input_blocked;
33f9662a JB	52
	53	/* Nonzero means an input interrupt has arrived
	54	during the current critical section. */
	55	extern int interrupt_input_pending;
	56
95d9dd00 GM	57
	58	/* Non-zero means asynchronous timers should be run when input is
	59	unblocked. */
	60
	61	extern int pending_atimers;
	62
33f9662a JB	63	/* Begin critical section. */
	64	#define BLOCK_INPUT (interrupt_input_blocked++)
	65
40a4095a JB	66	/* End critical section.
	67
	68	If doing signal-driven input, and a signal came in when input was
	69	blocked, reinvoke the signal handler now to deal with it.
	70
	71	We used to have two possible definitions of this macro - one for
	72	when SIGIO was #defined, and one for when it wasn't; when SIGIO
	73	wasn't #defined, we wouldn't bother to check if we should re-invoke
	74	the signal handler. But that doesn't work very well; some of the
	75	files which use this macro don't #include the right files to get
	76	SIGIO.
	77
	78	So, we always test interrupt_input_pending now; that's not too
	79	expensive, and it'll never get set if we don't need to resignal. */
95d9dd00 GM	80
	81	#define UNBLOCK_INPUT \
	82	do \
	83	{ \
	84	--interrupt_input_blocked; \
	85	if (interrupt_input_blocked == 0) \
	86	{ \
	87	if (interrupt_input_pending) \
	88	reinvoke_input_signal (); \
	89	if (pending_atimers) \
	90	do_pending_atimers (); \
	91	} \
	92	else if (interrupt_input_blocked < 0) \
	93	abort (); \
	94	} \
	95	while (0)
33f9662a	96
835ee136 RS	97	/* Undo any number of BLOCK_INPUT calls,
	98	and also reinvoke any pending signal. */
	99
	100	#define TOTALLY_UNBLOCK_INPUT \
	101	if (interrupt_input_blocked != 0) \
	102	{ \
	103	interrupt_input_blocked = 1; \
	104	UNBLOCK_INPUT; \
	105	} \
	106	else
	107
	108	/* Undo any number of BLOCK_INPUT calls down to level LEVEL,
	109	and also (if the level is now 0) reinvoke any pending signal. */
	110
	111	#define UNBLOCK_INPUT_TO(LEVEL) \
	112	do \
	113	{ \
	114	int oldlevel = interrupt_input_blocked; \
	115	interrupt_input_blocked = (LEVEL) + 1; \
	116	if (interrupt_input_blocked != oldlevel + 1) \
	117	UNBLOCK_INPUT; \
	118	} \
	119	while (0)
	120
33f9662a	121	#define UNBLOCK_INPUT_RESIGNAL UNBLOCK_INPUT
ec5d8db7	122
c2de28ef KS	123	/* In critical section ? */
	124	#define INPUT_BLOCKED_P (interrupt_input_blocked > 0)
	125
ec5d8db7	126	/* Defined in keyboard.c */
de4df76b RS	127	/* Don't use a prototype here; it causes trouble in some files. */
de4df76b RS	128	extern void reinvoke_input_signal ();
b6df5543 DL	129
b6df5543 DL	130	#endif /* EMACS_BLOCKINPUT_H */
ab5796a9 MB	131
	132	/* arch-tag: 51a9ec86-945a-4966-8f04-2d1341250e03
	133	(do not change this comment) */