view src/events/SDL_mouse.c @ 4158:96ce26f24b01 SDL-1.2

Date: Sun, 7 Sep 2008 15:17:00 +0200 From: c2woody@gmx.net Subject: [SDL] SDL 1.2 doube free/pointer zeroing missing Hello, this is about a crash/debug breakage for the current SDL 1.2 source tree (today's svn checkout, same problem in 1.2.13 and before as far as relevant). In some places memory is free()d but the associated pointer is not zeroed, leading to for example double free()s. For me this happened because SDL_StopEventThread() was executed twice (during restart of the subsystems), once for the close down in SDL_VideoQuit() and once at the startup, right at the beginning of SDL_StartEventLoop(). Thus the code SDL_DestroyMutex(SDL_EventQ.lock); (see SDL_events.c) was called twice and executed the SDL_free(mutex); twice as well, leading to a crash (msvc 64bit for which it was noticed). I've tried to check all other occurrences of SDL_free and similar code in msvc, see the attached patch (udiff against revision 4082). Non-windows only codepaths have neither been checked nor touched. Comments/ideas welcome. Attached patch: NULLifies some pointers after they have been free()d.
author Sam Lantinga <slouken@libsdl.org>
date Wed, 12 Nov 2008 17:23:40 +0000
parents 23a347cfbed8
children 782fd950bd46 c121d94672cb a1b03ba2fcd0
line wrap: on
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/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/
#include "SDL_config.h"

/* General mouse handling code for SDL */

#include "SDL_events.h"
#include "SDL_events_c.h"
#include "../video/SDL_cursor_c.h"
#include "../video/SDL_sysvideo.h"


/* These are static for our mouse handling code */
static Sint16 SDL_MouseX = 0;
static Sint16 SDL_MouseY = 0;
static Sint16 SDL_DeltaX = 0;
static Sint16 SDL_DeltaY = 0;
static Uint8  SDL_ButtonState = 0;


/* Public functions */
int SDL_MouseInit(void)
{
	/* The mouse is at (0,0) */
	SDL_MouseX = 0;
	SDL_MouseY = 0;
	SDL_DeltaX = 0;
	SDL_DeltaY = 0;
	SDL_ButtonState = 0;

	/* That's it! */
	return(0);
}
void SDL_MouseQuit(void)
{
}

/* We lost the mouse, so post button up messages for all pressed buttons */
void SDL_ResetMouse(void)
{
	Uint8 i;
	for ( i = 0; i < sizeof(SDL_ButtonState)*8; ++i ) {
		if ( SDL_ButtonState & SDL_BUTTON(i) ) {
			SDL_PrivateMouseButton(SDL_RELEASED, i, 0, 0);
		}
	}
}

Uint8 SDL_GetMouseState (int *x, int *y)
{
	if ( x ) {
		*x = SDL_MouseX;
	}
	if ( y ) {
		*y = SDL_MouseY;
	}
	return(SDL_ButtonState);
}

Uint8 SDL_GetRelativeMouseState (int *x, int *y)
{
	if ( x )
		*x = SDL_DeltaX;
	if ( y )
		*y = SDL_DeltaY;
	SDL_DeltaX = 0;
	SDL_DeltaY = 0;
	return(SDL_ButtonState);
}

static void ClipOffset(Sint16 *x, Sint16 *y)
{
	/* This clips absolute mouse coordinates when the apparent
	   display surface is smaller than the real display surface.
	 */
	if ( SDL_VideoSurface->offset ) {
		*y -= SDL_VideoSurface->offset/SDL_VideoSurface->pitch;
		*x -= (SDL_VideoSurface->offset%SDL_VideoSurface->pitch)/
				SDL_VideoSurface->format->BytesPerPixel;
	}
}

/* These are global for SDL_eventloop.c */
int SDL_PrivateMouseMotion(Uint8 buttonstate, int relative, Sint16 x, Sint16 y)
{
	int posted;
	Uint16 X, Y;
	Sint16 Xrel;
	Sint16 Yrel;

	/* Don't handle mouse motion if there's no cursor surface */
	if ( SDL_VideoSurface == NULL ) {
		return(0);
	}

	/* Default buttonstate is the current one */
	if ( ! buttonstate ) {
		buttonstate = SDL_ButtonState;
	}

	Xrel = x;
	Yrel = y;
	if ( relative ) {
		/* Push the cursor around */
		x = (SDL_MouseX+x);
		y = (SDL_MouseY+y);
	} else {
		/* Do we need to clip {x,y} ? */
		ClipOffset(&x, &y);
	}

	/* Mouse coordinates range from 0 - width-1 and 0 - height-1 */
	if ( x < 0 )
		X = 0;
	else
	if ( x >= SDL_VideoSurface->w )
		X = SDL_VideoSurface->w-1;
	else
		X = (Uint16)x;

	if ( y < 0 )
		Y = 0;
	else
	if ( y >= SDL_VideoSurface->h )
		Y = SDL_VideoSurface->h-1;
	else
		Y = (Uint16)y;

	/* If not relative mode, generate relative motion from clamped X/Y.
	   This prevents lots of extraneous large delta relative motion when
	   the screen is windowed mode and the mouse is outside the window.
	*/
	if ( ! relative ) {
		Xrel = X-SDL_MouseX;
		Yrel = Y-SDL_MouseY;
	}

	/* Drop events that don't change state */
	if ( ! Xrel && ! Yrel ) {
#if 0
printf("Mouse event didn't change state - dropped!\n");
#endif
		return(0);
	}

	/* Update internal mouse state */
	SDL_ButtonState = buttonstate;
	SDL_MouseX = X;
	SDL_MouseY = Y;
	SDL_DeltaX += Xrel;
	SDL_DeltaY += Yrel;
        SDL_MoveCursor(SDL_MouseX, SDL_MouseY);

	/* Post the event, if desired */
	posted = 0;
	if ( SDL_ProcessEvents[SDL_MOUSEMOTION] == SDL_ENABLE ) {
		SDL_Event event;
		SDL_memset(&event, 0, sizeof(event));
		event.type = SDL_MOUSEMOTION;
		event.motion.state = buttonstate;
		event.motion.x = X;
		event.motion.y = Y;
		event.motion.xrel = Xrel;
		event.motion.yrel = Yrel;
		if ( (SDL_EventOK == NULL) || (*SDL_EventOK)(&event) ) {
			posted = 1;
			SDL_PushEvent(&event);
		}
	}
	return(posted);
}

int SDL_PrivateMouseButton(Uint8 state, Uint8 button, Sint16 x, Sint16 y)
{
	SDL_Event event;
	int posted;
	int move_mouse;
	Uint8 buttonstate;

	SDL_memset(&event, 0, sizeof(event));

	/* Check parameters */
	if ( x || y ) {
		ClipOffset(&x, &y);
		move_mouse = 1;
		/* Mouse coordinates range from 0 - width-1 and 0 - height-1 */
		if ( x < 0 )
			x = 0;
		else
		if ( x >= SDL_VideoSurface->w )
			x = SDL_VideoSurface->w-1;

		if ( y < 0 )
			y = 0;
		else
		if ( y >= SDL_VideoSurface->h )
			y = SDL_VideoSurface->h-1;
	} else {
		move_mouse = 0;
	}
	if ( ! x )
		x = SDL_MouseX;
	if ( ! y )
		y = SDL_MouseY;

	/* Figure out which event to perform */
	buttonstate = SDL_ButtonState;
	switch ( state ) {
		case SDL_PRESSED:
			event.type = SDL_MOUSEBUTTONDOWN;
			buttonstate |= SDL_BUTTON(button);
			break;
		case SDL_RELEASED:
			event.type = SDL_MOUSEBUTTONUP;
			buttonstate &= ~SDL_BUTTON(button);
			break;
		default:
			/* Invalid state -- bail */
			return(0);
	}

	/* Update internal mouse state */
	SDL_ButtonState = buttonstate;
	if ( move_mouse ) {
		SDL_MouseX = x;
		SDL_MouseY = y;
		SDL_MoveCursor(SDL_MouseX, SDL_MouseY);
	}

	/* Post the event, if desired */
	posted = 0;
	if ( SDL_ProcessEvents[event.type] == SDL_ENABLE ) {
		event.button.state = state;
		event.button.button = button;
		event.button.x = x;
		event.button.y = y;
		if ( (SDL_EventOK == NULL) || (*SDL_EventOK)(&event) ) {
			posted = 1;
			SDL_PushEvent(&event);
		}
	}
	return(posted);
}