view test/testjoystick.c @ 1176:dd2a8deeb26d

Date: Mon, 17 Oct 2005 20:09:03 -0400 From: Mark Schreiber <mark7@alumni.cmu.edu> To: ryan@clutteredmind.org Subject: [PATCH]SDL mprotect() crash fix (I'm going to throw this patch your way at the suggestion of #SDL -- for some reason, I had some difficulty sending it to the main list last time, and I go bonkers subscribing to send each email or patch...) Currently, when I run SDL applications as non-root using SDL_VIDEODRIVER=dga, the fbdev fallback mprotect()s read/write the proper size of mmapped /dev/fb0 (7.5MB), but on framebuffer release mprotect()s read-only the range by the entire size of my video memory (128MB), which causes a segfault: #0 0x002a9a27 in ?? () from /lib/libc.so.6 #1 0x04a63eb6 in SDL_XDGAUnmapFramebuffer (screen=3D0) at XF86DGA2.c:978 #2 0x04a63efc in SDL_XDGACloseFramebuffer (dpy=3D0x9d3f008, screen=3D0) at XF86DGA2.c:268 #3 0x04a68b57 in DGA_Available () at SDL_dgavideo.c:98 #4 0x04a53677 in SDL_VideoInit (driver_name=3D0xbfb0bfc7 "dga", flags=3D0) at SDL_video.c:180 #5 0x04a2613f in SDL_InitSubSystem (flags=3D32) at SDL.c:74 #6 0x04a2617c in SDL_Init (flags=3D32) at SDL.c:166 #7 0x08049722 in main (argc=3D1, argv=3D0x0) at testwin.c:32 This is SDL 1.2.8 on Fedora Core 4, radeon driver for a Radeon 9250, xorg-x11-6.8.2-37. I've attached a one-line patch against SDL CVS that updates the size of the framebuffer at framebuffer map time so that the mprotect() on unmap will be the same size. I'm not sure if this is the best approach (i.e. one might want to retain the original value), but it does make my SDL applications work without segfaulting. -- Best of luck, Mark Schreiber
author Ryan C. Gordon <icculus@icculus.org>
date Sat, 19 Nov 2005 18:57:00 +0000
parents 74212992fb08
children 281d3f4870e5
line wrap: on
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/* Simple program to test the SDL joystick routines */

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

#include "SDL.h"

#define SCREEN_WIDTH	640
#define SCREEN_HEIGHT	480

void WatchJoystick(SDL_Joystick *joystick)
{
	SDL_Surface *screen;
	const char *name;
	int i, done;
	SDL_Event event;
	int x, y, draw;
	SDL_Rect axis_area[2];

	/* Set a video mode to display joystick axis position */
	screen = SDL_SetVideoMode(SCREEN_WIDTH, SCREEN_HEIGHT, 16, 0);
	if ( screen == NULL ) {
		fprintf(stderr, "Couldn't set video mode: %s\n",SDL_GetError());
		return;
	}

	/* Print info about the joystick we are watching */
	name = SDL_JoystickName(SDL_JoystickIndex(joystick));
	printf("Watching joystick %d: (%s)\n", SDL_JoystickIndex(joystick),
	       name ? name : "Unknown Joystick");
	printf("Joystick has %d axes, %d hats, %d balls, and %d buttons\n",
	       SDL_JoystickNumAxes(joystick), SDL_JoystickNumHats(joystick),
	       SDL_JoystickNumBalls(joystick),SDL_JoystickNumButtons(joystick));

	/* Initialize drawing rectangles */
	memset(axis_area, 0, (sizeof axis_area));
	draw = 0;

	/* Loop, getting joystick events! */
	done = 0;
	while ( ! done ) {
		while ( SDL_PollEvent(&event) ) {
			switch (event.type) {
			    case SDL_JOYAXISMOTION:
				printf("Joystick %d axis %d value: %d\n",
				       event.jaxis.which,
				       event.jaxis.axis,
				       event.jaxis.value);
				break;
			    case SDL_JOYHATMOTION:
				printf("Joystick %d hat %d value:",
				       event.jhat.which,
				       event.jhat.hat);
				if ( event.jhat.value == SDL_HAT_CENTERED )
					printf(" centered");
				if ( event.jhat.value & SDL_HAT_UP )
					printf(" up");
				if ( event.jhat.value & SDL_HAT_RIGHT )
					printf(" right");
				if ( event.jhat.value & SDL_HAT_DOWN )
					printf(" down");
				if ( event.jhat.value & SDL_HAT_LEFT )
					printf(" left");
				printf("\n");
				break;
			    case SDL_JOYBALLMOTION:
				printf("Joystick %d ball %d delta: (%d,%d)\n",
				       event.jball.which,
				       event.jball.ball,
				       event.jball.xrel,
				       event.jball.yrel);
				break;
			    case SDL_JOYBUTTONDOWN:
				printf("Joystick %d button %d down\n",
				       event.jbutton.which,
				       event.jbutton.button);
				break;
			    case SDL_JOYBUTTONUP:
				printf("Joystick %d button %d up\n",
				       event.jbutton.which,
				       event.jbutton.button);
				break;
			    case SDL_KEYDOWN:
				if ( event.key.keysym.sym != SDLK_ESCAPE ) {
					break;
				}
				/* Fall through to signal quit */
			    case SDL_QUIT:
				done = 1;
				break;
			    default:
				break;
			}
		}
		/* Update visual joystick state */
		for ( i=0; i<SDL_JoystickNumButtons(joystick); ++i ) {
			SDL_Rect area;

			area.x = i*34;
			area.y = SCREEN_HEIGHT-34;
			area.w = 32;
			area.h = 32;
			if (SDL_JoystickGetButton(joystick, i) == SDL_PRESSED) {
				SDL_FillRect(screen, &area, 0xFFFF);
			} else {
				SDL_FillRect(screen, &area, 0x0000);
			}
			SDL_UpdateRects(screen, 1, &area);
		}

		/* Erase previous axes */
		SDL_FillRect(screen, &axis_area[draw], 0x0000);

		/* Draw the X/Y axis */
		draw = !draw;
		x = (((int)SDL_JoystickGetAxis(joystick, 0))+32768);
		x *= SCREEN_WIDTH;
		x /= 65535;
		if ( x < 0 ) {
			x = 0;
		} else
		if ( x > (SCREEN_WIDTH-16) ) {
			x = SCREEN_WIDTH-16;
		}
		y = (((int)SDL_JoystickGetAxis(joystick, 1))+32768);
		y *= SCREEN_HEIGHT;
		y /= 65535;
		if ( y < 0 ) {
			y = 0;
		} else
		if ( y > (SCREEN_HEIGHT-16) ) {
			y = SCREEN_HEIGHT-16;
		}
		axis_area[draw].x = (Sint16)x;
		axis_area[draw].y = (Sint16)y;
		axis_area[draw].w = 16;
		axis_area[draw].h = 16;
		SDL_FillRect(screen, &axis_area[draw], 0xFFFF);

		SDL_UpdateRects(screen, 2, axis_area);
	}
}

int main(int argc, char *argv[])
{
	const char *name;
	int i;
	SDL_Joystick *joystick;

	/* Initialize SDL (Note: video is required to start event loop) */
	if ( SDL_Init(SDL_INIT_VIDEO|SDL_INIT_JOYSTICK) < 0 ) {
		fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError());
		exit(1);
	}

	/* Print information about the joysticks */
	printf("There are %d joysticks attached\n", SDL_NumJoysticks());
	for ( i=0; i<SDL_NumJoysticks(); ++i ) {
		name = SDL_JoystickName(i);
		printf("Joystick %d: %s\n",i,name ? name : "Unknown Joystick");
	}

	if ( argv[1] ) {
		joystick = SDL_JoystickOpen(atoi(argv[1]));
		if ( joystick == NULL ) {
			printf("Couldn't open joystick %d: %s\n", atoi(argv[1]),
			       SDL_GetError());
		} else {
			WatchJoystick(joystick);
			SDL_JoystickClose(joystick);
		}
	}
	SDL_QuitSubSystem(SDL_INIT_VIDEO|SDL_INIT_JOYSTICK);

	return(0);
}