view src/thread/riscos/SDL_syssem.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 1ccbb2b7d905
children c9b51268668f
line wrap: on
line source

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2004 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 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
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    slouken@libsdl.org
*/

/* RISC OS semiphores based on linux code */

#ifdef SAVE_RCSID
static char rcsid =
 "@(#) $Id$";
#endif


#include <stdlib.h>

#include "SDL_error.h"
#include "SDL_timer.h"
#include "SDL_thread.h"

#include "SDL_systhread_c.h"

#ifdef DISABLE_THREADS

SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
{
	SDL_SetError("SDL not configured with thread support");
	return (SDL_sem *)0;
}

void SDL_DestroySemaphore(SDL_sem *sem)
{
	return;
}

int SDL_SemTryWait(SDL_sem *sem)
{
	SDL_SetError("SDL not configured with thread support");
	return -1;
}

int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
{
	SDL_SetError("SDL not configured with thread support");
	return -1;
}

int SDL_SemWait(SDL_sem *sem)
{
	SDL_SetError("SDL not configured with thread support");
	return -1;
}

Uint32 SDL_SemValue(SDL_sem *sem)
{
	return 0;
}

int SDL_SemPost(SDL_sem *sem)
{
	SDL_SetError("SDL not configured with thread support");
	return -1;
}

#else


#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>			/* For getpid() */
#include <pthread.h>
#include <semaphore.h>

struct SDL_semaphore {
	sem_t *sem;
	sem_t sem_data;
};

/* Create a semaphore, initialized with value */
SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
{
	SDL_sem *sem = (SDL_sem *) malloc(sizeof(SDL_sem));
	if ( sem ) {
		if ( sem_init(&sem->sem_data, 0, initial_value) < 0 ) {
			SDL_SetError("sem_init() failed");
			free(sem);
			sem = NULL;
		} else {
			sem->sem = &sem->sem_data;
		}
	} else {
		SDL_OutOfMemory();
	}
	return sem;
}

void SDL_DestroySemaphore(SDL_sem *sem)
{
	if ( sem ) {
		sem_destroy(sem->sem);
		free(sem);
	}
}

int SDL_SemTryWait(SDL_sem *sem)
{
	int retval;

	if ( ! sem ) {
		SDL_SetError("Passed a NULL semaphore");
		return -1;
	}
	retval = SDL_MUTEX_TIMEDOUT;
	if ( sem_trywait(sem->sem) == 0 ) {
		retval = 0;
	}
	return retval;
}

int SDL_SemWait(SDL_sem *sem)
{
	int retval;

	if ( ! sem ) {
		SDL_SetError("Passed a NULL semaphore");
		return -1;
	}

	retval = sem_wait(sem->sem);
	if ( retval < 0 ) {
		SDL_SetError("sem_wait() failed");
	}
	return retval;
}

int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
{
	int retval;

	if ( ! sem ) {
		SDL_SetError("Passed a NULL semaphore");
		return -1;
	}

	/* Try the easy cases first */
	if ( timeout == 0 ) {
		return SDL_SemTryWait(sem);
	}
	if ( timeout == SDL_MUTEX_MAXWAIT ) {
		return SDL_SemWait(sem);
	}

	/* Ack!  We have to busy wait... */
	timeout += SDL_GetTicks();
	do {
		retval = SDL_SemTryWait(sem);
		if ( retval == 0 ) {
			break;
		}
		SDL_Delay(1);
	} while ( SDL_GetTicks() < timeout );

	return retval;
}

Uint32 SDL_SemValue(SDL_sem *sem)
{
	int ret = 0;
	if ( sem ) {
		sem_getvalue(sem->sem, &ret);
		if ( ret < 0 ) {
			ret = 0;
		}
	}
	return (Uint32)ret;
}

int SDL_SemPost(SDL_sem *sem)
{
	int retval;

	if ( ! sem ) {
		SDL_SetError("Passed a NULL semaphore");
		return -1;
	}

	retval = sem_post(sem->sem);
	if ( retval < 0 ) {
		SDL_SetError("sem_post() failed");
	}
	return retval;
}

#endif /* DISABLE_THREADS */