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view src/SDL_fatal.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 | 51a8702d8ecd |
children | c9b51268668f |
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/* 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 */ #ifdef SAVE_RCSID static char rcsid = "@(#) $Id$"; #endif #ifdef _WIN32_WCE #define NO_SIGNAL_H #endif /* General fatal signal handling code for SDL */ #ifdef NO_SIGNAL_H /* No signals on this platform, nothing to do.. */ void SDL_InstallParachute(void) { return; } void SDL_UninstallParachute(void) { return; } #else #include <stdlib.h> #include <stdio.h> #include <signal.h> #include <string.h> #include "SDL.h" #include "SDL_fatal.h" #ifdef __CYGWIN__ #define DISABLE_STDIO #endif /* This installs some signal handlers for the more common fatal signals, so that if the programmer is lazy, the app doesn't die so horribly if the program crashes. */ static void print_msg(const char *text) { #ifndef DISABLE_STDIO fprintf(stderr, "%s", text); #endif } static void SDL_Parachute(int sig) { signal(sig, SIG_DFL); print_msg("Fatal signal: "); switch (sig) { case SIGSEGV: print_msg("Segmentation Fault"); break; #ifdef SIGBUS #if SIGBUS != SIGSEGV case SIGBUS: print_msg("Bus Error"); break; #endif #endif /* SIGBUS */ #ifdef SIGFPE case SIGFPE: print_msg("Floating Point Exception"); break; #endif /* SIGFPE */ #ifdef SIGQUIT case SIGQUIT: print_msg("Keyboard Quit"); break; #endif /* SIGQUIT */ #ifdef SIGPIPE case SIGPIPE: print_msg("Broken Pipe"); break; #endif /* SIGPIPE */ default: #ifndef DISABLE_STDIO fprintf(stderr, "# %d", sig); #endif break; } print_msg(" (SDL Parachute Deployed)\n"); SDL_Quit(); exit(-sig); } static int SDL_fatal_signals[] = { SIGSEGV, #ifdef SIGBUS SIGBUS, #endif #ifdef SIGFPE SIGFPE, #endif #ifdef SIGQUIT SIGQUIT, #endif 0 }; void SDL_InstallParachute(void) { /* Set a handler for any fatal signal not already handled */ int i; #ifdef HAVE_SIGACTION struct sigaction action; for ( i=0; SDL_fatal_signals[i]; ++i ) { sigaction(SDL_fatal_signals[i], NULL, &action); if ( action.sa_handler == SIG_DFL ) { action.sa_handler = SDL_Parachute; sigaction(SDL_fatal_signals[i], &action, NULL); } } #ifdef SIGALRM /* Set SIGALRM to be ignored -- necessary on Solaris */ sigaction(SIGALRM, NULL, &action); if ( action.sa_handler == SIG_DFL ) { action.sa_handler = SIG_IGN; sigaction(SIGALRM, &action, NULL); } #endif #else void (*ohandler)(int); for ( i=0; SDL_fatal_signals[i]; ++i ) { ohandler = signal(SDL_fatal_signals[i], SDL_Parachute); if ( ohandler != SIG_DFL ) { signal(SDL_fatal_signals[i], ohandler); } } #endif /* HAVE_SIGACTION */ return; } void SDL_UninstallParachute(void) { /* Remove a handler for any fatal signal handled */ int i; #ifdef HAVE_SIGACTION struct sigaction action; for ( i=0; SDL_fatal_signals[i]; ++i ) { sigaction(SDL_fatal_signals[i], NULL, &action); if ( action.sa_handler == SDL_Parachute ) { action.sa_handler = SIG_DFL; sigaction(SDL_fatal_signals[i], &action, NULL); } } #else void (*ohandler)(int); for ( i=0; SDL_fatal_signals[i]; ++i ) { ohandler = signal(SDL_fatal_signals[i], SIG_DFL); if ( ohandler != SDL_Parachute ) { signal(SDL_fatal_signals[i], ohandler); } } #endif /* HAVE_SIGACTION */ } #endif /* NO_SIGNAL_H */