Some additional info: Here’s what gdb says:
michael at camille ourrpg $ gdb main
GNU gdb 6.7.1
Copyright © 2007 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
http://gnu.org/licenses/gpl.html
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show
copying"
and “show warranty” for details.
This GDB was configured as “i686-pc-linux-gnu”…
(no debugging symbols found)
Using host libthread_db library “/lib/libthread_db.so.1”.
(gdb) r
Starting program: /home/michael/ourrpg/main
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
[Thread debugging using libthread_db enabled]
[New Thread 0x4000 (LWP 14191)]
Line is 65; i = 0
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x4000 (LWP 14191)]
0xb7f5b752 in SDL_MapRGB () from /usr/lib/libSDL-1.2.so.0
(gdb) backtrace
#0 0xb7f5b752 in SDL_MapRGB () from /usr/lib/libSDL-1.2.so.0
#1 0x080498f9 in Battle::initialize ()
#2 0x0804aee1 in main ()
(gdb) quit
The program is running. Exit anyway? (y or n) y
And valgrind too:
michael at camille ourrpg $ valgrind ./main
==14210== Memcheck, a memory error detector.
==14210== Copyright © 2002-2007, and GNU GPL’d, by Julian Seward et
al.
==14210== Using LibVEX rev 1732, a library for dynamic binary
translation.
==14210== Copyright © 2004-2007, and GNU GPL’d, by OpenWorks LLP.
==14210== Using valgrind-3.2.3, a dynamic binary instrumentation
framework.
==14210== Copyright © 2000-2007, and GNU GPL’d, by Julian Seward et
al.
==14210== For more details, rerun with: -v
==14210==
==14210== Syscall param write(buf) points to uninitialised byte(s)
==14210== at 0x40DD69E: write (in /lib/libpthread-0.10.so)
==14210== by 0x458DE7D: (within /usr/lib/libX11.so.6.2.0)
==14210== Address 0x465897B is 19 bytes inside a block of size 16,384
alloc’d
==14210== at 0x4021ABE: calloc
(in /usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==14210== by 0x45731B3: XOpenDisplay (in /usr/lib/libX11.so.6.2.0)
==14210==
==14210== Conditional jump or move depends on uninitialised value(s)
==14210== at 0x80498A0: Battle::initialize()
(in /home/michael/ourrpg/main)
==14210== by 0x804AEE0: main (in /home/michael/ourrpg/main)
Line is 65; i = 0
==14210==
==14210== Use of uninitialised value of size 4
==14210== at 0x80498D6: Battle::initialize()
(in /home/michael/ourrpg/main)
==14210== by 0x804AEE0: main (in /home/michael/ourrpg/main)
==14210==
==14210== Invalid read of size 4
==14210== at 0x407F752: SDL_MapRGB (in /usr/lib/libSDL-1.2.so.0.11.0)
==14210== by 0x80498F8: Battle::initialize()
(in /home/michael/ourrpg/main)
==14210== by 0x804AEE0: main (in /home/michael/ourrpg/main)
==14210== Address 0x0 is not stack’d, malloc’d or (recently) free’d
==14210==
==14210== ERROR SUMMARY: 5 errors from 4 contexts (suppressed: 37 from
1)
==14210== malloc/free: in use at exit: 75,377 bytes in 476 blocks.
==14210== malloc/free: 4,930 allocs, 4,454 frees, 1,735,303 bytes
allocated.
==14210== For counts of detected errors, rerun with: -v
==14210== searching for pointers to 476 not-freed blocks.
==14210== checked 898,684 bytes.
==14210==
==14210== LEAK SUMMARY:
==14210== definitely lost: 10 bytes in 2 blocks.
==14210== possibly lost: 187 bytes in 8 blocks.
==14210== still reachable: 75,180 bytes in 466 blocks.
==14210== suppressed: 0 bytes in 0 blocks.
==14210== Rerun with --leak-check=full to see details of leaked memory.
Segmentation fault
I don’t completely understand how to interpret valgrind’s or gdb’s
output, so if there is something useful there, please tell me…On Sun, 2008-02-24 at 10:54 -0600, Michael Sullivan wrote:
I need help finding the source of a SegFault. I believe that I have the
search narrowed down to a single line of code. Here’s the build and run
output:
michael at camille ourrpg $ make && ./main
g++ -W -Wall sdl-config --cflags -c battle.cpp
battle.cpp: In member function ‘bool Battle::initialize()’:
battle.cpp:85: warning: name lookup of ‘i’ changed
battle.cpp:11: warning: matches this ‘i’ under ISO standard rules
battle.cpp:58: warning: matches this ‘i’ under old rules
battle.cpp: In member function ‘SDL_Surface* Battle::drawString(int,
int, std::string)’:
battle.cpp:109: warning: missing initializer for member
’SDL_Color::unused’
g++ -W -Wall sdl-config --cflags -c character.cpp
g++ -W -Wall sdl-config --cflags -c ally.cpp
g++ -W -Wall sdl-config --cflags -c main.cpp
g++ -o main battle.o character.o ally.o main.o sdl-config --libs
-lSDL_image -lSDL_gfx -lSDL_ttf -lz
Line is 65; i = 0
Segmentation fault
Here’s the offending function:
23 bool Battle::initialize()
24 {
25 if (SDL_Init(SDL_INIT_VIDEO) != 0)
26 {
27 printf("Unable to initialize SDL: %s\n", SDL_GetError());
28 return false;
29 }
30 atexit(SDL_Quit);
31
32 if( TTF_Init() == -1 )
33 {
34 printf("Could not intialize the font: %s\n",
SDL_GetError());
35 return false;
36 }
37 font = TTF_OpenFont( “lazy.ttf”, 18 );
38 if( font == NULL )
39 {
40 printf("Error loading font: %s\n", SDL_GetError());
41 return false;
42 }
43 SDL_WM_SetCaption( "OurRPG - Battle Screen", NULL );
44 screen = SDL_SetVideoMode(1000, 675, 16, SDL_DOUBLEBUF |
SDL_HWSURFACE);
45 if (screen == NULL)
46 {
47 printf(“Unable to set video mode: %s\n”, SDL_GetError());
48 return false;
49 }
50 for (int i = 0; i < 4; i++)
51 {
52 status[i] = NULL;
53 party[i].setX(600);
54 party[i].setY(i * 100);
55 image[i] = party[i].getImage();
56 if (image[i] == NULL) printf("It's NULL!!!\n");
57 printf ("Line is %d; i = %i\n", __LINE__, i);
58 colorkey = SDL_MapRGB(image[i]->format, 0, 255, 0);
59 printf ("Line is %d; i = %i\n", __LINE__, i);
60 SDL_SetColorKey(image[i], SDL_SRCCOLORKEY, colorkey);
61
62 printf ("Line is %d; i = %i\n", __LINE__, i);
63 src[i].x = 0;
64 printf ("Line is %d; i = %i\n", __LINE__, i);
65 src[i].y = 0;
66 printf ("Line is %d; i = %i\n", __LINE__, i);
67 src[i].w = image[i]->w;
68 printf ("Line is %d; i = %i\n", __LINE__, i);
69 src[i].h = image[i]->h;
70 printf ("Line is %d; i = %i\n", __LINE__, i);
71
72 dest[i].x = 600;
73 dest[i].y = i * 100;
74 dest[i].w = src[i].w;
75 dest[i].h = src[i].h;
76 }
77 printf ("Line is %d; i = %i\n", __LINE__, i);
78 drawLines();
79 drawStats();
80 return true;
81 }
As you can see, the printf on 65 is firing, so image[i] is not NULL.
The problem seems to be with the colorkey line. Is there anything wrong
with how I’ve written this line? Please help!
