Reputation: 567
The code posted is copied directly from an example of a popular SDL2 tutorial, to ensure that it wasn't I who had made some silly mistake. All I've done to the example is changing the path of the image file in question, I changed type bool to int, false to 0 and true to 1. As I understand it, nothing C++ specific should remain.
Everything seems to work regardless what I do, but when compiling with CC/GCC (I suppose that's really the same deal) I get a segmentation fault in the very end, I suspect in close(), which I've been unable to determine. Compiling with G++ somehow prevents the segmentation fault.
The solution of course is simple, just use G++, but I would very much like to know wherein the problem lies.
main.c:
//Using SDL and standard IO
#include <SDL2/SDL.h>
#include <stdio.h>
//Screen dimension constants
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
//Starts up SDL and creates window
int init();
//Loads media
int loadMedia();
//Frees media and shuts down SDL
void close();
//The window we'll be rendering to
SDL_Window* gWindow = NULL;
//The surface contained by the window
SDL_Surface* gScreenSurface = NULL;
//The image we will load and show on the screen
SDL_Surface* gHelloWorld = NULL;
int init()
{
//Initialization flag
int success = 1;
//Initialize SDL
if( SDL_Init( SDL_INIT_VIDEO ) < 0 )
{
printf( "SDL could not initialize! SDL_Error: %s\n", SDL_GetError() );
success = 0;
}
else
{
//Create window
gWindow = SDL_CreateWindow( "SDL Tutorial", SDL_WINDOWPOS_UNDEFINED,
SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH,
SCREEN_HEIGHT, SDL_WINDOW_SHOWN );
if( gWindow == NULL )
{
printf( "Window could not be created! SDL_Error: %s\n",
SDL_GetError() );
success = 0;
}
else
{
//Get window surface
gScreenSurface = SDL_GetWindowSurface( gWindow );
}
}
return success;
}
int loadMedia()
{
//Loading success flag
int success = 1;
//Load splash image
gHelloWorld = SDL_LoadBMP( "hello_world.bmp" );
if( gHelloWorld == NULL )
{
printf( "Unable to load image %s! SDL Error: %s\n", "hello_world.bmp",
SDL_GetError() );
success = 0;
}
return success;
}
void close()
{
//Deallocate surface
SDL_FreeSurface( gHelloWorld );
gHelloWorld = NULL;
//Destroy window
SDL_DestroyWindow( gWindow );
gWindow = NULL;
//Quit SDL subsystems
SDL_Quit();
}
int main( int argc, char* args[] )
{
//Start up SDL and create window
if( !init() )
{
printf( "Failed to initialize!\n" );
}
else
{
//Load media
if( !loadMedia() )
{
printf( "Failed to load media!\n" );
}
else
{
//Apply the image
SDL_BlitSurface( gHelloWorld, NULL, gScreenSurface, NULL );
//Update the surface
SDL_UpdateWindowSurface( gWindow );
//Wait two seconds
SDL_Delay( 2000 );
}
}
//Free resources and close SDL
close();
return 0;
}
I don't see how it's relevant, but just to be on the safe side, here's the standard Makefile I'm using
#OBJS specifies which files to compile as part of the project
OBJS = main.c
#CC specifies which compiler we're using
CC = cc
#COMPILER_FLAGS specifies the additional compilation options we're using
# -w suppresses all warnings
COMPILER_FLAGS = -Wall -Wextra -pedantic
#LINKER_FLAGS specifies the libraries we're linking against
LINKER_FLAGS = -lSDL2
#OBJ_NAME specifies the name of our exectuable
OBJ_NAME = test
#This is the target that compiles our executable
all : $(OBJS)
$(CC) $(OBJS) $(COMPILER_FLAGS) $(LINKER_FLAGS) -o $(OBJ_NAME)
I get no errors or warnings but unused argv and argc.
At this point I'm at a dead end, thus I ask here.
Best regards.
NB: I should be mentioned that whatever the issue, it's most definitely not a hardware issue, various search results have suggested, as I get the exact same result and problem, on two entirely different hardware platforms.
Upvotes: 4
Views: 702
Reputation: 5684
If you rename the function close()
the segfault goes away, looks like init()
calls into SDL which calls into X11 which calls into your driver which calls close()
, but instead of calling the right close()
it calls yours instead. In C++ functions will get name mangled to something else so it it not a problem.
Upvotes: 7