Simple SDL graphics test

sdl_test.c

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

#include <SDL/SDL.h>

int main(void)
{
    SDL_Surface *main_surf;
    SDL_Event *const ev = malloc(sizeof (SDL_Event));

    FILE *rnd = fopen("/dev/urandom", "r");
    unsigned rseed;

    SDL_Init(SDL_INIT_VIDEO);
    main_surf = SDL_SetVideoMode(640, 480, 32, 0);

    fread(&rseed, sizeof (unsigned), 1, rnd);
    fclose(rnd);
    srandom(rseed);
    
    for (;;) {
        SDL_WaitEvent(ev);
        switch (ev->type) {

            case SDL_MOUSEBUTTONDOWN: {
                const SDL_MouseButtonEvent mb_ev = ev->button;
                SDL_Rect rect = {.x = mb_ev.x, .y = mb_ev.y, .w = 2, .h = 2};
                fputs("Mouse button down\n", stderr);
                SDL_FillRect(
                    main_surf,
                    &rect,
                    SDL_MapRGB(main_surf->format,
                               random() % 0xFF,
                               random() % 0xFF,
                               random() % 0xFF)
                );
                SDL_Flip(main_surf);
                break;
            }

            case SDL_KEYDOWN:
                fputs("Key down\n", stderr);
                if (ev->key.keysym.sym == SDLK_q) {
                    free(ev);
                    SDL_Quit();
                    return EXIT_SUCCESS;
                }
                break;

            default: fputs("Other event\n", stderr);

        }
    }
}