Fixed sdl::get_error to not segfault

[TheNeikos]

This one was a bit tricky as I am not sure what the initial version had tried to do. SDL_GetError() returns a constant char pointer. (char const *) However they are already in bytes. c_str_to_bytes expects a pointer to a c_str as seen here: Rust Source

This version seems safer to me as we do not transmute, and since SDL explicitely states that those strings are fixed in memory this should not segfault.

[TheNeikos]

And to what this fixes.

This was my previous test setup:

extern crate sdl;
extern crate sdl_image;

use std::rand::Rng;

use sdl::video::{SurfaceFlag, VideoFlag};
use sdl::event::{Event, Key};

#[main]
pub fn main() {
    sdl::init(&[sdl::InitFlag::Video]);
    sdl_image::init(&[sdl_image::InitFlag::PNG]);
    sdl::wm::set_caption("rust-sdl demo - video", "rust-sdl");

    let mut rng = std::rand::thread_rng();
    let screen = match sdl::video::set_video_mode(800, 600, 32,
                                                  &[SurfaceFlag::HWSurface],
                                                  &[VideoFlag::DoubleBuf]) {
        Ok(screen) => screen,
        Err(err) => panic!("failed to set video mode: {}", err)
    };

    let img_path = Path::new("./test.png");
    let image = match sdl_image::load(&img_path) {
        Ok(surface) => surface,
        Err(err) => panic!("Failed to load image: {}", err)
    };

    screen.blit(&image);
    screen.flip();

    'main : loop {
        'event : loop {
            match sdl::event::poll_event() {
                Event::Quit => break 'main,
                Event::None => break 'event,
                Event::Key(k, _, _, _)
                    if k == Key::Escape
                        => break 'main,
                _ => {}
            }
        }
    }

    sdl::quit();
}

It segfaults without this fix, and correctly panics with.

[lgrz]

Thanks for tracking down this issue. You're absolutely right, the calls to transmute look like they were left over from previous changes and unnecessary, unless I'm missing something.

I think we can still use c_str_to_bytes as I don't think we need to call strlen directly, Rust does that for us in c_str_to_bytes.

It seems that SDL_GetError (SDL 1.2) returns a char * and not a const char *, so coercing the result of SDL_GetError to a *const c_schar or similar should do the trick. Thoughts?

[TheNeikos]

You are right about SDL_GetError returning a char*, however I am wondering about cleanup, is it like in SDL2 a static string or are we supposed to free it?

[lgrz]

Yes it's a static string like in SDL2.

[TheNeikos]

Okay, I have switched to using c_str_to_bytes I also tested it and it seems to work as intended.

[lgrz]

I think we can remove the strlen import otherwise it looks good to me. Thanks!

[TheNeikos]

Oh right, forgot to remove that, on it!

[lgrz]

Thanks again!