Possible race condition with MessageBox #49
Comments
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I trimmed down your example a bit further, see the end of this message. It's a bit difficult to reproduce here but something is indeed racy I don't have time to investigate this further at the moment. Could you please create an equivalent C program to make sure the bug is not on SDL's side. The full bt is: (* compile with ocamlfind ocamlopt -package tsdl -linkpkg -thread main.ml *)
open Tsdl
let log_err fmt = Format.eprintf (fmt ^^ "@.")
let close_message_box () =
let d =
let open Sdl.Message_box in
let action =
{ button_flags = button_returnkey_default;
button_id = 1; button_text = "Save then quit" }
in
let cancel =
{ button_flags = button_escapekey_default;
button_id = 3; button_text = "Cancel" }
in
let color_scheme =
{ color_background = (255, 255, 255);
color_text = (255, 0, 0);
color_button_border = (0, 255, 0);
color_button_background = (0, 0, 255);
color_button_selected = (0, 255, 255) }
in
{ flags = warning; window = None; title = "Action";
message = "Do you want to action ?"; buttons = [cancel; action];
color_scheme = Some color_scheme }
in
Sdl.show_message_box d
let event_loop () =
let keycode e = Sdl.Event.(get e keyboard_keycode) in
let e = Sdl.Event.create () in
let rec loop () = match Sdl.wait_event (Some e) with
| Error (`Msg e) -> log_err " Could not wait event: %s" e; 1
| Ok () ->
match Sdl.Event.(enum (get e typ)) with
| `Quit -> 0
| `Key_down when keycode e = Sdl.K.escape ->
begin match close_message_box () with
| Error (`Msg e) -> log_err "Could not show message box: %s" e; 1
| Ok 1 -> 0
| _ -> loop ()
end
| _ -> loop ()
in
loop ()
let main () = match Sdl.init Sdl.Init.(video + events) with
| Error (`Msg e) -> log_err "Could not init SDL: %s" e; exit 1
| Ok () ->
let ret = event_loop () in
Sdl.quit ();
exit ret
let () = main () |
|
I failed to reproduce the bug using the following C example. // Compile with:
// cc main.c `sdl2-config --libs --cflags` -Wall -Wextra
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <SDL.h>
int message()
{
const SDL_MessageBoxButtonData buttons[] = {
{ 0, 0, "Nothing" },
{ SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT, 1, "Return (quit)" },
{ SDL_MESSAGEBOX_BUTTON_ESCAPEKEY_DEFAULT, 2, "Escape" },
};
const SDL_MessageBoxColorScheme colorScheme = {
{
{ 255, 0, 0 },
{ 0, 255, 0 },
{ 255, 255, 0 },
{ 0, 0, 255 },
{ 255, 0, 255 }
}
};
const SDL_MessageBoxData messageboxdata = {
SDL_MESSAGEBOX_INFORMATION,
NULL,
"example message box",
"select a button",
SDL_arraysize(buttons),
buttons,
&colorScheme
};
int buttonid;
if (SDL_ShowMessageBox(&messageboxdata, &buttonid) < 0) {
SDL_Log("error displaying message box");
exit(1);
return 1;
}
if (buttonid == -1)
SDL_Log("no selection");
else
SDL_Log("selection was %s", buttons[buttonid].text);
return (buttonid == 1);
}
int main(void)
{
SDL_Window *win;
SDL_Surface *screen;
SDL_Event e;
SDL_Init(SDL_INIT_VIDEO);
win = SDL_CreateWindow("SDL",
SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
640, 480, 0);
screen = SDL_GetWindowSurface(win);
SDL_FillRect(screen, NULL, 0);
SDL_UpdateWindowSurface(win);
while (1)
{
if (SDL_WaitEvent(&e))
{
if (e.type == SDL_QUIT)
break;
if (e.type == SDL_KEYDOWN
&& e.key.keysym.sym == SDLK_ESCAPE)
{
if (message())
break;
}
}
}
SDL_DestroyWindow(win);
SDL_Quit();
} |
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@sguillia thanks for the C program. I think you can close the report upstream as this seems to be on our side. I need to recheck what we are doing here but I don't have According to the backtrace it seems that the pointer of the |
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So in 595d8a5 I tried to add a little bit of logging by attaching a finalizer on the struct that is given to the C function. It seems that structures are not freed for quite sometime and then a hundred of them is freed after around @yallop do you think this could be a problem in If you want to have a look this can be tried with the OCaml program in this message and: |
I'm not sure. I'll aim to dig into this later this week. |
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Things have become very busy here, and unfortunately it's going to be a little while longer before I can investigate this. But I think your suspicion about the lifetime of the |
While writing an application using OCaml and Tsdl, I encountered a bug which affects either Tsdl, SDL, Cocoa or Ocaml bindings.
I fully described the bug here:
https://bugzilla.libsdl.org/show_bug.cgi?id=4069
In short, the app crashes (sigabort or segfault) when repeatedly opening dialogs for 30 seconds.
Could you please take a look at it?
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