Re: [PATCH] ui/curses: Fix infinite loop on windows

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Thu, Apr 03, 2025 at 01:07:56AM +0000, William Hu via wrote:
> >From a42046272f0544dd18ed58661e53ea17d1584c2c Mon Sep 17 00:00:00 2001
> From: William Hu <purplearmadillo77@proton.me>
> Date: Wed, 2 Apr 2025 12:00:00 -0400
> Subject: [PATCH] ui/curses: Fix infinite loop on windows
> 
> Replace -1 comparisons for wint_t with WEOF to fix infinite loop caused by a
> 65535 == -1 comparison.
> 
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2905
> Signed-off-by: William Hu <purplearmadillo77@proton.me>
> ---
>  ui/curses.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)

I have CCed Gerd Hoffmann (git-shortlog(1) shows he is the most frequent
committer to this source file) and Marc-André Lureau (ui/ maintainer
according to the ./MAINTAINERS file) so they can also review your patch.

> 
> diff --git a/ui/curses.c b/ui/curses.c
> index a39aee8762..3f5c5adf78 100644
> --- a/ui/curses.c
> +++ b/ui/curses.c
> @@ -265,7 +265,12 @@ static int curses2foo(const int _curses2foo[], const int _curseskey2foo[],
>  
>  static void curses_refresh(DisplayChangeListener *dcl)
>  {
> -    int chr, keysym, keycode, keycode_alt;
> +    /*
> +     * DO NOT MAKE chr AN INT:
> +     * Causes silent conversion errors on Windows where wint_t is unsigned short.
> +     */
> +    wint_t chr = 0;
> +    int keysym, keycode, keycode_alt;
>      enum maybe_keycode maybe_keycode = CURSES_KEYCODE;
>  
>      curses_winch_check();
> @@ -284,8 +289,9 @@ static void curses_refresh(DisplayChangeListener *dcl)
>          /* while there are any pending key strokes to process */
>          chr = console_getch(&maybe_keycode);
>  
> -        if (chr == -1)
> +        if (chr == WEOF) {
>              break;
> +        }

Further below there appears to be another instance of the same bug:

  /* alt or esc key */
  if (keycode == 1) {
      enum maybe_keycode next_maybe_keycode = CURSES_KEYCODE;
      int nextchr = console_getch(&next_maybe_keycode);

      if (nextchr != -1) {
          ^^^^^^^^^^^^^

>  
>  #ifdef KEY_RESIZE
>          /* this shouldn't occur when we use a custom SIGWINCH handler */
> -- 
> 2.47.0
> 
> 

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