alacritty_terminal: infinite loop when double-width character resized into single column terminal

[ConradIrwin]

If you resize an alacritty terminal to 1 column wide while it is displaying a double-width character (in our example "🦀"), then it infinite loops and this allocation will continually increase the amount of RAM used until the process is killed by the system.

The fix we've gone with is to ensure that we always render at least 2 columns: zed-industries/zed#7471, but filing this in case it's of interest to other embedders. (It does not affect alacritty itself which seems to have a minimum width of closer to 10 columns).

System

We're embedding alacritty v0.21 in Zed.

[kchibisov]

alacritty sets the minimum amount of columns to 2 as well, since the alacritty_terminal supports only minimum of 1x2 sizes.

That should probably be a part of resize routine in alacritty_terminal...

[chrisduerr]

Yeah single-column is just not supported. It doesn't really make sense considering a fullwidth character is two columns wide.

[chrisduerr]

The fix we've gone with is to ensure that we always render at least 2 columns

Note that what Alacritty does is limiting the terminal to 2 columns, not the rendering. Alacritty works with a 1x1 window size last I checked.

[kchibisov]

yeah, but we limit that in alacritty itself, not alacritty_term, we could probably limit in alacritty_term instead, so you kind of not resize to 1x1.

[chrisduerr]

yeah, but we limit that in alacritty itself, not alacritty_term, we could probably limit in alacritty_term instead, so you kind of not resize to 1x1.

Yeah that's fair, we shouldn't allow resizing below our minimum size.