Cygwin doesn't handle SIGWINCH properly

[EmilyGraceSeville7cf]

Environment

Windows build number: Win32NT 10.0.19042.0 Microsoft Windows NT 10.0.19042.0
Windows Terminal version (if applicable): 1.5.10271.0

Steps to reproduce

Execute this Bash script and try resize Windows Terminal window:

#!/usr/bin/env bash
function outputText()
{
  local text=$1
  local -i textLength=${#text}

  local -i line="$(tput lines) / 2"
  local -i col="$(tput cols) / 2 - $textLength / 2"

  clear
  echo -en "\e[$line;${col}H$text"
}

trap "outputText 'Hello world!'" SIGWINCH

outputText 'Hello world!'
while true
do
    :
done

As you see Windows Terminal doesn't handles SIGWINCH properly. However everything works fine when I execute my script directly from Cygwin Terminal without Windows Terminal.

Expected behavior

Centered text is drawn on the screen after window resize.

Actual behavior

Text isn't centered after window resize.

[zadjii-msft]

You know, I coulda swore we were tracking this somewhere. #4062, #1461, #7581 are related, but those are all crashes from resizing the underlying buffer, not "resizing the underlying buffer doesn't resize the Terminal".

Just a question - are you doing this in WSL or git bash? I'm trying this script out with gnome-terminal on my Ubuntu 18.04 distro, and the script doesn't seem to resize that terminal either.

[EmilyGraceSeville7cf]

Just a question - are you doing this in WSL or git bash?

I'm doing it via Cygwin (please consider my settings.json for clarity):

I don't use WSL and Git Bash now.

[j4james]

You know, I coulda swore we were tracking this somewhere.

In issue #305 you decided that issue #281 would be the master thread for all window WINDOW_BUFFER_SIZE_EVENT / SIGWINCH discussion, so I suspect that's the one you're thinking of.

[zadjii-msft]

You know, I might have actually been thinking of #5094

[j4james]

I wouldn't have thought #5094 had anything to do with it. Unless I've misunderstood what is going on here, the script isn't resizing the window, it's just redrawing the text after it detects a resize. It works for me in both conhost and Windows Terminal when run from a WSL bash shell. I assumed the issue was something specific to Cygwin.

[zadjii-msft]

Oh, maybe I'm misunderstanding what the sample was supposed to be doing. I thought it was trying to resize the terminal to some size, not listen for buffer size events.

This is working perfectly fine in WSL, so I'd agree that this is probably a cygwin-specific issue and should be filed on their issue tracker.

[DHowett]

Marking this one external. Thanks all!

[EmilyGraceSeville7cf]

This is working perfectly fine in WSL, so I'd agree that this is probably a cygwin-specific issue and should be filed on their issue tracker.

I issued this problem to Cygwin developers and waiting for a feedback now. ;)

[determin1st]

SIGWINCH is unreliable, ive tested it doesnt work on fresh Debian install with gnome desktop. it should be abolished in preference to polling