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Date: Sun, 14 Feb 2021 17:43:58 +0900
From: Takashi Yano <takashi.yano@nifty.ne.jp>
To: cygwin@cygwin.com
Cc: Alvin Seville <alvinseville7cf@gmail.com>
Subject: Re: Cygwin doesn't handle SIGWINCH properly in Windows Terminal
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On Sat, 13 Feb 2021 20:39:39 +1000
Alvin Seville wrote:
> Windows build number: Win32NT 10.0.19042.0 Microsoft Windows NT 10.0.19042.0
> Windows Terminal version (if applicable): 1.5.10271.0
> 
> Script to reproduce this issue:
> 
> #!/usr/bin/env bashfunction 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 truedo
>     :done

This is because cygwin console handles SIGWINCH when the input
messages is processed. If the process does not call either read()
or select(), SIGWINCH will not be sent. This is the long standing
problem of the implementation and hard to fix.

Therefore, I expect the following code should work, however I
have noticed it does not.

#!/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
  read # <- Call read here
done

This seems to be a bug of console code. I will submit a patch
for this issue.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>