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To: cygwin@cygwin.com
Subject: Re: Bug: bash redirect "magic" variable content to input of command
 hangs (upstream of https://github.com/git-for-windows/git/issues/5001)
Date: Tue, 11 Jun 2024 23:19:11 +0900
Message-ID: <v49me6$sju$3@ciao.gmane.io>
References: <git-for-windows/git/issues/5001@github.com>
 <git-for-windows/git/issues/5001/2157897799@github.com>
 <trinity-3cedf922-0401-4736-a503-cfd5bb21f750-1718017964332@3c-app-gmx-bs33>
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From: jojelino via Cygwin <cygwin@cygwin.com>
Reply-To: jojelino <jojelino@gmail.com>
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On 6/10/2024 8:12 PM, Holger Klene via Cygwin wrote:
> This is:
> GNU bash, Version 5.2.21(1)-release (x86_64-pc-cygwin)
> 
> Was also reproduced in git-bash 5.2.26(1)-release (also cygwin)
> but not in WSL-bash 5.1.16 (independent of cygwin)
This regression is introduced in bash-5.1, Introduced changes in both 
here-string, here-document in 5.1 caused hangs.

Apart from that, unlike to Linux, Cygwin chunks io of pipe into 64K and 
NtWriteFile writes to a pipe even after the pipe exceeded buffer size 
while reporting STATUS_PENDING, So in Cygwin, divide by 2 of actual 
buffer size is within boundary of pipe buffer as seen below.
$ dd if=/dev/urandom bs=63K status=progress | sleep 3
129024 bytes (129 kB, 126 KiB) copied, 3 s, 42.8 kB/s
$ dd if=/dev/urandom bs=128 status=progress | sleep 3
65664 bytes (66 kB, 64 KiB) copied, 3 s, 21.9 kB/s

And current bash package make wrong estimate of pipe size of host 
environment according to builtins/psize.sh of cygport source package of 
bash.

====
Excerpt from builtins/psize.sh of bash, You can guess what the result 
will be From the above.
./psize.aux 2>"$TMPFILE" | sleep 3


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