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Date: Sat, 20 Dec 2008 01:14:39 -0800
From: Lawrence Mayer <lawmay3 AT i12 DOT com>
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To: cygwin AT cygwin DOT com
Subject: [1.7] Pipes intermittently lose data on Cygwin 1.7
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Pipes intermittently lose data on Cygwin 1.7.0-35 and -36. This bug 
appears generic to pipes under Cygwin 1.7 and not limited to any 
particular app.

To reproduce this bug, create a ~ 5 MB text file foo.

tr \32 \0 < foo | tr \0 \32 > bar

should make bar = foo. But intermittently, bar is truncated and missing 
the end of foo. You can quickly tell by monitoring the file sizes: 
intermittently bar is smaller than foo.

The bug appears generic to pipes under Cygwin 1.7, e.g.

sed s/\x1a/\x0/ foo | sed s/\x0/\x1a/ > bar

sort foo | tr \32 \0 > bar

cat foo | tr \32 \0 > bar

tac foo | tac > bar

cat foo | cat | cat > bar

all cause intermittent loss of data, where bar is sometimes truncated 
and missing the end of foo (or beginning of foo in tac example). (The 
last example contains 2 pipes, since cat foo | cat > bar appears more 
resistant to this bug and only occasionally loses data.)

This bug is difficult to reproduce on my system when foo < ~ 3 MB. Hence 
the recommendation above for foo ~ 5 MB.

This bug is present in Cygwin 1.7.0-35 and 1.7.0-36. I have not tested 
earlier 1.7 builds.

This bug appears new to Cygwin 1.7 and not present in Cygwin 1.5.25-15.

Greetings,
Lawrence

Versions tested:
Cygwin 1.7.0-36 and 1.7.0-35 with coreutils 7.0-2 and sed 4.1.5-2
Cygwin 1.5.25-15 with coreutils 6.10-2 and sed 4.1.5-2

OS: Windows Server 2003 sp2 32-bit. Cygwin installed on NTFS drive C:.


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