rsync - Oct 2021 - deflate on token returned 0 - rsync error: error in protocol data stream

Hello,

we're using rsync on SLES 12 SP 5 on both sides (for detailed version
info see below) and we're experiencing the following issue on the
sender's side:

```
 etc/test/windows2019_x86_64_20210929.gz
 deflate on token returned 0 (22199 bytes left)
 rsync error: error in rsync protocol data stream (code 12) at token.c(427)
[sender=3.1.3]
```

This happens with 1 out of about 4'000'000 files.
Transfer w/o compression works without any issues.

Question: Bug or feature?


The options we're using are:

    ```
    rsync',
    --rsh'        => "ssh -q -i $arg{privatekey} -l
$arg{user}",
    --rsync-path' => "sudo $arg{user}",

    # content
    '--archive',    # implies --links (-l), --recursive (-r)
    '--hard-links',
    (map { ('--exclude' => $_) } @{ $arg{exclude} }),
    $arg{delete} eq 'yes' ? '--delete' : (),

    # transfer
    '--compress',
    '--partial',
    '--bwlimit' => $arg{bwlimit},

    # logging
    '--stats',
    '--verbose',
    '--log-file'        => $arg{rsynclogfile},
    '--log-file-format' => 'Modified %i %n%L',
    ```


Detailed version information:
```
rsync  version 3.1.3  protocol version 31
Copyright (C) 1996-2018 by Andrew Tridgell, Wayne Davison, and others.
Web site: http://rsync.samba.org/
Capabilities:
    64-bit files, 64-bit inums, 64-bit timestamps, 64-bit long ints,
    socketpairs, hardlinks, symlinks, IPv6, batchfiles, inplace,
    append, ACLs, xattrs, iconv, symtimes, prealloc, SLP

rsync comes with ABSOLUTELY NO WARRANTY.  This is free software, and you
are welcome to redistribute it under certain conditions.  See the GNU
General Public Licence for details.
```

    Best regards from Dresden/Germany
    Viele Gr??e aus Dresden
    Heiko Schlittermann
--
 SCHLITTERMANN.de ---------------------------- internet & unix support -
 Heiko Schlittermann, Dipl.-Ing. (TU) - {fon,fax}: +49.351.802998{1,3} -
 gnupg encrypted messages are welcome --------------- key ID: F69376CE -
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Hi,

Heiko Schlittermann via rsync <rsync at lists.samba.org> (Mi 20 Okt 2021
10:56:51 CEST):
> Hello,
> 
> we're using rsync on SLES 12 SP 5 on both sides (for detailed version
> info see below) and we're experiencing the following issue on the
> sender's side:
?
>  deflate on token returned 0 (22199 bytes left)
>  rsync error: error in rsync protocol data stream (code 12) at token.c(427)
[sender=3.1.3]
I manged to create a reproducer:
https://code.schlittermann.de/heiko/rsync-bug/src/commit/d8176333f8ef08b7dbf7957c83055677cddcc080/bug

Several times in a row if successfully reproduced the issue on
SLES12SP5, using Rsync 3.1.3 (connection to localhost, so identical
rsyncs on both sides of the connection)

If you can confirm that this is a bug that is fixed already, then it
would be enough for us for pushing the Distro maintainer to backport the
fix or whatever their policy allows.

======8<------------------
#!/bin/bash
set -eu

size=1029

cd ${1:?Usage $0 DIR}

echo ---------------------
echo rsync: $(rsync --version | grep version)
hostnamectl | grep 'Operating System' | sed 's/^\s*//'
echo ----------------------


echo Creating src file ${size}MiB
dd status=progress if=/dev/urandom of=fail-src bs=1M count=$size iflag=fullblock

echo Local copy to avoid initial transfer
cp -a fail-{src,dst}

echo Touch source
touch fail-src

echo Trigger the bug now
rsync -Pv -z fail-src localhost:$PWD/fail-dst
======8<------------------

    Best regards from Dresden/Germany
    Viele Gr??e aus Dresden
    Heiko Schlittermann
--
 SCHLITTERMANN.de ---------------------------- internet & unix support -
 Heiko Schlittermann, Dipl.-Ing. (TU) - {fon,fax}: +49.351.802998{1,3} -
 gnupg encrypted messages are welcome --------------- key ID: F69376CE -
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