3.2.7: Not enough or too much encoding conversion lead to "rejecting unrequested file-list name"

[phdru]

Client and server: Debian 12 bookworm. Client: locale ru_RU.KOI8-R, FS encoding koi8-r. Server: locale ru_RU.UTF-8, FS encoding utf-8.

$ rsync --version
rsync  version 3.2.7  protocol version 31

Preparing a test file (its name is "test" in Russian):

$ ssh server "touch `echo тест | iconv -f koi8-r -t utf-8`"
$ ssh server "ls `echo тест | iconv -f koi8-r -t utf-8`" 
я┌п╣я│я┌

The last line is mojibake — it's Russian "test" in utf-8 shown in koi8-r font:

$ echo тест | iconv -f koi8-r -t utf-8                
я┌п╣я│я┌

No problem so far. Now let's rsync it:

$ rsync --iconv=koi8-r,utf-8 server:тест
rsync: [sender] link_stat "/home/phd/тест" failed: No such file or directory (2)

Hmm, pity. IWBN if rsync properly converts file names. But I can live without that. There is a worse problem:

$ rsync --iconv=koi8-r,utf-8 server:"`echo тест | iconv -f koi8-r -t utf-8`"
ERROR: rejecting unrequested file-list name: тест
rsync error: requested action not supported (code 4) at flist.c(1000) [Receiver=3.2.7]

Client rejects the name тест because it originally asked for я┌п╣я│я┌.

IMO it's a bug. Either rsync --iconv=koi8-r,utf-8 should encode file names on sending so that rsync --iconv=koi8-r,utf-8 server:тест works. Or it should check not encoded file names when receiving so that encoded file names passed through the check.

Currently the workaround is to turn off the check:

$ rsync --iconv=koi8-r,utf-8 --trust-sender server:"`echo тест | iconv -f koi8-r -t utf-8`"
-rw-------              0 2024/10/29 00:32:36 тест

--old-args also works. But IMO that are only workarounds.

Upd. For me the best solution would be proper file name encoding in both direction so this would work:

$ rsync --iconv=koi8-r,utf-8 server:тест
-rw-------              0 2024/10/29 00:32:36 тест