[New-bugs-announce] [issue44495] wrong FNAME in tarfile if tgz extension is used

[Maciej Misiak]

New submission from Maciej Misiak <maciej.mm.misiak at gmail.com>:

This code is incomplete:

def _init_write_gz(self):
...
    if self.name.endswith(".gz"):
        self.name = self.name[:-3]
    # RFC1952 says we must use ISO-8859-1 for the FNAME field.
    self.__write(self.name.encode("iso-8859-1", "replace") + NUL)

If it is used in following way '.gz' is stripped properly and FNAME='somefile.tar':
    tarfile.open('somefile.tar.gz', 'w:gz')
but with 
    tarfile.open('somefile.tgz', 'w:gz')

FNAME is incorrectly prepared as somefile.tgz

----------
components: Library (Lib)
messages: 396382
nosy: maciej.mm.misiak
priority: normal
severity: normal
status: open
title: wrong FNAME in tarfile if tgz extension is used
versions: Python 3.10, Python 3.11, Python 3.6, Python 3.7, Python 3.8, Python 3.9

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue44495>
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