Re: [Bug-tar] abort in 1.15.1 when using -rz

[Sergey Poznyakoff]

Eric Blake <address@hidden> wrote:

> avoids the abort by erroring out earlier with a complaint that you "Cannot
> update compressed archives".  I don't see any mention of this change in
> NEWS, and couldn't find it with a quick search of the ChangeLog.

Besides, tar documentation states clearly that "compressed archives
cannot be modified, i.e., you cannot update (--update (-u)) them
or delete (--delete) members from them.  Likewise, you cannot append
another tar archive to a compressed archive using --append (-r)." (See
node "gzip")

As far as I remember tar always behaved this way. At least versions
1.13, 1.13.25 and 1.14 were displaying "Cannot update compressed
archives". Version 1.15.1 contained a bug, indeed.

> Also, it seems like a strange limitation that
> you can't append files into a compressed archive.

It is quite logical: any update to a compressed archive implies its
uncompressing into a temporary file, making the operation on this file,
then compressing it back to the archive and deleting the
temporary. Possibly some time in the future this will be
implemented. However, I do not plan it for the nearest release (1.16).

Regards,
Sergey