[minicoredumper] Debugging corrupt tar files (invalid sparse archive member)

[John Ogness]

On 2023-02-09, "Jos Hulzink (Ellips B.V.)" <jos.hulzink at ellips.com> wrote:
> Unfortunately, your proposed solution to dump directly into gzip is
> not an option for us, since we have to send the core dumps from sites
> like rural Africa/Australia over connections with less than desired
> upstream bandwidth. We know that gzip will have a tough time
> compressing our memory data, and the slow compression process will
> cause longer downtime of the system.

It is not a solution, but a workaround so that I can release a new
bugfix version. The current behavior of creating broken tar files is
not acceptable.

However, hearing your argument about not being able to use gzip, I am
wondering if falling back to avoiding tar is the correct workaround. In
your case, you are expecting the dumps to be quick and if it suddenly
falls back to just gzip, you will suddenly have minutes of downtime
instead of seconds.

Perhaps instead of falling back to gzip I just should log an error
message saying the core file is too large? I do not want to implement
too much new code for a bugfix release.

A proper solution will be to use a more modern tar format that supports
unlimited sizes. But this is not a quick fix and would instead be a new
feature for a 2.1 release.

John