Bug#824078: libdvd-pkg: fails to report "apt-get check" errors (and others) correctly

Dmitry Smirnov onlyjob at debian.org
Sun May 15 12:54:11 UTC 2016

On Sunday, 15 May 2016 2:03:28 PM AEST Cyril Brulebois wrote:
> Failing to return success or failure properly really is Bad Programming
> 101. This means your uers have no programmatic way of knowing whether
> what they called worked, and how to behave accordingly.

I know, I know. :)  I agree. However here safety concerns are more important: 
we can afford to fail to build a package but not to compromise package 
management by propagating errors where they naturally do not occur.

I hope it make sense.

> Silently pretending everything went fine when it didn't seems like a
> reasonable behaviour? I strongly disagree.

Breaking package management would be more dangerous than "silently" failing.
(It does not really fail that silently).

You do not understand design of this package. Examples you quoted in the 
original bug report are meant to work like this. "apt-get check" is a way to 
check whether it is safe to attempt installing .deb (we could just go ahead 
with attempt and let it fail further down the road). Failure of "apt-get 
check" is expected (to certain extent, as it is merely a safety precaution) 
and its exit code should not normally propagate even if it safe to do so.

"dpkg -i /dev/zero" is already reworked into "dpkg -P non-existent-package" 
(as per #824093): it is to check whether DPKG database is locked hence 
failure is an expected behaviour (e.g. when APT is working) and exit code 
should not propagate either.

What you are suggesting to change are not improvements in the context of this 
package. Although I agree with you that returning original exit value without 
overriding it is a best practice for most situations.

> I didn't realize it got hooked up into apt (the build script is called
> directly in Tails). Actually, this makes this issue looks even worth
> than I thought…

"Even worse" maybe? I'm not sure I understand your concerns...

All the best,
 Dmitry Smirnov.


In individuals, insanity is rare; but in groups, parties, nations and
epochs, it is the rule.
        -- Friedrich Nietzsche
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