Date: Wed, 7 Apr 2021 18:08:25 -0600 (MDT)
From: Ariadne Conill <ariadne@dereferenced.org>
To: Wolf <wolf@wolfsden.cz>
cc: ~alpine/devel@lists.alpinelinux.org
Subject: Re: Why does apk fail to install packages with 0 size?
In-Reply-To: <20210407225006.thogaepvkqq2ytbx@wolfsden.cz>
Message-ID: <bc1dec8a-e93-8410-a5c9-b27b41c2ef91@dereferenced.org>
References: <20210407225006.thogaepvkqq2ytbx@wolfsden.cz>
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Hello,

On Thu, 8 Apr 2021, Wolf wrote:

> Hello,
>
> To follow up on my original mail thread (apk not installing a file),
> I've dived into apk's source code and managed to track the problem to:
>
> src/database.c:
> 2920
> 2921         if (newpkg->installed_size != 0) {
> 2922                 r = apk_db_unpack_pkg(db, ipkg, (oldpkg != NULL),
> 2923                                       cb, cb_ctx, script_args);
>
> Which I guess means that if installed size of the new package is zero, the
> unpacking is skipped. That might sound reasonable, but leads to packages with
> package function looking like:
>
> package() {
>        mkdir -p -- "$pkgdir"
>        touch -- "$pkgdir/test-foo"
> }
>
> To be silently skipped with no errors nor warnings. That is highly confusing,
> because there is not reason this should not work. For the time being, my
> workaround is:
>
> package() {
>        mkdir -p -- "$pkgdir"
>        echo >"$pkgdir/test-foo"
> }
>
> Which is bit sad result given how much time I've spent on this. :/
>
> So, my question is: Is this behaviour intentional? If so, why? And if it
> is not, what would be nice way to fix this? I can work on patch, however
> I'm not sure what would be the best angle.

I didn't think about the 0 installed-size at first.  Yes, this is 
intentional: packages with a 0 installed-size are treated as virtuals.

But, this can probably be fixed with a better design as part of apk-tools 
3.

Ariadne