[Rpm-ecosystem] lua, unprivileged rpm, and rpm-ostree

[Neal Gompa]

On Fri, Aug 12, 2016 at 3:41 PM, Florian Weimer <fweimer at redhat.com> wrote:
> On 08/11/2016 06:25 PM, Neal Gompa wrote:
>>
>> On Thu, Aug 11, 2016 at 11:27 AM, Colin Walters <walters at verbum.org>
>> wrote:
>>>
>>> Hi, more lua discussion.
>>>
>>>
>>> So finally, a problem is right now we aren't implementing lua:
>>> https://github.com/projectatomic/rpm-ostree/pull/424
>>>
>>> I'd actually like to avoid implementing lua for as long as possible -
>>> from my readings in Fedora, most of the usage is for legacy updates
>>> or workarounds.  glibc is however using it in a %posttrans, which
>>> we could easily port to shell.  I might submit a patch to do so.
>>>
>>
>> There is a very important reason for Lua: it's the only way to do
>> scripts without requiring an external interpreter. For packages that
>> are part of the minimal rootfs required for building packages or
>> creating containers or whatnot, this is critical in order to prevent a
>> circular dependency error (package requires /bin/bash but bash isn't
>> installed and can't be installed until the package is installed
>> first). So, we do need it.
>
>
> This is largely due to the lack of delayed script execution in RPM. dpkg,
> for instance, guarantees that the dependencies are at least unpacked before
> scripts run, so it's possible to use scripts safely in many more cases.
>

This is not completely true. The guarantee dpkg gives only applies
when a package uses "Pre-Depends" in its control file. If I recall
correctly, we had something similar in RPM a long time ago called
"PreReq", but today it just silently converts to "Requires(pre)" and
"Requires(preun)".


-- 
真実はいつも一つ！/ Always, there's only one truth!