[PATCH] dpkg & dpkg_deb: don't depend on FEATURE_SEAMLESS_GZ

[Kang-Che Sung]

On Tue, Jan 10, 2017 at 12:43 AM, Denys Vlasenko
<vda.linux at googlemail.com> wrote:
> On Sat, Jan 7, 2017 at 2:48 AM, Kang-Che Sung <explorer09 at gmail.com> wrote:
>>>> My understanding is that .deb files usually use .gz compression,
>>>> and building dpkg without support for .gz results in a useless tool:
>>>> there are no .deb files which it can process.
>>>
>>> Debian packages support gzip or xz for the control.tar file and a variety of
>>> common compression formats for the data.tar file.
>>
>> Yes. And my point is that there's no need to force a gz choice for users.
>> gz could be deprecated. And sometimes a custom distribution may decide
>> not to gz-compress its .deb packages at all.
>>
>> I think it will be better to just *recommend* the gz feature instead. Mention
>> in the help text:
>>
>>     Note that most .deb packages compress their metadata
>>     in gz (control.tar.gz), so you are likely to also enable the
>>     "understand .gz data" feature above (FEATURE_SEAMLESS_GZ).
>
> I still think the downsides (many people inadvertently building non-functional
> dpkg and complaining) are bigger than win for a rare case when someone gets
> .gz support he doesn't need.

Sigh. If only busybox's kconfig would support the "imply" clause (which a recent
addition in Linux kernel's kconfig though)...

For now, I wonder if it is a good idea to implement a warning or workaround such
as this:

    config FEATURE_DPKG_WITH_GZ
      bool "dpkg or dpkg-deb with gzip decompression"
      default y
      depends on DPKG || DPKG_DEB
      select FEATURE_SEAMLESS_GZ
      help
        Most .deb packages contain gzip-compressed metadata
(control.tar.gz) and so
        will require gzip decompression.

        Just say Y unless you know you are never working with most .deb packages
        on the Internet (i.e. you are working with custom .deb packages only).

        This option alone serves as a warning only and does not add any code.