> On Apr 6, 2018, at 8:49 AM, Aleksei Nikiforov <darktemp...@altlinux.org> 
> wrote:
> 
> Hi
> 
> 06.04.2018 15:39, Jeff Johnson пишет:

...

>>> 
>> Hack? I am not suggesting patching lib/rpminstall.c to add AUTOINSTALL.
>> I am suggesting that you write a custom callback that adds AUTOINSTALL when 
>> a specific event is received, and pointed you at the CLI example. There is 
>> another example in rpm-python methods.
>> The advantage to the notify callback is that all known rpm depsolvers 
>> already are using the callback.
> 
> Yes, I understood that it's proposed to not patch rpm library but use 
> existing interfaces in such unexpected way instead. I just agree that 
> proposed approach is obscure. I'd prefer to have more clean and 
> straightforward API for this task.
>>> 

Well the real hack is more historical than anything else and likely no longer 
matters.

The original "RedHat Package Manager" (circa 1998) was designed as an installer 
interface.

In order to run on 16Mb (that is megabyte, yes) i386 platforms, the installer 
used stripped (of all the bloated file information) headers in order to do 
dependency checking and ordering when all the headers needed to be memory 
resident.

All of the complex operations involved in upgrading through a transaction were 
unnecessary: only install was supported.

The full package header (and payload) was needed to actually perform an 
install. The original reason for the callback was to load the full header from 
the CD-ROM one-by-one as needed.

These days (heh: 20y later) all known users of rpmlib are just using full (not 
stripped) headers and so there is not much reason other than ancient legacy API 
compatibility that the original headers passed through dependency 
checking/ordering could not be kept (one would need to worry about fdno limits 
and/or re-positioning to the package payload, but that is rather 
straight-forward coding compared to what is actually implemented in rpm still).

If the headers were kept, then the most simple/obvious interface would be to 
add AUTOINSTALL (or other tags) before adding to a transaction.

There is likely a subtle way to support both modes of operation, keeping the 
original header or reloading the header from the original file name, by looking 
at some flag and not reloading the header. The file position of the payload is 
easily computed when needed, and the reopened file could be repositioned using 
seek.

So that is where the "real" hack is in rpm preventing simply adding an 
AUTOINSTALL tag ;-)

...

> 
> Best regards
> Aleksei Nikiforov
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