On Tue, 15 Jun 2010, Frank Cox wrote:
> By way of experimentation, I manually changed one of the files in the
> new version to match what the patch says it should be, then created a
> new patch file from that and it applies and appears to work fine. (I
> patched the previous version's file, compared the result to the original
> and made the same change in the new version's file.)
ugghhh --- doable, but laborious ... ;)
> I have two questions:
>
> First, am I going about this the right way?
no -- Usually one unrolls the old tree, applies the patches to
the old; and then unrolls the new in a directory 'next to' the
first, and diffs from a point above the top of each
This produces a new patch set, which may already have some of
what the older patches formerly needed to do (or a wholly
different approach, when two forks diverge)
> And if so, is there a way
> to automate the process as described in the previous paragraph?
Early automation of a partially understood technology
seems like a premature optimization ;)
> Second, what is the proper convention for handling this in a rpm? The
> obvious solution seems to be to create new patch files and throw the old
> ones away, then build the rpm from that. Some of these patches appear
> to go back several versions, though, so is there a better or more proper
> way to handle this than just throwing them out and making a whole new
> set of patches?
A serious developer will usually have available a complete
copy of the master upstream, and local branches which are used
and discarded without a second thought, once the 'fruit' from
an approach is 'cherrypicked' [disk space has become
inexpensive]; Mere re-packagers can usually get by with less,
and simply pluck prior packages containing (in part) tarballs
and patches, and diff between two points in time
This is to some degree a matter of taste and administrative
approach. A big fat batch was used in the old and early
kernel and libc days to distribute 'nightly deltas' which one
would D/L and apply one after another againast a periodic
master tarball. As bandwidth availability has grown, this
fell by the wayside, and later distributed version control
systems ('VCS') have emerged as the approach favored there
The world is moving to building from VCS as well as
snap-shotting; for safety's sake, periodically rolling and
signing a SRPM or saving a file containing a signed set of
checksums for a backup tarball comes to mind as 'good
practices' See:
http://www.unrealircd.com/
and the prior experience of the Linux kernel folks, as well as
at Fedora and Red Hat with the issue of detecting possible
hostile substituted checkins
> I have learned a lot more about patch and diff tonight than I ever
> needed to know before. Very cool stuff, and very useful.
I wrote this introduction to let people get an early success
doing patching and SRPM building
http://www.owlriver.com/tips/patching_srpms/
and it is designed to be approachible
-- Russ herrold