> On Oct 26, 2017, at 1:18 PM, zhang j <jullyzh...@gmail.com> wrote:
>
> Hi All,
>
> I have a question about md5sum of a 0 sized file. The md5sum of a 0 sized
> file built using rpm 5.4 on RHE 7 is 00000000000000000000000000000000. If do
> 'rpm -qp --dump' of that rpm, the md5sum is shown
> 00000000000000000000000000000000.
>
You are correct that the MD5 of a zero length file is not zeroes:
$ md5sum < /dev/null
d41d8cd98f00b204e9800998ecf8427e -
Are you sure this is rpm 5.4 (and not rpm4) on RHEL 7? There’s a fair amount of
work in switching rpm4 -> rpm5 on RHEL7, congratulations if you succeeded!
Also: MD5 (for file digests) has largely been replaced with SHA256 everywhere
in *.rpm packages.
>
> But the real md5sum of that file is not 00000000000000000000000000000000. How
> to build the correct md5sum in the rpm?
>
I dimly remember someone objecting to the overhead of computing digests of
empty files in *.rpm packages
like 8-10 years ago (but I could be mis-remembering).
That would have involved a patch to (likely) skip computing the digest for zero
length files that (wrongly)
returns the contents of a calloc’d buffer as 00000000000000000000000000000000.
73 de Jeff
>
> Thanks,
> Juan
