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Re: rpm-4.0.4: rpm -V md5sum failure, file corruption

On Mon, 20 Jan 2003, Jeff Johnson wrote:

> Think a bit.

You make it sound like I'm missing something obvious.  I've been
"thinking a bit" for days.

> You're getting strange results comparing two md5 sum checks. AFAICT,
> either md5sum or rpm -V may be "lying".

This is why I'm asking about rpm's potential for "lying".

> One possible explanation is that different data is being returned
> when reading. This wouldn't happen to be NFS, would it?

No.  NFS is not in use here.

> Another possible explanantion is memory/disk/cpu hardware problems.
> Dunno IDE patches, but you might want to check on, say, a SCSI disk.

This was my first thought, which is why I reran the tests on several
hardware platforms, as I said, one platform is IDE Compact Flash, one is
IDE hard drive, and one is IDE Compact Flash on a different mainboard.
All have similar amounts of RAM, and the same CPU power.  It doesn't
appear to be hardware.

> "Large number of machines": Hmmm, look for a common factor.

The common factor is software.  Each machine is running exactly the same
software.  The same complete set of RPMs.  The interesting links are
those that I described, the kernel, the filesystem, and rpm.  During the
tests nothing else is happening.  They are computers with a known set of
files, with RPM verifying the files over and over.  But, 2.2, IDE, and
ext2 should be pretty solid.  It seems to me that there are an awful lot
of users that should be seeing this if it were those.  The question mark
is how many users run rpm -Va many times a day and check the output?

> O_RDONLY means exactly what you think it does.
> Be forewarned: There's an unexpected transformation of file content
> with rpm -V if using prelinked libraries. Basically prelink -u is run,
> and the md5 sum of the output of prelink "undo" is computed.
> Transformation iff prelinked DSO, but /usr/lib/libadns.so.1.0 is a DSO.

Can you clarify this for me?  It isn't just libraries that fail this
test.  Some examples of files that have been reported bad:



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