On Sun, Feb 19, 2012 at 3:08 AM, Panu Matilainen <pmatilai@xxxxxxxxxxxxxxx> wrote:
The fundamental package file format hasn't changed. There's a padding between signature and regular header which your script doesn't appear to take signature header padding into account, so you've basically just been lucky if you haven't been hit by that with older rpms.On 02/19/2012 09:23 AM, Jordan Sissel wrote:
Howdy!
I am implementing a library for reading and writing RPM files. I've used
the rpm source and from max-rpm[1] as documentation on the file format.
[1] http://www.rpm.org/max-rpm/s1-rpm-file-format-rpm-file-format.html
I'm thus far able to happily read older RPMs from,CentOS5 and Fedora 10
(and earlier). I am not able to correctly read RPMs from CentOS 6 and
Fedora 11 (and beyond)
The problem seems to be around the length of each header section
(signature and regular header). With older RPMs, my calculation
correctly computes the length, but for newer rpms (Fedora 11+ and
CentOS6+) I am usually short by 4 bytes.
This causes me a problem because I'll read the Signature header and fail
when reading the next header because I'm 4 bytes behind the actual start
of the next header.
I have wrangled it down to a small example script that can read older
rpms but fails on newer ones as described. I have also included some
data and output as well in a gist found here:
https://gist.github.com/1862256
If you have any pointers on how I'm reading these newer RPM files
incorrectly, I'd love to know :)
See eg http://rpm.org/gitweb?p=rpm.git;a=blob;f=lib/signature.c;h=63e59c00f255a538e48cbc8b0cf3b9bd4a4dbd56;hb=HEAD#l203 how to calculate the pad, or alternatively if you prefer reading obscure shell-script to C:
http://rpm.org/gitweb?p=rpm.git;a=blob;f=scripts/rpm2cpio.sh;h=b03ee361f7f6948c979195eefc50295aa8fa0cf7;hb=HEAD
- Panu -
Ahha, that's what I was missing. I have working sample code now with to this information.
Thanks :)
-Jordan
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