Observations about Cygwin's md5 checksums

[Marco Atzeri]

On 07/07/2014 06:38, Luke Kendall wrote:
> Here are five observations about md5 checksums in Cygwin.  I share it in
> case it may be of some small interest to a few people.  Please note that
> I may be wrong; if so, I'm happy to be corrected.
>
> 1) For each package, Cygwin stores the md5sum for the components of the
> main parts of the package in the setup.ini file.  The exception is the
> setup.hint file: its md5 sum is not recorded in setup.ini.

setup.ini is built using the setup.hint's of the several packages.
No further usage outside the www.cygwin.com server.



> 2) In each zip file for each package, an md5.sum file is almost always
> provided.  But not always. (*)
>
> 3) These md5.sum files list all the components of the package (including
> setup.hint), but these md5 sums are not reliable: they often don't match
> the actual md5 checksum (of the file itself, or of course the md5 stored
> for it in setup.ini).(**)

during upload of new files the creation of md5.sum is out of sync
with the directory content. Md5.sum is updated 1 time per hour
If the mirror sync before the creation of the md5sum it has still the 
old version.

> 4) The most common file to have the wrong md5 checksum is setup.hint
>
> 5) It's not rare for files to be mentioned in a package's md5.sum which
> are be absent from the package itself.(***)
>
> I'm curious about the purpose of having the md5.sum file in each
> package.  Is it a relic of a previous system?
>
> The above observations are based on a few weeks of mirroring and
> automatically checking the md5 sums of what we downloaded.  The main
> site we used was aarnet.edu.au (IIRC); recently we changed to
> mirrors.kernel.org, but from my ad hoc checks there wasn't much
> difference between the two).
>
> Regards,
>
> luke
>
> (*)
> For mirrors.kernel.org last night:
>
> Worrying: X11/khronos-opengl-registry has no md5.sum file
> Worrying: X11/xlaunch has no md5.sum file
> Worrying: cygwin64-gcc/cygwin64-gcc-debuginfo has no md5.sum file
> Worrying: git/git-oodiff has no md5.sum file
> Worrying: git/stgit has no md5.sum file
> Worrying: git/tig has no md5.sum file
> Worrying: man has no md5.sum file
> Worrying: python/python-paramiko has no md5.sum file

some of this directory does not exist anymore on www.cygwin.com

>
> (**)
> $ grep FAILED [path-omitted]/x86/cygwin-archive-incomplete.txt | wc
>       55     110    1463
> $ grep "^setup.hint: FAILED"
> [path-omitted]/x86/cygwin-archive-incomplete.txt | wc
>       28      56     560
>
> (***)
> $ wc -l < [path-omitted]/x86/cygwin-archive-all-missing-files.txt
> 406
>
>

Regards
MArco


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