Re: Checksums on versions

[Larry Jones]

Marshall, Joshua writes:
> 
> The investigation I have had shows that the client / server protocol has 
> the option for Checksums to be set (I read the protocol for 1.9 [1] 
> because I couldn't find 1.11) but it says that it is optional. Is there a 
> way to tell whether this is actually being used? 

The standard CVS server implementation only sends checksums when
updating a file via a patch (to assure that the file afer applying the
patch matches the repository file).  (The client/server protocol is
documented [sic] in doc/cvsclient.texi in the source distribution.  You
can browse it on-line at www.cvshome.org.)

> I looked through the file in the repository (the ,v file) and can't see 
> any references to checksums etc being in there. I found a webpage [2] 
> which stated that there aren't any checksums done on the files. Although 
> what it says is true about backups being long gone if file corruption is 
> detected, it would be very useful for the developers to know if a file is 
> corrupted, and at least know that what they have isn't exactly what was 
> committed.

RCS files do not have checksums.  What exactly is it that you're worried
about:  Are you worried about bugs in CVS?  Bugs in your file system? 
Bugs in your hard drive?  Malicious users?

> Is there a way to get an external program to checksum these files and 
> store a checksum somewhere so that they can be checked when they are 
> pulled out of the repository for validity - and is there a way to do this 
> automatically?

Not without an inordinate amount of work -- what is the higher-level
goal that you're trying to accomplish?

-Larry Jones

These things just seem to happen. -- Calvin