Since very large timeouts may make sense, I've committed a change to accept `d', `h', `m', & `s' units (days, hours, minuts, & seconds, respectively) as arguments to --timeout and updated the documentation accordingly, including a warning about short server timeouts.

What about a default like 24h, or even 30m?  That seems like plenty of time to leave a connection open and there shouldn't be much more CPU cost to run this code.

I've committed this patch plus doc and a test, with a default timeout value of 0.  I'm not closing this issue until we settle the default timeout discussion.

The present default in main.c:

>+long connection_timeout = 0;

will mean that the functionality
of CVS waiting forever not change
by default. I therefore consider
this to be a fairly safe patch at
present.

I would support a non-zero default
to enable timeouts to be used, and
the CVSLCKSLEEP + 1 value seems like
it could be okay, but even a longer
delay as a default would still make
sense to me given that the current
default behavior is to wait forever.

Any thoughts on the attached patch to feature, other than the fact that I haven't added test cases and doc yet?  It adds a connection timeout to the client or server via a command line option.

The original impetus for this feature was a bunch of hung CVS servers on Solaris that appear to be hung either in the read to or write from net routines.  Since some of these servers were hung for weeks and the reporter was fairly certain that the client connections were gone, it is fairly obvious that SO_KEEPALIVE wasn't working as advertised on this system to return an error when the connection breaks.

This was the fix I came up with.  It has the additional advantages of noticing broken connections after a configurable amount of time (a working SO_KEEPALIVE is defined such that it can take up to two hours to notice a broken connection) and being a line of defense against simple DOS attacks that might open multiple connections to a CVS server without sending data across them in an attempt to create many servers and fill up the server's available memory.

Once you have applied this patch, a simple test it to run `cvs --timeout 5 server' and see the error message output after 5 seconds.

I may have to add a bit of timeout code to the proxy server select()s as well.  If this timeout feature is considered acceptable, I will add that with tests and doc before committing the final version.