[2639] in Kerberos_V5_Development
Re: Kerberos NT source code
daemon@ATHENA.MIT.EDU (Theodore Y. Ts'o)
Thu Oct 23 14:22:12 1997
Date: Thu, 23 Oct 1997 14:21:21 -0400
From: "Theodore Y. Ts'o" <tytso@MIT.EDU>
To: Assar Westerlund <assar@sics.se>
Cc: Sam Hartman <hartmans@mesas.com>, Ezra Peisach <epeisach@MIT.EDU>,
Ken Hornstein <kenh@cmf.nrl.navy.mil>, krbdev@MIT.EDU
In-Reply-To: Assar Westerlund's message of 22 Oct 1997 21:43:19 +0200,
<5lpvoxeg88.fsf@assaris.sics.se>
From: Assar Westerlund <assar@sics.se>
Date: 22 Oct 1997 21:43:19 +0200
Why can't you move auth contexts between contexts? Is this something
specific to the MIT implementation (with which I'm not familiar, due
to obvious reasons)? I don't see any reason why you shouldn't be able
to that in Heimdal.
I was concerned about future implementations where you might play
tricking games with allocation and deallocation routines which might be
more restrictive than malloc. We have that to some extent in Windows
DLL's --- it's not necessarily safe to have a calling application call
free() on something allocated by a DLL, because (a) they may be using a
different libc, with a different malloc, and (b) because they be
allocating out of completely different memory pools.
If you had a scheme where different krb5_context's used different memory
pools (perhaps to avoid certain inter-thread locking problems), it might
not be safe to mix auth_contexts and krb5_contexts.
This might not be something which is a real problem in the future, but
my feeling was that we can always relax restrictions, but once we let
folks start doing certain questionable things, we'd never be able to get
that flexibility back.
I still think there are many problems for which it is technically
possible to use threads, but it's not always clear that threads are the
best way to solve that problem. For example, I recall Chris Provenzano
once claiming that you might use threads as a way of structuring a
program which computed the answer to a math problem. I don't remember
enough of the details, but it was enough to convince me that for there
were certainly folks for which a threads package was a hammer, and
everything ended up looking like a nail.....
- Ted
