[Bug 17195] NamedPipe datagrams need to be _really_ datagrams

[wine-bugs at winehq.org]

http://bugs.winehq.org/show_bug.cgi?id=17195





--- Comment #2 from Luke Kenneth Casson Leighton <lkcl at lkcl.net>  2009-01-30 14:05:10 ---
(In reply to comment #1)
> This is a longstanding bug in our named pipe implementation.  We never got
> around to fixing it because a) it's harder than not doing so, and b) we hadn't
> yet found an app that needed it.

 well, there are two.  one exists - python 2.7 - the new multithreading module
uses named pipes in message mode - and messages are used to exchange a
digest-based authentication across processes, as a cheap way of not checking
the security context.  the exchange is interfered with by the first _actual_
bit of data that needs to be sent being "glommed" onto the end of the last part
of the authentication exchange.

so instead of 9 bytes being read "#SUCCESS#", 43 bytes are read -
"#SUCCESS#firstpacket....." and thus it all goes pear-shaped.

the second one app - that doesn't yet exist - is for named pipe integration
with samba.  Named Pipes over SMB allow MessageMode to be set.  the DCE/RPC
layer (ncacn_np) _definitely_ sets MessageMode.

i saw well over 8mb of data being exchanged over one "message", at hp.  they
had well over 2,000 printers on one domain.  it took _forever_ to complete the
transfer (order n-squared) because some idiot in microsot implemented
"ERR_MORE_DATA" over an MSRPC interface in the spoolss service.  so it first
asked for 64k, then 128k, then 192k .... all the way up to 8mb!!!

all using NamedPipes. yeuuch :)


> Do the python tests depend on this being correct?

 oh yeah.  the entire multiprocessing infrastructure now depends critically on
this working correctly.  they're moving away from the posix implementation of
popen(), and also moving away from all sorts of other bunged-up stuff.  all in
the new module "multiprocessing" which abstracts out pipe communication,
forking, threading, messaging, inter-process communication, all this lovely
stuff.

it's already become a major part of the python infrastructure for 2.7 and 3.0,
so it's a bit of a big deal that this works.


-- 
Configure bugmail: http://bugs.winehq.org/userprefs.cgi?tab=email
Do not reply to this email, post in Bugzilla using the
above URL to reply.
------- You are receiving this mail because: -------
You are watching all bug changes.