Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!usenet.ins.cwru.edu!ncoast!allbery
From: allbery@NCoast.ORG (Brandon S. Allbery KB8JRR)
Newsgroups: comp.unix.internals
Subject: Re: shmat() & shmdt() questions.
Message-ID: <1990Sep22.163631.23688@NCoast.ORG>
Date: 22 Sep 90 16:36:31 GMT
References: <13782@hydra.gatech.EDU> <13783@hydra.gatech.EDU> <583@dptechno.UUCP>
Reply-To: allbery@ncoast.ORG (Brandon S. Allbery KB8JRR/KT)
Followup-To: comp.unix.internals
Organization: North Coast Public Access *NIX, Cleveland, OH
Lines: 34

As quoted from <583@dptechno.UUCP> by dave@dptechno.UUCP (Dave Lee):
+---------------
| In article <13783@hydra.gatech.EDU> gt0178a@prism.gatech.EDU (BURNS,JIM) writes:
| >in article <13782@hydra.gatech.EDU>, I write:
| >>    myshmid = shmget (some-made-up-not-in-use-int-id, 4096, IPC_CREAT|600);
| >                                               ^^^
| >I suppose that should actually be 'long', as in 'key_t'. I actually
| >normally use an ascii representation of a 4-char string (assuming
| >key_t=long). E.g. - if I want the key to be 'phs1', I use '0x70687331'.
| 
| And just how is one supposed to know what is "not-in-use" ?, unless ofcourse,
| you just happen to be in controll of all the sources to all programs that 
| may ever run on your machine.
| 
| If everyone would use ftok(path,id)  (see stdipc(3C)) as recomended in the FM,
| (and then document the path and id used), then selecting a key would have a 
| lot less chance of colliding with other program uses.  Unless you really
| want a private key, then use IPC_PRIVATE.
+---------------

If shared memory were in the standard namespace, this wouldn't be a problem.

Yes, this is a change of tune for me.  But I was hoping that AT&T would
eventually integrate the two namespaces into a single one.  From the
UNIX/WORLD description, it looks like they have... research, at least.  (See
the article on Plan 9.)  I wonder how long before the commercial side picks up
on that concept?

++Brandon
-- 
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