Date: Mon, 5 May 2003 19:05:08 +0200 (CEST) From: Martin Blapp <mb@imp.ch> To: Ian Dowse <iedowse@maths.tcd.ie> Cc: src-committers@FreeBSD.org Subject: Re: cvs commit: src/sys/compat/linux linux_ipc.c src/sys/sys syscallsubr.h src/sys/kern sysv_shm.c Message-ID: <20030505190401.V2898@cvs.imp.ch> In-Reply-To: <200305051653.aa98706@salmon.maths.tcd.ie> References: <200305051653.aa98706@salmon.maths.tcd.ie>
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Hi Ian,
> I had a few incomplete stack-gap patches in this area, so I was
> just looking over this change while merging. The shmctl() system
> call is unfortunately quite messy to deal with, since its `struct
> shmid_ds *buf' argument can point at a different type of structure
> (struct shm_info) for some commands. BTW, it seems that these
> additional commands (IPC_INFO, SHM_INFO) and also SHM_STAT are not
> documented in shmctl(2) so they really only exist for use by the
> Linux emulator.
>
> A few comments about these changes:
> - shmctl() now assumes that it can fit a `struct shm_info' into
> `struct shmid_ds buf'. While it does fit now, it would be much
> better to use a union so as not to need this assumption.
>
> - The `bufsz' argument to kern_shmctl() seems to be unnecessary,
> since callers are required to know already how much space is
> required - they supplied that space. It would be better just to
> have shmctl() switch on the command code and then copyout
> sizeof(struct shm_info) or sizeof(struct shm_info) accordingly.
>
> - Is the 'if (error) {td->td_retval[0] = -1;}' at the end of shmctl()
> really necessary? The syscall() code should ignore td->td_retval[0]
> in the error case.
Ok, I'll discuss these changes with Orlando and come up with
a fix.
Thanks for looking at the change !
Martin
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