cvs commit: src/sys/compat/linux linux_ipc.c src/sys/sys syscallsubr.h src/sys/kern sysv_shm.c

[Martin Blapp]

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