[solved] Re: [tlug] shmget fails with error code = 22

["Nguyen Vu Hung" <vuhung16plus@example.com>]

2008/1/15, Botond Botyanszki <tlug@example.com>:
> On Tue, 15 Jan 2008 20:32:50 +0900
> "Nguyen Vu Hung" <vuhung16plus@example.com> wrote:
>
> > Hi,
> >
> > The following code has failed and the error code ( errno ) is 22.
> >
> >
> >         shmid = shmget((key_t)ShmKey, (size_t)mem_size, 0666 | IPC_CREAT);
> >         iErrorCode = errno;
> >
> >
> > I've checked /usr/include/asm/error.h and found that
> >
> > #define EINVAL      22  /* Invalid argument */
> >
> > which is not very informative.
>
> If you check the manpage on linux, it says:
>        EINVAL      A new segment was to be created and size < SHMMIN or size >
>                    SHMMAX, or no new segment was to be created, a segment with
>                    given  key  existed,  but  size is greater than the size of
>                    that segment.
>
> Adding proper error handling with debug helpers to your code can help a
> lot is such situations, ie:
> if ( errno != 0 )
> {
>   fprintf(STDERR, "shmget(mem_size: %d) failed, %s", mem_size, strerror(errno));
> }

I did have an error handling.

The cause of the problem turns out to be: We tried to shmget() with
mem_size = 64MB but the shared memory, which was created before that,
is a different value. The size of shared memory is define in
configuration file someone has changed it.

Thanks all for hinting me.

-- 
Best Regards,
Nguyen Hung Vu ( Nguyễn Vũ Hưng )
vuhung16plus{remove}@example.com
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