Re: OpenVMS getdtablesize.c

[John E. Malmberg]

On 6/28/2017 3:56 PM, Bruno Haible wrote:
> John E. Malmberg wrote:
> > OpenVMS has the function.  Configure detects it exists, but the test for
> > it working is failing.
> > ...
> > The OpenVMS getdtablesize() is returning the maximum number of open
> > files that a process can have.
> >
> > It is not returning the highest file descriptor + 1 that can be used in
> > the system.  That number is 65535 for OpenVMS Alpha and Integrity.
> >
> > That is why it is failing the configure test.
>
> There are two possibilities:
>    (a) change the configure test so that is duplicates
>        fd 0 to 1, 2, 3, ..., getdtablesize() and see if that fails.
>    (b) special-case OpenVMS.
>
> I'm not in favour of (a) because it might allocate so many file descriptors
> that the kernel gets problems.
>
> So (b). Just add a few lines
>
>    case "$host_os" in
>      vms*) ...
>
> at the appropriate place. Can you propose such a patch?
>
>
> Please try to approximate the wording of POSIX [1] as closely as possible.
>
> Bruno
>
> [1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/getrlimit.html
According to that link, a system is not required to fail a request for a 
file descriptor to be created higher than RLIMIT_NOFILE.

Attached is a patch for the test to pass on OpenVMS.

Regards,
-John

0001-getdtablesize.m4-Fix-for-OpenVMS.patch.gz
Description: GNU Zip compressed data