Re: [Iverilog-devel] NULL file descriptor or MCD

[Michael S. <mic...@gm...>]

As long it is a warning message, I think it's ok. It is a good practice to
show people that something is not right.
Best regards,
Michael Strelnikov


On Mon, 18 May 2020 at 04:24, Cary R. via Iverilog-devel <
ive...@li...> wrote:

> The other issue I see is if you call $fclose() with a MCD and any of the
> bits are invalid files none of the files will be closed. This is existing
> functionality and not something new. It almost seems like we need to pass
> the MCD to vpi_mcd_close() and then report an failures based on what could
> not be closed. All other routines that take a MCD also just return with a
> warning message.
>
> Cary
>
> On Sunday, May 17, 2020, 11:11:22 AM PDT, Cary R. <cy...@ya...>
> wrote:
>
>
> Here is example code and what I have implemented for checking the return
> value of vpi_mcd_close(). The "could not close ..." lines are the new
> output from checking the close return value. If this is acceptable I will
> commit this and update the tests as needed.
>
> module top;
>   integer fd;
>
>   initial begin
>     // MCD
>     fd = 0;
>     $fclose(fd); // NULL
>     fd = 1;
>     $fclose(fd); // STDOUT
>     fd = 2;
>     $fclose(fd); // Invalid
>
>     // FD
>     fd=32'h80000000;
>     $fclose(fd); // STDIN
>     fd=32'h80000001;
>     $fclose(fd); // STDOUT
>     fd=32'h80000002;
>     $fclose(fd); // STDERR
>     fd=32'h80000003;
>     $fclose(fd); // Invalid
>   end
> endmodule
>
> WARNING: tmp.v:9: could not close MCD STDOUT (0x1) in $fclose().
> WARNING: tmp.v:11: invalid MCD (0x2) given to $fclose().
> WARNING: tmp.v:15: could not close file descriptor STDIN (0x80000000) in
> $fclose().
> WARNING: tmp.v:17: could not close file descriptor STDOUT (0x80000001) in
> $fclose().
> WARNING: tmp.v:19: could not close file descriptor STDERR (0x80000002) in
> $fclose().
> WARNING: tmp.v:21: invalid file descriptor (0x80000003) given to $fclose().
>
> Cary
> On Sunday, May 17, 2020, 2:18:34 AM PDT, Cary R. via Iverilog-devel <
> ive...@li...> wrote:
>
>
> Thanks Martin,
>
> That is what is currently implemented except for the fclose() failure. At
> the moment $fclose() is implemented using vpi_mcd_close(), which now
> returns the failing MCD/FD correctly. One of the fixes I added is if you
> try to close the preopened descriptors (STDOUT either MCD or FD along with
> the STDIN or STDERR FDs) it returns them since they were not closed (it's
> an error). Should we report an error when trying to close these or just
> when the underlying fclose() fails? My inclination would be report them
>
> The big-3 simulator I use appears to not report any messages when invalid
> FD/MCDs are used. I guess a place where we can do things better. I get a
> failing fclose() is fairly benign, but it seems like giving information
> regarding bugs would be helpful.
>
> Cary
> On Sunday, May 17, 2020, 1:11:27 AM PDT, Martin Whitaker <
> ic...@ma...> wrote:
>
>
> A null MCD (empty set) was accepted by the file I/O tasks in Verilog-XL
> without any warning. I have used that feature in test benches (including
> passing it to $fclose), and would not want a warning.
>
> I'm not against warnings if you pass an invalid FD/MCD to $fclose or
> $fclose fails.
>
> On 17/05/2020 03:38, Cary R. via Iverilog-devel wrote:
> >  And on the subject of $fclose() should it print a warning when you try
> to close one of the preopened MDC/FDs?  Should it print a message if the
> underlying fclose() fails for some reason? We do cleanup the entry even if
> it fails so it is no longer available, but vpi_mcd_close() returns the
> descriptor for any failing items (well it does it correctly now) so we
> could report underlying issues correctly.
> > Cary
> >
> >      On Saturday, May 16, 2020, 4:24:29 PM PDT, Cary R. via
> Iverilog-devel <ive...@li...> wrote:
> >
> >  It looks like Icarus along with at least one of the Big-3 simulators
> allows, without warning, the various file I/O system tasks/functions to
> accept a NULL (0) file descriptor/MCD. I can see this as helpful if you
> want to disable output by just setting the FD/MCD to zero, but it could be
> an issue if the $fopen failed and the user did not check so having a
> warning would be beneficial for that. We do print a warning for an invalid
> non-zero FD/MCD.
> >
> > So should a zero FD/MCD print a warning or do we just want it to return
> as if nothing happened?
> > I tend to like the warnings, but I'm not certain if there is an easy way
> to disable MCD output without using the zero value. Should $fclose be
> handled differently?
> >
> > Thoughts/suggestions appreciated.
> >
> > Thanks,
> > Cary
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