[Mono-dev] Unix.Native

[Greg Young]

Rodrigo,

What do you think as a pattern (there are quite a few places like
this) if it were to do something like:

[Conditional("DEBUG")]
private void VerifyCommandEnum<T>(T enum) {
    if(!Enum.IsDefined(typeof(T), command))
           throw new Exception(string.Format("The value passed '{0}'
for {1} is not  a defined value and will fail at runtime.", enum,
typeof(T).ToString());
}

This will be slower but will give a reasonably sane error in debug at
least. I can send over a PR with a few of them covered but wanted to
run it by here before I spent the time on it.

Greg

On Tue, Jan 13, 2015 at 4:16 AM, Greg Young <gregoryyoung1 at gmail.com> wrote:
> btw if anyone runs into this (should be a top google result) and the
> constants are not in commands here is how to do it:
>
> Not the prettiest but it should work
>
> #if __MonoCS__ || USE_UNIX_IO
> [DllImport("libc")]
> static extern int fcntl(int fd, uint command, int arg);
> #endif
>
> if (OS.OsFlavor != OsFlavor.MacOS) return;
> #if __MonoCS__ || USE_UNIX_IO
> long r = 0;
> do {
> r = fcntl (handle.DangerousGetHandle().ToInt32(), MAC_F_NOCACHE, 1);
> } while (UnixMarshal.ShouldRetrySyscall ((int) r));
> if (r == -1)
> UnixMarshal.ThrowExceptionForLastError ();
> #endif
>
> On Tue, Jan 13, 2015 at 3:49 AM, Greg Young <gregoryyoung1 at gmail.com> wrote:
>> If we can get a list of all the params that need to be supported and
>> the varying mappings I have no problem working on it.
>>
>> I will look into its build etc as I have never dealt with it internally.
>>
>> Greg
>>
>> On Tue, Jan 13, 2015 at 3:48 AM, Rodrigo Kumpera <kumpera at gmail.com> wrote:
>>> I agree we would be better with a better error message.
>>>
>>> Said that, right now Mono.Posix lacks a more dedicated maintainer and it
>>> would be lovely if you
>>> could bring some love to it. :)
>>>
>>> On Mon, Jan 12, 2015 at 8:39 PM, Greg Young <gregoryyoung1 at gmail.com> wrote:
>>>>
>>>> There are a ton to surface ... I just ran into this one :)
>>>>
>>>> In general I agree with you surfacing is better I was thinking just
>>>> letting me call it if it doesn't understand it (or having a better
>>>> message) would be useful. I spun for hours thinking what was wrong
>>>> with my parameters to the call thinking it for some undocumented
>>>> reason was returning EINVAL :)
>>>>
>>>> On Tue, Jan 13, 2015 at 3:30 AM, Rodrigo Kumpera <kumpera at gmail.com>
>>>> wrote:
>>>> > That would change the behavior of the function and translate into a more
>>>> > fragile API.
>>>> >
>>>> > The way to go is to surface this option.
>>>> >
>>>> > On Mon, Jan 12, 2015 at 8:23 PM, Greg Young <gregoryyoung1 at gmail.com>
>>>> > wrote:
>>>> >>
>>>> >> I figured out why after a while of looking. The C code translates the
>>>> >> argument
>>>> >>
>>>> >> int Mono_Posix_FromFcntlCommand (int x, int *r)
>>>> >>
>>>> >> When its something that is not a known command it returns EINVAL.
>>>> >> Might a better option be to try to let it pass through otherwise how
>>>> >> could I call for instance a value on a ac?
>>>> >>
>>>> >> Cheers,
>>>> >>
>>>> >> Greg
>>>> >>
>>>> >> On Tue, Jan 13, 2015 at 2:28 AM, Greg Young <gregoryyoung1 at gmail.com>
>>>> >> wrote:
>>>> >> > I have been trying to set F_NOCACHE via fcntl on a mac to no avail.
>>>> >> >
>>>> >> >                  r = Syscall.fcntl
>>>> >> > (handle.DangerousGetHandle().ToInt32(), (FcntlCommand) MAC_F_NOCACHE,
>>>> >> > 1);
>>>> >> >                  } while (UnixMarshal.ShouldRetrySyscall ((int) r));
>>>> >> >                  if (r == -1)
>>>> >> >                      UnixMarshal.ThrowExceptionForLastError ();
>>>> >> >
>>>> >> > (EINVAL)
>>>> >> >
>>>> >> > I have tried
>>>> >> > 48
>>>> >> > 0x400
>>>> >> > and 0x40000
>>>> >> > for F_NOCACHE though from
>>>> >> >
>>>> >> >
>>>> >> > https://github.com/realthunder/mac-headers/blob/master/usr/include/sys/fcntl.h#L256
>>>> >> >
>>>> >> > Given FcntlCommandFlags does not expose F_NOCACHE but it still should
>>>> >> > be fine to jam the value into the enum
>>>> >> >
>>>> >> > Has anyone set this before? Chances of finding this on google are
>>>> >> > slightly better than 0 :)
>>>> >> >
>>>> >> > Cheers,
>>>> >> >
>>>> >> > Greg
>>>> >> > --
>>>> >> > Studying for the Turing test
>>>> >>
>>>> >>
>>>> >>
>>>> >> --
>>>> >> Studying for the Turing test
>>>> >> _______________________________________________
>>>> >> Mono-devel-list mailing list
>>>> >> Mono-devel-list at lists.ximian.com
>>>> >> http://lists.ximian.com/mailman/listinfo/mono-devel-list
>>>> >
>>>> >
>>>>
>>>>
>>>>
>>>> --
>>>> Studying for the Turing test
>>>
>>>
>>
>>
>>
>> --
>> Studying for the Turing test
>
>
>
> --
> Studying for the Turing test



-- 
Studying for the Turing test