[FFmpeg-devel] [PATCH] Return ENOTSUP if codec does not support feature

[Ronald S. Bultje]

Hi,

On 7/20/07, Panagiotis Issaris <takis.issaris at uhasselt.be> wrote:
>
> Do you know a source for the correct and exact meaning of these
> codes? I am only aware of the OpenGroup's website, but the
> definitions on that site aren't really clear:
> [ENOTSUP] Not supported.
> [ENOSYS] Function not supported.
> [EINVAL] Invalid argument.
> ...
>
> As can be found here:
> http://www.opengroup.org/onlinepubs/009695399/basedefs/errno.h.html


The best descriptions are in the man pages, but they are syscall-specific.
There is no general, good resource, I'm affraid.

If you were referring to the definition in the libc infopages, I'd
> interpreted them differently. It says (notice the empasis I added):
> "... the functionality they request is not available. This _can_ mean
> that the function does not implement a particular command ..."
>
> I had read that as, "the codec does not provide that functionality",
> not meaning the implementation, but that the feature can't be used
> for a codec. And that a complete implementation of the codec would
> not have provided it either.


Either way, this is just as ambiguous as the "not supported" vs. "invalid
parameter". :-). It can be read either way. One way to solve it is to just
do the same that syscalls do - pick a few, extend and specify their meaning
more clearly in a document and use those in that exact way.

Ronald