Re: [PATCH v2 2/2] pcapng: check if writev() returns a partial write

[Stephen Hemminger <stephen@networkplumber.org>]

On Fri, 29 Jul 2022 19:08:41 +0200
Mário Kuka <kuka@cesnet.cz> wrote:

> > Since this is being written to a file, handling partial writes makes little
> > sense. The only case where partial write would happen would be if filesystem
> > was full. Retrying just adds unnecessary complexity.
> >
> > If you really want to track this, then add a dropped counter.  
> 
> But the file descriptor doesn't have to refer to just a regular file, what
> if it's a socket or a pipe or some device? The pcapng documentation doesn't
> say anything about any restrictions, so the implementation should be fully
> generic. What's the point of a function to write packets to a file 
> descriptor
> where there's a risk that it won't write all the packets or that the 
> file will
> by corrupted due to a partial write and still not even let me know about 
> it?

As pcapng is used in the dpdk application it writes to a file.
You could repurpose it to something else, but even a pipe will not
give partial writes unless you configure the pipe as non-blocking.

Writing to a non-blocking pipe is going to have a load of other problems.

This seems like a purely hypothetical case, can't see why it needs to be addressed.