Re: [musl] errno not set to EBADF when reading from invalid descriptor

[Markus Wichmann <nullplan@gmx.net>]

On Thu, Jun 25, 2020 at 11:38:04AM -0400, Rich Felker wrote:
> Note that there are lots of other reasons you can't safely use stdio
> read functions on a stream you don't know is suitable for it.
> Switching from writing to reading without a successful flush produces
> UB, and switching the other direction without a successful seek does,
> even if the FILE stream is open for both.
>
> Rich

So I can't actually use a FILE open for reading and writing that refers
to something non-seekable, like a serial line, to both read and write to
it? I mean, I suppose I could write something and then flush and stay in
read mode forever, but that is not really the nature of my application.
I suppose I'll just open the serial line twice.

Ciao,
Markus