Openwall GNU/*/Linux - a small security-enhanced Linux distro for servers
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Fri, 26 Jun 2020 15:39:51 +1000 (AEST)
From: Damian McGuckin <damianm@....com.au>
To: musl@...ts.openwall.com
Subject: Re: errno not set to EBADF when reading from invalid
 descriptor

On Fri, 26 Jun 2020, Markus Wichmann wrote:

> 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?

Certainly STDIO allows this, but you need to be very careful. about doing 
it.

Years ago, I would send a string down a serial line opened Read/Write, as 
an atomic write, and then immediately, sit on the line waiting for a reply 
on the same serial line. I was simply trying to retreive the Postscript 
handshake between the system and the printer which was a very small number 
of characters.

Doing it with 2 FILEs is much smarter for the general case.

Regards - Damian

Pacific Engineering Systems International, 277-279 Broadway, Glebe NSW 2037
Ph:+61-2-8571-0847 .. Fx:+61-2-9692-9623 | unsolicited email not wanted here
Views & opinions here are mine and not those of any past or present employer

Powered by blists - more mailing lists

Your e-mail address:

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.