From: bernd@petrovitsch.priv.at (Bernd Petrovitsch)
To: kernelnewbies@lists.kernelnewbies.org
Subject: Simple Misc Driver - Problem with string copy to user
Date: Tue, 27 May 2014 15:33:15 +0200 [thread overview]
Message-ID: <1401197613.7926.8.camel@thorin> (raw)
In-Reply-To: <CAJyon0tAB+htm6oMbHF-YWS9XfLmiX=ZAjYzUyBC=TxcVhpQ4w@mail.gmail.com>
Hi!
On Die, 2014-05-27 at 10:09 -0300, Lucas Tanure wrote:
> Wow, many thanks.
> So the read operation should return the total number of bytes, not a
> true/false int.
The syscall here (done by `head`) is read() ...
> I need to read more about this operations.
.. and the drivers .read function is called if the user-space calls
read() on the (opened) device.
This .read function returns
*) > 0 with the number of successfully read bytes
*) == 0 on end-of-file.
*) < 0 on errors. And these error codes are found on `man errno` and
one just returns them as "-Exxxx".
[ Fullquote deleted ]
Kind regards,
Bernd
next prev parent reply other threads:[~2014-05-27 13:33 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-27 12:48 Simple Misc Driver - Problem with string copy to user Lucas Tanure
2014-05-27 12:59 ` Bjørn Mork
2014-05-27 13:03 ` Lucas Tanure
2014-05-27 13:05 ` Bjørn Mork
2014-05-27 13:09 ` Lucas Tanure
2014-05-27 13:33 ` Bernd Petrovitsch [this message]
2014-05-28 0:27 ` Le Tan
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