From mboxrd@z Thu Jan  1 00:00:00 1970
From: bernd@petrovitsch.priv.at (Bernd Petrovitsch)
Date: Tue, 27 May 2014 15:33:15 +0200
Subject: Simple Misc Driver - Problem with string copy to user
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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