[prev in list] [next in list] [prev in thread] [next in thread] 

List:       linux-audio-dev
Subject:    Re: [LAD] Segfault when trying to dereference __midi_event.buffer (c++ newbie question)
From:       Paul Davis <paul () linuxaudiosystems ! com>
Date:       2012-11-21 13:11:11
Message-ID: CAFa_cKnDfp+LHgSFowSUEqm+HYYdb=EsR9t6nsbmykRnUdNyZg () mail ! gmail ! com
[Download RAW message or body]

[Attachment #2 (multipart/alternative)]


On Wed, Nov 21, 2012 at 7:49 AM, Shani Hadiyanto Pribadi <
shanipribadi@gmx.net> wrote:

> That's it. Apparently the cause of segfault is dereferencing the pointer
> when there's no data.
> After adding checks for available data the segfault does not happen
> anymore.
>
> It never occured to me that was the cause because on the C version,
> accessing the pointer when there's no data
> returns 0x6a but didn't segfault.
>

accessing an undefined pointer has undefined results. you can rely on that.
in C, in C++ and in any other language with pointers.

[Attachment #5 (text/html)]

<br><br><div class="gmail_quote">On Wed, Nov 21, 2012 at 7:49 AM, Shani Hadiyanto \
Pribadi <span dir="ltr">&lt;<a href="mailto:shanipribadi@gmx.net" \
target="_blank">shanipribadi@gmx.net</a>&gt;</span> wrote:<br><blockquote \
class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc \
solid;padding-left:1ex"> That&#39;s it. Apparently the cause of segfault is \
dereferencing the pointer when there&#39;s no data.<br>After adding checks for \
available data the segfault does not happen anymore.<br><br>It never occured to me \
that was the cause because on the C version, accessing the pointer when there&#39;s \
no data<br>

returns 0x6a but didn&#39;t segfault. <br></blockquote><div><br>accessing an \
undefined pointer has undefined results. you can rely on that. in C, in C++ and in \
any other language with pointers.<br></div></div>



_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev@lists.linuxaudio.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev


[prev in list] [next in list] [prev in thread] [next in thread]