Wireshark mailing list archives

I need wmem_alloc advice please


From: Paul Offord <Paul.Offord () advance7 com>
Date: Thu, 15 Sep 2016 16:44:49 +0000

My porting of TRANSUM from LUA to C continues.  I now have a working dissector but I then read README.developer and 
noted the guidance regarding use of static buffers.  I assume this applies to arrays too and so I'm now trying to 
convert the statically defined arrays to versions based on dynamic memory allocation.  I've converted some string 
buffers and a simple gboolean array without problems.  I then tried to convert an array of structures and this caused 
crashes all over the place.

Before the conversion I had this as a global variable:

    PKT_INFO sub_packet[MAX_SUBPKTS_PER_PACKET];

I replaced this with a global variable:

    PKT_INFO *sub_packet;

And this in my init function:

    sub_packet = (PKT_INFO *)wmem_alloc(wmem_file_scope(), (MAX_SUBPKTS_PER_PACKET * sizeof(PKT_INFO)));

I subsequently use it like this:

    sub_packet[i].frame_number = 0;

I seem to be getting memory corruption as a result of this change.  Weird things happen, like I lose preference 
variables.

What am I doing wrong here?

Thanks and regards...Paul

______________________________________________________________________

This message contains confidential information and is intended only for the individual named. If you are not the named 
addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if 
you have received this e-mail by mistake and delete this e-mail from your system.

Any views or opinions expressed are solely those of the author and do not necessarily represent those of Advance Seven 
Ltd. E-mail transmission cannot be guaranteed to be secure or error-free as information could be intercepted, 
corrupted, lost, destroyed, arrive late or incomplete, or contain viruses. The sender therefore does not accept 
liability for any errors or omissions in the contents of this message, which arise as a result of e-mail transmission.

Advance Seven Ltd. Registered in England & Wales numbered 2373877 at Endeavour House, Coopers End Lane, Stansted, Essex 
CM24 1SJ

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please visit http://www.symanteccloud.com
______________________________________________________________________
___________________________________________________________________________
Sent via:    Wireshark-dev mailing list <wireshark-dev () wireshark org>
Archives:    https://www.wireshark.org/lists/wireshark-dev
Unsubscribe: https://www.wireshark.org/mailman/options/wireshark-dev
             mailto:wireshark-dev-request () wireshark org?subject=unsubscribe

Current thread: