Wireshark · Wireshark-dev: [Wireshark-dev] I need wmem_alloc advice please

[Paul Offord <Paul.Offord@xxxxxxxxxxxx>]

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

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