Wireshark · Ethereal-dev: Re: [Ethereal-dev] Regarding Memory allocation

[Guy Harris <gharris@xxxxxxxxx>]

Jaap Keuter wrote:

> > From README.developer
>
>    If you're setting it to a string you've constructed, or will be
>    appending to the column later, use "col_add_str()".
>
> So it all depends on how you _start_ filling the column. If it's already
> filled using col_set_str(pinfo->cinfo, COL_INFO, "Blah"); you'll need to
> clear it first, like so:
>
>     col_clear(pinfo->cinfo, COL_INFO);

No, you don't need to - that note from README.developer is an 
optimization hint, not a strict requirement.

The problem is that "col_set_str()" just sets a pointer, it doesn't copy 
the string - but if you're going to append to the column, a copy has to 
be made of the string to a buffer, because "col_append_str()" and 
"col_append_fstr()" can't just append to the string passed in the 
"col_set_str()" call.  If it's going to copy the string anyway, you 
might as well use "col_add_str()" and do the copy up front.