Re: FT_BYTES hf with len==0

[Martin Kaiser <lists () kaiser cx>]

Thus wrote Martin Kaiser (lists () kaiser cx):

> > > 5392             label_fill(label_str, 0, hfinfo,
> > > 5393                             (bytes) ? bytes_to_str(bytes, fvalue_length(&fi->value)) : "<MISSING>");
> > > 5394             break;

> > > It'd be good to make them consistent, allow empty bytes (+1 from me) or assert in both place.

> > ok, I'll change this.

> done in r54290.

I've just found one more issue with empty FT_BYTES:
When I click on an empty FT_BYTES element in the tree and select Apply
as Filter / Selected, wireshark creates a filter expression

<filter name>==

that results in a syntax error.

This is created by construct_match_selected_string(), which calls
fvalue_to_string_repr() and uses the fvalue's string representation by
default.

One way to resolve this would be to change an empty FT_BYTES' string
representation from <nothing> to "" (as <filter name>=="" is a valid
filter expression). See the attached patch.

Is that ok or does it break someone else's code? Should I check for
FTREPR_DFILTER and modify the representation for empty FT_BYTES only in
this case?

Attachment: bytes_repr.patch
Description:

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