Thus wrote Martin Kaiser (lists@xxxxxxxxx):
> > > 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?
commit f7aeaec74abab8e11165ea742778d4875100cfac
Author: Martin Kaiser <martin@xxxxxxxxxxxxxxxxxx>
Date: Fri Dec 20 17:31:21 2013 +0100
change the string representation of an empty FT_BYTES fvalue to ""
this creates a correct filter expression for Apply as Filter / Selected, etc.
diff --git a/epan/ftypes/ftype-bytes.c b/epan/ftypes/ftype-bytes.c
index de7adac..5bcb20d 100644
--- a/epan/ftypes/ftype-bytes.c
+++ b/epan/ftypes/ftype-bytes.c
@@ -63,9 +63,8 @@ static int
bytes_repr_len(fvalue_t *fv, ftrepr_t rtype _U_)
{
if (fv->value.bytes->len == 0) {
- /* Empty array of bytes, so the representation
- * is an empty string. */
- return 0;
+ /* Empty array of bytes, the representation is two double quotes */
+ return 2;
} else {
/* 3 bytes for each byte of the byte "NN:" minus 1 byte
* as there's no trailing ":". */
@@ -143,6 +142,11 @@ bytes_to_repr(fvalue_t *fv, ftrepr_t rtype _U_, char *buf)
c = fv->value.bytes->data;
write_cursor = buf;
+ if (fv->value.bytes->len==0) {
+ sprintf(write_cursor, "\"\"");
+ return;
+ }
+
for (i = 0; i < fv->value.bytes->len; i++) {
if (i == 0) {
sprintf(write_cursor, "%02x", *c++);
