Some tag data is hold in GtkEntry, other in GtkTextView, which are not
parent to each other. Previous checks were wrong and resulted in
"invalid cast from 'GtkEntry' to 'GtkTextView'" WARNINGs (followed by
many CRITICALs because of this first error).
Also properly free the data returned by gtk_text_buffer_get_text() which
is allocated (unlike strings returned by gtk_entry_get_text() which must
not be freed).
When running strtok() the first time, it needs to be non-NULL so we must
check for the string. This is even more important because NULL actually
has a special meaning in strtok() to indicate further search on the same
string, in a stateful way. So searching with NULL at first call was
crashing the metadata editor plug-in in my case.
I could also imagine it could have reused strings from previous
searches, mixing metadata contents in some edge cases. Anyway that would
be bad as well!
While I was there, I also checked for non-null search string before
strstr() calls, when there was not already such a check before. This
function also requires non-NULL haystack argument.
It feels like this code doesn't do much validity checks, and it's likely
there are more similar issues. I haven't reviewed the whole code, only
this part which was crashing here.
