gtk-text-iter-backward-search (iter str flags limit)

iter -- a gtk-text-iter instance where the search begins
str -- a search string
flags -- the gtk-text-search-flags flags affecting the search
limit -- a gtk-text-iter instance with the location of last possible match-start, or nil for start of the text buffer

search-p -- a boolean whether a match was found
match-start -- a gtk-text-iter instance with the start of match, or nil
match-end -- a gtk-text-iter instance with the end of match, or nil

Same as the function gtk-text-iter-forward-search, but moves backward.