Improved rtlo element source mapping

slither/detectors/source/rtlo.py

@@ -44,21 +44,33 @@ contract Token
 '''
     WIKI_RECOMMENDATION = 'Special control characters must not be allowed.'
 
+    RTLO_CHARACTER_ENCODED = "\u202e".encode('utf-8')
+
     def _detect(self):
         results = []
 
-        pattern = re.compile(".*\u202e.*")
         for filename, source in self.slither.source_code.items():
-            info = "{} contains a unicode right-to-left-override character:\n".format(filename)
-            found = False
-            for match in pattern.finditer(source):
-                match_line = match.group(0)
-                info += "\t- {}\n".format(match_line)
-                found = True
-
-            if found:
-                json = self.generate_json_result(info)
-                self.add_other_to_json("rtlo-character", (filename, 0, 0), json)
-                results.append(json)
+            # Attempt to find all RTLO characters in this source file.
+            source_encoded = source.encode('utf-8')
+            start_index = 0
+
+            # Keep searching all file contents for the character.
+            while True:
+                result_index = source_encoded.find(self.RTLO_CHARACTER_ENCODED, start_index)
+
+                # If we couldn't find the character in the remainder of source, stop.
+                if result_index == -1:
+                    break
+                else:
+                    # We found another instance of the character, define our output
+                    info = f"{filename} contains a unicode right-to-left-override character at byte offset {result_index}"
+
+                    json = self.generate_json_result(info)
+                    self.add_other_to_json("rtlo-character",
+                                           (filename, result_index, len(self.RTLO_CHARACTER_ENCODED)), json)
+                    results.append(json)
+
+                    # Advance the start index for the next iteration
+                    start_index = result_index + 1
 
         return results