[libfuzzer] Fix escaping of quotes in dictionary_generator.py and dicts affected.

testing/libfuzzer/dictionary_generator.py

 #!/usr/bin/python2
 #
 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Generate a dictionary for libFuzzer or AFL-based fuzzer.
 
 Invoked manually using a fuzzer binary and target format/protocol specification.
 Works better for text formats or protocols. For binary ones may be useless.
@@ skipping 18 matching lines @@
 
 def DecodeHTML(html_data):
   """HTML-decoding of the data."""
   html_parser = HTMLParser.HTMLParser()
   data = html_parser.unescape(html_data.decode('ascii', 'ignore'))
   return data.encode('ascii', 'ignore')
 
 
 def EscapeDictionaryElement(element):
   """Escape all unprintable and control characters in an element."""
-  return element.encode('string_escape').replace('"', '\"')
+  element_escaped = element.encode('string_escape')
+  # Remove escaping for single quote because it breaks libFuzzer.
+  element_escaped = element_escaped.replace('\\\'', '\'')
+  # Add escaping for double quote.
+  element_escaped = element_escaped.replace('"', '\\"')
+  return element_escaped
 
 
 def ExtractWordsFromBinary(filepath, min_length=MIN_STRING_LENGTH):
   """Extract words (splitted strings) from a binary executable file."""
   rodata = PreprocessAndReadRodata(filepath)
   words = []
 
   strings_re = re.compile(r'[^\x00-\x1F\x7F-\xFF]{%d,}' % min_length)
   # Use different encodings for strings extraction.
   for encoding in ENCODING_TYPES:
@@ skipping 172 matching lines @@
                       'i - intersection, q - quoted, u - uppercase.')
   args = parser.parse_args()
 
   dictionary = GenerateDictionary(args.fuzzer, args.spec, args.strategy,
                                   is_html=bool(args.html))
   WriteDictionary(args.out, dictionary)
 
 
 if __name__ == '__main__':
   main()