[Config] Fix loading config with double-quotes in string

If a password or other string contained a double-quote then the config
would fail to be loaded on startup and reset.

This occurred due to fixing a similar issue with curly braces for #3079
in commit 33e9545cd44 and the checking for double-quotes had unforseen
consequences.

To resolve both these issues the code to check for json objects in
config files was simplified and utilises the json module raw_decode
method to ensure the extracted string indexes are json objects.

deluge/config.py

@@ -74,38 +74,33 @@ def prop(func):
     return property(doc=func.__doc__, **func())
 
 
-def find_json_objects(s):
-    """Find json objects in a string.
+def find_json_objects(text, decoder=json.JSONDecoder()):
+    """Find json objects in text.
 
     Args:
-        s (str): the string to find json objects in
+        text (str): The text to find json objects within.
 
     Returns:
         list: A list of tuples containing start and end locations of json
-            objects in string `s`. e.g. [(start, end), ...]
+            objects in the text. e.g. [(start, end), ...]
+
 
     """
     objects = []
-    opens = 0
-    start = s.find('{')
-    offset = start
+    offset = 0
+    while True:
+        try:
+            start = text.index('{', offset)
+        except ValueError:
+            break
 
-    if start < 0:
-        return []
-
-    quoted = False
-    for index, c in enumerate(s[offset:]):
-        if c == '"':
-            quoted = not quoted
-        elif quoted:
-            continue
-        elif c == '{':
-            opens += 1
-        elif c == '}':
-            opens -= 1
-            if opens == 0:
-                objects.append((start, index + offset + 1))
-                start = index + offset + 1
+        try:
+            __, index = decoder.raw_decode(text[start:])
+        except json.decoder.JSONDecodeError:
+            offset = start + 1
+        else:
+            offset = start + index
+            objects.append((start, offset))
 
     return objects
 

deluge/tests/test_config.py

@@ -25,6 +25,7 @@ DEFAULTS = {
     'float': 0.435,
     'bool': True,
     'unicode': 'foobar',
+    'password': 'abc123*\\[!]?/<>#{@}=|"+$%(^)~',
 }
 
 
@@ -95,6 +96,7 @@ class ConfigTestCase(unittest.TestCase):
 
             self.assertEqual(config['string'], 'foobar')
             self.assertEqual(config['float'], 0.435)
+            self.assertEqual(config['password'], 'abc123*\\[!]?/<>#{@}=|"+$%(^)~')
 
         # Test opening a previous 1.2 config file of just a json object
         import json
@@ -107,8 +109,8 @@ class ConfigTestCase(unittest.TestCase):
         # Test opening a previous 1.2 config file of having the format versions
         # as ints
         with open(os.path.join(self.config_dir, 'test.conf'), 'wb') as _file:
-            _file.write(bytes(1) + b'\n')
-            _file.write(bytes(1) + b'\n')
+            _file.write(b'1\n')
+            _file.write(b'1\n')
             json.dump(DEFAULTS, getwriter('utf8')(_file), **JSON_FORMAT)
 
         check_config()
@@ -184,9 +186,27 @@ class ConfigTestCase(unittest.TestCase):
 }{
   "ssl": true,
   "enabled": false,
-  "port": 8115
+  "port": 8115,
   "password": "abc{def"
-}\n"""
+}"""
+
+        from deluge.config import find_json_objects
+
+        objects = find_json_objects(s)
+        self.assertEqual(len(objects), 2)
+
+    def test_find_json_objects_double_quote(self):
+        """Test with string containing double quote"""
+        s = r"""{
+  "file": 1,
+  "format": 1
+}{
+  "ssl": true,
+  "enabled": false,
+  "port": 8115,
+  "password": "abc\"def"
+}
+"""
 
         from deluge.config import find_json_objects