Get rid of safe_pickle

Dont need it since we were only storing binary strings anyway

src/calibre/db/backend.py

@@ -8,7 +8,7 @@ __copyright__ = '2011, Kovid Goyal <kovid@kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
 
 # Imports {{{
-import os, shutil, uuid, json, glob, time, cPickle, hashlib, errno, sys
+import os, shutil, uuid, json, glob, time, hashlib, errno, sys
 from functools import partial
 
 import apsw
@@ -23,6 +23,7 @@ from calibre.db.delete_service import delete_service
 from calibre.db.errors import NoSuchFormat
 from calibre.library.field_metadata import FieldMetadata
 from calibre.ebooks.metadata import title_sort, author_to_author_sort
+from calibre.utils import pickle_binary_string, unpickle_binary_string
 from calibre.utils.icu import sort_key
 from calibre.utils.config import to_json, from_json, prefs, tweaks
 from calibre.utils.date import utcfromtimestamp, parse_date
@@ -35,7 +36,6 @@ from calibre.utils.formatter_functions import (load_user_template_functions,
             unload_user_template_functions,
             compile_user_template_functions,
             formatter_functions)
-import calibre.utils.safe_pickle as safe_pickle
 from calibre.db.tables import (OneToOneTable, ManyToOneTable, ManyToManyTable,
         SizeTable, FormatsTable, AuthorsTable, IdentifiersTable, PathTable,
         CompositeTable, UUIDTable, RatingTable)
@@ -1695,11 +1695,7 @@ class DB(object):
     def conversion_options(self, book_id, fmt):
         for (data,) in self.conn.get('SELECT data FROM conversion_options WHERE book=? AND format=?', (book_id, fmt.upper())):
             if data:
-                try:
-                    return safe_pickle.loads(bytes(data))
-                except Exception:
-                    import traceback
-                    traceback.print_exc()
+                return unpickle_binary_string(bytes(data))
 
     def has_conversion_options(self, ids, fmt='PIPE'):
         ids = frozenset(ids)
@@ -1716,7 +1712,8 @@ class DB(object):
             [(book_id, fmt.upper()) for book_id in book_ids])
 
     def set_conversion_options(self, options, fmt):
-        options = [(book_id, fmt.upper(), buffer(cPickle.dumps(data, -1))) for book_id, data in options.iteritems()]
+        options = [(book_id, fmt.upper(), buffer(pickle_binary_string(data.encode('utf-8') if isinstance(data, unicode) else data)))
+                for book_id, data in options.iteritems()]
         self.executemany('INSERT OR REPLACE INTO conversion_options(book,format,data) VALUES (?,?,?)', options)
 
     def get_top_level_move_items(self, all_paths):

src/calibre/utils/__init__.py

@@ -24,3 +24,29 @@ def join_with_timeout(q, timeout=2):
     finally:
         q.all_tasks_done.release()
 
+
+def unpickle_binary_string(data):
+    # Maintains compatibility with python's pickle module protocol version 2
+    import struct
+    from pickle import PROTO, SHORT_BINSTRING, BINSTRING
+    if data.startswith(PROTO + b'\x02'):
+        offset = 2
+        which = data[offset]
+        offset += 1
+        if which == BINSTRING:
+            sz, = struct.unpack_from(b'<i', data, offset)
+            offset += struct.calcsize(b'<i')
+        elif which == SHORT_BINSTRING:
+            sz = ord(data[offset])
+            offset += 1
+        else:
+            return
+        return data[offset:offset + sz]
+
+
+def pickle_binary_string(data):
+    # Maintains compatibility with python's pickle module protocol version 2
+    import struct
+    from pickle import PROTO, BINSTRING
+    data = bytes(data)
+    return PROTO + b'\x1b' + BINSTRING + struct.pack(b'<i', len(data)) + data