Fix SpooledTemporaryFile on python3

src/calibre/gui2/save.py

@@ -7,7 +7,6 @@ __copyright__ = '2014, Kovid Goyal <kovid at kovidgoyal.net>'
 
 import traceback, errno, os, time, shutil
 from collections import namedtuple, defaultdict
-from tempfile import SpooledTemporaryFile
 
 from PyQt5.Qt import QObject, Qt, pyqtSignal
 
@@ -17,7 +16,7 @@ from calibre.customize.ui import can_set_metadata
 from calibre.db.errors import NoSuchFormat
 from calibre.ebooks.metadata import authors_to_string
 from calibre.ebooks.metadata.opf2 import metadata_to_opf
-from calibre.ptempfile import PersistentTemporaryDirectory
+from calibre.ptempfile import PersistentTemporaryDirectory, SpooledTemporaryFile
 from calibre.gui2 import error_dialog, warning_dialog, gprefs, open_local_file
 from calibre.gui2.dialogs.progress import ProgressDialog
 from calibre.utils.formatter_functions import load_user_template_functions
@@ -63,10 +62,6 @@ class SpooledFile(SpooledTemporaryFile):  # {{{
 
         self._rolled = True
 
-    def truncate(self, *args):
-        # The stdlib SpooledTemporaryFile implementation of truncate() doesn't
-        # allow specifying a size.
-        self._file.truncate(*args)
 # }}}
 
 

src/calibre/ptempfile.py

@@ -277,10 +277,15 @@ class SpooledTemporaryFile(tempfile.SpooledTemporaryFile):
     def name(self, val):
         self._name = val
 
-    def truncate(self, *args):
-        # The stdlib SpooledTemporaryFile implementation of truncate() doesn't
-        # allow specifying a size.
-        self._file.truncate(*args)
+    # See https://bugs.python.org/issue26175
+    def readable(self):
+        return self._file.readable()
+
+    def seekable(self):
+        return self._file.seekable()
+
+    def writable(self):
+        return self._file.writable()
 
 
 def better_mktemp(*args, **kwargs):

src/calibre/utils/localunzip.py

@@ -16,7 +16,7 @@ Tries to only use the local headers to extract data from the damaged zip file.
 import os, sys, zlib, shutil
 from struct import calcsize, unpack, pack
 from collections import namedtuple, OrderedDict
-from tempfile import SpooledTemporaryFile
+from calibre.ptempfile import SpooledTemporaryFile
 
 from polyglot.builtins import itervalues, getcwd
 

src/calibre/utils/zipfile.py

@@ -3,15 +3,22 @@
 Read and write ZIP files. Modified by Kovid Goyal to support replacing files in
 a zip archive, detecting filename encoding, updating zip files, etc.
 """
-import struct, os, time, sys, shutil, stat, re, io
 import binascii
+import io
+import os
+import re
+import shutil
+import stat
+import struct
+import sys
+import time
 from contextlib import closing
-from tempfile import SpooledTemporaryFile
 
 from calibre import sanitize_file_name
 from calibre.constants import filesystem_encoding
 from calibre.ebooks.chardet import detect
-from polyglot.builtins import unicode_type, string_or_bytes, getcwd, map, as_bytes
+from calibre.ptempfile import SpooledTemporaryFile
+from polyglot.builtins import getcwd, map, string_or_bytes, unicode_type, as_bytes
 
 try:
     import zlib  # We may need its compression method