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Fix ZIP attribute "external_attr" getting reset

This commit is contained in:
NoDRM 2022-08-06 13:53:03 +02:00
parent 9a11f480b5
commit 80cbaa4841
7 changed files with 114 additions and 9 deletions
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1
CHANGELOG.md
View File

@ -72,3 +72,4 @@ List of changes since the fork of Apprentice Harper's repository:
- Fix a bug introduced with #48 that breaks DeDRM'ing on Calibre 4 (fixes #101).
- Fix some more Calibre-6 bugs in the Obok plugin (should fix #114).
- Fix a bug where invalid Adobe keys could cause the plugin to stop trying subsequent keys (partially fixes #109).
- Fix DRM removal sometimes resetting the ZIP's internal "external_attr" value on Calibre 5 and newer.

9
DeDRM_plugin/epubfontdecrypt.py
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@ -25,6 +25,7 @@ import traceback
import zlib
import zipfile
from zipfile import ZipInfo, ZipFile, ZIP_STORED, ZIP_DEFLATED
from zeroedzipinfo import ZeroedZipInfo
from contextlib import closing
from lxml import etree
import itertools
@ -298,13 +299,21 @@ def decryptFontsBook(inpath, outpath):
zi.internal_attr = oldzi.internal_attr
# external attributes are dependent on the create system, so copy both.
zi.external_attr = oldzi.external_attr
zi.volume = oldzi.volume
zi.create_system = oldzi.create_system
zi.create_version = oldzi.create_version
if any(ord(c) >= 128 for c in path) or any(ord(c) >= 128 for c in zi.comment):
# If the file name or the comment contains any non-ASCII char, set the UTF8-flag
zi.flag_bits |= 0x800
except:
pass
# Python 3 has a bug where the external_attr is reset to `0o600 << 16`
# if it's NULL, so we need a workaround:
if zi.external_attr == 0:
zi = ZeroedZipInfo(zi)
if path == "mimetype":
outf.writestr(zi, inf.read('mimetype'))
elif path == "META-INF/encryption.xml":

26
DeDRM_plugin/epubwatermark.py
View File

@ -16,6 +16,7 @@ Removes various watermarks from EPUB files
import traceback
from zipfile import ZipInfo, ZipFile, ZIP_STORED, ZIP_DEFLATED
from zeroedzipinfo import ZeroedZipInfo
from contextlib import closing
from lxml import etree
import re
@ -133,13 +134,22 @@ def removeHTMLwatermarks(object, path_to_ebook):
zi.extra = oldzi.extra
zi.internal_attr = oldzi.internal_attr
zi.external_attr = oldzi.external_attr
zi.volume = oldzi.volume
zi.create_system = oldzi.create_system
zi.create_version = oldzi.create_version
if any(ord(c) >= 128 for c in path) or any(ord(c) >= 128 for c in zi.comment):
# If the file name or the comment contains any non-ASCII char, set the UTF8-flag
zi.flag_bits |= 0x800
except:
pass
# Python 3 has a bug where the external_attr is reset to `0o600 << 16`
# if it's NULL, so we need a workaround:
if zi.external_attr == 0:
zi = ZeroedZipInfo(zi)
outf.writestr(zi, data)
except:
traceback.print_exc()
@ -249,13 +259,21 @@ def removeOPFwatermarks(object, path_to_ebook):
zi.extra = oldzi.extra
zi.internal_attr = oldzi.internal_attr
zi.external_attr = oldzi.external_attr
zi.volume = oldzi.volume
zi.create_system = oldzi.create_system
zi.create_version = oldzi.create_version
if any(ord(c) >= 128 for c in path) or any(ord(c) >= 128 for c in zi.comment):
# If the file name or the comment contains any non-ASCII char, set the UTF8-flag
zi.flag_bits |= 0x800
except:
pass
# Python 3 has a bug where the external_attr is reset to `0o600 << 16`
# if it's NULL, so we need a workaround:
if zi.external_attr == 0:
zi = ZeroedZipInfo(zi)
outf.writestr(zi, data)
except:
traceback.print_exc()
@ -301,13 +319,21 @@ def removeCDPwatermark(object, path_to_ebook):
zi.extra = oldzi.extra
zi.internal_attr = oldzi.internal_attr
zi.external_attr = oldzi.external_attr
zi.volume = oldzi.volume
zi.create_system = oldzi.create_system
zi.create_version = oldzi.create_version
if any(ord(c) >= 128 for c in path) or any(ord(c) >= 128 for c in zi.comment):
# If the file name or the comment contains any non-ASCII char, set the UTF8-flag
zi.flag_bits |= 0x800
except:
pass
# Python 3 has a bug where the external_attr is reset to `0o600 << 16`
# if it's NULL, so we need a workaround:
if zi.external_attr == 0:
zi = ZeroedZipInfo(zi)
outf.writestr(zi, data)
print("Watermark: Successfully removed cdp.info watermark")

12
DeDRM_plugin/ineptepub.py
View File

@ -48,6 +48,7 @@ import base64
import zlib
import zipfile
from zipfile import ZipInfo, ZipFile, ZIP_STORED, ZIP_DEFLATED
from zeroedzipinfo import ZeroedZipInfo
from contextlib import closing
from lxml import etree
from uuid import UUID
@ -356,12 +357,23 @@ def decryptBook(userkey, inpath, outpath):
zi.internal_attr = oldzi.internal_attr
# external attributes are dependent on the create system, so copy both.
zi.external_attr = oldzi.external_attr
zi.volume = oldzi.volume
zi.create_system = oldzi.create_system
zi.create_version = oldzi.create_version
if any(ord(c) >= 128 for c in path) or any(ord(c) >= 128 for c in zi.comment):
# If the file name or the comment contains any non-ASCII char, set the UTF8-flag
zi.flag_bits |= 0x800
except:
pass
# Python 3 has a bug where the external_attr is reset to `0o600 << 16`
# if it's NULL, so we need a workaround:
if zi.external_attr == 0:
zi = ZeroedZipInfo(zi)
if path == "META-INF/encryption.xml":
outf.writestr(zi, data)
else:

30
DeDRM_plugin/zeroedzipinfo.py Normal file
View File

@ -0,0 +1,30 @@
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Python 3's "zipfile" has an annoying bug where the `external_attr` field
of a ZIP file cannot be set to 0. However, if the original DRMed ZIP has
that set to 0 then we want the DRM-free ZIP to have that as 0, too.
See https://github.com/python/cpython/issues/87713
We cannot just set the "external_attr" to 0 as the code to save the ZIP
resets that variable.
So, here's a class that inherits from ZipInfo and ensures that EVERY
read access to that variable will return a 0 ...
"""
import zipfile
class ZeroedZipInfo(zipfile.ZipInfo):
def __init__(self, zinfo):
for k in self.__slots__:
if hasattr(zinfo, k):
setattr(self, k, getattr(zinfo, k))
def __getattribute__(self, name):
if name == "external_attr":
return 0
return object.__getattribute__(self, name)

13
DeDRM_plugin/zipfilerugged.py
View File

@ -394,6 +394,19 @@ class ZipInfo (object):
extra = extra[ln+4:]
class ZeroedZipInfo(ZipInfo):
def __init__(self, zinfo):
for k in self.__slots__:
if hasattr(zinfo, k):
setattr(self, k, getattr(zinfo, k))
def __getattribute__(self, name):
if name == "external_attr":
return 0
return object.__getattribute__(self, name)
class _ZipDecrypter:
"""Class to handle decryption of files stored within a ZIP archive.

30
DeDRM_plugin/zipfix.py
View File

@ -26,6 +26,7 @@ import sys, os
import zlib
import zipfilerugged
from zipfilerugged import ZipInfo, ZeroedZipInfo
import getopt
from struct import unpack
@ -36,12 +37,6 @@ _FILENAME_OFFSET = 30
_MAX_SIZE = 64 * 1024
_MIMETYPE = 'application/epub+zip'
class ZipInfo(zipfilerugged.ZipInfo):
def __init__(self, *args, **kwargs):
if 'compress_type' in kwargs:
compress_type = kwargs.pop('compress_type')
super(ZipInfo, self).__init__(*args, **kwargs)
self.compress_type = compress_type
class fixZip:
def __init__(self, zinput, zoutput):
@ -117,7 +112,8 @@ class fixZip:
# if epub write mimetype file first, with no compression
if self.ztype == 'epub':
# first get a ZipInfo with current time and no compression
mimeinfo = ZipInfo(b'mimetype',compress_type=zipfilerugged.ZIP_STORED)
mimeinfo = ZipInfo(b'mimetype')
mimeinfo.compress_type = zipfilerugged.ZIP_STORED
mimeinfo.internal_attr = 1 # text file
try:
# if the mimetype is present, get its info, including time-stamp
@ -129,8 +125,16 @@ class fixZip:
mimeinfo.internal_attr = oldmimeinfo.internal_attr
mimeinfo.external_attr = oldmimeinfo.external_attr
mimeinfo.create_system = oldmimeinfo.create_system
mimeinfo.create_version = oldmimeinfo.create_version
mimeinfo.volume = oldmimeinfo.volume
except:
pass
# Python 3 has a bug where the external_attr is reset to `0o600 << 16`
# if it's NULL, so we need a workaround:
if mimeinfo.external_attr == 0:
mimeinfo = ZeroedZipInfo(mimeinfo)
self.outzip.writestr(mimeinfo, _MIMETYPE.encode('ascii'))
# write the rest of the files
@ -145,13 +149,23 @@ class fixZip:
zinfo.filename = local_name
# create new ZipInfo with only the useful attributes from the old info
nzinfo = ZipInfo(zinfo.filename, zinfo.date_time, compress_type=zinfo.compress_type)
nzinfo = ZipInfo(zinfo.filename)
nzinfo.date_time = zinfo.date_time
nzinfo.compress_type = zinfo.compress_type
nzinfo.comment=zinfo.comment
nzinfo.extra=zinfo.extra
nzinfo.internal_attr=zinfo.internal_attr
nzinfo.external_attr=zinfo.external_attr
nzinfo.create_system=zinfo.create_system
nzinfo.create_version = zinfo.create_version
nzinfo.volume = zinfo.volume
nzinfo.flag_bits = zinfo.flag_bits & 0x800 # preserve UTF-8 flag
# Python 3 has a bug where the external_attr is reset to `0o600 << 16`
# if it's NULL, so we need a workaround:
if nzinfo.external_attr == 0:
nzinfo = ZeroedZipInfo(nzinfo)
self.outzip.writestr(nzinfo,data)
self.bzf.close()