Current File : //usr/lib/calibre/calibre/utils/localunzip.py
#!/usr/bin/env python3
__license__ = 'GPL v3'
__copyright__ = '2012, Kovid Goyal <kovid at kovidgoyal.net>'
__docformat__ = 'restructuredtext en'
'''
Try to read invalid zip files with missing or damaged central directories.
These are apparently produced in large numbers by the fruitcakes over at B&N.
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 calibre.ptempfile import SpooledTemporaryFile
from polyglot.builtins import itervalues
HEADER_SIG = 0x04034b50
HEADER_BYTE_SIG = pack(b'<L', HEADER_SIG)
local_header_fmt = b'<L5HL2L2H'
local_header_sz = calcsize(local_header_fmt)
ZIP_STORED, ZIP_DEFLATED = 0, 8
DATA_DESCRIPTOR_SIG = pack(b'<L', 0x08074b50)
LocalHeader = namedtuple('LocalHeader',
'signature min_version flags compression_method mod_time mod_date '
'crc32 compressed_size uncompressed_size filename_length extra_length '
'filename extra')
if hasattr(sys, 'getwindowsversion'):
windows_reserved_filenames = (
'CON', 'PRN', 'AUX', 'CLOCK$', 'NUL' 'COM0', 'COM1', 'COM2', 'COM3',
'COM4', 'COM5', 'COM6', 'COM7', 'COM8', 'COM9' 'LPT0', 'LPT1', 'LPT2',
'LPT3', 'LPT4', 'LPT5', 'LPT6', 'LPT7', 'LPT8', 'LPT9')
def is_reserved_filename(x):
base = x.partition('.')[0].upper()
return base in windows_reserved_filenames
else:
def is_reserved_filename(x):
return False
def decode_arcname(name):
if isinstance(name, bytes):
from calibre.ebooks.chardet import detect
try:
name = name.decode('utf-8')
except:
res = detect(name)
encoding = res['encoding']
try:
name = name.decode(encoding)
except:
name = name.decode('utf-8', 'replace')
return name
def find_local_header(f):
pos = f.tell()
raw = f.read(50*1024)
try:
f.seek(pos + raw.index(HEADER_BYTE_SIG))
except ValueError:
f.seek(pos)
return
raw = f.read(local_header_sz)
if len(raw) != local_header_sz:
f.seek(pos)
return
header = LocalHeader(*(unpack(local_header_fmt, raw) + (None, None)))
if header.signature == HEADER_SIG:
return header
f.seek(pos)
def find_data_descriptor(f):
pos = f.tell()
DD = namedtuple('DataDescriptor', 'crc32 compressed_size uncompressed_size')
raw = b'a'*16
try:
while len(raw) >= 16:
raw = f.read(50*1024)
idx = raw.find(DATA_DESCRIPTOR_SIG)
if idx != -1:
f.seek(f.tell() - len(raw) + idx + len(DATA_DESCRIPTOR_SIG))
return DD(*unpack(b'<LLL', f.read(12)))
# Rewind to handle the case of the signature being cut off
# by the 50K boundary
f.seek(f.tell()-len(DATA_DESCRIPTOR_SIG))
raise ValueError('Failed to find data descriptor signature. '
'Data descriptors without signatures are not '
'supported.')
finally:
f.seek(pos)
def read_local_file_header(f):
pos = f.tell()
raw = f.read(local_header_sz)
if len(raw) != local_header_sz:
f.seek(pos)
return
header = LocalHeader(*(unpack(local_header_fmt, raw) + (None, None)))
if header.signature != HEADER_SIG:
f.seek(pos)
header = find_local_header(f)
if header is None:
return
if header.min_version > 20:
raise ValueError('This ZIP file uses unsupported features')
if header.flags & 0b1:
raise ValueError('This ZIP file is encrypted')
if header.flags & (1 << 13):
raise ValueError('This ZIP file uses masking, unsupported.')
if header.compression_method not in {ZIP_STORED, ZIP_DEFLATED}:
raise ValueError('This ZIP file uses an unsupported compression method')
has_data_descriptors = header.flags & (1 << 3)
fname = extra = None
if header.filename_length > 0:
fname = f.read(header.filename_length)
if len(fname) != header.filename_length:
return
try:
fname = fname.decode('ascii')
except UnicodeDecodeError:
if header.flags & (1 << 11):
try:
fname = fname.decode('utf-8')
except UnicodeDecodeError:
pass
fname = decode_arcname(fname).replace('\\', '/')
if header.extra_length > 0:
extra = f.read(header.extra_length)
if len(extra) != header.extra_length:
return
if has_data_descriptors:
desc = find_data_descriptor(f)
header = header._replace(crc32=desc.crc32,
compressed_size=desc.compressed_size,
uncompressed_size=desc.uncompressed_size)
return LocalHeader(*(
header[:-2] + (fname, extra)
))
def read_compressed_data(f, header):
cdata = f.read(header.compressed_size)
return cdata
def copy_stored_file(src, size, dest):
read = 0
amt = min(size, 20*1024)
while read < size:
raw = src.read(min(size-read, amt))
if not raw:
raise ValueError('Premature end of file')
dest.write(raw)
read += len(raw)
def copy_compressed_file(src, size, dest):
d = zlib.decompressobj(-15)
read = 0
amt = min(size, 20*1024)
while read < size:
raw = src.read(min(size-read, amt))
if not raw and read < size:
raise ValueError('Invalid ZIP file, local header is damaged')
read += len(raw)
dest.write(d.decompress(raw, 200*1024))
count = 0
while d.unconsumed_tail:
count += 1
dest.write(d.decompress(d.unconsumed_tail, 200*1024))
if count > 100:
raise ValueError('This ZIP file contains a ZIP bomb in %s'%
os.path.basename(dest.name))
def _extractall(f, path=None, file_info=None):
found = False
while True:
header = read_local_file_header(f)
if not header:
break
has_data_descriptors = header.flags & (1 << 3)
seekval = header.compressed_size + (16 if has_data_descriptors else 0)
found = True
# Sanitize path changing absolute to relative paths and removing .. and
# .
fname = header.filename.replace(os.sep, '/')
fname = os.path.splitdrive(fname)[1]
parts = [x for x in fname.split('/') if x not in {'', os.path.pardir, os.path.curdir}]
if not parts:
continue
if header.uncompressed_size == 0:
# Directory
f.seek(f.tell()+seekval)
if path is not None:
bdir = os.path.join(path, *parts)
if not os.path.exists(bdir):
os.makedirs(bdir)
continue
# File
if file_info is not None:
file_info[header.filename] = (f.tell(), header)
if path is not None:
bdir = os.path.join(path, *(parts[:-1]))
if not os.path.exists(bdir):
os.makedirs(bdir)
dest = os.path.join(path, *parts)
try:
df = open(dest, 'wb')
except OSError:
if is_reserved_filename(os.path.basename(dest)):
raise ValueError('This ZIP file contains a file with a reserved filename'
' that cannot be processed on Windows: {}'.format(os.path.basename(dest)))
raise
with df:
if header.compression_method == ZIP_STORED:
copy_stored_file(f, header.compressed_size, df)
else:
copy_compressed_file(f, header.compressed_size, df)
else:
f.seek(f.tell()+seekval)
if not found:
raise ValueError('Not a ZIP file')
def extractall(path_or_stream, path=None):
f = path_or_stream
close_at_end = False
if not hasattr(f, 'read'):
f = open(f, 'rb')
close_at_end = True
if path is None:
path = os.getcwd()
pos = f.tell()
try:
_extractall(f, path)
finally:
f.seek(pos)
if close_at_end:
f.close()
class LocalZipFile:
def __init__(self, stream):
self.file_info = OrderedDict()
_extractall(stream, file_info=self.file_info)
self.stream = stream
def _get_file_info(self, name):
fi = self.file_info.get(name)
if fi is None:
raise ValueError('This ZIP container has no file named: %s'%name)
return fi
def open(self, name, spool_size=5*1024*1024):
if isinstance(name, LocalHeader):
name = name.filename
offset, header = self._get_file_info(name)
self.stream.seek(offset)
dest = SpooledTemporaryFile(max_size=spool_size)
if header.compression_method == ZIP_STORED:
copy_stored_file(self.stream, header.compressed_size, dest)
else:
copy_compressed_file(self.stream, header.compressed_size, dest)
dest.seek(0)
return dest
def getinfo(self, name):
offset, header = self._get_file_info(name)
return header
def read(self, name, spool_size=5*1024*1024):
with self.open(name, spool_size=spool_size) as f:
return f.read()
def extractall(self, path=None):
self.stream.seek(0)
_extractall(self.stream, path=(path or os.getcwd()))
def close(self):
pass
def safe_replace(self, name, datastream, extra_replacements={},
add_missing=False):
from calibre.utils.zipfile import ZipFile, ZipInfo
replacements = {name:datastream}
replacements.update(extra_replacements)
names = frozenset(list(replacements.keys()))
found = set()
def rbytes(name):
r = replacements[name]
if not isinstance(r, bytes):
r = r.read()
return r
with SpooledTemporaryFile(max_size=100*1024*1024) as temp:
ztemp = ZipFile(temp, 'w')
for offset, header in itervalues(self.file_info):
if header.filename in names:
zi = ZipInfo(header.filename)
zi.compress_type = header.compression_method
ztemp.writestr(zi, rbytes(header.filename))
found.add(header.filename)
else:
ztemp.writestr(header.filename, self.read(header.filename,
spool_size=0))
if add_missing:
for name in names - found:
ztemp.writestr(name, rbytes(name))
ztemp.close()
zipstream = self.stream
temp.seek(0)
zipstream.seek(0)
zipstream.truncate()
shutil.copyfileobj(temp, zipstream)
zipstream.flush()
if __name__ == '__main__':
extractall(sys.argv[-1])
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