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MozZipFile.py
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# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
import zipfile
import time
import binascii, struct
import zlib
import os
from utils import lockFile
class ZipFile(zipfile.ZipFile):
""" Class with methods to open, read, write, close, list zip files.
Subclassing zipfile.ZipFile to allow for overwriting of existing
entries, though only for writestr, not for write.
"""
def __init__(self, file, mode="r", compression=zipfile.ZIP_STORED,
lock = False):
if lock:
assert isinstance(file, basestring)
self.lockfile = lockFile(file + '.lck')
else:
self.lockfile = None
if mode == 'a' and lock:
# appending to a file which doesn't exist fails, but we can't check
# existence util we hold the lock
if (not os.path.isfile(file)) or os.path.getsize(file) == 0:
mode = 'w'
zipfile.ZipFile.__init__(self, file, mode, compression)
self._remove = []
self.end = self.fp.tell()
self.debug = 0
def writestr(self, zinfo_or_arcname, bytes):
"""Write contents into the archive.
The contents is the argument 'bytes', 'zinfo_or_arcname' is either
a ZipInfo instance or the name of the file in the archive.
This method is overloaded to allow overwriting existing entries.
"""
if not isinstance(zinfo_or_arcname, zipfile.ZipInfo):
zinfo = zipfile.ZipInfo(filename=zinfo_or_arcname,
date_time=time.localtime(time.time()))
zinfo.compress_type = self.compression
# Add some standard UNIX file access permissions (-rw-r--r--).
zinfo.external_attr = (0x81a4 & 0xFFFF) << 16L
else:
zinfo = zinfo_or_arcname
# Now to the point why we overwrote this in the first place,
# remember the entry numbers if we already had this entry.
# Optimizations:
# If the entry to overwrite is the last one, just reuse that.
# If we store uncompressed and the new content has the same size
# as the old, reuse the existing entry.
doSeek = False # store if we need to seek to the eof after overwriting
if self.NameToInfo.has_key(zinfo.filename):
# Find the last ZipInfo with our name.
# Last, because that's catching multiple overwrites
i = len(self.filelist)
while i > 0:
i -= 1
if self.filelist[i].filename == zinfo.filename:
break
zi = self.filelist[i]
if ((zinfo.compress_type == zipfile.ZIP_STORED
and zi.compress_size == len(bytes))
or (i + 1) == len(self.filelist)):
# make sure we're allowed to write, otherwise done by writestr below
self._writecheck(zi)
# overwrite existing entry
self.fp.seek(zi.header_offset)
if (i + 1) == len(self.filelist):
# this is the last item in the file, just truncate
self.fp.truncate()
else:
# we need to move to the end of the file afterwards again
doSeek = True
# unhook the current zipinfo, the writestr of our superclass
# will add a new one
self.filelist.pop(i)
self.NameToInfo.pop(zinfo.filename)
else:
# Couldn't optimize, sadly, just remember the old entry for removal
self._remove.append(self.filelist.pop(i))
zipfile.ZipFile.writestr(self, zinfo, bytes)
self.filelist.sort(lambda l, r: cmp(l.header_offset, r.header_offset))
if doSeek:
self.fp.seek(self.end)
self.end = self.fp.tell()
def close(self):
"""Close the file, and for mode "w" and "a" write the ending
records.
Overwritten to compact overwritten entries.
"""
if not self._remove:
# we don't have anything special to do, let's just call base
r = zipfile.ZipFile.close(self)
self.lockfile = None
return r
if self.fp.mode != 'r+b':
# adjust file mode if we originally just wrote, now we rewrite
self.fp.close()
self.fp = open(self.filename, 'r+b')
all = map(lambda zi: (zi, True), self.filelist) + \
map(lambda zi: (zi, False), self._remove)
all.sort(lambda l, r: cmp(l[0].header_offset, r[0].header_offset))
# empty _remove for multiple closes
self._remove = []
lengths = [all[i+1][0].header_offset - all[i][0].header_offset
for i in xrange(len(all)-1)]
lengths.append(self.end - all[-1][0].header_offset)
to_pos = 0
for (zi, keep), length in zip(all, lengths):
if not keep:
continue
oldoff = zi.header_offset
# python <= 2.4 has file_offset
if hasattr(zi, 'file_offset'):
zi.file_offset = zi.file_offset + to_pos - oldoff
zi.header_offset = to_pos
self.fp.seek(oldoff)
content = self.fp.read(length)
self.fp.seek(to_pos)
self.fp.write(content)
to_pos += length
self.fp.truncate()
zipfile.ZipFile.close(self)
self.lockfile = None

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