overwriting file in ziparchive

Solution 1:

There's no way to do that with python zipfile module. You have to create a new zip file and recompress everything again from the first file, plus the new modified file.

Below is some code to do just that. But note that it isn't efficient, since it decompresses and then recompresses all data.

import tempfile
import zipfile
import shutil
import os

def remove_from_zip(zipfname, *filenames):
    tempdir = tempfile.mkdtemp()
    try:
        tempname = os.path.join(tempdir, 'new.zip')
        with zipfile.ZipFile(zipfname, 'r') as zipread:
            with zipfile.ZipFile(tempname, 'w') as zipwrite:
                for item in zipread.infolist():
                    if item.filename not in filenames:
                        data = zipread.read(item.filename)
                        zipwrite.writestr(item, data)
        shutil.move(tempname, zipfname)
    finally:
        shutil.rmtree(tempdir)

Usage:

remove_from_zip('archive.zip', 'hello.txt')
with zipfile.ZipFile('archive.zip', 'a') as z:
    z.write('hello.txt')

Solution 2:

Building on nosklo's answer. UpdateableZipFile A class that inherits from ZipFile, maintians the same interface but adds the ability to overwrite files (via writestr or write) and removing files.

import os
import shutil
import tempfile
from zipfile import ZipFile, ZIP_STORED, ZipInfo


class UpdateableZipFile(ZipFile):
    """
    Add delete (via remove_file) and update (via writestr and write methods)
    To enable update features use UpdateableZipFile with the 'with statement',
    Upon  __exit__ (if updates were applied) a new zip file will override the exiting one with the updates
    """

    class DeleteMarker(object):
        pass

    def __init__(self, file, mode="r", compression=ZIP_STORED, allowZip64=False):
        # Init base
        super(UpdateableZipFile, self).__init__(file, mode=mode,
                                                compression=compression,
                                                allowZip64=allowZip64)
        # track file to override in zip
        self._replace = {}
        # Whether the with statement was called
        self._allow_updates = False

    def writestr(self, zinfo_or_arcname, bytes, compress_type=None):
        if isinstance(zinfo_or_arcname, ZipInfo):
            name = zinfo_or_arcname.filename
        else:
            name = zinfo_or_arcname
        # If the file exits, and needs to be overridden,
        # mark the entry, and create a temp-file for it
        # we allow this only if the with statement is used
        if self._allow_updates and name in self.namelist():
            temp_file = self._replace[name] = self._replace.get(name,
                                                                tempfile.TemporaryFile())
            temp_file.write(bytes)
        # Otherwise just act normally
        else:
            super(UpdateableZipFile, self).writestr(zinfo_or_arcname,
                                                    bytes, compress_type=compress_type)

    def write(self, filename, arcname=None, compress_type=None):
        arcname = arcname or filename
        # If the file exits, and needs to be overridden,
        # mark the entry, and create a temp-file for it
        # we allow this only if the with statement is used
        if self._allow_updates and arcname in self.namelist():
            temp_file = self._replace[arcname] = self._replace.get(arcname,
                                                                   tempfile.TemporaryFile())
            with open(filename, "rb") as source:
                shutil.copyfileobj(source, temp_file)
        # Otherwise just act normally
        else:
            super(UpdateableZipFile, self).write(filename, 
                                                 arcname=arcname, compress_type=compress_type)

    def __enter__(self):
        # Allow updates
        self._allow_updates = True
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        # call base to close zip file, organically
        try:
            super(UpdateableZipFile, self).__exit__(exc_type, exc_val, exc_tb)
            if len(self._replace) > 0:
                self._rebuild_zip()
        finally:
            # In case rebuild zip failed,
            # be sure to still release all the temp files
            self._close_all_temp_files()
            self._allow_updates = False

    def _close_all_temp_files(self):
        for temp_file in self._replace.itervalues():
            if hasattr(temp_file, 'close'):
                temp_file.close()

    def remove_file(self, path):
        self._replace[path] = self.DeleteMarker()

    def _rebuild_zip(self):
        tempdir = tempfile.mkdtemp()
        try:
            temp_zip_path = os.path.join(tempdir, 'new.zip')
            with ZipFile(self.filename, 'r') as zip_read:
                # Create new zip with assigned properties
                with ZipFile(temp_zip_path, 'w', compression=self.compression,
                             allowZip64=self._allowZip64) as zip_write:
                    for item in zip_read.infolist():
                        # Check if the file should be replaced / or deleted
                        replacement = self._replace.get(item.filename, None)
                        # If marked for deletion, do not copy file to new zipfile
                        if isinstance(replacement, self.DeleteMarker):
                            del self._replace[item.filename]
                            continue
                        # If marked for replacement, copy temp_file, instead of old file
                        elif replacement is not None:
                            del self._replace[item.filename]
                            # Write replacement to archive,
                            # and then close it (deleting the temp file)
                            replacement.seek(0)
                            data = replacement.read()
                            replacement.close()
                        else:
                            data = zip_read.read(item.filename)
                        zip_write.writestr(item, data)
            # Override the archive with the updated one
            shutil.move(temp_zip_path, self.filename)
        finally:
            shutil.rmtree(tempdir)

usage example:

with UpdateableZipFile("C:\Temp\Test2.docx", "a") as o:
    # Overwrite a file with a string
    o.writestr("word/document.xml", "Some data")
    # exclude an exiting file from the zip
    o.remove_file("word/fontTable.xml")
    # Write a new file (with no conflict) to the zp
    o.writestr("new_file", "more data")
    # Overwrite a file with a file
    o.write(r"C:\Temp\example.png", "word/settings.xml")