Question

Without using zip64 extensions, a Zip file cannot be more than 2GB in size, so trying to write to a file that would put it over that limit won’t work. I expected that when such a writing was attempted, it would raise an exception, but I’ve not been able to cause one to be raised. (The documentation is silent on the matter.) If an exception doesn’t get raised in such a circumstance, how would I (efficiently) go about determining if the write succeeded or not?

Answer 1

I’ve got an exception trying to write big strings to a zip archive:

$ python write-big-zip.py
Traceback (most recent call last):
  File "write-big-zip.py", line 7, in <module>
    myzip.writestr('arcname%d'% i, b'a'*2**30)
  File "/usr/lib/python2.7/zipfile.py", line 1125, in writestr
    self._writecheck(zinfo)
  File "/usr/lib/python2.7/zipfile.py", line 1020, in _writecheck
    raise LargeZipFile("Zipfile size would require ZIP64 extensions")
zipfile.LargeZipFile: Zipfile size would require ZIP64 extensions

Using the script:

#!/usr/bin/env python
"""Write big strings to zip file until error."""
from zipfile import ZipFile

with ZipFile('big.zip', 'w') as myzip:
    for i in range(4):
        myzip.writestr('arcname%d'% i, b'a'*2**30)