Bad magic number error with ZipFile module in Python

Question

I am using Python 2.7 on Windows 7 (64 bit). When I try to unzip a zip file with ZipFile module I get the following error:-

Traceback (most recent call last):
  File "unzip.py", line 8, in <module>
    z.extract(name)
  File "C:\Python27\lib\zipfile.py", line 950, in extract
    return self._extract_member(member, path, pwd)
  File "C:\Python27\lib\zipfile.py", line 993, in _extract_member
    source = self.open(member, pwd=pwd)
  File "C:\Python27\lib\zipfile.py", line 897, in open
    raise BadZipfile, "Bad magic number for file header"
zipfile.BadZipfile: Bad magic number for file header

WinRAR could extract the file I am trying to extract just fine. Here is the code I used to extract files from myzip.zip

from zipfile import ZipFile
z = ZipFile('myzip.zip')   //myzip.zip contains just one file, a password protected pdf        
for name in z.namelist():
    z.extract(name)

This code is working fine for many other zip files I created using WinRAR but myzip.zip

I tried commenting the following lines in Python27\Lib\zipfile.py:-

if fheader[0:4] != stringFileHeader:
   raise BadZipfile, "Bad magic number for file header"

But this didn't really help. Running my code with this in effect, I get some dump on my shell.

Answer 1

Correct ZIP files always have "\x50\x4B\x03\x04" in the beginning. You can test whether file is really ZIP file with this code:

with open('/path/to/file', 'rb') as MyZip:
  print(MyZip.read(4))

It will print header of file so you can check.

UPDATE Strange, testzip() and all other functions work good. Had you tried such code?

with zipfile.GzipFile('/path/to/file') as Zip:
  for ZipMember in Zip.infolist():
    Zip.extract(ZipMember, path='/dir/where/to/extract', pwd='your-password')

Answer 2

Make sure you are really opening a ZIP file, not for example a RAR file named with a .zip extension. Proper zip files have a header, which was not found in this case.

The zipfile module can only open zip files. WinRAR can also open other formats, and it likely ignores the filename and only looks at the file itself.