Script to make Windows XP-readable ZIP file

Larry Bates larry.bates at websafe.com
Fri May 19 16:52:12 CEST 2006


pac wrote:
> I'm preparing to distribute a Windows XP Python program and some
> ancillary files,
> and I wanted to put everything in a .ZIP archive.  It proved to be
> inordinately
> difficult and I thought I would post my solution here.   Is there a
> better one?
> 
> Suppose you have a set of files in a directory c:\a\b and some
> additional
> files in c:\a\b\subdir.  Using a Python script, you would
> like to make a Windows-readable archive (.zip) that preserves this
> directory structure, and where the root directory of the archive is
> c:\a\b.  In other words, all the files from c:\a\b appear in the
> archive
> without a path prefix, and all the files in c:\a\b\subdir have a path
> prefix of \subdir.
> 
> This looks like it should be easy with module zipfile and the handy
> function os.walk.  Create a zip file, call os.walk, and add the files
> to
> the archive like so:
> 
> import os
> import zipfile
> 
> z =
> zipfile.ZipFile(r"c:\a\b\myzip.zip",mode="w",compression=zipfile.ZIP_DEFLATED)
> 
> for dirpath,dirs,files in os.walk(r"c:\a\b"):
>     for a_file in files:
>         a_path = os.path.join(dirpath,a_file)
> 	z.write(a_path)  # Change, see below
> z.close()
> 
> This creates an archive that can be read by WinZip or by another Python
> script
> that uses zipfile.  But when you try to view it with the Windows
> compressed folder
> viewer it will appear empty.  If you try to extract the files anyway
> (because
> you know they are really there), you get a Windows Security Warning and
> XP
> refuses to decompress the folder - XP is apparently afraid it might be
> bird flu
> or something.
> 
> If you change the line marked #Change to "z.write(a_path,file)",
> explicitly naming
> each file, now the compressed folder viewer will show all the files in
> the archive.
> XP will not treat it like a virus and it will extract the files.
> However, the
> archive does not contain a subdirectory; all the files are in a single
> directory.
> 
> Some experimentation suggests that Windows does not like any filename
> in the
> archive that begins with either a drive designator like c:, or has a
> path containing
> a leading slash like "\a\b\afile.txt".  Relative paths like
> "subdir\afile.txt" are
> okay, and cause the desired behavior when the archive is extracted,
> e.g., a new directory subdir is created and afile.txt is placed in it.
> 
> Since the method ZipFile.write needs a valid pathname for each file,
> the correct
> solution to the original problem entails messing around with the OS's
> current
> working directory.  Position the CWD in the desired base directory of
> the archive,
> add the files to the archive using their relative pathnames, and put
> the CWD back
> where it was when you started:
> 
> import os
> import zipfile
> 
> z =
> zipfile.ZipFile(r"c:\a\b\myzip.zip",mode="w",compression=zipfile.ZIP_DEFLATED)
> 
> cwd = os.getcwd()
> os.chdir(base_dir)
> try:
>     for dirpath,dirs,files in os.walk(''):   # This starts the walk at
> the CWD
>         for a_file in files:
>             a_path = os.path.join(dirpath,a_file)
>             z.write(a_path,a_path)   # Can the second argument be
> omitted?
>     z.close()
> finally:
>     os.chdir(cwd)
> 
> This produces an archive that can be extracted by Windows XP using its
> built-in
> capability, by WinZip, or by another Python script.  Now that I have
> the solution it
> seems to make sense, but it wasn't at all obvious when I started.
> 
> Paul Cornelius
> 
Others have addressed your specific question, I wanted to make a
more general suggestion.

You should really take a look at Inno Installer and py2exe combination
for creating .zip library and Windows distribution.  I PROMISE it will
be worth your time on future projects.  Rolling your own installer will
take much more time/effort over the long haul.

-Larry Bates



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