Fix-OneDrive-Zip

This program fixes an issue with Zip files larger than 4 Gig created by OneDrive and also the Windows 10 right-click action "Send-To/Compressed (zip) folder". At the time of writing these Zip files cannot be unzipped using some of the well-know Zip archivers.

For a really detailed summary of the issue, see Does Microsoft OneDrive export large ZIP files that are corrupt?.

This program automates the manual process described in the referenced page.

Notes

1. This program will modify your Zip file, so it is good practice to take a backup copy of the original file just in case.

2. You need a 64-bit build of perl installed on your system to run this program.

Usage

perl fix-onedrive-zip [--dry-run] file1.zip [file2.zip...]

The --dry-run option will simulate running of the program without making any changes to the Zip file.

Notes for Windows users

If you are running Windows and don't know what a perl script is, or how to run one, this section will walk you through the process.

Step 1: Check if you have perl already installed

The fix-onedrive-zip script is written in perl. To run it on your PC you need the perl executable.

To check if it is already installed, create a terminal window by typing Windows+R. In the pop-up window type cmd. You should now have a terminal window open.

Type perl -v. If perl is installed you should see text like this. The Perl version doesn't matter.

C:\Users\me>perl -v

This is perl 5, version 32, subversion 1 (v5.32.1) built for MSWin32-x64-multi-thread

Copyright 1987-2021, Larry Wall

Perl may be copied only under the terms of either the Artistic License or the
GNU General Public License, which may be found in the Perl 5 source kit.

Complete documentation for Perl, including FAQ lists, should be found on
this system using "man perl" or "perldoc perl".  If you have access to the
Internet, point your browser at http://www.perl.org/, the Perl Home Page.

If you don't have perl, the output will look like this

'perl' is not recognized as an internal or external command,
operable program or batch file.

Step 2: Install Perl if you don't already have it

There are a number of perl executables available for Windows. For this tutorial I've used Strawberry Perl, but there are others available.

Use the instructions here to install the 64-bit "Recommended version" of perl from the Strawberry Perl site.

Once the installation is complete, run Step 1, above, to check that the perl works ok from the command-line in a terminal window.

Step 3: Download the script

You now need to get the script fix-onedrive-zip downloaded from GitHub and stored on your PC. In a browser navigate to here and select the "Download raw file" icon, as highlighted below

That should download the file fix-onedrive-zip into your Downloads directory.

Step 4: Running the script

The easiest approach to running this script if you are not confortable with running from the command-line is to put the fix-onedrive-zip script and the zip file you want to fix in the same folder. Lets assume you have both stored in the folder C:\fixzip and the name of the OneDrive zip file is myfile.zip.

Start by creating a terminal window by typing Windows+R and typing cmd in the pop-up window.

Now run the command below in the terminal window to move to the folder where your zip file is stored, replacing C:\fixzip with the name of the folder you are using

cd C:\fixzip

You can now run the fix-onedrive-zip script by typing this in the terminal window. Remember to change myfile.zip to the name of the zip file you want fixed.

perl fix-onedrive-zip myfile.zip

What if this program doesn't fix the issue?

The most common issue reported with this script is the following error message:

Error: Cannot find Zip signature at end of 'somefile.zip'

To understand the reson for this message you need to know a little bit about the structure of a zip file. Firstly, at the start of a zip file there are 4 bytes called the "local file header signature" (which get unpacked as the litte-endian value 0x04034b50). For this error case these signature bytes will be present, so the script knows it likely dealing with a zip file.

Once that initial test is done, the script moves to 22 bytes before the end of the file and checks that the 4 bytes of the "end of central dir signature" (little-endian value 0x06054b50) are present. In this case it doesn't find these signature bytes and terminates with the error message shown above.

This typically means that the zip file has been either truncated or has become corrupt.

If possible, try downloading the file again.

Technical Details

If you want to understand more about the internal structuire of Zip files, the primary reference is APPNOTE.TXT.

The issue with the OneNote/Windows Zip files larger than 4 Gig is they have an invalid Total Number of Disks field in the ZIP64 End Central Directory Locator record (see APPNOTE.TXT version 6.3.9, section 4.3.15). The value in this field should be 1, but OneDrive/Windows sets it to 0.

This program simply changes the Total Number of Disks field value to 1 if it finds it set to 0 in the Zip file.

Support

https://github.com/pmqs/Fix-OneDrive-Zip/issues

Copyright

Copyright (c) 2020-2023 Paul Marquess ([email protected]). All rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.