What file permissions are needed in an XPI?

Question

I recently received the following comment from the reviewer of one of my add-ons at the official Mozilla Add-ons website:

The permissions in your XPI are broken. Most files and directories do not have the expected read and execute permissions, or indeed any permissions at all.

I wasn't aware that file permissions were an issue in XPI files. To my knowledge, none of the files in my XPI need the execute bit set (I only package standard stuff: XUL, JavaScript, CSS, etc). I create my XPI in Windows using the Cygwin zip tool, and since Windows knows nothing about file permissions, they aren't stored as they would be in Linux.

What file permissions are expected for file and directory entries in an XPI? The Extension Packaging page at MDN has the following quote, but no associated details on what they should be:

... you must verify that the file system permissions for the directories and files for the extension are set properly. Otherwise, the Extension Manager may not function properly with the extension or the extension itself may not work properly.

Answer 1

This is typically an issue if you create the extension package on Windows but the extension is used on Linux or OS X later - Windows doesn't have any file permissions to be put into a ZIP archive and unpacking on Linux or OS X sometimes creates bogus file permissions (000 rather than the usual 755 or 644). You could try using a different ZIP packer, e.g. Info-ZIP that doesn't cause such issues for me. Better yet, don't require your extension to be unpacked at all - <em:unpack> is often used but rarely really required.