Open a direct file on the hard drive from firefox (file:///)

Although i still think it is a programming question, it was answered here: https://superuser.com/questions/103026/open-a-direct-file-on-the-hard-drive-from-firefox-file

Both Firefox and IE8 support the File URI scheme.

Here are some examples valid for Windows systems, referring to the same file c:\WINDOWS\clock.avi

file://localhost/c|/WINDOWS/clock.avi
file:///c|/WINDOWS/clock.avi
file://localhost/c:/WINDOWS/clock.avi
file:///c:/WINDOWS/clock.avi

While the last is the most obvious and human-readable, the first one is the most complete and correct one.

Apparently (from the same url):

Mozilla browsers refuse to follow file URLs on a page that it has fetched with the HTTP protocol.

but:

Mozilla browsers can be configured to override this security restriction as detailed in Mozillazine's "Links to Local Pages Don't Work".

Access to local files in Firefox can't be done unfortunately due to security restrictions. As far as I know (I have asked here repeated times myself) it's not even possible to allow select sites through a configuration setting or similar.

There is a workaround (ponentially unsafe and to be handled with care), you could register a custom protocol as outlined in this question.