Re: [PATCH] Speeding up FAT operations

H. Peter Anvin (hpa@transmeta.com)
23 Sep 1998 09:46:54 GMT

Followup to: <3608475A.60C13D2D@amdyne.net>
By author: Russell Lambert <russell@amdyne.net>
In newsgroup: linux.dev.kernel
>
> This may not mean much, but two years ago when I first started learning a
> computer I was learning QBASIC. And I read a post somewhere of an error in
> QBASIC that would allow you to make a space in the name that no other program
> could read except another QBASIC program that opened it the same way. It was
> something like the following... (I haven't touched it for over a year and a
> half so it may not be completely accurate)
>
> open "blah hi" as binary #1 (or something like this)
> print #1, "jkfsdjlkfsdjkl"
> close #1
>
> Then you can open "blah hi" with the QBASIC program again.
>
> The system never reported it as an error or anything, and it would show up as
> a valid file when you did a DIR. In fact, when you got a directory listing,
> it would show it with the space.
>
> This was back when I was using DOS/Windows 3.1 so I know it wasn't a long
> filename or anything. Sorry I can't remember exactly where I originally
> found it, but just wanted to let you know that skipping a space check might
> be dangerous. Some people were using that as a way to protect passwords and
> things like that because only another QBASIC program could open it. (of
> course, that was almost 2 years ago)
>

No, this is due to the fact that space is actually a legal character
in a filename in DOS; it is just that the command-line shell
considered it a separator, as did most other programs. There were a
grand many programs that would let you create such filenames, and read
them just fine. You just couldn't mess with them in COMMAND.COM. I
don't know if 4DOS allowed you to manipulate these files or not.

-hpa

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