Re: in place writing

[grahame angrygoats net (Grahame Bowland)]

On Fri, Dec 05, 2003 at 01:27:17PM -0600, Jacob Perkins wrote:
> I've implemented a 'secure' delete operation that overwrites (using
> gnome-vfs) a file multiple times with random data.
> Does gnome-vfs provide any guarantees that the writing will actually be in
> the same place on disk each time?
> Here's the relevant code:
> 
> result = gnome_vfs_write (handle, buffer, info.size, &wrote);
> result = gnome_vfs_seek (handle, GNOME_VFS_SEEK_START, 0);
> g_return_if_fail (result == GNOME_VFS_OK);
> 
> this is all in a loop where buffer is refilled with random data.
> 
> Thanks, and please cc me since I'm not on the list.

gnome-vfs can't provide any such guarantee. The "simple" case 
is doing secure deletes on a local filesystem (the file: URIs), 
I suggest you check out the manpage for "shred". Even in this 
case, journalled / logging filesystems mean a naive implementation 
won't work.

Given gnome-vfs abstracts network file systems such as WebDAV 
and SMB, which might be backing to arbitrary local filesystems, 
(insert huge murky cloud on diagram here), I'd have to say it's 
a lost cause..