On Wed, Jun 12, 2002 at 11:21:18AM +0300, Adi Stav wrote:
> On Tue, Jun 11, 2002 at 01:25:11PM +0300, Muli Ben-Yehuda wrote:
> > Is there a way to open a file (get an fd) and then delete it, in one
> > atomic operation?
> >
> > I need to open a temporary file (but with a fixed name, so mkstemp()
> > and friends are not an option) and then make sure it doesn't remain
> > behind if the program should die unexpectedly. Doing
> >
> > open("foo", ...);
> > unlink("foo", ...);
> >
> > is obviously unsafe, since foo might be pointing to something else by
> > the time I unlink it. Suggestions?
>
> Let's see... open() increases the inode reference count, while
> unlink() decreases it. What you want to do is to keep it constant,
> just _transfer_ the reference (atomically) from the directory to your
> process. Transferring an inode reference is rename(). I don't know if
> you can rename a file into /proc/self/fd, but you can use an
> intermediate private directory:Using a secure, private directory was indeed the answer. Thanks to everyone who replied. The code, for the curious, is available at http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/syscalltrack/syscalltrack/tests/tester.c?rev=1.25&content-type=text/vnd.viewcvs-markup Look for dir_cleanup() and dir_setup(). Let me know if you poke any holes in it ;) -- Sunday 21 Forelithe 7466 http://vipe.technion.ac.il/~mulix/ http://syscalltrack.sf.net/
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