too many close calls for non-opened fds

[William Ahern]

On Wed, Aug 16, 2006 at 02:25:05PM -0700, Carson Gaspar wrote:
> --On Wednesday, August 16, 2006 10:56 PM +0200 Markus Friedl 
> <markus.r.friedl at arcor.de> wrote:
> 
> > if a file is opened and the resource limit is decreased,
> > then looping to the resource limit will miss some open files.
> 
> Does any UNIX variant have a "close all my open fds except for these" 
> syscall? Or an easy way to get back a list of in-use fds? I really wish 
> such a beast would be added, as calling close() on all possible fd numbers 
> is _such_ a hack...
> 

OpenBSD has closefrom(2) and AIX has an fcntl capability using F_CLOSEM. On
Linux you can read the entries in /proc/$$/fd--see
openbsd-compat/closefrom.c in the OpenSSH source--however that wouldn't work
in a chroot environment.