svn commit: r194262 - in head: include lib/libc/sys sys/compat/freebsd32 sys/kern tools/regression/file/closefrom

[Maxim Konovalov]

kern/121522 and more or less related kern/19363.

On Mon, 15 Jun 2009, 20:38-0000, John Baldwin wrote:

> Author: jhb
> Date: Mon Jun 15 20:38:55 2009
> New Revision: 194262
> URL: http://svn.freebsd.org/changeset/base/194262
>
> Log:
>   Add a new 'void closefrom(int lowfd)' system call.  When called, it closes
>   any open file descriptors >= 'lowfd'.  It is largely identical to the same
>   function on other operating systems such as Solaris, DFly, NetBSD, and
>   OpenBSD.  One difference from other *BSD is that this closefrom() does not
>   fail with any errors.  In practice, while the manpages for NetBSD and
>   OpenBSD claim that they return EINTR, they ignore internal errors from
>   close() and never return EINTR.  DFly does return EINTR, but for the common
>   use case (closing fd's prior to execve()), the caller really wants all
>   fd's closed and returning EINTR just forces callers to call closefrom() in
>   a loop until it stops failing.
>
>   Note that this implementation of closefrom(2) does not make any effort to
>   resolve userland races with open(2) in other threads.  As such, it is not
>   multithread safe.
>
>   Submitted by:	rwatson (initial version)
>   Reviewed by:	rwatson
>   MFC after:	2 weeks
>

-- 
Maxim Konovalov