svn commit: r194262 - in head: include lib/libc/sys
sys/compat/freebsd32 sys/kern tools/regression/file/closefrom
Maxim Konovalov
maxim at macomnet.ru
Tue Jun 16 06:10:29 UTC 2009
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
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