Message-ID: <4A65BCC9.1020002@byu.net>
Date: Tue, 21 Jul 2009 07:04:09 -0600
From: Eric Blake <ebb9@byu.net>
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To: cygwin@cygwin.com, newlib@sources.redhat.com
Subject: close on exec atomics
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It seems like it would be pretty easy to add several new close-on-exec
features required by POSIX 2008:

open(name, O_RDONLY | O_CLOEXEC);
// skips the need to use fcntl

fcntl(fd, F_DUPFD_CLOEXEC);
// like F_DUPFD, but closes window without having to use
// fcntl(fd, F_SETFD, fcntl(fd, F_GETFD))

and those provided by glibc as extensions:

fopen(name, "re");
// like fopen "r", but with cloexec set

The argument is that in multi-threaded apps, if one thread opens a file
but has not yet turned on the close-on-exec bit while another thread does
a fork-and-exec, then you leaked the fd into the child; and these new
flags close the window.

Should I go ahead and prepare a patch for the newlib side?

- --
Don't work too hard, make some time for fun as well!

Eric Blake             ebb9@byu.net
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