On 13 August 2012 23:49, Richard O'Keefe <ok@cs.otago.ac.nz> wrote:

On 13/08/2012, at 11:26 PM, Alexander Kjeldaas wrote:

>
> This isn't that hard - a pipe shouldn't be needed anymore.  Just require a post-2003 glibc.
>
> fexecve is a system call in most BSDs.  It is also implemented in glibc using a /proc hack.

fexecve is now in the Single Unix Specification, based on
POSIX as of 2008, I believe.  However,
http://www.gnu.org/software/gnulib/manual/html_node/fexecve.html
says
Portability problems not fixed by Gnulib:
  *  This function is missing on many non-glibc platforms: MacOS X 10.5, FreeBSD 6.0,
     NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, OSF/1 5.1,
     Solaris 11 2010-11, Cygwin 1.5.x, mingw, MSVC 9, Interix 3.5, BeOS.

That warning doesn't seem to be fully up to date.  I'm using MacOS X 10.6.8
and fexecve() isn't in the manuals or in <unistd.h>.


FreeBSD 8.0 is covered.
OpenBSD not covered
OS X not covered
http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man2/execve.2.html
Solaris probably not covered.

So support is pretty good, I'd say. For non-modern systems, checking the existence of the file first is possible.  The race isn't important, and one can always upgrade to a modern operating system.

Alexander