[libvirt] main: fix some compilation issues on non-linux platforms

[Eric Blake]

On 08/16/2011 12:07 PM, Stefan Berger wrote:
> I split this off and pushed the rest.
> If procfs's are different, then maybe we should use #if
> PROCFS_PID_EXE_LINK_AVAIL here.

Seems like a reasonable name.

> What is needed in this case seems to be that /proc/<pid>/exe is a
> symbolic link to the executable. This works in Linux and cygwin. Would
> testing via
>
> stat /proc/<pid>/exe | sed -n 's/.*\(symbolic link\).*/\1/p'
>
> be a valid test for this that works on all targeted platforms?

stat(1) is not universal, and while it is on both Linux and Cygwin, it 
might not be present on some other platform that has a procfs that does 
what we want.  It may be sufficient to just use 'test -h /proc/pid/exe' 
to see if there is a symlink.

Also, you'd need to wrap the test in a cache variable (to allow 
overrides if we guessed wrong), as well as to skip the test (and assume 
the worst or at least make some default guesses based on known $host_os) 
when cross-compiling, since the existence of procfs on the host machine 
says nothing about it being on the target machine.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org