Bug#632682: base-files: please provide a /lib64 -> /lib symlink on 64-bit systems

[Jonathan Nieder <jrnieder@gmail.com>]

Aurelien Jarno wrote:

> I don't think we want any manual intervention for this transition. For
> the symlink I would prefer not having /lib64 left, as a lot of configure
> scripts are actually looking to /lib64 to determine random things. Also
> we have just seen that leaving leftover that are not handled by dpkg can
> be a pain years after.

Ok, that's convincing enough.  I'm tempted to suggest (*)

	mkdir /lib64.real
	symlink $(readlink -e /lib/ld-linux-x86-64.so.2) to
		/lib64.real/ld-linux-x86-64.so.2

	if this is a chroot:
		sync
		unlink /lib64
		rename /lib64.real to /lib64
		sync
	else:
		ln -s lib64.real /lib64.eglibc-tmp
		rename lib64.eglibc-tmp to /lib64

and replacing the /lib64 symlink with a directory on startup in the
non-chroot case, hoping that

 (1) in chroots, hopefully not too much is happening concurrently
 (2) in non-chroots, people reboot from time to time to get security
     updates

But for now, why not always take the "if this is a chroot" branch.
The atomicity part can happen later (when it is reported as a bug or
someone implements it).  If we're lucky, the syncs will stall other
processes long enough to avoid trouble. :)