[Libvir] [RFC] 3 of 4 Linux Container support
Daniel P. Berrange
berrange at redhat.com
Thu Mar 20 16:14:21 UTC 2008
On Thu, Mar 20, 2008 at 12:11:39PM -0400, Daniel Veillard wrote:
> On Wed, Mar 19, 2008 at 11:14:59PM -0700, Dave Leskovec wrote:
> > This patch adds the lxc_driver source files.
> [...]
> > +static int lxcCheckContainerSupport( void )
> > +{
> > + int rc = 0;
> > + int flags = CLONE_NEWPID|CLONE_NEWNS|CLONE_NEWUTS|CLONE_NEWUSER|
> > + CLONE_NEWIPC|SIGCHLD;
> > + int cpid;
> > + char *childStack;
> > + char *stack;
> > + int childStatus;
> > +
> > + stack = malloc(getpagesize() * 4);
> > + if(!stack) {
> > + DEBUG0("Unable to allocate stack");
> > + rc = -1;
> > + goto check_complete;
> > + }
> > +
> > + childStack = stack + (getpagesize() * 4);
> > +
> > + cpid = clone(lxcDummyChild, childStack, flags, NULL);
> > + if ((0 > cpid) && (EINVAL == errno)) {
> > + DEBUG0("clone call returned EINVAL, container support is not enabled");
> > + rc = -1;
>
> haha, I would have expected a checking of /proc or something similar.
> That test could still fail, say if the kernel started to disagree on
> stack of only 4 pages for example.
If there was insufficient mem it would return ENOMEM. The EINVAL errors are all
related to invalid flags, so this is a reasonable check.
Dan.
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