[pve-devel] applied: [PATCH container v2] fix: cloning a locked container creates an empty config

[Wolfgang Bumiller <w.bumiller@proxmox.com>]

applied,


*sigh*
We should probably think about getting rid functions that set a lock and
return, requiring the caller to call a cleanup, *in general* in all of
our perl code.
Scope guards or functions taking closures would be somewhat safer.
However, since this is perl, a `die` can get thrown in at *any* line (eg
from a timer signal handler), and fixing that is a different beast...

On Fri, Jun 17, 2022 at 12:40:01PM +0200, Daniel Tschlatscher wrote:
> When an attempt was made to clone a locked container the API would
> correctly present the error 'CT is locked (disk)' but create the
> config files for the new container anyway.
> 
> There was also a potential problem when the config of the new ct would
> already be present and the creation of the container failed. In this
> case the config of the new CT would be incorrectly removed.
> The config locks for the new and the old configs should now be
> correctly released depending on from which call a problem originates.
> 
> Futhermore, I moved some related function calls into the eval block to
> avoid similar problems with leftover config files in the future.
> 
> Signed-off-by: Daniel Tschlatscher <d.tschlatscher@proxmox.com>
> ---
> Changes from v1
> Some problems which I was made aware of by Fabian (G) through a quick
> chat off-list (thanks btw!):
> 
> * Added a dedicated check to conditionally remove the locks for the
>   new and old config files depending on where a potential error
>   originates.
> * Moved some potentially failing function calls into the eval block
> 
>  src/PVE/API2/LXC.pm | 23 ++++++++++++++++-------
>  1 file changed, 16 insertions(+), 7 deletions(-)
> 
> diff --git a/src/PVE/API2/LXC.pm b/src/PVE/API2/LXC.pm
> index 64724cb..06f759e 100644
> --- a/src/PVE/API2/LXC.pm
> +++ b/src/PVE/API2/LXC.pm
> @@ -1461,9 +1461,6 @@ __PACKAGE__->register_method({
>  	my $vollist = [];
>  	my $running;
>  
> -	PVE::LXC::Config->create_and_lock_config($newid, 0);
> -	PVE::Firewall::clone_vmfw_conf($vmid, $newid);
> -
>  	my $lock_and_reload = sub {
>  	    my ($vmid, $code) = @_;
>  	    return PVE::LXC::Config->lock_config($vmid, sub {
> @@ -1477,14 +1474,26 @@ __PACKAGE__->register_method({
>  
>  	my $src_conf = PVE::LXC::Config->set_lock($vmid, 'disk');
>  
> -	$running = PVE::LXC::check_running($vmid) || 0;
> +	eval {
> +	    PVE::LXC::Config->create_and_lock_config($newid, 0);
> +	};
> +	if (my $err = $@) {
> +	    eval { PVE::LXC::Config->remove_lock($vmid, 'disk') };
> +	    warn "Failed to remove source CT config lock - $@\n" if $@;
>  
> -	my $full = extract_param($param, 'full');
> -	if (!defined($full)) {
> -	    $full = !PVE::LXC::Config->is_template($src_conf);
> +	    die $err;
>  	}
>  
>  	eval {
> +	    $running = PVE::LXC::check_running($vmid) || 0;
> +
> +	    my $full = extract_param($param, 'full');
> +	    if (!defined($full)) {
> +		$full = !PVE::LXC::Config->is_template($src_conf);
> +	    }
> +
> +	    PVE::Firewall::clone_vmfw_conf($vmid, $newid);
> +
>  	    die "parameter 'storage' not allowed for linked clones\n"
>  		if defined($storage) && !$full;
>  
> -- 
> 2.30.2