Bug 15553: [QA Follow-up] Replace hardcoded tmp and add instance to dirname

If you use multiple instances on one server, you could have the situation
that instance A creates the cgisess subfolder and instance B could have a
permission problem. This patch resolves that by allowing each instance to
have its own cgisess subfolder.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>

Signed-off-by: Brendan A Gallagher <brendan@bywatersolutions.com>

C4/Auth.pm

@@ -20,6 +20,7 @@ package C4::Auth;
 use strict;
 use warnings;
 use Digest::MD5 qw(md5_base64);
+use File::Spec;
 use JSON qw/encode_json/;
 use URI::Escape;
 use CGI::Session;
@@ -1713,7 +1714,9 @@ sub get_session {
     }
     else {
         # catch all defaults to tmp should work on all systems
-        $session = new CGI::Session( "driver:File;serializer:yaml;id:md5", $sessionID, { Directory => '/tmp/cgisess' } );
+        my $dir = File::Spec->tmpdir;
+        my $instance = C4::Context->config( 'database' ); #actually for packages not exactly the instance name, but generally safer to leave it as it is
+        $session = new CGI::Session( "driver:File;serializer:yaml;id:md5", $sessionID, { Directory => "$dir/cgisess_$instance" } );
     }
     return $session;
 }