- Fix automatic unsubscribe of non-existent folders (with small perf fix)

program/include/rcube_imap.php

@@ -2527,9 +2527,10 @@ class rcube_imap extends rcube_storage
                     NULL, array('SUBSCRIBED'));
 
                 // unsubscribe non-existent folders, remove from the list
-                if (is_array($a_folders) && $name == '*') {
+                // we can do this only when LIST response is available
+                if (is_array($a_folders) && $name == '*' && !empty($this->conn->data['LIST'])) {
                     foreach ($a_folders as $idx => $folder) {
-                        if ($this->conn->data['LIST'] && ($opts = $this->conn->data['LIST'][$folder])
+                        if (($opts = $this->conn->data['LIST'][$folder])
                             && in_array('\\NonExistent', $opts)
                         ) {
                             $this->conn->unsubscribe($folder);
@@ -2542,11 +2543,12 @@ class rcube_imap extends rcube_storage
             else {
                 $a_folders = $this->conn->listSubscribed($root, $name);
 
-                // unsubscribe non-existent folders, remove from the list
-                if (is_array($a_folders) && $name == '*') {
+                // unsubscribe non-existent folders, remove them from the list,
+                // we can do this only when LIST response is available
+                if (is_array($a_folders) && $name == '*' && !empty($this->conn->data['LIST'])) {
                     foreach ($a_folders as $idx => $folder) {
-                        if ($this->conn->data['LIST'] && ($opts = $this->conn->data['LIST'][$folder])
-                            && in_array('\\Noselect', $opts)
+                        if (!isset($this->conn->data['LIST'][$folder])
+                            || in_array('\\Noselect', $this->conn->data['LIST'][$folder])
                         ) {
                             // Some servers returns \Noselect for existing folders
                             if (!$this->folder_exists($folder)) {

program/include/rcube_imap_generic.php

@@ -1352,12 +1352,16 @@ class rcube_imap_generic
                         $folders[$mailbox] = array();
                     }
 
-                    // Add to options array
-                    if (empty($this->data['LIST'][$mailbox]))
-                        $this->data['LIST'][$mailbox] = $opts;
-                    else if (!empty($opts))
-                        $this->data['LIST'][$mailbox] = array_unique(array_merge(
-                            $this->data['LIST'][$mailbox], $opts));
+                    // store LSUB options only if not empty, this way
+                    // we can detect a situation when LIST doesn't return specified folder
+                    if (!empty($opts) || $cmd == 'LIST') {
+                        // Add to options array
+                        if (empty($this->data['LIST'][$mailbox]))
+                            $this->data['LIST'][$mailbox] = $opts;
+                        else if (!empty($opts))
+                            $this->data['LIST'][$mailbox] = array_unique(array_merge(
+                                $this->data['LIST'][$mailbox], $opts));
+                    }
                 }
                 // * STATUS <mailbox> (<result>)
                 else if ($cmd == 'STATUS') {