add some output why some of the external filesystems might not work

apps/files_external/lib/config.php

@@ -394,4 +394,35 @@ class OC_Mount_Config {
 		return true;
 	}
 
+	/**
+	 * check if smbclient is installed 
+	 */
+	public static function checksmbclient() {
+		$output=shell_exec('which smbclient');
+		return (empty($output)?false:true);
+	}
+
+	/**
+	 * check if php-ftp is installed 
+	 */
+	public static function checkphpftp() {
+		if(function_exists('ftp_login')) {
+			return(true);
+		}else{
+			return(false);
+		}
+	}
+
+	/**
+	 * check dependencies
+	 */
+	public static function checkDependencies() {
+		$l= new OC_L10N;
+		$txt='';
+
+		if(!OC_Mount_Config::checksmbclient()) $txt.=$l->t('<b>Warning:</b> "smbclient" is not installed. Mounting of CIFS/SMB shares is not possible. Please ask your system administrator to install it.').'<br />';
+		if(!OC_Mount_Config::checkphpftp()) $txt.=$l->t('<b>Warning:</b> The FTP support in PHP is not enabled or installed. Mounting of FTP shares is not possible. Please ask your system administrator to install it.').'<br />';
+
+		return($txt);
+	}
 }

apps/files_external/personal.php

@@ -29,5 +29,6 @@ $tmpl = new OCP\Template('files_external', 'settings');
 $tmpl->assign('isAdminPage', false, false);
 $tmpl->assign('mounts', OC_Mount_Config::getPersonalMountPoints());
 $tmpl->assign('certs', OC_Mount_Config::getCertificates());
+$tmpl->assign('dependencies', OC_Mount_Config::checkDependencies(),false);
 $tmpl->assign('backends', $backends);
 return $tmpl->fetchPage();

apps/files_external/settings.php

@@ -30,5 +30,6 @@ $tmpl->assign('mounts', OC_Mount_Config::getSystemMountPoints());
 $tmpl->assign('backends', OC_Mount_Config::getBackends());
 $tmpl->assign('groups', OC_Group::getGroups());
 $tmpl->assign('users', OCP\User::getUsers());
+$tmpl->assign('dependencies', OC_Mount_Config::checkDependencies(),false);
 $tmpl->assign('allowUserMounting', OCP\Config::getAppValue('files_external', 'allow_user_mounting', 'yes'));
 return $tmpl->fetchPage();

apps/files_external/templates/settings.php

 <form id="files_external">
 	<fieldset class="personalblock">
 	<legend><strong><?php echo $l->t('External Storage'); ?></strong></legend>
+                <?php if (isset($_['dependencies']) and ($_['dependencies']<>'')) echo ''.$_['dependencies'].''; ?>
 		<table id="externalStorage" data-admin='<?php echo json_encode($_['isAdminPage']); ?>'>
 			<thead>
 				<tr>