Don't use cached informations for app version

When installing an app from the appstore the `\OC_App::getAppVersion` code is triggered twice:

- First when the downloader tries to compare the current version to the new version on the appstore to check if there is a newer version. This protects against downgrade attacks and is implemented in `\OC\Installer::downloadApp`.
- Second, when the app is actually installed the current version is written to the database. (`\OC\Installer::installApp`)

This fails however when the version is actually cached. Because in step 1 the cached version will be set to "0" and then be reused in the second step.

While this is probably not the cleanest version I assume this is an approach that is least invasive. Feedback and suggestions welcome :)

Signed-off-by: Lukas Reschke <lukas@statuscode.ch>

2 files changed, 8 insertions, 5 deletions

diff --git a/lib/private/Installer.php b/lib/private/Installer.php
index db71f7b1432..38d0ce13684 100644
--- a/lib/private/Installer.php
+++ b/lib/private/Installer.php
@@ -121,7 +121,7 @@ class Installer {
 		OC_App::executeRepairSteps($appId, $appData['repair-steps']['install']);
 
 		//set the installed version
-		\OC::$server->getConfig()->setAppValue($info['id'], 'installed_version', OC_App::getAppVersion($info['id']));
+		\OC::$server->getConfig()->setAppValue($info['id'], 'installed_version', OC_App::getAppVersion($info['id'], false));
 		\OC::$server->getConfig()->setAppValue($info['id'], 'enabled', 'no');
 
 		//set remote/public handlers
diff --git a/lib/private/legacy/app.php b/lib/private/legacy/app.php
index 0d9adfa9d2b..adf29601ac6 100644
--- a/lib/private/legacy/app.php
+++ b/lib/private/legacy/app.php
@@ -653,13 +653,16 @@ class OC_App {
 	 * get the last version of the app from appinfo/info.xml
 	 *
 	 * @param string $appId
+	 * @param bool $useCache
 	 * @return string
 	 */
-	public static function getAppVersion($appId) {
-		if (!isset(self::$appVersion[$appId])) {
-			$file = self::getAppPath($appId);
-			self::$appVersion[$appId] = ($file !== false) ? self::getAppVersionByPath($file) : '0';
+	public static function getAppVersion($appId, $useCache = true) {
+		if($useCache && isset(self::$appVersion[$appId])) {
+			return self::$appVersion[$appId];
 		}
+
+		$file = self::getAppPath($appId);
+		self::$appVersion[$appId] = ($file !== false) ? self::getAppVersionByPath($file) : '0';
 		return self::$appVersion[$appId];
 	}