Merge pull request #18684 from owncloud/explicit-upgrade-version

Explicit upgrade version + prevent downgrades

2 files changed, 23 insertions, 11 deletions

diff --git a/lib/private/updater.php b/lib/private/updater.php
index f73fa8ff655..71e9732c307 100644
--- a/lib/private/updater.php
+++ b/lib/private/updater.php
@@ -212,19 +212,26 @@ class Updater extends BasicEmitter {
 	}
 
 	/**
+	 * Return version from which this version is allowed to upgrade from
+	 *
+	 * @return string allowed previous version
+	 */
+	private function getAllowedPreviousVersion() {
+		// this should really be a JSON file
+		require \OC::$SERVERROOT . '/version.php';
+		return implode('.', $OC_VersionCanBeUpgradedFrom);
+	}
+
+	/**
 	 * Whether an upgrade to a specified version is possible
 	 * @param string $oldVersion
 	 * @param string $newVersion
+	 * @param string $allowedPreviousVersion
 	 * @return bool
 	 */
-	public function isUpgradePossible($oldVersion, $newVersion) {
-		$oldVersion = explode('.', $oldVersion);
-		$newVersion = explode('.', $newVersion);
-
-		if($newVersion[0] > ($oldVersion[0] + 1) || $oldVersion[0] > $newVersion[0]) {
-			return false;
-		}
-		return true;
+	public function isUpgradePossible($oldVersion, $newVersion, $allowedPreviousVersion) {
+		return (version_compare($allowedPreviousVersion, $oldVersion, '<=')
+			&& version_compare($oldVersion, $newVersion, '<='));
 	}
 
 	/**
@@ -259,8 +266,9 @@ class Updater extends BasicEmitter {
 	 */
 	private function doUpgrade($currentVersion, $installedVersion) {
 		// Stop update if the update is over several major versions
-		if (!self::isUpgradePossible($installedVersion, $currentVersion)) {
-			throw new \Exception('Updates between multiple major versions are unsupported.');
+		$allowedPreviousVersion = $this->getAllowedPreviousVersion();
+		if (!self::isUpgradePossible($installedVersion, $currentVersion, $allowedPreviousVersion)) {
+			throw new \Exception('Updates between multiple major versions and downgrades are unsupported.');
 		}
 
 		// Update .htaccess files
diff --git a/lib/private/util.php b/lib/private/util.php
index f110d618f77..eb1de5be5a4 100644
--- a/lib/private/util.php
+++ b/lib/private/util.php
@@ -1456,8 +1456,12 @@ class OC_Util {
 		if ($config->getSystemValue('installed', false)) {
 			$installedVersion = $config->getSystemValue('version', '0.0.0');
 			$currentVersion = implode('.', OC_Util::getVersion());
-			if (version_compare($currentVersion, $installedVersion, '>')) {
+			$versionDiff = version_compare($currentVersion, $installedVersion);
+			if ($versionDiff > 0) {
 				return true;
+			} else if ($versionDiff < 0) {
+				// downgrade attempt, throw exception
+				throw new \OC\HintException('Downgrading is not supported and is likely to cause unpredictable issues (from ' . $installedVersion . ' to ' . $currentVersion . ')');
 			}
 
 			// also check for upgrades for apps (independently from the user)