fix(Config): Prevent setting or deleting config values that are overw…

…ritten by additional config files

Signed-off-by: provokateurin <[email protected]>

lib/private/Config.php

@@ -124,6 +124,12 @@ public function setValue($key, $value) {
 	 */
 	protected function set($key, $value) {
 		if (!isset($this->cache[$key]) || $this->cache[$key] !== $value) {
+			foreach ($this->cachePaths as $file => $keys) {
+				if ($file !== $this->configFilePath && in_array($key, $keys)) {
+					throw new HintException('The config key "' . $key . '" is already specified in "' . $file . '" and thus can not be overwritten.');
+				}
+			}
+
 			// Add change
 			$this->cache[$key] = $value;
 			return true;
@@ -154,6 +160,12 @@ public function deleteKey($key) {
 	 */
 	protected function delete($key) {
 		if (isset($this->cache[$key])) {
+			foreach ($this->cachePaths as $file => $keys) {
+				if ($file !== $this->configFilePath && in_array($key, $keys)) {
+					throw new HintException('The config key "' . $key . '" is already specified in "' . $file . '" and thus can not be overwritten.');
+				}
+			}
+
 			// Delete key from cache
 			unset($this->cache[$key]);
 			return true;

tests/lib/ConfigTest.php

@@ -8,6 +8,7 @@
 namespace Test;
 
 use OC\Config;
+use OCP\HintException;
 
 class ConfigTest extends TestCase {
 	public const TESTCONTENT = '<?php $CONFIG=array("foo"=>"bar", "beers" => array("Appenzeller", "Guinness", "Kölsch"), "alcohol_free" => false);';
@@ -175,4 +176,25 @@ public function testConfigMerge(): void {
 		// Cleanup
 		unlink($additionalConfigPath);
 	}
+
+	public function testConfigAdditionalSetDelete(): void {
+		$additionalConfig = '<?php $CONFIG=array("php53"=>"totallyOutdated");';
+		$additionalConfigPath = $this->randomTmpDir . 'additionalConfig.testconfig.php';
+		file_put_contents($additionalConfigPath, $additionalConfig);
+
+		$config = new Config($this->randomTmpDir, 'testconfig.php');
+
+		$this->assertSame('totallyOutdated', $config->getValue('php53', 'bogusValue'));
+		$this->assertEquals(self::TESTCONTENT, file_get_contents($this->configFile));
+
+		$this->expectException(HintException::class);
+
+		$this->expectExceptionMessage('The config key "php53" is already specified in "' . $additionalConfigPath . '" and thus can not be overwritten.');
+		$config->setValue('php53', 'actuallyNew');
+
+		$this->expectExceptionMessage('The config key "php53" is specified in "' . $additionalConfigPath . '" and thus can not be deleted.');
+		$config->deleteKey('php53');
+
+		unlink($additionalConfigPath);
+	}
 }