Revert "Make config file saving safe against write failures"

diff --git a/lib/private/Config.php b/lib/private/Config.php
index e338d3f2332b2bd2f28c35ec460433c1bdb8106a..ba3b8c6fe4d362e590b0ba153140d678f7f3e45a 100644 (file)
--- a/lib/private/Config.php
+++ b/lib/private/Config.php
@@ -224,6 +224,11 @@ class Config {
                                continue;
                        }
 
+                       // Try to acquire a file lock
+                       if (!flock($filePointer, LOCK_SH)) {
+                               throw new \Exception(sprintf('Could not acquire a shared lock on the config file %s', $file));
+                       }
+
                        unset($CONFIG);
                        include $file;
                        if (!defined('PHPUNIT_RUN') && headers_sent()) {
@@ -239,6 +244,7 @@ class Config {
                        }
 
                        // Close the file pointer and release the lock
+                       flock($filePointer, LOCK_UN);
                        fclose($filePointer);
                }
 
@@ -250,7 +256,8 @@ class Config {
         *
         * Saves the config to the config file.
         *
-        * @throws HintException If the config file cannot be written to, etc
+        * @throws HintException If the config file cannot be written to
+        * @throws \Exception If no file lock can be acquired
         */
        private function writeData() {
                $this->checkReadOnly();
@@ -265,41 +272,30 @@ class Config {
                $content .= var_export($this->cache, true);
                $content .= ";\n";
 
-               // tmpfile must be in the same filesystem for the rename() to be atomic
-               $tmpfile = tempnam(dirname($this->configFilePath), 'config.php.tmp.');
-               // dirname check is for PHP's fallback quirk
-               if (!$tmpfile || dirname($tmpfile) != dirname($this->configFilePath)) {
-                       if ($tmpfile) {
-                               unlink($tmpfile);
-                       }
-                       throw new HintException(
-                               "Can't create temporary file in config directory!",
-                               'This can usually be fixed by giving the webserver write access to the config directory.');
-               }
+               touch($this->configFilePath);
+               $filePointer = fopen($this->configFilePath, 'r+');
 
-               chmod($tmpfile, 0640);
-               $filePointer = fopen($tmpfile, 'w');
+               // Prevent others not to read the config
+               chmod($this->configFilePath, 0640);
+
+               // File does not exist, this can happen when doing a fresh install
                if (!is_resource($filePointer)) {
                        throw new HintException(
-                               "Failed to open temporary file in config directory for writing",
-                               'Please report this to Nextcloud developers.');
+                               "Can't write into config directory!",
+                               'This can usually be fixed by giving the webserver write access to the config directory.');
                }
 
-               $write_ok = fwrite($filePointer, $content);
-               $close_ok = fclose($filePointer);
-               if (!$write_ok || !$close_ok) {
-                       unlink($tmpfile);
-                       throw new HintException(
-                               "Failed to save temporary file in config directory",
-                               'Please report this to Nextcloud developers.');
+               // Try to acquire a file lock
+               if (!flock($filePointer, LOCK_EX)) {
+                       throw new \Exception(sprintf('Could not acquire an exclusive lock on the config file %s', $this->configFilePath));
                }
 
-               if (!rename($tmpfile, $this->configFilePath)) {
-                       unlink($tmpfile);
-                       throw new HintException(
-                               "Failed to replace the config file with the new copy",
-                               'Please report this to Nextcloud developers.');
-               }
+               // Write the config and release the lock
+               ftruncate($filePointer, 0);
+               fwrite($filePointer, $content);
+               fflush($filePointer);
+               flock($filePointer, LOCK_UN);
+               fclose($filePointer);
 
                if (function_exists('opcache_invalidate')) {
                        @opcache_invalidate($this->configFilePath, true);