From b3772163d821401427f4cb3996b4bff8d89337cb Mon Sep 17 00:00:00 2001
From: Philipp <admin@philipp.info>
Date: Fri, 6 Jan 2023 03:06:11 +0100
Subject: [PATCH] Add doc
---
src/Core/Config/Util/ConfigFileManager.php | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/src/Core/Config/Util/ConfigFileManager.php b/src/Core/Config/Util/ConfigFileManager.php
index eb20317cb4..cdef2dd699 100644
--- a/src/Core/Config/Util/ConfigFileManager.php
+++ b/src/Core/Config/Util/ConfigFileManager.php
@@ -234,14 +234,31 @@ class ConfigFileManager
$fileExists = false;
}
+ /**
+ * Creates a read-write stream
+ *
+ * @see https://www.php.net/manual/en/function.fopen.php
+ * @note Open the file for reading and writing. If the file does not exist, it is created.
+ * If it exists, it is neither truncated (as opposed to 'w'), nor the call to this function fails
+ * (as is the case with 'x'). The file pointer is positioned on the beginning of the file.
+ *
+ */
$configStream = fopen($filename, 'c+');
try {
+ // We do want an exclusive lock, so we wait until every LOCK_SH (config reading) is unlocked
if (flock($configStream, LOCK_EX)) {
+ /**
+ * If the file exists, read the whole file again
+ * Since we're currently exclusive locked, no other process can now change the config again
+ */
if ($fileExists) {
+ // When reading the config file too fast, we get a wrong filesize, "clearstatcache" prevents that
clearstatcache(true, $filename);
$content = fread($configStream, filesize($filename));
+ // Event truncating the whole content wouldn't automatically rewind the stream,
+ // so we need to do it manually
rewind($configStream);
if (!$content) {
throw new ConfigFileException(sprintf('Cannot read file %s', $filename));
@@ -249,6 +266,8 @@ class ConfigFileManager
$dataArray = eval('?>' . $content);
+ // Merge the new content into the existing file based config cache and use it
+ // as the new config cache
if (is_array($dataArray)) {
$fileConfigCache = new Cache();
$fileConfigCache->load($dataArray, Cache::SOURCE_DATA);
@@ -256,6 +275,7 @@ class ConfigFileManager
}
}
+ // Only SOURCE_DATA is wanted, the rest isn't part of the node.config.php file
$data = $configCache->getDataBySource(Cache::SOURCE_DATA);
$encodedData = ConfigFileTransformer::encode($data);
@@ -264,6 +284,7 @@ class ConfigFileManager
throw new ConfigFileException('config source cannot get encoded');
}
+ // Once again to avoid wrong, implicit "filesize" calls during the fwrite() or ftruncate() call
clearstatcache(true, $filename);
if (!ftruncate($configStream, 0) ||
!fwrite($configStream, $encodedData) ||
@@ -272,6 +293,7 @@ class ConfigFileManager
}
}
} finally {
+ // unlock and close the stream for every circumstances
flock($configStream, LOCK_UN);
fclose($configStream);
}