FileStorage: Fix bug retrieving the first record

The file pointer is positioned at the line of the previously read record.
When reading the next record, the current one is skipped. After opening
the index file, the position is zero and reading the next record then skips
the first record. The fix adds a flag that handles this corner-case.

Clockwork/Storage/FileStorage.php

@@ -24,6 +24,10 @@ class FileStorage extends Storage
 	// Index file handle
 	protected $indexHandle;
 
+	// Flag whether the first record is to be retrieved next
+	/** @var bool */
+	protected $indexInitial;
+
 	// Return new storage, takes path where to store files as argument
 	public function __construct($path, $pathPermissions = 0700, $expiration = null, $compress = false)
 	{
@@ -176,6 +180,7 @@ protected function openIndex($position = 'start', $lock = false, $force = false)
 		}
 
 		$this->indexHandle = fopen("{$this->path}/index", 'r');
+		$this->indexInitial = true;
 
 		if ($lock) flock($this->indexHandle, LOCK_EX);
 		if ($position == 'end') fseek($this->indexHandle, 0, SEEK_END);
@@ -236,8 +241,14 @@ protected function readNextIndex()
 	{
 		if (feof($this->indexHandle)) return;
 
-		// File pointer is always at the start of the line, call extra fgets to skip current line
-		fgets($this->indexHandle);
+		// File pointer is always at the start of the last retrieved line.
+		// Call an extra `fgets()` to skip current line, unless it is the
+		// first line actually being read.
+		if (!$this->indexInitial) {
+			fgets($this->indexHandle);
+		} else {
+			$this->indexInitial = false;
+		}
 		$line = fgets($this->indexHandle);
 
 		// Check if we read an empty line or reached the end of file