Description:
------------
I am trying to insert a line in a file after a line that is searched for.
The line to insert is inserted fine, but the text after it gets truncated partially.

********* test.txt ************
PHP is a great language.
It is a tool for the ages.
It is easy to use and fast too!

Test script:
---------------
$absoluteFilePath = '<your_root_path>/test.txt';
$splFile = new \SplFileObject($absoluteFilePath, 'c+');
$splFile->flock(LOCK_EX);
$splFile->rewind();
		
// Add to next line.
while ($splFile->valid()) {
	$currentLine = $splFile->fgets();
	if (strpos($currentLine, "It is a tool for the ages.") !== false) {
		$splFile->fwrite("But it has a few bugs.\n");
	}
}
$splFile->flock(LOCK_UN);

Expected result:
----------------
PHP is a great language.
It is a tool for the ages.
But it has a few bugs.
It is easy to use and fast too!


Actual result:
--------------
PHP is a great language.
It is a tool for the ages.
But it has a few bugs.
ast too!