Note that this method will cause a PHP fatal error if the file being read contains no recognizable line termination characters and is larger than the allowable memory size for PHP to allocate, i.e. memory_limit set in php.ini or similar. In other words, PHP keeps reading until it finds a line termination, if it runs out of memory first, it will throw a fatal error.
This is different from the file resource fread() function, which allows an optional maximum length argument to be passed to limit this behavior.