Look for trailer record in potentially large text file

[NogDog]

I have to FTP a potentially large text file, and before I process it I want to make sure I got the whole thing and as a byproduct verify it contains a valid trailer record. The file is pipe-delimited, and fields may or may not be double-quote encased. A trailer record (and only a trailer record) will be in the format "TTn|n" (where "n" will be one or more digits). This was the best solution I could come up with that did not have to parse the whole file nor load it into memory. I'm just curious if anyone has a "better" solution. I considered using shel_exec() along with the "tail -200" command, but prefer not to depend on OS commands if I don't have to.

/**
 * See if we got the whole file by looking for the trailer record
 * @return boolean
 * @param string path to file
 */
function isFullFile($filePath)
{
	$fh = fopen($filePath, 'r');
	if($fh === false) {
		return false;
	}
	fseek($fh, -200, SEEK_END);
	$line = fgets($fh); // make sure we start following loop after a line break
	while(($line = fgets($fh)) !== false) {
		$line = trim($line);
		$line = trim($line, '"');
		$fields = preg_split('#"?|"?#', $line);
		if(!empty($fields[0])) {
			if(preg_match('#^TT\d+$#', $fields[0])) {
				return true;
			}
		}
	}
	return false;
}

[NogDog]

I ended up with a somewhat simpler version, since only a trailer record can start with "TT". Seems to work in a "sunny day" scenario, now have to test with an incomplete file to simulate an incomplete download. 🙂

/**
 * See if we got the whole file by looking for the trailer record
 * @return boolean
 * @param string path to file
 */
function isFullFile($filePath)
{
	$fh = fopen($filePath, 'r');
	if($fh === false) {
		return false;
	}
	fseek($fh, -200, SEEK_END);
	$line = fgets($fh); // make sure we start following loop after a line end
	while(($line = fgets($fh)) !== false) {
		$line = trim($line);
		$line = trim($line, '"');
		if(strpos($line, 'TT') === 0) {
			print "looking...'$line'".PHP_EOL;
			return true;
		}
	}
	return false;
}