Description:
------------
When using file_get_contents or fread to read a file completely in memory, PHP allocates twice the filesize memory.

PHP versions 5.2.5 and 5.2.6 don't have this problem but 5.2.8 and 5.2.9 do.

We're working a lot with large files and this problem affects the memory usage (out of memory) and the performance (longer duration).

Are there any alternatives to work-around this problem besides not reading the complete file in memory?


Reproduce code:
---------------
$filePath = tempnam(sys_get_temp_dir(), '');
$data = str_pad('', 1024);
if (($fh = fopen($filePath, 'wb'))){
	for ($i=0; $i < 4096; $i++){
		fputs($fh, $data);
	}
	fclose($fh);
	$filesize = filesize($filePath);
	print "filesize = " . number_format($filesize) . "\n";
	print "Memory usage at start\n";
	print "mem = " . number_format(memory_get_usage()) . "; peak = " . number_format(memory_get_peak_usage()) . "\n";
	$x = file_get_contents($filePath);
		
	print "\nAfter\n";
	print "mem = " . number_format(memory_get_usage()) . "; peak = " . number_format(memory_get_peak_usage()) . "\n";
	
	unlink($filePath);
}


Expected result:
----------------
PHP allocates once the filesize memory.

filesize = 4,194,304
Memory usage at start
mem = 66,992; peak = 90,228

After
mem = 4,261,396; peak = 4,269,740


Actual result:
--------------
filesize = 4,194,304
Memory usage at start
mem = 71,300; peak = 96,044

After
mem = 4,265,704; peak = 8,460,160