Atomic Write File

gistfile1.php

// code adapted from http://uk.php.net/manual/en/function.file-put-contents.php#82934

// a subfolder called 'cache' within the directory that this code is in
define("FILE_PUT_CONTENTS_ATOMIC_TEMP", dirname(__FILE__).DIRECTORY_SEPARATOR."cache");
// give owner, group and public write access after writing the file
define("FILE_PUT_CONTENTS_ATOMIC_MODE", 0777);

function file_put_contents_atomic($filename, $content) {
  
	// generate a temporary file
	$temp = tempnam(FILE_PUT_CONTENTS_ATOMIC_TEMP, 'temp');
	// try to open temporary file (for writing, as binary)
	if (!($f = @fopen($temp, 'wb'))) {
		// try again if tmpname didn't work
		$temp = FILE_PUT_CONTENTS_ATOMIC_TEMP.DIRECTORY_SEPARATOR.uniqid('temp');
		if (!($f = @fopen($temp, 'wb'))) {
			
			trigger_error("file_put_contents_atomic() : error writing temporary file '$temp'", E_USER_WARNING);
			return false;
		}
	}
	
	// write content to temporary file
	fwrite($f, $content);
	// close the file
	fclose($f);
	
	// try to rename the temp file to the new file
	if (!@rename($temp, $filename)) {
		// delete the old file
		@unlink($filename);
		// rename the temp file
		@rename($temp, $filename);
	}
	
	// give file appropriate permissions
	@chmod($filename, FILE_PUT_CONTENTS_ATOMIC_MODE);
  
	return true;
  
}