Race Conditions & File Appendages

[DonCoder]

Do race conditions usually exist when writing OR appending to an existing file?

 

$f1 = fopen($filename1, 'r+');
$f2 = fopen($filename2, 'a');
flock($f1, LOCK_EX);
flock($f2, LOCK_EX);
fwrite($f1, 'foo');
fwrite($f2, 'foo');
flock($f1, LOCK_UN);
flock($f2, LOCK_UN);
fclose($f1);
fclose($f2);

 

What would happen if this code ran at the exact same time? Is there a chance that the data could be corrupted in the aforementioned code example?

[sunfighter]

Do the files separately and use an if statement:

 

$f1 = fopen($filename1, 'r+');

if (flock($f1, LOCK_EX)) 
{
    do your stuf here;
} else {
    echo "Couldn't get the lock!";
}
fclose($f1);