Problem w/ text based counter

[Anon]

Hi y'all,

since I don't have access to a database, I store views and clicks in some text files with the following function:

function countHits($file) {
if($fd = @fopen($file, "r")) {
$counter = fgets($fd, 1024);
fclose($fd);
}
$counter = ((int)$counter) + 1;
if($fd = fopen($file, "w")) {
fwrite($fd, "$counter\n");
fclose($fd);
}
}
(Found it somewhere in an article)
Now the problem is, that every now and then the counter is reset to 0, on reasons I can't figure. Could it be that simultaneously write access kills the file?

Hope someone can help,

thx, Joerg

[cvincent]

you might want to try reading the file with $counter = fgets($fd, filesize($file)); becuase its just good practice if you want to load the entire file into the variable. You can cut your code short by increasing the value of the counter with $counter++ instead of $counter=((int)$counter) + 1;.

-Chris

[Anon]

The simple answer...yes

[Anon]

And the fix isn't that hard, either.

First of all, whoever wrote that magazine article needs to have their knuckles rapped from now until kingdom come! To be completely safe, you have to lock the file, but the example makes it so much worse by closing and reopening the file, which greatly lengthens the time when the file is "at risk".

So for starters:

[Anon]

And the fix isn't that hard, either.

First of all, whoever wrote that magazine article needs to have their knuckles rapped from now until kingdom come! To be completely safe, you have to lock the file, but the example makes it so much worse by closing and reopening the file, which greatly lengthens the time when the file is "at risk".

So for starters:

function countHits($file)
{
  if($fd = @fopen($file, "r+"))
    {
    $counter = fgets($fd, 1024);
    rewind($fd);
    }
  elseif (! ($fd = fopen($file,"w")))
    { // can't create, either
    return;
    }
  fwrite($fd, $counter + 1);
  fclose($fd);

[Anon]

To be even safer, you need to add a call to flock() after opening the file in "r+" mode.
Now, the only vulnerability is when you're first creating the counter.

[Anon]

That would be flock($fd, 2) to lock, and flock($fd, 3) after closing, then? Just to be sure ;-)

Thanks, Joerg