[Resolved] class method changes file ownership - help

[ppowell]

class EmailActionGenerator extends DataFileHandler {

/**
 * Clear bundling file
 *
 * @access private
 * @see file_put_contents
 */
function &clearBundlingFile() {										// STATIC VOID METHOD
	global $willUseEmailBundling, $bundleEmailFilePath, $bundleEmailFileName, $nullPath;
	if ($this->isSuccessful && $willUseEmailBundling && is_file("$bundleEmailFilePath/$bundleEmailFileName") && 
	    @!copy("$nullPath $bundleEmailFilePath/$bundleEmailFileName")
	    ) {
	 list($copyKommand, $copyRedirect) = @array_values($this->getKommandOSArray('copy'));
	 $msg = exec("$copyKommand $nullPath $bundleEmailFilePath/$bundleEmailFileName $copyRedirect");
	 if ($msg) {
	  unset($msg);	// CLEAR ORIGINAL ERROR MESSAGE FOR ATTEMPTING TO OVERWRITE WITH NULL
	  @file_put_contents("$bundleEmailFilePath/$bundleEmailFileName", null);
	  if (file_get_contents("$bundleEmailFilePath/$bundleEmailFileName")) {	// CONTENT STILL FOUND - PROBLEM
	   $this->isSuccessful = false;
	   $this->setErrorArray(array('action' => "Could not rewrite file \"$bundleEmailFileName\" for clearing"));
	  }
	 }
	 if ($msg) {
	  $this->isSuccessful = false;
	  $this->setErrorArray(array('action' => "Could not clear bundling file \"$bundleEmailFileName\": " . nl2br($msg)));
	 }
	}
}

}

This method is supposed to clear out the file contents of an existing file while keeping it intact (reducing it to 0 bytes).

However, while doing that it constantly changes ownership of the file to "apache", making it impossible for required outside scripts within sendmail to manipulate the very same file.

I can't use PHP's chown() command to change ownership back as "apache" has no permissions to do so.

Bottom line: I just want to erase all content from an existing file, that's all.

Thanx
Phil

[sneakyimp]

it looks like this is the line that empties the file:

copy("$nullPath $bundleEmailFilePath/$bundleEmailFileName")

it looks difficult to change because a) this appears to be a class definition and i don't know what all it might be doing and b) the copy() command is in the middle of an if statement.

HOWEVER, you might be able to put something like this:

fopen("$bundleEmailFilePath/$bundleEmailFileName", "w");

in its place. you'd need to make sure you closed the file when you were done. so you'd get something like this:

function &clearBundlingFile() {                                        // STATIC VOID METHOD 
  global $willUseEmailBundling, $bundleEmailFilePath, $bundleEmailFileName, $nullPath; 
  if ($this->isSuccessful && $willUseEmailBundling && is_file("$bundleEmailFilePath/$bundleEmailFileName") &&  

            @!($fp = fopen("$bundleEmailFilePath/$bundleEmailFileName", "w")) 
            ) {
    list($copyKommand, $copyRedirect) = @array_values($this->getKommandOSArray('copy')); 
    $msg = exec("$copyKommand $nullPath $bundleEmailFilePath/$bundleEmailFileName $copyRedirect"); 
    if ($msg) { 
      unset($msg);    // CLEAR ORIGINAL ERROR MESSAGE FOR ATTEMPTING TO OVERWRITE WITH NULL 
      @file_put_contents("$bundleEmailFilePath/$bundleEmailFileName", null); 
      if (file_get_contents("$bundleEmailFilePath/$bundleEmailFileName")) {    // CONTENT STILL FOUND - PROBLEM 
        $this->isSuccessful = false; 
        $this->setErrorArray(array('action' => "Could not rewrite file \"$bundleEmailFileName\" for clearing")); 
      } 
    } 
    if ($msg) { 
      $this->isSuccessful = false; 
      $this->setErrorArray(array('action' => "Could not clear bundling file \"$bundleEmailFileName\": " . nl2br($msg))); 
    } 
  } else {
    fclose($fp);
  }
} 

EDIT: I haven't tested that and i'm not sure it'll work, so try it at your own risk.

[ppowell]

Sorry that made matters worse. That completely DESTROYED the file altogether!

🙁

Phil

[sneakyimp]

really? sorry about that. i'm not sure what the problem is. on my server, this empties out a file without destroying it, leaving the file permissions and everything else the same.

<?
if ($fp = fopen('foo.txt', 'w')) {
fclose($fp);
echo 'success!';
} else {
echo 'could not open';
}
?>

did you make sure to put the fclose part in there in the else section? if you fopened the file in your script and didn't fclose it, perhaps that caused a problem.

i'm curious about a few things
what platform are you on? win? linux?

what are the permissions on the file? i'm assuming apache has access.
* what does $nullpath point to? perhaps not-completely-empty file?

[ppowell]

Linux Fedora Core 3, Red Hat EL 3, FreeBSD and Windows XP

PHP 4.1.2, 4.3.2, and 4.3.8

And I got it! I came up with a series of steps to ensure it will EVENTUALLY zero out the file:

class EmailActionGenerator extends DataFileHandler {

/**
 * Clear bundling file
 *
 * @access private
 * @link [url]http://us4.php.net/manual/en/function.fopen.php[/url]
 * @see link regarding use of fopen() in PHP to open-and-close a file to ensure existence with built-in zero'ed truncation
 * @link [url]http://us4.php.net/manual/en/function.ftruncate.php[/url]
 * @see link regarding use of ftruncate() PHP function to reduce size of email bundling file to 0 bytes while maintaining file pointer via 'append' mode
 */
function &clearBundlingFile() {										// STATIC VOID METHOD
	global $willUseEmailBundling, $bundleEmailFilePath, $bundleEmailFileName, $nullPath;
	if ($this->isSuccessful && $willUseEmailBundling && is_file("$bundleEmailFilePath/$bundleEmailFileName")) {
	 // STEP 1: USE ftruncate() TO TRUNCATE FILE SIZE TO 0 BYTES
 	 $fileID = @fopen("$bundleEmailFilePath/$bundleEmailFileName", 'a');	// SEE DOCUMENTATION NOTES ON 'a' APPEND MODE REQUIREMENT
	 if ($fileID) {
	  @ftruncate($fileID, 0);
	  @fclose($fileID);
	 }
	 if (file_get_contents("$bundleEmailFilePath/$bundleEmailFileName")) {	// CONTENT STILL FOUND - USE DEFAULT BUILT-IN 'w+' TRUNCATE
	  // STEP 2: USE BUILT-IN TRUNCATION METHOD FOUND WITHIN 'w+' READ/WRITE OPEN WITHIN fopen()
	  $fileID = @fopen("$bundleEmailFilePath/$bundleEmailFileName", 'w+');
	  @fclose($fileID);														// OPEN-AND-CLOSE
	 }
	 // STEP 3: USE OS-BASED COPYING SYSTEM TO COPY NULL DIRECTLY INTO FILE *** WARNING *** MIGHT CHANGE FILE "META" PROPERTIES
	 if (file_get_contents("$bundleEmailFilePath/$bundleEmailFileName") && @!copy("$bundleEmailFilePath/$bundleEmailFileName", $nullPath)) {
	  list($copyKommand, $copyRedirect) = @array_values($this->getKommandOSArray('copy'));
	  $msg = exec("$copyKommand $nullPath $bundleEmailFilePath/$bundleEmailFileName $copyRedirect");
	 }
	 // STEP 4: GIVE UP
	 if ($msg || file_get_contents("$bundleEmailFilePath/$bundleEmailFileName")) {	// CONTENT STILL FOUND - PROBLEM
	  $this->isSuccessful = false;
	  $this->setErrorArray(array('action' => "Could not rewrite file \"$bundleEmailFileName\" for clearing"));
	 }
	}
}

}

Phil

[sneakyimp]

excellent. i think your version of the code looks a lot better. any idea what the disappearing file problem was?

[ppowell]

I had to get an engineer to explain it to me and this is the best I could recollect:

When opening a file with fopen() with 'w' you are opening up a write stream. This ensures that the file may or may not exist; if not, it creates it, nonetheless, it truncates it to 0 bytes. Best I can recollect is that a write stream is not depending upon existence so if nothing is written it automagically just destroys the file since it doesn't allow for 0KB files to just float out there.

However, when using fopen() with 'w+' you are opening up a read/write 2-way stream. This means that while the file does not have to initially exist, it is then required to EVENTUALLY exist for the read portion of the stream to work, thus, even at 0KB it is still an existing file that could be read, thus, it keeps it around.

Phil

[sneakyimp]

hm...weird.

that code worked on my server (red hat / php 4.3.8). good to know for future reference i guess.