changes to locking to attempt to prevent races on read that might result in incomplete reads.

Author: arcfieldOSS

phpfastcache/3.0.0/abstract.php

@@ -280,10 +280,14 @@ protected function readfile($file) {
                 throw new Exception("Can't Read File",96);
 
             }
+            if (flock($file_handle, LOCK_SH | LOCK_NB)) {
             while (!feof($file_handle)) {
                 $line = fgets($file_handle);
                 $string .= $line;
             }
+            } else {
+                throw new Exception("Can't Read File",96);
+            }
             fclose($file_handle);
 
             return $string;

phpfastcache/3.0.0/drivers/files.php

@@ -70,6 +70,7 @@ private function getFilePath($keyword, $skip = false) {
 
     function driver_set($keyword, $value = "", $time = 300, $option = array() ) {
         $file_path = $this->getFilePath($keyword);
+        $tmp_path = $file_path . ".tmp";
       //  echo "<br>DEBUG SET: ".$keyword." - ".$value." - ".$time."<br>";
         $data = $this->encode($value);
 
@@ -86,11 +87,23 @@ function driver_set($keyword, $value = "", $time = 300, $option = array() ) {
             }
         }
 
-        if($toWrite == true) {
+        /*
+         * write to intent file to prevent race during read; race during write is ok
+         * because first-to-lock wins and the file will exist before the writer attempts
+         * to write.
+         */
+        if($toWrite == true && !@file_exists($tmp_path && !@file_exists($file_path))) {
                 try {
-                    $f = @fopen($file_path, "w+");
+                    $f = @fopen($tmp_path, "c");
+                    if (flock($f,LOCK_EX| LOCK_NB))  {
                     fwrite($f, $data);
+                        fflush($f);
+                        flock($f,LOCK_UN);
+                    } else {
+                        //arguably the file is being written to so the job is done
+                    }
                     fclose($f);
+                    @rename($tmp_path,$file_path);
                 } catch (Exception $e) {
                     // miss cache
                     return false;