bugfix Smarty_Internal_Write_File::writeFile() could cause race-conditions on linux systems (Issue 101)

change_log.txt

@@ -1,4 +1,7 @@
 ===== trunk  =====
+24.05.2012
+- bugfix Smarty_Internal_Write_File::writeFile() could cause race-conditions on linux systems (Issue 101)
+
 22.05.2012
 - bugfix recursive {include} within {section} did fail (Smarty developer group)
 

libs/Smarty.class.php

@@ -190,6 +190,10 @@ class Smarty extends Smarty_Internal_TemplateBase {
      */
     public static $_UTF8_MODIFIER = 'u';
     
+    /**
+     * Flag denoting if operating system is windows
+     */
+    public static $_IS_WINDOWS = false;
     
     /**#@+
      * variables
@@ -1464,6 +1468,9 @@ class Smarty extends Smarty_Internal_TemplateBase {
     }
 }
 
+// Check if we're running on windows
+Smarty::$_IS_WINDOWS = strtoupper(substr(PHP_OS, 0, 3)) === 'WIN';
+
 // let PCRE (preg_*) treat strings as ISO-8859-1 if we're not dealing with UTF-8
 if (Smarty::$_CHARSET !== 'UTF-8') {
     Smarty::$_UTF8_MODIFIER = '';

libs/sysplugins/smarty_internal_write_file.php

@@ -44,12 +44,30 @@ class Smarty_Internal_Write_File {
             throw new SmartyException("unable to write file {$_tmp_file}");
             return false;
         }
+        
+        /*
+         * Windows' rename() fails if the destination exists,
+         * Linux' rename() properly handles the overwrite.
+         * Simply unlink()ing a file might cause other processes 
+         * currently reading that file to fail, but linux' rename()
+         * seems to be smart enough to handle that for us.
+         */
+        if (Smarty::$_IS_WINDOWS) {
+            // remove original file
+            @unlink($_filepath);
+            // rename tmp file
+            $success = @rename($_tmp_file, $_filepath);
+        } else {
+            // rename tmp file
+            $success = @rename($_tmp_file, $_filepath);
+            if (!$success) {
+                // remove original file
+                @unlink($_filepath);
+                // rename tmp file
+                $success = @rename($_tmp_file, $_filepath);
+            }
+        }
 
-        // remove original file
-        @unlink($_filepath);
-
-        // rename tmp file
-        $success = rename($_tmp_file, $_filepath);
         if (!$success) {
             error_reporting($_error_reporting);
             throw new SmartyException("unable to write file {$_filepath}");