Allow setting the value of <input type="file"> to an empty string even in

untrusted script.  Bug 266744, r=sicking, sr=jst


git-svn-id: svn://10.0.0.236/trunk@164672 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/content/html/content/src/nsHTMLInputElement.cpp

@@ -639,8 +639,9 @@ nsHTMLInputElement::GetValue(nsAString& aValue)
 NS_IMETHODIMP 
 nsHTMLInputElement::SetValue(const nsAString& aValue)
 {
-  //check secuity
-  if (mType == NS_FORM_INPUT_FILE) {
+  // check security.  Note that setting the value to the empty string is always
+  // OK and gives pages a way to clear a file input if necessary.
+  if (mType == NS_FORM_INPUT_FILE && !aValue.IsEmpty()) {
     nsIScriptSecurityManager *securityManager =
       nsContentUtils::GetSecurityManager();