* Async open(<filename>)
*
* mode is a combination of the flags :
- * O_RDOLNY, O_WRONLY, O_RDWR , O_SYNC, O_APPEND
+ * O_RDOLNY, O_WRONLY, O_RDWR , O_SYNC, O_APPEND, O_TRUNC
*
* Function returns
* 0 : The operation was initiated. Once the operation finishes, the callback will be invoked.
* O_RDONLY
* O_WRONLY
* O_RDWR
+ * O_SYNC
* O_TRUNC (Only valid with O_RDWR or O_WRONLY. Ignored otherwise.)
*
* When the callback is invoked, status indicates the result: