/*
* Async open(<filename>)
*
- * mode is a combination of the flags : O_RDOLNY, O_WRONLY, O_RDWR , O_SYNC
+ * mode is a combination of the flags :
+ * O_RDOLNY, O_WRONLY, O_RDWR , O_SYNC, O_APPEND
*
* Function returns
* 0 : The operation was initiated. Once the operation finishes, the callback will be invoked.
* <0 : An error occured when trying to set up the operation. The callback will not be invoked.
*
* Supported flags are
+ * O_APPEND
* O_RDONLY
* O_WRONLY
* O_RDWR