Starts an IO buffer reader.
INKIOBufferBlock INKIOBufferReaderStart
(INKIOBufferReader
readerp)
Gets the read start block for the IO buffer reader.
INKIOBufferReaderStart may return
NULL if there is no data available for reading; it
may also return an IO buffer block with no data available for
reading. You should check for both conditions.
The read start block for the IO buffer reader.
INK_ERROR_PTR if an error occurs.