+
+/**
+ * Split I/O buffer
+ *
+ * @v iobuf I/O buffer
+ * @v len Length to split into a new I/O buffer
+ * @ret split New I/O buffer, or NULL on allocation failure
+ *
+ * Split the first @c len bytes of the existing I/O buffer into a
+ * separate I/O buffer. The resulting buffers are likely to have no
+ * headroom or tailroom.
+ *
+ * If this call fails, then the original buffer will be unmodified.
+ */
+struct io_buffer * iob_split ( struct io_buffer *iobuf, size_t len ) {
+ struct io_buffer *split;
+
+ /* Sanity checks */
+ assert ( len <= iob_len ( iobuf ) );
+
+ /* Allocate new I/O buffer */
+ split = alloc_iob ( len );
+ if ( ! split )
+ return NULL;
+
+ /* Copy in data */
+ memcpy ( iob_put ( split, len ), iobuf->data, len );
+ iob_pull ( iobuf, len );
+ return split;
+}