+ * @internal used by rte_pktmbuf_read().
+ */
+const void *__rte_pktmbuf_read(const struct rte_mbuf *m, uint32_t off,
+ uint32_t len, void *buf);
+
+/**
+ * Read len data bytes in a mbuf at specified offset.
+ *
+ * If the data is contiguous, return the pointer in the mbuf data, else
+ * copy the data in the buffer provided by the user and return its
+ * pointer.
+ *
+ * @param m
+ * The pointer to the mbuf.
+ * @param off
+ * The offset of the data in the mbuf.
+ * @param len
+ * The amount of bytes to read.
+ * @param buf
+ * The buffer where data is copied if it is not contigous in mbuf
+ * data. Its length should be at least equal to the len parameter.
+ * @return
+ * The pointer to the data, either in the mbuf if it is contiguous,
+ * or in the user buffer. If mbuf is too small, NULL is returned.
+ */
+static inline const void *rte_pktmbuf_read(const struct rte_mbuf *m,
+ uint32_t off, uint32_t len, void *buf)
+{
+ if (likely(off + len <= rte_pktmbuf_data_len(m)))
+ return rte_pktmbuf_mtod_offset(m, char *, off);
+ else
+ return __rte_pktmbuf_read(m, off, len, buf);
+}
+
+/**
+ * Chain an mbuf to another, thereby creating a segmented packet.
+ *
+ * Note: The implementation will do a linear walk over the segments to find
+ * the tail entry. For cases when there are many segments, it's better to
+ * chain the entries manually.
+ *
+ * @param head
+ * The head of the mbuf chain (the first packet)
+ * @param tail
+ * The mbuf to put last in the chain
+ *
+ * @return
+ * - 0, on success.
+ * - -EOVERFLOW, if the chain is full (256 entries)
+ */
+static inline int rte_pktmbuf_chain(struct rte_mbuf *head, struct rte_mbuf *tail)
+{
+ struct rte_mbuf *cur_tail;
+
+ /* Check for number-of-segments-overflow */
+ if (head->nb_segs + tail->nb_segs >= 1 << (sizeof(head->nb_segs) * 8))
+ return -EOVERFLOW;
+
+ /* Chain 'tail' onto the old tail */
+ cur_tail = rte_pktmbuf_lastseg(head);
+ cur_tail->next = tail;
+
+ /* accumulate number of segments and total length. */
+ head->nb_segs = (uint8_t)(head->nb_segs + tail->nb_segs);
+ head->pkt_len += tail->pkt_len;
+
+ /* pkt_len is only set in the head */
+ tail->pkt_len = tail->data_len;
+
+ return 0;
+}
+
+/**
+ * Dump an mbuf structure to a file.