[dpdk-dev] [PATCH 4/5] mbuf: new helper to copy data from a mbuf

[Olivier Matz <olivier.matz@6wind.com>]

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---
 app/test/test_mbuf.c       |  7 +++++++
 lib/librte_mbuf/rte_mbuf.h | 32 +++++++++++++++++++++++++++++++-
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/app/test/test_mbuf.c b/app/test/test_mbuf.c
index 5f1bc5d..73fd7df 100644
--- a/app/test/test_mbuf.c
+++ b/app/test/test_mbuf.c
@@ -451,6 +451,13 @@ testclone_testupdate_testdetach(void)
 		GOTO_FAIL("invalid data");
 	if (data != check_data)
 		GOTO_FAIL("data should have been copied");
+	if (rte_pktmbuf_read_copy(m2, 0, sizeof(uint32_t), check_data) < 0)
+		GOTO_FAIL("cannot copy data");
+	if (check_data[0] != MAGIC_DATA)
+		GOTO_FAIL("invalid data");
+	if (data != check_data)
+		GOTO_FAIL("data should have been copied");
+
 	/* free mbuf */
 	rte_pktmbuf_free(m);
 	m = NULL;
diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index e898d25..edae89f 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -1643,7 +1643,7 @@ static inline int rte_pktmbuf_data_is_shared(const struct rte_mbuf *m,
 }
 
 /**
- * @internal used by rte_pktmbuf_read().
+ * @internal used by rte_pktmbuf_read() and rte_pktmbuf_read_copy().
  */
 void *__rte_pktmbuf_read(const struct rte_mbuf *m, uint32_t off,
 	uint32_t len, void *buf);
@@ -1728,6 +1728,36 @@ static inline int rte_pktmbuf_write(const struct rte_mbuf *m,
 }
 
 /**
+ * Copy data from a mbuf into a linear buffer
+ *
+ * @param m
+ *   The pointer to the mbuf.
+ * @param off
+ *   The offset of the data in the mbuf.
+ * @param len
+ *   The amount of bytes to copy.
+ * @param buf
+ *   The buffer where data is copied, it should be at least
+ *   as large as len.
+ * @return
+ *   - (0) on success
+ *   - (-1) on error: mbuf is too small
+ */
+static inline int rte_pktmbuf_read_copy(const struct rte_mbuf *m,
+	uint32_t off, uint32_t len, void *buf)
+{
+	if (likely(off + len <= rte_pktmbuf_data_len(m))) {
+		rte_memcpy(buf, rte_pktmbuf_mtod_offset(m, char *, off), len);
+		return 0;
+	}
+
+	if (__rte_pktmbuf_read(m, off, len, buf) == NULL)
+		return -1;
+
+	return 0;
+}
+
+/**
  * Chain an mbuf to another, thereby creating a segmented packet.
  *
  * Note: The implementation will do a linear walk over the segments to find
-- 
2.8.1