[PATCH v3 4/4] test: add pcapng test for copy before open

Stephen Hemminger
2026-02-25T22:59:47Z

If packets are copied before open is called, the timestamps
will be before the start of epoch. Add a test for this which
makes sure pcapng file is still valid.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
app/test/test_pcapng.c | 82 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 82 insertions(+)

diff --git a/app/test/test_pcapng.c b/app/test/test_pcapng.c
index af31e7d996..69a8f44f1a 100644
--- a/app/test/test_pcapng.c
+++ b/app/test/test_pcapng.c
@@ -585,6 +585,87 @@ test_write_packets(void)
return -1;
}

+static int
+test_write_before_open(void)
+{
+ char file_name[PATH_MAX] = "/tmp/pcapng_test_XXXXXX.pcapng";
+ struct dummy_mbuf mbfs;
+ struct rte_mbuf *clones[MAX_BURST];
+ rte_pcapng_t *pcapng = NULL;
+ int ret, tmp_fd, i;
+ unsigned int count = 8;
+ uint64_t now;
+ ssize_t len;
+
+ mbuf1_prepare(&mbfs);
+ mbuf1_resize(&mbfs, rte_rand_max(MAX_DATA_SIZE));
+
+ /* Copy packets BEFORE opening the pcapng file.
+ * This exercises the negative TSC delta path in tsc_to_ns_epoch().
+ */
+ for (i = 0; i < (int)count; i++) {
+ clones[i] = rte_pcapng_copy(port_id, 0, &mbfs.mb[0], mp,
+ rte_pktmbuf_pkt_len(&mbfs.mb[0]),
+ RTE_PCAPNG_DIRECTION_IN, NULL);
+ if (clones[i] == NULL) {
+ fprintf(stderr, "Cannot copy packet before open\n");
+ rte_pktmbuf_free_bulk(clones, i);
+ return -1;
+ }
+ }
+
+ /* Small delay so fdopen's tsc_base is measurably after the copies */
+ rte_delay_us_block(100);
+
+ now = current_timestamp();
+
+ tmp_fd = mkstemps(file_name, strlen(".pcapng"));
+ if (tmp_fd == -1) {
+ perror("mkstemps() failure");
+ rte_pktmbuf_free_bulk(clones, count);
+ return -1;
+ }
+
+ pcapng = rte_pcapng_fdopen(tmp_fd, NULL, NULL, "pcapng_preopen", NULL);
+ if (pcapng == NULL) {
+ fprintf(stderr, "rte_pcapng_fdopen failed\n");
+ close(tmp_fd);
+ rte_pktmbuf_free_bulk(clones, count);
+ return -1;
+ }
+
+ ret = rte_pcapng_add_interface(pcapng, port_id, DLT_EN10MB,
+ NULL, NULL, NULL);
+ if (ret < 0) {
+ fprintf(stderr, "can not add port %u\n", port_id);
+ goto fail;
+ }
+
+ /* Write the pre-captured packets — timestamps precede tsc_base */
+ len = rte_pcapng_write_packets(pcapng, clones, count);
+ rte_pktmbuf_free_bulk(clones, count);
+ if (len <= 0) {
+ fprintf(stderr, "Write of pre-open packets failed: %s\n",
+ rte_strerror(rte_errno));
+ goto fail;
+ }
+
+ rte_pcapng_close(pcapng);
+
+ /* Validate the file is parseable — timestamps should be
+ * slightly before 'now' but still reasonable.
+ */
+ ret = valid_pcapng_file(file_name, now - NS_PER_S, count);
+ if (ret == 0)
+ remove(file_name);
+
+ return ret;
+
+fail:
+ rte_pcapng_close(pcapng);
+ return -1;
+}
+
static void
test_cleanup(void)
{
@@ -600,6 +681,7 @@ unit_test_suite test_pcapng_suite = {
.unit_test_cases = {
TEST_CASE(test_add_interface),
TEST_CASE(test_write_packets),
+ TEST_CASE(test_write_before_open),
TEST_CASES_END()
}
};
--
2.51.0