[PATCH v3 4/4] selftests: add a test for bpf_prog_test_run_xattr

[Lorenz Bauer]

Make sure that bpf_prog_test_run_xattr returns the correct length
and that the kernel respects the output size hint. Also check
that errno indicates ENOSPC if there is a short output buffer given.

Signed-off-by: Lorenz Bauer <l...@cloudflare.com>
---
 tools/testing/selftests/bpf/test_progs.c | 49 ++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/tools/testing/selftests/bpf/test_progs.c 
b/tools/testing/selftests/bpf/test_progs.c
index c1e688f61061..f9f5b1dbcc83 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -124,6 +124,54 @@ static void test_pkt_access(void)
        bpf_object__close(obj);
 }
 
+static void test_prog_run_xattr(void)
+{
+       const char *file = "./test_pkt_access.o";
+       __u32 duration, retval, size_out;
+       struct bpf_object *obj;
+       char buf[10];
+       int err;
+       struct bpf_prog_test_run_attr tattr = {
+               .repeat = 1,
+               .data = &pkt_v4,
+               .size = sizeof(pkt_v4),
+               .data_out = buf,
+               .size_out = 5,
+       };
+
+       err = bpf_prog_load(file, BPF_PROG_TYPE_SCHED_CLS, &obj,
+                           &tattr.prog_fd);
+       if (CHECK(err, "load", "err %d errno %d\n", err, errno))
+               return;
+
+       memset(buf, 0, sizeof(buf));
+
+       err = bpf_prog_test_run_xattr(&tattr, &size_out, &retval, &duration);
+       CHECK(err != -1 || errno != ENOSPC || retval, "run",
+             "err %d errno %d retval %d\n", err, errno, retval);
+
+       CHECK(size_out != sizeof(pkt_v4), "output_size",
+             "incorrect output size, want %lu have %u\n",
+             sizeof(pkt_v4), size_out);
+
+       CHECK(buf[5] != 0, "overflow",
+             "BPF_PROG_TEST_RUN ignored size hint\n");
+
+       tattr.data_out = NULL;
+       tattr.size_out = 0;
+       errno = 0;
+
+       err = bpf_prog_test_run_xattr(&tattr, NULL, &retval, &duration);
+       CHECK(err || errno || retval, "run_no_output",
+             "err %d errno %d retval %d\n", err, errno, retval);
+
+       tattr.size_out = 1;
+       err = bpf_prog_test_run_xattr(&tattr, NULL, NULL, &duration);
+       CHECK(err != -EINVAL, "run_wrong_size_out", "err %d\n", err);
+
+       bpf_object__close(obj);
+}
+
 static void test_xdp(void)
 {
        struct vip key4 = {.protocol = 6, .family = AF_INET};
@@ -1837,6 +1885,7 @@ int main(void)
        jit_enabled = is_jit_enabled();
 
        test_pkt_access();
+       test_prog_run_xattr();
        test_xdp();
        test_xdp_adjust_tail();
        test_l4lb_all();
-- 
2.17.1