vsock/test: Adapt send_byte()/recv_byte() to handle MSG_ZEROCOPY

For a zerocopy send(), buffer (always byte 'A') needs to be preserved (thus
it can not be on the stack) or the data recv()ed check in recv_byte() might
fail.

While there, change the printf format to 0x%02x so the '\0' bytes can be
seen.

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Link: https://patch.msgid.link/20241219-test-vsock-leaks-v4-4-a416e554d9d7@rbox.co
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/tools/testing/vsock/util.c b/tools/testing/vsock/util.c
index 81b9a31059d8173a47ea87324da50e7aedd7308a..7058dc614c25f546fc3219d6b9ade2dcef21a9bd 100644 (file)
--- a/tools/testing/vsock/util.c
+++ b/tools/testing/vsock/util.c
@@ -401,7 +401,7 @@ void recv_buf(int fd, void *buf, size_t len, int flags, ssize_t expected_ret)
  */
 void send_byte(int fd, int expected_ret, int flags)
 {
-       const uint8_t byte = 'A';
+       static const uint8_t byte = 'A';
 
        send_buf(fd, &byte, sizeof(byte), flags, expected_ret);
 }
@@ -420,7 +420,7 @@ void recv_byte(int fd, int expected_ret, int flags)
        recv_buf(fd, &byte, sizeof(byte), flags, expected_ret);
 
        if (byte != 'A') {
-               fprintf(stderr, "unexpected byte read %c\n", byte);
+               fprintf(stderr, "unexpected byte read 0x%02x\n", byte);
                exit(EXIT_FAILURE);
        }
 }