On Tue, Jan 13, 2026 at 03:48:11PM +0100, Markus Elfring wrote:

…

quoted

+++ b/tools/testing/selftests/net/tfo.c

@@ -82,8 +82,10 @@ static void run_server(void)

…

quoted

 	if (read(connfd, buf, 64) < 0)
-		perror("read()");
-	fprintf(outfile, "%d\n", opt);
+		error(1, errno, "read()");
+
+	if (fprintf(outfile, "%d\n", opt) < 0)
+		error(1, errno, "fprintf()");
 
 	fclose(outfile);
 	close(connfd);

…

Why was error detection omitted for close() calls here so far?

Because I believe that checking the return value of fclose() would not
provide additional value in this test case, which is focused on testing
the behavior of passive TFO.

I understand that fclose() could fail there, but considering the
trade-off between test reliability and code complexity (which increases
review and maintenance costs), I think checking the return value there
does not provide benefits to justify the added complexity. In fact, as
far as I can see, none of the existing tests in selftests/net check the
fclose() return value.

Thank you,
Yohei

https://pubs.opengroup.org/onlinepubs/9799919799/functions/fclose.html

Regards,
Markus