[LTP] [PATCH 3/3] syscalls: select: Verify that data is available to read

[Viresh Kumar]

select() returns a positive value on success if timeout hasn't happened,
else returns 0. Check that and send some data to the write file
descriptor for the same.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

---
Cyril,

Is this what you were looking for ? I am not sure why, but the last
test (with named pipe) times out all the time.
---
 testcases/kernel/syscalls/select/select01.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/testcases/kernel/syscalls/select/select01.c b/testcases/kernel/syscalls/select/select01.c
index 4367e7f3af3f..b3dcf1fff6f3 100644
--- a/testcases/kernel/syscalls/select/select01.c
+++ b/testcases/kernel/syscalls/select/select01.c
@@ -25,24 +25,31 @@ static struct select_info {
 	int nfds;
 	fd_set *readfds;
 	fd_set *writefds;
+	int *writefd;
 } tests[] = {
-	{4, &readfds_reg, NULL},
-	{5, &readfds_pipe, &writefds_pipe},
-	{5, &readfds_npipe, &writefds_npipe},
+	{4, &readfds_reg, NULL, NULL},
+	{5, &readfds_pipe, &writefds_pipe, &fds_pipe[1]},
+	{5, &readfds_npipe, &writefds_npipe, &fd_npipe},
 };
 
 static void run(unsigned int n)
 {
 	struct select_info *tc = &tests[n];
 	struct timeval timeout;
+	char buf;
 
 	timeout.tv_sec = 0;
 	timeout.tv_usec = 100000;
 
+	if (tc->writefd)
+		SAFE_WRITE(0, *tc->writefd, &buf, sizeof(buf));
+
 	TEST(do_select(tc->nfds, tc->readfds, tc->writefds, 0, &timeout));
 
 	if (TST_RET == -1)
 		tst_res(TFAIL | TTERRNO, "select() failed");
+	else if (!TST_RET)
+		tst_res(TFAIL, "select() timed out");
 	else
 		tst_res(TPASS, "select() passed");
 }
-- 
2.25.0.rc1.19.g042ed3e048af