[LTP] [PATCH v2 1/2] syscalls/pidfd_open01.c: Add check for close-on-exec flag

[Xiao Yang]

pidfd_open(2) will set close-on-exec flag on the file descriptor as it
manpage states, so check close-on-exec flag by fcntl(2).

BTW:
I tried to pass (long) TST_RET to fcntl() but triggered the following
compiler warning, so pass (int) pidfd instead.
------------------------------------------------------
In file included from pidfd_open01.c:9:
pidfd_open01.c: In function ‘run’:
../../../../include/tst_test.h:76:41: warning: format ‘%i’ expects argument of type ‘int’, but argument 5 has type ‘long int’ [-Wformat=]
   76 |   tst_brk_(__FILE__, __LINE__, (ttype), (arg_fmt), ##__VA_ARGS__);\
      |                                         ^~~~~~~~~
../../../../include/tst_safe_macros.h:224:5: note: in expansion of macro ‘tst_brk’
  224 |     tst_brk(TBROK | TERRNO,                          \
      |     ^~~~~~~
pidfd_open01.c:20:9: note: in expansion of macro ‘SAFE_FCNTL’
   20 |  flag = SAFE_FCNTL(TST_RET, F_GETFD);
------------------------------------------------------

Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 testcases/kernel/syscalls/pidfd_open/pidfd_open01.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/testcases/kernel/syscalls/pidfd_open/pidfd_open01.c b/testcases/kernel/syscalls/pidfd_open/pidfd_open01.c
index 93bb86687..ba1580bc7 100644
--- a/testcases/kernel/syscalls/pidfd_open/pidfd_open01.c
+++ b/testcases/kernel/syscalls/pidfd_open/pidfd_open01.c
@@ -11,13 +11,20 @@
 
 static void run(void)
 {
-	TEST(pidfd_open(getpid(), 0));
+	int pidfd, flag;
+
+	TEST(pidfd = pidfd_open(getpid(), 0));
 
 	if (TST_RET == -1)
 		tst_brk(TFAIL | TTERRNO, "pidfd_open(getpid(), 0) failed");
 
+	flag = SAFE_FCNTL(pidfd, F_GETFD);
+
 	SAFE_CLOSE(TST_RET);
 
+	if (!(flag & FD_CLOEXEC))
+		tst_brk(TFAIL, "pidfd_open(getpid(), 0) didn't set close-on-exec flag");
+
 	tst_res(TPASS, "pidfd_open(getpid(), 0) passed");
 }
 
-- 
2.21.0