[PATCH] selftests/memfd: Rename local union semun to avoid bionic clash

[Wake Liu <wakel@google.com>]

Commit b24335521de9 ("selftests/memfd: use IPC semaphore instead of
SIGSTOP/SIGCONT") added a local definition of union semun, since glibc
and musl expect the caller to define it before calling semctl().
Bionic, however, already defines union semun in <sys/sem.h>, so
memfd_test no longer builds against it:

  memfd_test.c:45:7: error: redefinition of 'semun'

Rename the local union to memfd_semun. Its layout is unchanged, so it
can still be passed as the variadic semctl() argument with any C
library.

Fixes: b24335521de9 ("selftests/memfd: use IPC semaphore instead of SIGSTOP/SIGCONT")
Signed-off-by: Wake Liu <wakel@google.com>
---
 tools/testing/selftests/memfd/memfd_test.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c
index cdab3a837624..188cb7c32db1 100644
--- a/tools/testing/selftests/memfd/memfd_test.c
+++ b/tools/testing/selftests/memfd/memfd_test.c
@@ -42,7 +42,13 @@
 		    F_SEAL_EXEC)
 
 #define MFD_NOEXEC_SEAL	0x0008U
-union semun {
+
+/*
+ * glibc and musl leave union semun for the caller to define, but bionic
+ * already provides it in <sys/sem.h>. Use a private name so the test
+ * builds against all of them.
+ */
+union memfd_semun {
 	int val;
 	struct semid_ds *buf;
 	unsigned short int *array;
@@ -1387,7 +1393,7 @@ static void test_sysctl_sysctl2_failset(void)
 static int sysctl_nested_child(void *arg)
 {
 	int pid, sem;
-	union semun semun;
+	union memfd_semun semun;
 	struct sembuf sembuf;
 
 	printf("%s nested sysctl 0\n", memfd_str);

base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
-- 
2.56.0.398.g882cbad275-goog