[Msan] Fix the shmctl unit tests to pass on FreeBSD

[samsonov]

LGTM

lib/msan/tests/msan_test.cc

 #include "msan_test_config.h"
 #endif // MSAN_EXTERNAL_TEST_CONFIG
 
 #include "sanitizer_common/tests/sanitizer_test_utils.h"
 
 #include "sanitizer/allocator_interface.h"
 #include "sanitizer/msan_interface.h"
 
+#if defined(__FreeBSD__)
+# define _KERNEL  // To declare 'shminfo' structure.
+# include <sys/shm.h>
+# undef _KERNEL
+extern "C" {
+// <sys/shm.h> doesn't declare these functions in _KERNEL mode.
+void *shmat(int, const void *, int);
+int shmget(key_t, size_t, int);
+int shmctl(int, int, struct shmid_ds *);
+int shmdt(const void *);
+}
+#endif
+
 #include <inttypes.h>
 #include <stdlib.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <wchar.h>
 #include <math.h>
 
 #include <arpa/inet.h>
TEST(MemorySanitizer, shmctl) {
   int id = shmget(IPC_PRIVATE, 4096, 0644 | IPC_CREAT);
   ASSERT_GT(id, -1);
 
   struct shmid_ds ds;
   int res = shmctl(id, IPC_STAT, &ds);
   ASSERT_GT(res, -1);
   EXPECT_NOT_POISONED(ds);
 
+  // FreeBSD does not support shmctl(IPC_INFO) and shmctl(SHM_INFO).
+#if !defined(__FreeBSD__)
   struct shminfo si;
   res = shmctl(id, IPC_INFO, (struct shmid_ds *)&si);
   ASSERT_GT(res, -1);
   EXPECT_NOT_POISONED(si);
 
   struct shm_info s_i;
   res = shmctl(id, SHM_INFO, (struct shmid_ds *)&s_i);
   ASSERT_GT(res, -1);
   EXPECT_NOT_POISONED(s_i);
+#endif
 
   res = shmctl(id, IPC_RMID, 0);
   ASSERT_GT(res, -1);
 }
 
 TEST(MemorySanitizer, shmat) {
   void *p = mmap(NULL, 4096, PROT_READ | PROT_WRITE,
                  MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);