basic: use _nonnull_if_nonzero_ where appropriate

src/basic/memfd-util.h

@@ -6,6 +6,8 @@
 #include <stdint.h>
 #include <sys/types.h>
 
+#include "macro.h"
+
 int memfd_create_wrapper(const char *name, unsigned mode);
 
 int memfd_new_full(const char *name, unsigned extra_flags);
@@ -13,7 +15,7 @@ static inline int memfd_new(const char *name) {
         return memfd_new_full(name, 0);
 }
 
-int memfd_new_and_seal(const char *name, const void *data, size_t sz);
+int memfd_new_and_seal(const char *name, const void *data, size_t sz) _nonnull_if_nonzero_(2, 3);
 static inline int memfd_new_and_seal_string(const char *name, const char *s) {
         return memfd_new_and_seal(name, s, SIZE_MAX);
 }