+/* Define C11 noreturn without <stdnoreturn.h> and even on older gcc
+ * compiler versions */
+#ifndef noreturn
+#if __STDC_VERSION__ >= 201112L
+#define noreturn _Noreturn
+#else
+#define noreturn __attribute__((noreturn))
+#endif
+#endif
+
+#define UID_INVALID ((uid_t) -1)
+#define GID_INVALID ((gid_t) -1)
+#define MODE_INVALID ((mode_t) -1)
+
+static inline bool UID_IS_INVALID(uid_t uid) {
+ /* We consider both the old 16bit -1 user and the newer 32bit
+ * -1 user invalid, since they are or used to be incompatible
+ * with syscalls such as setresuid() or chown(). */
+
+ return uid == (uid_t) ((uint32_t) -1) || uid == (uid_t) ((uint16_t) -1);
+}
+
+static inline bool GID_IS_INVALID(gid_t gid) {
+ return gid == (gid_t) ((uint32_t) -1) || gid == (gid_t) ((uint16_t) -1);
+}
+
+#define DEFINE_TRIVIAL_CLEANUP_FUNC(type, func) \
+ static inline void func##p(type *p) { \
+ if (*p) \
+ func(*p); \
+ } \
+ struct __useless_struct_to_allow_trailing_semicolon__
+
+#define CMSG_FOREACH(cmsg, mh) \
+ for ((cmsg) = CMSG_FIRSTHDR(mh); (cmsg); (cmsg) = CMSG_NXTHDR((mh), (cmsg)))
+