-/* The following macros add 1 when converting things, since UID 0 is a
- * valid UID, while the pointer NULL is special */
+/* Let's pick a UIDs within the 16bit range, so that we are compatible with containers using 16bit
+ * user namespacing. At least on Fedora normal users are allocated until UID 60000, hence do not
+ * allocate from below this. Also stay away from the upper end of the range as that is often used
+ * for overflow/nobody users. */
+#define DYNAMIC_UID_MIN ((uid_t) UINT32_C(0x0000EF00))
+#define DYNAMIC_UID_MAX ((uid_t) UINT32_C(0x0000FFEF))
+
+static inline bool uid_is_dynamic(uid_t uid) {
+ return DYNAMIC_UID_MIN <= uid && uid <= DYNAMIC_UID_MAX;
+}
+
+/* The following macros add 1 when converting things, since UID 0 is a valid UID, while the pointer
+ * NULL is special */