+
+unsigned long cap_last_cap(void) {
+ static __thread unsigned long saved;
+ static __thread bool valid = false;
+ unsigned long p;
+
+ if (valid)
+ return saved;
+
+ p = (unsigned long) CAP_LAST_CAP;
+
+ if (prctl(PR_CAPBSET_READ, p) < 0) {
+
+ /* Hmm, look downwards, until we find one that
+ * works */
+ for (p--; p > 0; p --)
+ if (prctl(PR_CAPBSET_READ, p) >= 0)
+ break;
+
+ } else {
+
+ /* Hmm, look upwards, until we find one that doesn't
+ * work */
+ for (;; p++)
+ if (prctl(PR_CAPBSET_READ, p+1) < 0)
+ break;
+ }
+
+ saved = p;
+ valid = true;
+
+ return p;
+}