+/* Set all deferrable signals into *s. */
+extern void sigaddset_deferrable(sigset_t *s);
+/* Set all blockable signals into *s. */
+extern void sigaddset_blockable(sigset_t *s);
+/* Set all gc signals into *s. */
+extern void sigaddset_gc(sigset_t *s);
+
+extern sigset_t deferrable_sigset;
+extern sigset_t blockable_sigset;
+extern sigset_t gc_sigset;
+
+extern void block_deferrable_signals(void);
+extern void block_blockable_signals(void);
+extern void unblock_deferrable_signals(void);
+extern void unblock_gc_signals(void);
+extern void unblock_signals_in_context_and_maybe_warn(os_context_t *context);
+
+extern boolean deferrables_blocked_in_sigset_p(sigset_t *sigset);
+extern void check_deferrables_blocked_or_lose(void);
+extern void check_blockables_blocked_or_lose(void);
+extern void check_gc_signals_unblocked_or_lose(void);
+extern void check_gc_signals_unblocked_in_sigset_or_lose(sigset_t *sigset);
+
+extern void maybe_save_gc_mask_and_block_deferrables(sigset_t *sigset);