libthr: add stable user interface for sigfastblock(2)

Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D50377

include/pthread_np.h

@@ -59,6 +59,8 @@ int pthread_resume_np(pthread_t);
 int pthread_peekjoin_np(pthread_t, void **);
 void pthread_set_name_np(pthread_t, const char *);
 int pthread_setaffinity_np(pthread_t, size_t, const cpuset_t *);
+void pthread_signals_block_np(void);
+void pthread_signals_unblock_np(void);
 int pthread_single_np(void);
 void pthread_suspend_all_np(void);
 int pthread_suspend_np(pthread_t);

lib/libthr/pthread.map

@@ -339,5 +339,7 @@ FBSD_1.6 {
 };
 
 FBSD_1.8 {
+	 pthread_signals_block_np;
+	 pthread_signals_unblock_np;
 	 pthread_sigqueue;
 };

lib/libthr/thread/thr_sig.c

@@ -37,6 +37,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <pthread.h>
+#include <pthread_np.h>
 #include "un-namespace.h"
 #include "libc_private.h"
 
@@ -163,6 +164,24 @@ _thr_signal_block_setup(struct pthread *curthread)
 	__sys_sigfastblock(SIGFASTBLOCK_SETPTR, &curthread->fsigblock);
 }
 
+void
+pthread_signals_block_np(void)
+{
+	struct pthread *curthread;
+
+	curthread = _get_curthread();
+	_thr_signal_block(curthread);
+}
+
+void
+pthread_signals_unblock_np(void)
+{
+	struct pthread *curthread;
+
+	curthread = _get_curthread();
+	_thr_signal_unblock(curthread);
+}
+
 int
 _thr_send_sig(struct pthread *thread, int sig)
 {