runtime: unblock signals when we try to core dump

Fixes #6988.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/44070046

src/pkg/runtime/os_darwin.c

@@ -517,3 +517,9 @@ runtime·signalstack(byte *p, int32 n)
 		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
+
+void
+runtime·unblocksignals(void)
+{
+	runtime·sigprocmask(SIG_SETMASK, &sigset_none, nil);
+}

src/pkg/runtime/os_darwin.h

@@ -23,6 +23,7 @@ int32	runtime·sysctl(uint32*, uint32, byte*, uintptr*, byte*, uintptr);
 
 typedef uint32 Sigset;
 void	runtime·sigprocmask(int32, Sigset*, Sigset*);
+void	runtime·unblocksignals(void);
 
 struct Sigaction;
 void	runtime·sigaction(uintptr, struct Sigaction*, struct Sigaction*);
@@ -39,4 +40,3 @@ void	runtime·setitimer(int32, Itimerval*, Itimerval*);
 #define	SIG_BLOCK 1
 #define	SIG_UNBLOCK 2
 #define	SIG_SETMASK 3
-

src/pkg/runtime/os_dragonfly.c

@@ -280,3 +280,9 @@ runtime·signalstack(byte *p, int32 n)
 		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
+
+void
+runtime·unblocksignals(void)
+{
+	runtime·sigprocmask(&sigset_none, nil);
+}

src/pkg/runtime/os_dragonfly.h

@@ -12,6 +12,7 @@ void	runtime·sigaltstack(Sigaltstack*, Sigaltstack*);
 struct	sigaction;
 void	runtime·sigaction(int32, struct sigaction*, struct sigaction*);
 void	runtime·sigprocmask(Sigset *, Sigset *);
+void	runtime·unblocksignals(void);
 void	runtime·setitimer(int32, Itimerval*, Itimerval*);
 int32	runtime·sysctl(uint32*, uint32, byte*, uintptr*, byte*, uintptr);
 

src/pkg/runtime/os_freebsd.c

@@ -288,3 +288,9 @@ runtime·signalstack(byte *p, int32 n)
 		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
+
+void
+runtime·unblocksignals(void)
+{
+	runtime·sigprocmask(&sigset_none, nil);
+}

src/pkg/runtime/os_freebsd.h

@@ -12,6 +12,7 @@ void	runtime·sigaltstack(Sigaltstack*, Sigaltstack*);
 struct	sigaction;
 void	runtime·sigaction(int32, struct sigaction*, struct sigaction*);
 void	runtime·sigprocmask(Sigset *, Sigset *);
+void	runtime·unblocksignals(void);
 void	runtime·setitimer(int32, Itimerval*, Itimerval*);
 int32	runtime·sysctl(uint32*, uint32, byte*, uintptr*, byte*, uintptr);
 

src/pkg/runtime/os_linux.c

@@ -331,3 +331,9 @@ runtime·signalstack(byte *p, int32 n)
 		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
+
+void
+runtime·unblocksignals(void)
+{
+	runtime·rtsigprocmask(SIG_SETMASK, &sigset_none, nil, sizeof sigset_none);
+}

src/pkg/runtime/os_linux.h

@@ -28,6 +28,7 @@ struct Sigset
 	uint32 mask[2];
 };
 void	runtime·rtsigprocmask(int32, Sigset*, Sigset*, int32);
+void	runtime·unblocksignals(void);
 #define SIG_SETMASK 2
 
 #define RLIMIT_AS 9

src/pkg/runtime/os_netbsd.c

@@ -326,3 +326,9 @@ runtime·signalstack(byte *p, int32 n)
 		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
+
+void
+runtime·unblocksignals(void)
+{
+	runtime·sigprocmask(SIG_SETMASK, &sigset_none, nil);
+}

src/pkg/runtime/os_netbsd.h

@@ -18,6 +18,7 @@ void	runtime·setitimer(int32, Itimerval*, Itimerval*);
 void	runtime·sigaction(int32, struct sigaction*, struct sigaction*);
 void	runtime·sigaltstack(Sigaltstack*, Sigaltstack*);
 void	runtime·sigprocmask(int32, Sigset*, Sigset*);
+void	runtime·unblocksignals(void);
 int32	runtime·sysctl(uint32*, uint32, byte*, uintptr*, byte*, uintptr);
 extern void runtime·lwp_tramp(void);
 

src/pkg/runtime/os_openbsd.c

@@ -300,3 +300,9 @@ runtime·signalstack(byte *p, int32 n)
 		st.ss_flags = SS_DISABLE;
 	runtime·sigaltstack(&st, nil);
 }
+
+void
+runtime·unblocksignals(void)
+{
+	runtime·sigprocmask(SIG_SETMASK, &sigset_none);
+}

src/pkg/runtime/os_openbsd.h

@@ -18,6 +18,7 @@ void	runtime·setitimer(int32, Itimerval*, Itimerval*);
 void	runtime·sigaction(int32, struct sigaction*, struct sigaction*);
 void	runtime·sigaltstack(Sigaltstack*, Sigaltstack*);
 Sigset	runtime·sigprocmask(int32, Sigset);
+void	runtime·unblocksignals(void);
 int32	runtime·sysctl(uint32*, uint32, byte*, uintptr*, byte*, uintptr);
 
 #define	NSIG 33

src/pkg/runtime/signal_unix.c

@@ -113,6 +113,7 @@ runtime·crash(void)
 		return;
 #endif
 
+	runtime·unblocksignals();
 	runtime·setsig(SIGABRT, SIG_DFL, false);
 	runtime·raise(SIGABRT);
 }