Merge branch 'egil/20/erts/signal-service/OTP-14186'

* egil/20/erts/signal-service/OTP-14186:
  kernel: Document signal server
  erts: Use os module instead of erts_internal for set_signal/2
  erts: Do not handle SIGILL
  erts: Fix thread suspend in crashdump
  erts: Do not enable SIGINT
  erts: Use generic signal handler
  erts: Add OS signal tests
  erts: Handle SIGUSR1 via signal service instead
  erts: Handle SIGTERM via signal service instead
  kernel: Add gen_event signal server and default handler
  erts: Add SIGHUP signal handler
  erts: Remove whitespace errors

Conflicts:
	erts/emulator/beam/bif.tab

14 files changed, 650 insertions, 242 deletions

diff --git a/erts/emulator/beam/atom.names b/erts/emulator/beam/atom.names
index dd0a42b5ba..1efe5fe300 100644
--- a/erts/emulator/beam/atom.names
+++ b/erts/emulator/beam/atom.names
@@ -195,6 +195,7 @@ atom current_stacktrace
 atom data
 atom debug_flags
 atom decimals
+atom default
 atom delay_trap
 atom dexit
 atom depth
@@ -245,6 +246,7 @@ atom Eq='=:='
 atom Eqeq='=='
 atom erl_tracer
 atom erlang
+atom erl_signal_server
 atom ERROR='ERROR'
 atom error_handler
 atom error_logger
@@ -312,6 +314,7 @@ atom global
 atom Gt='>'
 atom grun
 atom group_leader
+atom handle
 atom have_dt_utag
 atom heap_block_size
 atom heap_size
@@ -572,7 +575,7 @@ atom running_procs
 atom runtime
 atom safe
 atom save_calls
-atom scheduler 
+atom scheduler
 atom scheduler_id
 atom scheduler_wall_time
 atom scheduler_wall_time_all
@@ -600,6 +603,19 @@ atom set_tcw
 atom set_tcw_fake
 atom separate
 atom shared
+atom sighup
+atom sigterm
+atom sigusr1
+atom sigusr2
+atom sigill
+atom sigchld
+atom sigabrt
+atom sigalrm
+atom sigstop
+atom sigint
+atom sigsegv
+atom sigtstp
+atom sigquit
 atom silent
 atom size
 atom sl_alloc
diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index c35002cf06..a2d2433ed8 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -5555,12 +5555,10 @@ BIF_RETTYPE dt_restore_tag_1(BIF_ALIST_1)
 	    SEQ_TRACE_TOKEN(BIF_P) = am_have_dt_utag;
 	}
     }
-#else    
+#else
     if (BIF_ARG_1 != am_true) {
 	BIF_ERROR(BIF_P,BADARG);
     }
 #endif
     BIF_RET(am_true);
 }
-
-
diff --git a/erts/emulator/beam/bif.tab b/erts/emulator/beam/bif.tab
index 476c4b9632..a6510ace81 100644
--- a/erts/emulator/beam/bif.tab
+++ b/erts/emulator/beam/bif.tab
@@ -670,3 +670,4 @@ gcbif erlang:ceil/1
 bif math:floor/1
 bif math:ceil/1
 bif math:fmod/2
+bif os:set_signal/2
diff --git a/erts/emulator/beam/erl_bif_os.c b/erts/emulator/beam/erl_bif_os.c
index 46777d3aa5..edc3c82b23 100644
--- a/erts/emulator/beam/erl_bif_os.c
+++ b/erts/emulator/beam/erl_bif_os.c
@@ -203,3 +203,17 @@ BIF_RETTYPE os_unsetenv_1(BIF_ALIST_1)
     }
     BIF_RET(am_true);
 }
+
+BIF_RETTYPE os_set_signal_2(BIF_ALIST_2) {
+    if (is_atom(BIF_ARG_1) && ((BIF_ARG_2 == am_ignore) ||
+                               (BIF_ARG_2 == am_default) ||
+                               (BIF_ARG_2 == am_handle))) {
+        if (!erts_set_signal(BIF_ARG_1, BIF_ARG_2))
+            goto error;
+
+        BIF_RET(am_ok);
+    }
+
+error:
+    BIF_ERROR(BIF_P, BADARG);
+}
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index b6568e85ea..bc15f2a6f1 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -1077,6 +1077,9 @@ void print_process_info(fmtfn_t, void *, Process*);
 void info(fmtfn_t, void *);
 void loaded(fmtfn_t, void *);
 
+/* sighandler sys.c */
+int erts_set_signal(Eterm signal, Eterm type);
+
 /* erl_arith.c */
 double erts_get_positive_zero_float(void);
 
diff --git a/erts/emulator/beam/register.c b/erts/emulator/beam/register.c
index acda51c9fc..7f60710124 100644
--- a/erts/emulator/beam/register.c
+++ b/erts/emulator/beam/register.c
@@ -272,13 +272,13 @@ erts_whereis_name_to_id(Process *c_p, Eterm name)
     int ix;
     HashBucket* b;
 #ifdef ERTS_SMP
-    ErtsProcLocks c_p_locks = c_p ? ERTS_PROC_LOCK_MAIN : 0;
-
-#ifdef ERTS_ENABLE_LOCK_CHECK
-    if (c_p) ERTS_SMP_CHK_HAVE_ONLY_MAIN_PROC_LOCK(c_p);
-#endif
-
+    ErtsProcLocks c_p_locks = 0;
+    if (c_p) {
+        c_p_locks = ERTS_PROC_LOCK_MAIN;
+        ERTS_SMP_CHK_HAVE_ONLY_MAIN_PROC_LOCK(c_p);
+    }
     reg_safe_read_lock(c_p, &c_p_locks);
+
     if (c_p && !c_p_locks)
         erts_smp_proc_lock(c_p, ERTS_PROC_LOCK_MAIN);
 #endif
diff --git a/erts/emulator/beam/sys.h b/erts/emulator/beam/sys.h
index 14b8a5950d..a11fb16b39 100644
--- a/erts/emulator/beam/sys.h
+++ b/erts/emulator/beam/sys.h
@@ -487,20 +487,6 @@ extern volatile int erts_break_requested;
 void erts_do_break_handling(void);
 #endif
 
-#ifdef ERTS_WANT_GOT_SIGUSR1
-#  ifndef UNIX
-#    define ERTS_GOT_SIGUSR1 0
-#  else
-#    ifdef ERTS_SMP
-extern erts_smp_atomic32_t erts_got_sigusr1;
-#      define ERTS_GOT_SIGUSR1 ((int) erts_smp_atomic32_read_mb(&erts_got_sigusr1))
-#    else
-extern volatile int erts_got_sigusr1;
-#      define ERTS_GOT_SIGUSR1 erts_got_sigusr1
-#    endif
-#  endif
-#endif
-
 #ifdef ERTS_SMP
 extern erts_smp_atomic32_t erts_writing_erl_crash_dump;
 extern erts_tsd_key_t erts_is_crash_dumping_key;
diff --git a/erts/emulator/sys/common/erl_poll.c b/erts/emulator/sys/common/erl_poll.c
index b8a28bcc18..5e7ae8953a 100644
--- a/erts/emulator/sys/common/erl_poll.c
+++ b/erts/emulator/sys/common/erl_poll.c
@@ -51,7 +51,6 @@
 #ifndef WANT_NONBLOCKING
 #  define WANT_NONBLOCKING
 #endif
-#define ERTS_WANT_GOT_SIGUSR1
 
 #include "erl_poll.h"
 #if ERTS_POLL_USE_KQUEUE
diff --git a/erts/emulator/sys/unix/sys.c b/erts/emulator/sys/unix/sys.c
index e135dbff99..cb20c690b4 100644
--- a/erts/emulator/sys/unix/sys.c
+++ b/erts/emulator/sys/unix/sys.c
@@ -50,7 +50,6 @@
 #endif
 
 #define ERTS_WANT_BREAK_HANDLING
-#define ERTS_WANT_GOT_SIGUSR1
 #define WANT_NONBLOCKING    /* must define this to pull in defs from sys.h */
 #include "sys.h"
 #include "erl_thr_progress.h"
@@ -96,18 +95,10 @@ static int debug_log = 0;
 #endif
 
 #ifdef ERTS_SMP
-erts_smp_atomic32_t erts_got_sigusr1;
-#define ERTS_SET_GOT_SIGUSR1 \
-  erts_smp_atomic32_set_mb(&erts_got_sigusr1, 1)
-#define ERTS_UNSET_GOT_SIGUSR1 \
-  erts_smp_atomic32_set_mb(&erts_got_sigusr1, 0)
 static erts_smp_atomic32_t have_prepared_crash_dump;
 #define ERTS_PREPARED_CRASH_DUMP \
   ((int) erts_smp_atomic32_xchg_nob(&have_prepared_crash_dump, 1))
 #else
-volatile int erts_got_sigusr1;
-#define ERTS_SET_GOT_SIGUSR1 (erts_got_sigusr1 = 1)
-#define ERTS_UNSET_GOT_SIGUSR1 (erts_got_sigusr1 = 0)
 static volatile int have_prepared_crash_dump;
 #define ERTS_PREPARED_CRASH_DUMP \
   (have_prepared_crash_dump++)
@@ -116,7 +107,7 @@ static volatile int have_prepared_crash_dump;
 erts_smp_atomic_t sys_misc_mem_sz;
 
 #if defined(ERTS_SMP)
-static void smp_sig_notify(char c);
+static void smp_sig_notify(int signum);
 static int sig_notify_fds[2] = {-1, -1};
 
 #ifdef ERTS_SYS_SUSPEND_SIGNAL
@@ -152,7 +143,7 @@ volatile int erts_break_requested = 0;
 static struct termios initial_tty_mode;
 static int replace_intr = 0;
 /* assume yes initially, ttsl_init will clear it */
-int using_oldshell = 1; 
+int using_oldshell = 1;
 
 #ifdef ERTS_ENABLE_KERNEL_POLL
 
@@ -403,13 +394,6 @@ erts_sys_pre_init(void)
     /* After creation in parent */
     eid.thread_create_parent_func = thr_create_cleanup,
 
-#ifdef ERTS_THR_HAVE_SIG_FUNCS
-    sigemptyset(&thr_create_sigmask);
-    sigaddset(&thr_create_sigmask, SIGINT);   /* block interrupt */
-    sigaddset(&thr_create_sigmask, SIGTERM);  /* block terminate signal */
-    sigaddset(&thr_create_sigmask, SIGUSR1);  /* block user defined signal */
-#endif
-
     erts_thr_init(&eid);
 
 #ifdef ERTS_ENABLE_LOCK_CHECK
@@ -428,11 +412,9 @@ erts_sys_pre_init(void)
 
 #ifdef ERTS_SMP
     erts_smp_atomic32_init_nob(&erts_break_requested, 0);
-    erts_smp_atomic32_init_nob(&erts_got_sigusr1, 0);
     erts_smp_atomic32_init_nob(&have_prepared_crash_dump, 0);
 #else
     erts_break_requested = 0;
-    erts_got_sigusr1 = 0;
     have_prepared_crash_dump = 0;
 #endif
 
@@ -624,6 +606,28 @@ int erts_sys_prepare_crash_dump(int secs)
     return prepare_crash_dump(secs);
 }
 
+static void signal_notify_requested(Eterm type) {
+    Process* p = NULL;
+    Eterm msg, *hp;
+    ErtsProcLocks locks = 0;
+    ErlOffHeap *ohp;
+
+    Eterm id = erts_whereis_name_to_id(NULL, am_erl_signal_server);
+
+    if ((p = (erts_pid2proc_opt(NULL, 0, id, 0, ERTS_P2P_FLG_INC_REFC))) != NULL) {
+        ErtsMessage *msgp = erts_alloc_message_heap(p, &locks, 3, &hp, &ohp);
+
+        /* erl_signal_server ! {notify, sighup} */
+        msg = TUPLE2(hp, am_notify, type);
+        erts_queue_message(p, locks, msgp, msg, am_system);
+
+        if (locks)
+            erts_smp_proc_unlock(p, locks);
+        erts_proc_dec_refc(p);
+    }
+}
+
+
 static ERTS_INLINE void
 break_requested(void)
 {
@@ -641,76 +645,15 @@ break_requested(void)
   ERTS_CHK_IO_AS_INTR(); /* Make sure we don't sleep in poll */
 }
 
-/* set up signal handlers for break and quit */
-#if (defined(SIG_SIGSET) || defined(SIG_SIGNAL))
-static RETSIGTYPE request_break(void)
-#else
 static RETSIGTYPE request_break(int signum)
-#endif
 {
 #ifdef ERTS_SMP
-    smp_sig_notify('I');
+    smp_sig_notify(signum);
 #else
     break_requested();
 #endif
 }
 
-static void stop_requested(void) {
-    Process* p = NULL;
-    Eterm msg, *hp;
-    ErtsProcLocks locks = 0;
-    ErlOffHeap *ohp;
-    Eterm id = erts_whereis_name_to_id(NULL, am_init);
-
-    if ((p = (erts_pid2proc_opt(NULL, 0, id, 0, ERTS_P2P_FLG_INC_REFC))) != NULL) {
-        ErtsMessage *msgp = erts_alloc_message_heap(p, &locks, 3, &hp, &ohp);
-
-        /* init ! {stop,stop} */
-        msg = TUPLE2(hp, am_stop, am_stop);
-        erts_queue_message(p, locks, msgp, msg, am_system);
-
-        if (locks)
-            erts_smp_proc_unlock(p, locks);
-        erts_proc_dec_refc(p);
-    }
-}
-
-#if (defined(SIG_SIGSET) || defined(SIG_SIGNAL))
-static RETSIGTYPE request_stop(void)
-#else
-static RETSIGTYPE request_stop(int signum)
-#endif
-{
-#ifdef ERTS_SMP
-    smp_sig_notify('S');
-#else
-    stop_requested();
-#endif
-}
-
-
-static ERTS_INLINE void
-sigusr1_exit(void)
-{
-    char env[21]; /* enough to hold any 64-bit integer */
-    size_t envsz;
-    int i, secs = -1;
-
-    /* We do this at interrupt level, since the main reason for
-     * wanting to generate a crash dump in this way is that the emulator
-     * is hung somewhere, so it won't be able to poll any flag we set here.
-     */
-    ERTS_SET_GOT_SIGUSR1;
-
-    envsz = sizeof(env);
-    if ((i = erts_sys_getenv_raw("ERL_CRASH_DUMP_SECONDS", env, &envsz)) >= 0) {
-	secs = i != 0 ? 0 : atoi(env);
-    }
-
-    prepare_crash_dump(secs);
-    erts_exit(ERTS_DUMP_EXIT, "Received SIGUSR1\n");
-}
-
 #ifdef ETHR_UNUSABLE_SIGUSRX
 #warning "Unusable SIGUSR1 & SIGUSR2. Disabling use of these signals"
 
@@ -731,19 +674,6 @@ sys_thr_resume(erts_tid_t tid) {
 }
 #endif
 
-#if (defined(SIG_SIGSET) || defined(SIG_SIGNAL))
-static RETSIGTYPE user_signal1(void)
-#else
-static RETSIGTYPE user_signal1(int signum)
-#endif
-{
-#ifdef ERTS_SMP
-   smp_sig_notify('1');
-#else
-   sigusr1_exit();
-#endif
-}
-
 #ifdef ERTS_SYS_SUSPEND_SIGNAL
 #if (defined(SIG_SIGSET) || defined(SIG_SIGNAL))
 static RETSIGTYPE suspend_signal(void)
@@ -763,29 +693,101 @@ static RETSIGTYPE suspend_signal(int signum)
 
 #endif /* #ifndef ETHR_UNUSABLE_SIGUSRX */
 
-static void
-quit_requested(void)
-{
-    erts_exit(ERTS_INTR_EXIT, "");
+/*
+ Signal      Action   Comment
+ ─────────────────────────────────────────────────────────────
+  SIGHUP     Term     Hangup detected on controlling terminal or death of controlling process
+ !SIGINT     Term     Interrupt from keyboard
+  SIGQUIT    Core     Quit from keyboard
+ !SIGILL     Core     Illegal Instruction
+  SIGABRT    Core     Abort signal from abort(3)
+ !SIGFPE     Core     Floating point exception
+ !SIGKILL    Term     Kill signal
+ !SIGSEGV    Core     Invalid memory reference
+ !SIGPIPE    Term     Broken pipe: write to pipe with no readers
+  SIGALRM    Term     Timer signal from alarm(2)
+  SIGTERM    Term     Termination signal
+  SIGUSR1    Term     User-defined signal 1
+  SIGUSR2    Term     User-defined signal 2
+ !SIGCHLD    Ign      Child stopped or terminated
+ !SIGCONT    Cont     Continue if stopped
+  SIGSTOP    Stop     Stop process
+  SIGTSTP    Stop     Stop typed at terminal
+ !SIGTTIN    Stop     Terminal input for background process
+ !SIGTTOU    Stop     Terminal output for background process
+*/
+
+
+static ERTS_INLINE int
+signalterm_to_signum(Eterm signal)
+{
+    switch (signal) {
+    case am_sighup:  return SIGHUP;
+    /* case am_sigint:  return SIGINT; */
+    case am_sigquit: return SIGQUIT;
+    /* case am_sigill:  return SIGILL; */
+    case am_sigabrt: return SIGABRT;
+    /* case am_sigsegv: return SIGSEGV; */
+    case am_sigalrm: return SIGALRM;
+    case am_sigterm: return SIGTERM;
+    case am_sigusr1: return SIGUSR1;
+    case am_sigusr2: return SIGUSR2;
+    case am_sigchld: return SIGCHLD;
+    case am_sigstop: return SIGSTOP;
+    case am_sigtstp: return SIGTSTP;
+    default:         return 0;
+    }
 }
 
-#if (defined(SIG_SIGSET) || defined(SIG_SIGNAL))
-static RETSIGTYPE do_quit(void)
-#else
-static RETSIGTYPE do_quit(int signum)
-#endif
+static ERTS_INLINE Eterm
+signum_to_signalterm(int signum)
+{
+    switch (signum) {
+    case SIGHUP:  return am_sighup;
+    /* case SIGINT:  return am_sigint; */    /* ^c */
+    case SIGQUIT: return am_sigquit;   /* ^\ */
+    /* case SIGILL:  return am_sigill; */
+    case SIGABRT: return am_sigabrt;
+    /* case SIGSEGV: return am_sigsegv; */
+    case SIGALRM: return am_sigalrm;
+    case SIGTERM: return am_sigterm;
+    case SIGUSR1: return am_sigusr1;
+    case SIGUSR2: return am_sigusr2;
+    case SIGCHLD: return am_sigchld;
+    case SIGSTOP: return am_sigstop;
+    case SIGTSTP: return am_sigtstp;   /* ^z */
+    default:      return am_error;
+    }
+}
+
+static RETSIGTYPE generic_signal_handler(int signum)
 {
 #ifdef ERTS_SMP
-    smp_sig_notify('Q');
+    smp_sig_notify(signum);
 #else
-    quit_requested();
+    Eterm signal = signum_to_signalterm(signum);
+    signal_notify_requested(signal);
 #endif
 }
 
+int erts_set_signal(Eterm signal, Eterm type) {
+    int signum;
+    if ((signum = signalterm_to_signum(signal)) > 0) {
+        if (type == am_ignore) {
+            sys_signal(signum, SIG_IGN);
+        } else if (type == am_default) {
+            sys_signal(signum, SIG_DFL);
+        } else {
+            sys_signal(signum, generic_signal_handler);
+        }
+        return 1;
+    }
+    return 0;
+}
+
 /* Disable break */
 void erts_set_ignore_break(void) {
     sys_signal(SIGINT,  SIG_IGN);
-    sys_signal(SIGTERM, SIG_IGN);
     sys_signal(SIGQUIT, SIG_IGN);
     sys_signal(SIGTSTP, SIG_IGN);
 }
@@ -797,11 +799,11 @@ void erts_replace_intr(void) {
 
   if (isatty(0)) {
     tcgetattr(0, &mode);
-    
+
     /* here's an example of how to replace ctrl-c with ctrl-u */
     /* mode.c_cc[VKILL] = 0;
        mode.c_cc[VINTR] = CKILL; */
-    
+
     mode.c_cc[VINTR] = 0;	/* disable ctrl-c */
     tcsetattr(0, TCSANOW, &mode);
     replace_intr = 1;
@@ -810,12 +812,13 @@ void erts_replace_intr(void) {
 
 void init_break_handler(void)
 {
-   sys_signal(SIGINT, request_break);
-   sys_signal(SIGTERM, request_stop);
+   sys_signal(SIGINT,  request_break);
+   sys_signal(SIGTERM, generic_signal_handler);
+   sys_signal(SIGHUP,  generic_signal_handler);
 #ifndef ETHR_UNUSABLE_SIGUSRX
-   sys_signal(SIGUSR1, user_signal1);
+   sys_signal(SIGUSR1, generic_signal_handler);
 #endif /* #ifndef ETHR_UNUSABLE_SIGUSRX */
-   sys_signal(SIGQUIT, do_quit);
+   sys_signal(SIGQUIT, generic_signal_handler);
 }
 
 void sys_init_suspend_handler(void)
@@ -855,10 +858,7 @@ get_number(char **str_ptr)
     }
 }
 
-void
-os_flavor(char* namebuf, 	/* Where to return the name. */
-	  unsigned size) 	/* Size of name buffer. */
-{
+void os_flavor(char* namebuf, unsigned size) {
     struct utsname uts;		/* Information about the system. */
     char* s;
 
@@ -871,22 +871,16 @@ os_flavor(char* namebuf, 	/* Where to return the name. */
     strcpy(namebuf, uts.sysname);
 }
 
-void
-os_version(pMajor, pMinor, pBuild)
-int* pMajor;			/* Pointer to major version. */
-int* pMinor;			/* Pointer to minor version. */
-int* pBuild;			/* Pointer to build number. */
-{
+void os_version(int *pMajor, int *pMinor, int *pBuild) {
     struct utsname uts;		/* Information about the system. */
     char* release;		/* Pointer to the release string:
-				 * X.Y or X.Y.Z.
-				 */
+				 * X.Y or X.Y.Z.  */
 
     (void) uname(&uts);
     release = uts.release;
-    *pMajor = get_number(&release);
-    *pMinor = get_number(&release);
-    *pBuild = get_number(&release);
+    *pMajor = get_number(&release); /* Pointer to major version. */
+    *pMinor = get_number(&release); /* Pointer to minor version. */
+    *pBuild = get_number(&release); /* Pointer to build number. */
 }
 
 void init_getenv_state(GETENV_STATE *state)
@@ -921,7 +915,7 @@ void erts_do_break_handling(void)
 {
     struct termios temp_mode;
     int saved = 0;
-    
+
     /*
      * Most functions that do_break() calls are intentionally not thread safe;
      * therefore, make sure that all threads but this one are blocked before
@@ -939,14 +933,14 @@ void erts_do_break_handling(void)
       tcsetattr(0,TCSANOW,&initial_tty_mode);
       saved = 1;
     }
-    
+
     /* call the break handling function, reset the flag */
     do_break();
 
     ERTS_UNSET_BREAK_REQUESTED;
 
     fflush(stdout);
-    
+
     /* after break we go back to saved settings */
     if (using_oldshell && !replace_intr) {
       SET_NONBLOCKING(1);
@@ -1054,37 +1048,12 @@ erts_sys_unsetenv(char *key)
     return res;
 }
 
-void
-sys_init_io(void)
-{
-}
-
-#if (0) /* unused? */
-static int write_fill(fd, buf, len)
-int fd, len;
-char *buf;
-{
-    int i, done = 0;
-    
-    do {
-	if ((i = write(fd, buf+done, len-done)) < 0) {
-	    if (errno != EINTR)
-		return (i);
-	    i = 0;
-	}
-	done += i;
-    } while (done < len);
-    return (len);
-}
-#endif
+void sys_init_io(void) { }
+void erts_sys_alloc_init(void) { }
 
 extern const char pre_loaded_code[];
 extern Preload pre_loaded[];
 
-void erts_sys_alloc_init(void)
-{
-}
-
 #if ERTS_HAVE_ERTS_SYS_ALIGNED_ALLOC
 void *erts_sys_aligned_alloc(UWord alignment, UWord size)
 {
@@ -1185,9 +1154,7 @@ void sys_preload_end(Preload* p)
    Here we assume that all schedulers are stopped so that erl_poll
    does not interfere with the select below.
 */
-int sys_get_key(fd)
-int fd;
-{
+int sys_get_key(int fd) {
     int c, ret;
     unsigned char rbuf[64];
     fd_set fds;
@@ -1206,15 +1173,14 @@ int fd;
         if (c <= 0)
             return c;
     }
-
-    return rbuf[0]; 
+    return rbuf[0];
 }
 
 
 extern int erts_initialized;
 void
 erl_assert_error(const char* expr, const char* func, const char* file, int line)
-{   
+{
     fflush(stdout);
     fprintf(stderr, "%s:%d:%s() Assertion failed: %s\n",
             file, line, func, expr);
@@ -1239,7 +1205,7 @@ erl_debug(char* fmt, ...)
 {
     char sbuf[1024];		/* Temporary buffer. */
     va_list va;
-    
+
     if (debug_log) {
 	va_start(va, fmt);
 	vsprintf(sbuf, fmt, va);
@@ -1268,14 +1234,14 @@ erl_sys_schedule(int runnable)
 static erts_smp_tid_t sig_dispatcher_tid;
 
 static void
-smp_sig_notify(char c)
+smp_sig_notify(int signum)
 {
     int res;
     do {
 	/* write() is async-signal safe (according to posix) */
-	res = write(sig_notify_fds[1], &c, 1);
+	res = write(sig_notify_fds[1], &signum, sizeof(int));
     } while (res < 0 && errno == EINTR);
-    if (res != 1) {
+    if (res != sizeof(int)) {
 	char msg[] =
 	    "smp_sig_notify(): Failed to notify signal-dispatcher thread "
 	    "about received signal";
@@ -1291,60 +1257,55 @@ signal_dispatcher_thread_func(void *unused)
     erts_lc_set_thread_name("signal_dispatcher");
 #endif
     while (1) {
-	char buf[32];
-	int res, i;
+        union {int signum; char buf[4];} sb;
+        Eterm signal;
+	int res, i = 0;
 	/* Block on read() waiting for a signal notification to arrive... */
-	res = read(sig_notify_fds[0], (void *) &buf[0], 32);
+
+        do {
+            res = read(sig_notify_fds[0], (void *) &sb.buf[i], sizeof(int) - i);
+            i += res;
+        } while ((i != sizeof(int) && res >= 0) || (res < 0 && errno == EINTR));
+
 	if (res < 0) {
-	    if (errno == EINTR)
-		continue;
 	    erts_exit(ERTS_ABORT_EXIT,
 		     "signal-dispatcher thread got unexpected error: %s (%d)\n",
 		     erl_errno_id(errno),
 		     errno);
 	}
-	for (i = 0; i < res; i++) {
-	    /*
-	     * NOTE 1: The signal dispatcher thread should not do work
-	     *         that takes a substantial amount of time (except
-	     *         perhaps in test and debug builds). It needs to
-	     *         be responsive, i.e, it should only dispatch work
-	     *         to other threads.
-	     *
-	     * NOTE 2: The signal dispatcher thread is not a blockable
-	     *         thread (i.e., not a thread managed by the
-	     *         erl_thr_progress module). This is intentional.
-	     *         We want to be able to interrupt writing of a crash
-	     *         dump by hitting C-c twice. Since it isn't a
-	     *         blockable thread it is important that it doesn't
-	     *         change the state of any data that a blocking thread
-	     *         expects to have exclusive access to (unless the
-	     *         signal dispatcher itself explicitly is blocking all
-	     *         blockable threads).
-	     */
-	    switch (buf[i]) {
-	    case 0: /* Emulator initialized */
+        /*
+         * NOTE 1: The signal dispatcher thread should not do work
+         *         that takes a substantial amount of time (except
+         *         perhaps in test and debug builds). It needs to
+         *         be responsive, i.e, it should only dispatch work
+         *         to other threads.
+         *
+         * NOTE 2: The signal dispatcher thread is not a blockable
+         *         thread (i.e., not a thread managed by the
+         *         erl_thr_progress module). This is intentional.
+         *         We want to be able to interrupt writing of a crash
+         *         dump by hitting C-c twice. Since it isn't a
+         *         blockable thread it is important that it doesn't
+         *         change the state of any data that a blocking thread
+         *         expects to have exclusive access to (unless the
+         *         signal dispatcher itself explicitly is blocking all
+         *         blockable threads).
+         */
+        switch (sb.signum) {
+            case 0: continue;
+            case SIGINT:
+                break_requested();
                 break;
-	    case 'S': /* SIGTERM */
-		stop_requested();
-		break;
-	    case 'I': /* SIGINT */
-		break_requested();
-		break;
-	    case 'Q': /* SIGQUIT */
-		quit_requested();
-		break;
-	    case '1': /* SIGUSR1 */
-		sigusr1_exit();
-		break;
-	    default:
-		erts_exit(ERTS_ABORT_EXIT,
-			 "signal-dispatcher thread received unknown "
-			 "signal notification: '%c'\n",
-			 buf[i]);
-	    }
-	}
-	ERTS_SMP_LC_ASSERT(!erts_thr_progress_is_blocking());
+            default:
+                if ((signal = signum_to_signalterm(sb.signum)) == am_error) {
+                    erts_exit(ERTS_ABORT_EXIT,
+                            "signal-dispatcher thread received unknown "
+                            "signal notification: '%d'\n",
+                            sb.signum);
+                }
+                signal_notify_requested(signal);
+        }
+        ERTS_SMP_LC_ASSERT(!erts_thr_progress_is_blocking());
     }
     return NULL;
 }
@@ -1387,9 +1348,9 @@ init_smp_sig_suspend(void) {
 int erts_darwin_main_thread_pipe[2];
 int erts_darwin_main_thread_result_pipe[2];
 
-static void initialize_darwin_main_thread_pipes(void) 
+static void initialize_darwin_main_thread_pipes(void)
 {
-    if (pipe(erts_darwin_main_thread_pipe) < 0 || 
+    if (pipe(erts_darwin_main_thread_pipe) < 0 ||
 	pipe(erts_darwin_main_thread_result_pipe) < 0) {
 	erts_exit(ERTS_ERROR_EXIT,"Fatal error initializing Darwin main thread stealing");
     }
@@ -1555,5 +1516,4 @@ erl_sys_args(int* argc, char** argv)
 	    argv[j++] = argv[i];
     }
     *argc = j;
-
 }
diff --git a/erts/emulator/sys/win32/sys.c b/erts/emulator/sys/win32/sys.c
index f3881e0736..408b4f47ab 100644
--- a/erts/emulator/sys/win32/sys.c
+++ b/erts/emulator/sys/win32/sys.c
@@ -294,6 +294,10 @@ int erts_sys_prepare_crash_dump(int secs)
     return 0;
 }
 
+int erts_set_signal(Eterm signal, Eterm type) {
+    return 0;
+}
+
 static void
 init_console(void)
 {
diff --git a/erts/emulator/test/Makefile b/erts/emulator/test/Makefile
index 7c9927c4f3..6f9827002a 100644
--- a/erts/emulator/test/Makefile
+++ b/erts/emulator/test/Makefile
@@ -86,6 +86,7 @@ MODULES= \
 	num_bif_SUITE \
 	message_queue_data_SUITE \
 	op_SUITE \
+	os_signal_SUITE \
 	port_SUITE \
 	port_bif_SUITE \
 	process_SUITE \
diff --git a/erts/emulator/test/os_signal_SUITE.erl b/erts/emulator/test/os_signal_SUITE.erl
new file mode 100644
index 0000000000..9aa49a453e
--- /dev/null
+++ b/erts/emulator/test/os_signal_SUITE.erl
@@ -0,0 +1,354 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2017. All Rights Reserved.
+%% 
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%% 
+%% %CopyrightEnd%
+%%
+
+%%
+%% File:    os_signal_SUITE.erl
+%% Author:  Björn-Egil Dahlberg
+%% Created: 2017-01-13
+%%
+
+-module(os_signal_SUITE).
+
+-include_lib("common_test/include/ct.hrl").
+-export([all/0, suite/0]).
+-export([init_per_testcase/2, end_per_testcase/2]).
+-export([init_per_suite/1, end_per_suite/1]).
+
+-export([set_alarm/1, fork/0, get_exit_code/1]).
+
+% Test cases
+-export([set_unset/1,
+         t_sighup/1,
+         t_sigusr1/1,
+         t_sigusr2/1,
+         t_sigterm/1,
+         t_sigalrm/1,
+         t_sigchld/1,
+         t_sigchld_fork/1]).
+
+-define(signal_server, erl_signal_server).
+
+suite() ->
+    [{ct_hooks,[ts_install_cth]},
+     {timetrap, {minutes, 2}}].
+
+all() ->
+    case os:type() of
+        {win32, _} -> [];
+        _ -> [set_unset,
+              t_sighup,
+              t_sigusr1,
+              t_sigusr2,
+              t_sigterm,
+              t_sigalrm,
+              t_sigchld,
+              t_sigchld_fork]
+    end.
+
+init_per_testcase(Func, Config) when is_atom(Func), is_list(Config) ->
+    Pid = erlang:whereis(?signal_server),
+    true = erlang:unregister(?signal_server),
+    [{signal_server, Pid}|Config].
+
+end_per_testcase(_Func, Config) ->
+    case proplists:get_value(signal_server, Config) of
+        undefined -> ok;
+        Pid ->
+            true = erlang:register(?signal_server, Pid),
+            ok
+    end.
+
+init_per_suite(Config) ->
+    load_nif(Config),
+    Config.
+
+end_per_suite(_Config) ->
+    ok.
+
+%% tests
+
+set_unset(_Config) ->
+    Signals = [sighup, %sigint,
+               sigquit, %sigill,
+               sigabrt,
+               sigalrm, sigterm,
+               sigusr1, sigusr2,
+               sigchld,
+               sigstop, sigtstp],
+    F1 = fun(Sig) -> ok = os:set_signal(Sig,handle) end,
+    F2 = fun(Sig) -> ok = os:set_signal(Sig,default) end,
+    F3 = fun(Sig) -> ok = os:set_signal(Sig,ignore) end,
+    %% set handle
+    ok = lists:foreach(F1, Signals),
+    %% set ignore
+    ok = lists:foreach(F2, Signals),
+    %% set default
+    ok = lists:foreach(F3, Signals),
+    ok.
+
+t_sighup(_Config) ->
+    Pid1 = setup_service(),
+    OsPid = os:getpid(),
+    os:set_signal(sighup, handle),
+    ok = kill("HUP", OsPid),
+    ok = kill("HUP", OsPid),
+    ok = kill("HUP", OsPid),
+    Msgs1 = fetch_msgs(Pid1),
+    io:format("Msgs1: ~p~n", [Msgs1]),
+    [{notify,sighup},
+     {notify,sighup},
+     {notify,sighup}] = Msgs1,
+    %% no proc
+    ok = kill("HUP", OsPid),
+    ok = kill("HUP", OsPid),
+    ok = kill("HUP", OsPid),
+    %% ignore
+    Pid2 = setup_service(),
+    os:set_signal(sighup, ignore),
+    ok = kill("HUP", OsPid),
+    ok = kill("HUP", OsPid),
+    ok = kill("HUP", OsPid),
+    Msgs2 = fetch_msgs(Pid2),
+    io:format("Msgs2: ~p~n", [Msgs2]),
+    [] = Msgs2,
+    %% reset to handle (it's the default)
+    os:set_signal(sighup, handle),
+    ok.
+
+t_sigusr1(_Config) ->
+    Pid1 = setup_service(),
+    OsPid = os:getpid(),
+    os:set_signal(sigusr1, handle),
+    ok = kill("USR1", OsPid),
+    ok = kill("USR1", OsPid),
+    ok = kill("USR1", OsPid),
+    Msgs1 = fetch_msgs(Pid1),
+    io:format("Msgs1: ~p~n", [Msgs1]),
+    [{notify,sigusr1},
+     {notify,sigusr1},
+     {notify,sigusr1}] = Msgs1,
+    %% no proc
+    ok = kill("USR1", OsPid),
+    ok = kill("USR1", OsPid),
+    ok = kill("USR1", OsPid),
+    %% ignore
+    Pid2 = setup_service(),
+    os:set_signal(sigusr1, ignore),
+    ok = kill("USR1", OsPid),
+    ok = kill("USR1", OsPid),
+    ok = kill("USR1", OsPid),
+    Msgs2 = fetch_msgs(Pid2),
+    io:format("Msgs2: ~p~n", [Msgs2]),
+    [] = Msgs2,
+    %% reset to ignore (it's the default)
+    os:set_signal(sigusr1, handle),
+    ok.
+
+t_sigusr2(_Config) ->
+    Pid1 = setup_service(),
+    OsPid = os:getpid(),
+    os:set_signal(sigusr2, handle),
+    ok = kill("USR2", OsPid),
+    ok = kill("USR2", OsPid),
+    ok = kill("USR2", OsPid),
+    Msgs1 = fetch_msgs(Pid1),
+    io:format("Msgs1: ~p~n", [Msgs1]),
+    [{notify,sigusr2},
+     {notify,sigusr2},
+     {notify,sigusr2}] = Msgs1,
+    %% no proc
+    ok = kill("USR2", OsPid),
+    ok = kill("USR2", OsPid),
+    ok = kill("USR2", OsPid),
+    %% ignore
+    Pid2 = setup_service(),
+    os:set_signal(sigusr2, ignore),
+    ok = kill("USR2", OsPid),
+    ok = kill("USR2", OsPid),
+    ok = kill("USR2", OsPid),
+    Msgs2 = fetch_msgs(Pid2),
+    io:format("Msgs2: ~p~n", [Msgs2]),
+    [] = Msgs2,
+    %% reset to ignore (it's the default)
+    os:set_signal(sigusr2, ignore),
+    ok.
+
+t_sigterm(_Config) ->
+    Pid1 = setup_service(),
+    OsPid = os:getpid(),
+    os:set_signal(sigterm, handle),
+    ok = kill("TERM", OsPid),
+    ok = kill("TERM", OsPid),
+    ok = kill("TERM", OsPid),
+    Msgs1 = fetch_msgs(Pid1),
+    io:format("Msgs1: ~p~n", [Msgs1]),
+    [{notify,sigterm},
+     {notify,sigterm},
+     {notify,sigterm}] = Msgs1,
+    %% no proc
+    ok = kill("TERM", OsPid),
+    ok = kill("TERM", OsPid),
+    ok = kill("TERM", OsPid),
+    %% ignore
+    Pid2 = setup_service(),
+    os:set_signal(sigterm, ignore),
+    ok = kill("TERM", OsPid),
+    ok = kill("TERM", OsPid),
+    ok = kill("TERM", OsPid),
+    Msgs2 = fetch_msgs(Pid2),
+    io:format("Msgs2: ~p~n", [Msgs2]),
+    [] = Msgs2,
+    %% reset to handle (it's the default)
+    os:set_signal(sigterm, handle),
+    ok.
+
+t_sigchld(_Config) ->
+    Pid1 = setup_service(),
+    OsPid = os:getpid(),
+    os:set_signal(sigchld, handle),
+    ok = kill("CHLD", OsPid),
+    ok = kill("CHLD", OsPid),
+    ok = kill("CHLD", OsPid),
+    Msgs1 = fetch_msgs(Pid1),
+    io:format("Msgs1: ~p~n", [Msgs1]),
+    [{notify,sigchld},
+     {notify,sigchld},
+     {notify,sigchld}] = Msgs1,
+    %% no proc
+    ok = kill("CHLD", OsPid),
+    ok = kill("CHLD", OsPid),
+    ok = kill("CHLD", OsPid),
+    %% ignore
+    Pid2 = setup_service(),
+    os:set_signal(sigchld, ignore),
+    ok = kill("CHLD", OsPid),
+    ok = kill("CHLD", OsPid),
+    ok = kill("CHLD", OsPid),
+    Msgs2 = fetch_msgs(Pid2),
+    io:format("Msgs2: ~p~n", [Msgs2]),
+    [] = Msgs2,
+    %% reset to handle (it's the default)
+    os:set_signal(sigchld, ignore),
+    ok.
+
+
+t_sigalrm(_Config) ->
+    Pid1 = setup_service(),
+    ok = os:set_signal(sigalrm, handle),
+    ok = os_signal_SUITE:set_alarm(1),
+    receive after 3000 -> ok end,
+    Msgs1 = fetch_msgs(Pid1),
+    [{notify,sigalrm}] = Msgs1,
+    io:format("Msgs1: ~p~n", [Msgs1]),
+    os:set_signal(sigalrm, ignore),
+    Pid2 = setup_service(),
+    ok = os_signal_SUITE:set_alarm(1),
+    receive after 3000 -> ok end,
+    Msgs2 = fetch_msgs(Pid2),
+    [] = Msgs2,
+    io:format("Msgs2: ~p~n", [Msgs2]),
+    Pid3 = setup_service(),
+    os:set_signal(sigalrm, handle),
+    ok = os_signal_SUITE:set_alarm(1),
+    receive after 3000 -> ok end,
+    Msgs3 = fetch_msgs(Pid3),
+    [{notify,sigalrm}] = Msgs3,
+    io:format("Msgs3: ~p~n", [Msgs3]),
+    os:set_signal(sigalrm, ignore),
+    ok.
+
+t_sigchld_fork(_Config) ->
+    Pid1 = setup_service(),
+    ok = os:set_signal(sigchld, handle),
+    {ok,OsPid} = os_signal_SUITE:fork(),
+    receive after 3000 -> ok end,
+    Msgs1 = fetch_msgs(Pid1),
+    io:format("Msgs1: ~p~n", [Msgs1]),
+    [{notify,sigchld}] = Msgs1,
+    {ok,Status} = os_signal_SUITE:get_exit_code(OsPid),
+    io:format("exit status from ~w : ~w~n", [OsPid,Status]),
+    42 = Status,
+    %% reset to ignore (it's the default)
+    os:set_signal(sigchld, ignore),
+    ok.
+
+
+%% nif stubs
+
+set_alarm(_Secs) -> no.
+fork() -> no.
+get_exit_code(_OsPid) -> no.
+
+%% aux
+
+setup_service() ->
+    Pid = spawn_link(fun msgs/0),
+    true = erlang:register(?signal_server, Pid),
+    Pid.
+
+msgs() ->
+    msgs([]).
+msgs(Ms) ->
+    receive
+        {Pid, fetch_msgs} -> Pid ! {self(), lists:reverse(Ms)};
+        Msg ->
+            msgs([Msg|Ms])
+    end.
+
+fetch_msgs(Pid) ->
+    Pid ! {self(), fetch_msgs},
+    receive {Pid, Msgs} -> Msgs end.
+
+kill(Signal, Pid) ->
+    {0,_} = run("kill", ["-s", Signal, Pid]),
+    receive after 200 -> ok end,
+    ok.
+
+load_nif(Config) ->
+    Path = proplists:get_value(data_dir, Config),
+    ok = erlang:load_nif(filename:join(Path,"os_signal_nif"), 0).
+
+run(Program0, Args) -> run(".", Program0, Args).
+run(Cwd, Program0, Args) when is_list(Cwd) ->
+    Program = case os:find_executable(Program0) of
+                  Path when is_list(Path) ->
+                      Path;
+                  false ->
+                      exit(no)
+              end,
+    Options = [{args,Args},binary,exit_status,stderr_to_stdout,
+               {line,4096}, {cd, Cwd}],
+    try open_port({spawn_executable,Program}, Options) of
+        Port ->
+            run_loop(Port, [])
+    catch
+        error:_ ->
+                      exit(no)
+    end.
+
+run_loop(Port, Output) ->
+    receive
+        {Port,{exit_status,Status}} ->
+            {Status,lists:reverse(Output)};
+        {Port,{data,{eol,Bin}}} ->
+            run_loop(Port, [Bin|Output]);
+        _Msg ->
+            run_loop(Port, Output)
+    end.
diff --git a/erts/emulator/test/os_signal_SUITE_data/Makefile.src b/erts/emulator/test/os_signal_SUITE_data/Makefile.src
new file mode 100644
index 0000000000..a7f5cdbba5
--- /dev/null
+++ b/erts/emulator/test/os_signal_SUITE_data/Makefile.src
@@ -0,0 +1,6 @@
+
+NIF_LIBS = os_signal_nif@dll@
+
+all: $(NIF_LIBS)
+
+@SHLIB_RULES@
diff --git a/erts/emulator/test/os_signal_SUITE_data/os_signal_nif.c b/erts/emulator/test/os_signal_SUITE_data/os_signal_nif.c
new file mode 100644
index 0000000000..78e1348383
--- /dev/null
+++ b/erts/emulator/test/os_signal_SUITE_data/os_signal_nif.c
@@ -0,0 +1,66 @@
+#include <sys/wait.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+
+#include <erl_nif.h>
+
+static int load(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info)
+{
+    return 0;
+}
+
+static ERL_NIF_TERM set_alarm(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    int t;
+    if (!enif_get_int(env, argv[0], &t)) {
+        return enif_make_badarg(env);
+    }
+
+    alarm(t);
+
+    return enif_make_atom(env, "ok");
+}
+
+static ERL_NIF_TERM fork_0(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    pid_t pid;
+
+    pid = fork();
+
+    if (pid == 0) {
+        /* child */
+        exit(42);
+    }
+
+    return enif_make_tuple(env, 2,
+            enif_make_atom(env, "ok"),
+            enif_make_int(env, (int)pid));
+}
+
+static ERL_NIF_TERM get_exit_code(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    int x;
+    pid_t pid;
+    if (!enif_get_int(env, argv[0], &x)) {
+        return enif_make_badarg(env);
+    }
+
+    pid = (pid_t) x;
+
+    waitpid(pid, &x, 0);
+
+    return enif_make_tuple(env, 2,
+            enif_make_atom(env, "ok"),
+            enif_make_int(env, WEXITSTATUS(x)));
+}
+
+
+static ErlNifFunc nif_funcs[] =
+{
+    {"set_alarm", 1, set_alarm},
+    {"fork", 0, fork_0},
+    {"get_exit_code", 1, get_exit_code}
+};
+
+ERL_NIF_INIT(os_signal_SUITE,nif_funcs,load,NULL,NULL,NULL)