Kill processes which ignore signals thatshould not be ignored

man/man2/sigaction.2

@@ -130,19 +130,19 @@ signal	num	notes	description
 SIGHUP	1	km	Hangup
 SIGINT	2	k	Interrupt (usually DEL or CTRL\-C)
 SIGQUIT	3	kcm	Quit (usually CTRL\-\e)
-SIGILL	4	kc	Illegal instruction
-SIGTRAP	5	kc	Trace trap
+SIGILL	4	Kc	Illegal instruction
+SIGTRAP	5	Kc	Trace trap
 SIGABRT	6	kcm	Abort program
-SIGBUS	7	kc	Bus error
-SIGFPE	8	kc	Floating point exception
+SIGBUS	7	Kc	Bus error
+SIGFPE	8	Kc	Floating point exception
 SIGKILL	9	k	Kill
 SIGUSR1	10	k	User defined signal #1
-SIGSEGV	11	kc	Segmentation fault
+SIGSEGV	11	Kc	Segmentation fault
 SIGUSR2	12	k	User defined signal #2
 SIGPIPE	13	k	Write to a pipe with no reader
 SIGALRM	14	k	Alarm clock
 SIGTERM	15	km	Terminate (default for kill(1))
-SIGEMT	16	xkc	Emulator trap
+SIGEMT	16	xKc	Emulator trap
 SIGCHLD	17	pi	Child process terminated
 SIGCONT	18	pi	Continue if stopped
 SIGSTOP	19	ps	Stop signal
@@ -161,6 +161,11 @@ The letters in the notes column indicate:
 .B k
 The process is killed if the signal is not caught.
 .TP
+.B K
+The process is killed if the signal is not caught. If the signal is received
+while ignored or masked, the process is killed even if a handler is defined to 
+catch the signal.
+.TP
 .B c
 The signal causes a core dump.
 .TP

servers/pm/glo.h

@@ -21,6 +21,7 @@ EXTERN int call_nr;		/* system call number */
 extern _PROTOTYPE (int (*call_vec[]), (void) );	/* system call handlers */
 EXTERN sigset_t core_sset;	/* which signals cause core images */
 EXTERN sigset_t ign_sset;	/* which signals are by default ignored */
+EXTERN sigset_t noign_sset;	/* which signals cannot be ignored */
 
 EXTERN u32_t system_hz;		/* System clock frequency. */
 EXTERN int abort_flag;

servers/pm/main.c

@@ -200,6 +200,8 @@ PRIVATE int sef_cb_init_fresh(int type, sef_init_info_t *info)
 				SIGEMT, SIGFPE, SIGBUS, SIGSEGV };
   static char ign_sigs[] = { SIGCHLD, SIGWINCH, SIGCONT };
   static char mess_sigs[] = { SIGTERM, SIGHUP, SIGABRT, SIGQUIT };
+  static char noign_sigs[] = { SIGILL, SIGTRAP, SIGEMT, SIGFPE, 
+				SIGBUS, SIGSEGV };
   register struct mproc *rmp;
   register char *sig_ptr;
   message mess;
@@ -218,6 +220,9 @@ PRIVATE int sef_cb_init_fresh(int type, sef_init_info_t *info)
   sigemptyset(&ign_sset);
   for (sig_ptr = ign_sigs; sig_ptr < ign_sigs+sizeof(ign_sigs); sig_ptr++)
 	sigaddset(&ign_sset, *sig_ptr);
+  sigemptyset(&noign_sset);
+  for (sig_ptr = noign_sigs; sig_ptr < noign_sigs+sizeof(noign_sigs); sig_ptr++)
+	sigaddset(&noign_sset, *sig_ptr);
 
   /* Obtain a copy of the boot monitor parameters and the kernel info struct.  
    * Parse the list of free memory chunks. This list is what the boot monitor 

servers/pm/signal.c

@@ -351,7 +351,7 @@ int trace;			/* pass signal to tracer first? */
  * context from the sigcontext structure.
  * If there is insufficient stack space, kill the process.
  */
-  int r, slot;
+  int r, slot, badignore;
 
   slot = (int) (rmp - mproc);
   if ((rmp->mp_flags & (IN_USE | EXITING)) != IN_USE) {
@@ -387,16 +387,22 @@ int trace;			/* pass signal to tracer first? */
 	return;
   }
 
-  if (sigismember(&rmp->mp_ignore, signo)) { 
+  /* some signals cannot be safely ignored */
+  badignore = sigismember(&noign_sset, signo) && (
+	  sigismember(&rmp->mp_ignore, signo) ||
+	  sigismember(&rmp->mp_sigmask, signo) ||
+	  sigismember(&rmp->mp_sig2mess, signo));
+
+  if (!badignore && sigismember(&rmp->mp_ignore, signo)) { 
 	/* Signal should be ignored. */
 	return;
   }
-  if (sigismember(&rmp->mp_sigmask, signo)) {
+  if (!badignore && sigismember(&rmp->mp_sigmask, signo)) {
 	/* Signal should be blocked. */
 	sigaddset(&rmp->mp_sigpending, signo);
 	return;
   }
-  if (sigismember(&rmp->mp_sig2mess, signo)) {
+  if (!badignore && sigismember(&rmp->mp_sig2mess, signo)) {
 	/* Mark event pending in process slot and send notification. */
 	sigaddset(&rmp->mp_sigpending, signo);
 	notify(rmp->mp_endpoint);
@@ -412,7 +418,7 @@ int trace;			/* pass signal to tracer first? */
 	return;
   }
 
-  if (sigismember(&rmp->mp_catch, signo)) {
+  if (!badignore && sigismember(&rmp->mp_catch, signo)) {
 	/* Signal is caught. First interrupt the process's current call, if
 	 * applicable. This may involve a roundtrip to FS, in which case we'll
 	 * have to check back later.
@@ -436,7 +442,7 @@ int trace;			/* pass signal to tracer first? */
 
 	/* We were unable to spawn a signal handler. Kill the process. */
   }
-  else if (sigismember(&ign_sset, signo)) {
+  else if (!badignore && sigismember(&ign_sset, signo)) {
 	/* Signal defaults to being ignored. */
 	return;
   }

test/test5.c

@@ -279,11 +279,11 @@ void test5g()
   int n;
 
   subtest = 7;
-  Signal(11, func11);
-  Signal(11, SIG_IGN);
+  Signal(SIGUSR1, func11);
+  Signal(SIGUSR1, SIG_IGN);
   n = getpid();
-  if (kill(n, 11) != 0) e(1);
-  Signal(11, SIG_DFL);
+  if (kill(n, SIGUSR1) != 0) e(1);
+  Signal(SIGUSR1, SIG_DFL);
 }
 
 void funcalrm(s)