Don't let SIGINT handling block SIGCHLD indefinitely.

* atimer.c (block_atimers):
* callproc.c (block_child_signal): Block SIGINT too;
otherwise, its handler might now unblock signals that it shouldn't.
* keyboard.c (read_char): Clear signal mask, since we may
be in a SIGINT handler, and many signals may be masked.
* keyboard.c (handle_interrupt):
* sysdep.c (handle_arith_signal):
Clear signal mask instead of just unblocking the signal that
was received, since several signals may be blocked at this point.

Fixes: debbugs:17561

5 files changed, 25 insertions, 11 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 33952e159bf..6ecf7dbee99 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,16 @@
+2014-05-30  Paul Eggert  <eggert@cs.ucla.edu>
+
+        Don't let SIGINT handling block SIGCHLD indefinitely (Bug#17561).
+        * atimer.c (block_atimers):
+        * callproc.c (block_child_signal): Block SIGINT too;
+        otherwise, its handler might now unblock signals that it shouldn't.
+        * keyboard.c (read_char): Clear signal mask, since we may
+        be in a SIGINT handler, and many signals may be masked.
+        * keyboard.c (handle_interrupt):
+        * sysdep.c (handle_arith_signal):
+        Clear signal mask instead of just unblocking the signal that
+        was received, since several signals may be blocked at this point.
+
 2014-05-29  Eli Zaretskii  <eliz@gnu.org>
 
         * Makefile.in (TEMACS_POST_LINK): Remove target.
diff --git a/src/atimer.c b/src/atimer.c
index a5a2b0714e3..e457a7fcf1c 100644
--- a/src/atimer.c
+++ b/src/atimer.c
@@ -55,6 +55,7 @@ block_atimers (sigset_t *oldset)
   sigset_t blocked;
   sigemptyset (&blocked);
   sigaddset (&blocked, SIGALRM);
+  sigaddset (&blocked, SIGINT);
   pthread_sigmask (SIG_BLOCK, &blocked, oldset);
 }
 static void
@@ -404,7 +405,6 @@ turn_on_atimers (bool on)
 void
 init_atimer (void)
 {
-  struct sigaction action;
 #ifdef HAVE_ITIMERSPEC
   struct sigevent sigev;
   sigev.sigev_notify = SIGEV_SIGNAL;
@@ -413,7 +413,9 @@ init_atimer (void)
   alarm_timer_ok = timer_create (CLOCK_REALTIME, &sigev, &alarm_timer) == 0;
 #endif
   free_atimers = stopped_atimers = atimers = NULL;
-  /* pending_signals is initialized in init_keyboard.*/
+
+  /* pending_signals is initialized in init_keyboard.  */
+  struct sigaction action;
   emacs_sigaction_init (&action, handle_alarm_signal);
   sigaction (SIGALRM, &action, 0);
 }
diff --git a/src/callproc.c b/src/callproc.c
index a2c52e5b5ba..0506bf53a25 100644
--- a/src/callproc.c
+++ b/src/callproc.c
@@ -115,6 +115,7 @@ block_child_signal (sigset_t *oldset)
   sigset_t blocked;
   sigemptyset (&blocked);
   sigaddset (&blocked, SIGCHLD);
+  sigaddset (&blocked, SIGINT);
   pthread_sigmask (SIG_BLOCK, &blocked, oldset);
 }
 
diff --git a/src/keyboard.c b/src/keyboard.c
index e92c86b7dbf..17bfc81b82f 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -2664,6 +2664,7 @@ read_char (int commandflag, Lisp_Object map,
       /* We must have saved the outer value of getcjmp here,
          so restore it now.  */
       restore_getcjmp (save_jump);
+      pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
       unbind_to (jmpcount, Qnil);
       XSETINT (c, quit_char);
       internal_last_event_frame = selected_frame;
@@ -10323,9 +10324,6 @@ static void
 handle_interrupt (bool in_signal_handler)
 {
   char c;
-  sigset_t blocked;
-  sigemptyset (&blocked);
-  sigaddset (&blocked, SIGINT);
 
   cancel_echoing ();
 
@@ -10337,6 +10335,9 @@ handle_interrupt (bool in_signal_handler)
           /* If SIGINT isn't blocked, don't let us be interrupted by
              a SIGINT.  It might be harmful due to non-reentrancy
              in I/O functions.  */
+          sigset_t blocked;
+          sigemptyset (&blocked);
+          sigaddset (&blocked, SIGINT);
           pthread_sigmask (SIG_BLOCK, &blocked, 0);
         }
 
@@ -10421,7 +10422,7 @@ handle_interrupt (bool in_signal_handler)
           struct gcpro gcpro1, gcpro2, gcpro3, gcpro4;
 
           immediate_quit = 0;
-          pthread_sigmask (SIG_UNBLOCK, &blocked, 0);
+          pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
           saved = gl_state;
           GCPRO4 (saved.object, saved.global_code,
                   saved.current_syntax_table, saved.old_prop);
@@ -10442,7 +10443,7 @@ handle_interrupt (bool in_signal_handler)
         }
     }
 
-  pthread_sigmask (SIG_UNBLOCK, &blocked, 0);
+  pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
 
 /* TODO: The longjmp in this call throws the NS event loop integration off,
          and it seems to do fine without this.  Probably some attention
diff --git a/src/sysdep.c b/src/sysdep.c
index e5b29205e96..573d419970d 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -1645,10 +1645,7 @@ deliver_fatal_thread_signal (int sig)
 static _Noreturn void
 handle_arith_signal (int sig)
 {
-  sigset_t blocked;
-  sigemptyset (&blocked);
-  sigaddset (&blocked, sig);
-  pthread_sigmask (SIG_UNBLOCK, &blocked, 0);
+  pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
   xsignal0 (Qarith_error);
 }