Signal-handler cleanup.

Emacs's signal handlers were written in the old 4.2BSD style with
sigblock and sigmask and so forth, and this led to some
inefficiencies and confusion.  Rewrite these to use
pthread_sigmask etc. without copying signal sets around.  Also,
get rid of the confusing macros 'SIGNAL_THREAD_CHECK' and
'signal', and instead use functions that do not attempt to take
over the system name space.  This patch causes Emacs's text
segment to shrink by 0.7% on my platform, Fedora 17 x86-64.
* configure.ac (PTY_OPEN, PTY_TTY_NAME_SPRINTF):
Adjust to syssignal.h changes.
(SIGNAL_H_AB): Remove; no longer needed.
* src/alloc.c, src/emacsgtkfixed.c, src/nsfns.m, src/widget.c, src/xmenu.c:
Do not include <signal.h> or "syssignal.h", as these
modules do not use signals.
* src/atimer.c, src/callproc.c, src/data.c, src/dispnew.c, src/emacs.c:
* src/floatfns.c, src/gtkutil.c, src/keyboard.c, src/process.c, src/sound.c:
* src/sysdep.c, src/term.c, src/xterm.c:
Do not include <signal.h>, as "syssignal.h" does that for us now.
* src/atimer.c (sigmask_atimers): New function.
(block_atimers, unblock_atimers): New functions,
replacing the old macros BLOCK_ATIMERS and UNBLOCK_ATIMERS.
All uses replaced.
* src/conf_post.h [SIGNAL_H_AHB]: Do not include <signal.h>;
no longer needed here.
* src/emacs.c (main): Inspect existing signal handler with sigaction,
so that there's	no need to block and unblock SIGHUP.
* src/sysdep.c (struct save_signal): New member 'action', replacing
old member 'handler'.
(save_signal_handlers, restore_signal_handlers):
Use sigaction instead of 'signal' to save and restore.
(get_set_sighandler, set_sighandler) [!WINDOWSNT]:
New function.  All users of 'signal' modified to use set_sighandler
if they're writeonly, and to use sys_signal if they're read+write.
(emacs_sigaction_init, forwarded_signal): New functions.
(sys_signal): Remove.  All uses replaced by calls to sigaction
and emacs_sigaction_init, or by direct calls to 'signal'.
(sys_sigmask) [!__GNUC__]: Remove; no longer needed.
(sys_sigblock, sys_sigunblock, sys_sigsetmask): Remove;
all uses replaced by pthread_sigmask etc. calls.
* src/syssignal.h: Include <signal.h>.
(emacs_sigaction_init, forwarded_signal): New decls.
(SIGMASKTYPE): Remove.  All uses replaced by its definiens, sigset_t.
(SIGEMPTYMASK): Remove; all uses replaced by its definiens, empty_mask.
(sigmask, sys_sigmask): Remove; no longer needed.
(sigpause): Remove.  All uses replaced by its definiens, sigsuspend.
(sigblock, sigunblock, sigfree):
(sigsetmask) [!defined sigsetmask]:
Remove.  All uses replaced by pthread_sigmask.
(signal): Remove.  Its remaining uses (with SIG_DFL and SIG_IGN)
no longer need to be replaced, and its typical old uses
are now done via emacs_sigaction_init and sigaction.
(sys_sigblock, sys_sigunblock, sys_sigsetmask): Remove decls.
(sys_sigdel): Remove; unused.
(NSIG): Remove a FIXME; the code's fine.  Remove an unnecessary ifdef.

Fixes: debbugs:12327

1 files changed, 48 insertions, 24 deletions

diff --git a/src/keyboard.c b/src/keyboard.c
index 128f9280911..d26cf35e108 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -21,7 +21,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #define KEYBOARD_INLINE EXTERN_INLINE
 
-#include <signal.h>
 #include <stdio.h>
 #include <setjmp.h>
 #include "lisp.h"
@@ -3680,7 +3679,7 @@ kbd_buffer_store_event_hold (register struct input_event *event,
       if (immediate_quit && NILP (Vinhibit_quit))
 	{
 	  immediate_quit = 0;
-	  sigfree ();
+	  pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
 	  QUIT;
 	}
     }
@@ -3832,7 +3831,11 @@ kbd_buffer_get_event (KBOARD **kbp,
       unhold_keyboard_input ();
 #ifdef SIGIO
       if (!noninteractive)
-        signal (SIGIO, deliver_input_available_signal);
+	{
+	  struct sigaction action;
+	  emacs_sigaction_init (&action, deliver_input_available_signal);
+	  sigaction (SIGIO, &action, 0);
+	}
 #endif /* SIGIO */
       start_polling ();
     }
@@ -6780,10 +6783,12 @@ gobble_input (int expected)
 #ifdef SIGIO
   if (interrupt_input)
     {
-      SIGMASKTYPE mask;
-      mask = sigblock (sigmask (SIGIO));
+      sigset_t blocked, procmask;
+      sigemptyset (&blocked);
+      sigaddset (&blocked, SIGIO);
+      pthread_sigmask (SIG_BLOCK, &blocked, &procmask);
       read_avail_input (expected);
-      sigsetmask (mask);
+      pthread_sigmask (SIG_SETMASK, &procmask, 0);
     }
   else
 #ifdef POLL_FOR_INPUT
@@ -6792,10 +6797,12 @@ gobble_input (int expected)
      it's always set.  */
   if (!interrupt_input && poll_suppress_count == 0)
     {
-      SIGMASKTYPE mask;
-      mask = sigblock (sigmask (SIGALRM));
+      sigset_t blocked, procmask;
+      sigemptyset (&blocked);
+      sigaddset (&blocked, SIGALRM);
+      pthread_sigmask (SIG_BLOCK, &blocked, &procmask);
       read_avail_input (expected);
-      sigsetmask (mask);
+      pthread_sigmask (SIG_SETMASK, &procmask, 0);
     }
   else
 #endif
@@ -6831,10 +6838,12 @@ record_asynch_buffer_change (void)
 #ifdef SIGIO
   if (interrupt_input)
     {
-      SIGMASKTYPE mask;
-      mask = sigblock (sigmask (SIGIO));
+      sigset_t blocked, procmask;
+      sigemptyset (&blocked);
+      sigaddset (&blocked, SIGIO);
+      pthread_sigmask (SIG_BLOCK, &blocked, &procmask);
       kbd_buffer_store_event (&event);
-      sigsetmask (mask);
+      pthread_sigmask (SIG_SETMASK, &procmask, 0);
     }
   else
 #endif
@@ -7295,6 +7304,7 @@ static struct user_signal_info *user_signals = NULL;
 void
 add_user_signal (int sig, const char *name)
 {
+  struct sigaction action;
   struct user_signal_info *p;
 
   for (p = user_signals; p; p = p->next)
@@ -7309,7 +7319,8 @@ add_user_signal (int sig, const char *name)
   p->next = user_signals;
   user_signals = p;
 
-  signal (sig, deliver_user_signal);
+  emacs_sigaction_init (&action, deliver_user_signal);
+  sigaction (sig, &action, 0);
 }
 
 static void
@@ -7381,7 +7392,7 @@ store_user_signal_events (void)
   for (p = user_signals; p; p = p->next)
     if (p->npending > 0)
       {
-	SIGMASKTYPE mask;
+	sigset_t blocked, procmask;
 
 	if (nstored == 0)
 	  {
@@ -7391,7 +7402,10 @@ store_user_signal_events (void)
 	  }
 	nstored += p->npending;
 
-	mask = sigblock (sigmask (p->sig));
+	sigemptyset (&blocked);
+	sigaddset (&blocked, p->sig);
+	pthread_sigmask (SIG_BLOCK, &blocked, &procmask);
+
 	do
 	  {
 	    buf.code = p->sig;
@@ -7399,7 +7413,8 @@ store_user_signal_events (void)
 	    p->npending--;
 	  }
 	while (p->npending > 0);
-	sigsetmask (mask);
+
+	pthread_sigmask (SIG_SETMASK, &procmask, 0);
       }
 
   return nstored;
@@ -10838,7 +10853,10 @@ handle_interrupt (void)
       /* If SIGINT isn't blocked, don't let us be interrupted by
 	 another SIGINT, it might be harmful due to non-reentrancy
 	 in I/O functions.  */
-      sigblock (sigmask (SIGINT));
+      sigset_t blocked;
+      sigemptyset (&blocked);
+      sigaddset (&blocked, SIGINT);
+      pthread_sigmask (SIG_BLOCK, &blocked, 0);
 
       fflush (stdout);
       reset_all_sys_modes ();
@@ -10909,7 +10927,7 @@ handle_interrupt (void)
 #endif /* not MSDOS */
       fflush (stdout);
       init_all_sys_modes ();
-      sigfree ();
+      pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
     }
   else
     {
@@ -10922,7 +10940,7 @@ handle_interrupt (void)
 	  struct gcpro gcpro1, gcpro2, gcpro3, gcpro4;
 
 	  immediate_quit = 0;
-          sigfree ();
+	  pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
 	  saved = gl_state;
 	  GCPRO4 (saved.object, saved.global_code,
 		  saved.current_syntax_table, saved.old_prop);
@@ -10967,7 +10985,7 @@ quit_throw_to_read_char (int from_signal)
   if (!from_signal && EQ (Vquit_flag, Qkill_emacs))
     Fkill_emacs (Qnil);
 
-  sigfree ();
+  pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
   /* Prevent another signal from doing this before we finish.  */
   clear_waiting_for_input ();
   input_pending = 0;
@@ -11402,17 +11420,23 @@ init_keyboard (void)
          SIGINT.  There is special code in interrupt_signal to exit
          Emacs on SIGINT when there are no termcap frames on the
          controlling terminal.  */
-      signal (SIGINT, deliver_interrupt_signal);
+      struct sigaction action;
+      emacs_sigaction_init (&action, deliver_interrupt_signal);
+      sigaction (SIGINT, &action, 0);
 #ifndef DOS_NT
       /* For systems with SysV TERMIO, C-g is set up for both SIGINT and
 	 SIGQUIT and we can't tell which one it will give us.  */
-      signal (SIGQUIT, deliver_interrupt_signal);
+      sigaction (SIGQUIT, &action, 0);
 #endif /* not DOS_NT */
     }
 /* Note SIGIO has been undef'd if FIONREAD is missing.  */
 #ifdef SIGIO
   if (!noninteractive)
-    signal (SIGIO, deliver_input_available_signal);
+    {
+      struct sigaction action;
+      emacs_sigaction_init (&action, deliver_input_available_signal);
+      sigaction (SIGIO, &action, 0);
+    }
 #endif /* SIGIO */
 
 /* Use interrupt input by default, if it works and noninterrupt input
@@ -11424,7 +11448,7 @@ init_keyboard (void)
   interrupt_input = 0;
 #endif
 
-  sigfree ();
+  pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
   dribble = 0;
 
   if (keyboard_init_hook)