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, 34 insertions, 15 deletions

diff --git a/src/atimer.c b/src/atimer.c
index 060dead9b17..34731920af5 100644
--- a/src/atimer.c
+++ b/src/atimer.c
@@ -17,7 +17,6 @@ You should have received a copy of the GNU General Public License
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include <config.h>
-#include <signal.h>
 #include <stdio.h>
 #include <setjmp.h>
 #include "lisp.h"
@@ -51,8 +50,24 @@ int pending_atimers;
 
 /* Block/unblock SIGALRM.  */
 
-#define BLOCK_ATIMERS   sigblock (sigmask (SIGALRM))
-#define UNBLOCK_ATIMERS sigunblock (sigmask (SIGALRM))
+static void
+sigmask_atimers (int how)
+{
+  sigset_t blocked;
+  sigemptyset (&blocked);
+  sigaddset (&blocked, SIGALRM);
+  pthread_sigmask (how, &blocked, 0);
+}
+static void
+block_atimers (void)
+{
+  sigmask_atimers (SIG_BLOCK);
+}
+static void
+unblock_atimers (void)
+{
+  sigmask_atimers (SIG_UNBLOCK);
+}
 
 /* Function prototypes.  */
 
@@ -109,7 +124,7 @@ start_atimer (enum atimer_type type, EMACS_TIME timestamp, atimer_callback fn,
   t->fn = fn;
   t->client_data = client_data;
 
-  BLOCK_ATIMERS;
+  block_atimers ();
 
   /* Compute the timer's expiration time.  */
   switch (type)
@@ -130,7 +145,7 @@ start_atimer (enum atimer_type type, EMACS_TIME timestamp, atimer_callback fn,
 
   /* Insert the timer in the list of active atimers.  */
   schedule_atimer (t);
-  UNBLOCK_ATIMERS;
+  unblock_atimers ();
 
   /* Arrange for a SIGALRM at the time the next atimer is ripe.  */
   set_alarm ();
@@ -146,7 +161,7 @@ cancel_atimer (struct atimer *timer)
 {
   int i;
 
-  BLOCK_ATIMERS;
+  block_atimers ();
 
   for (i = 0; i < 2; ++i)
     {
@@ -173,7 +188,7 @@ cancel_atimer (struct atimer *timer)
         }
     }
 
-  UNBLOCK_ATIMERS;
+  unblock_atimers ();
 }
 
 
@@ -204,7 +219,7 @@ append_atimer_lists (struct atimer *list_1, struct atimer *list_2)
 void
 stop_other_atimers (struct atimer *t)
 {
-  BLOCK_ATIMERS;
+  block_atimers ();
 
   if (t)
     {
@@ -229,7 +244,7 @@ stop_other_atimers (struct atimer *t)
 
   stopped_atimers = append_atimer_lists (atimers, stopped_atimers);
   atimers = t;
-  UNBLOCK_ATIMERS;
+  unblock_atimers ();
 }
 
 
@@ -244,7 +259,7 @@ run_all_atimers (void)
       struct atimer *t = atimers;
       struct atimer *next;
 
-      BLOCK_ATIMERS;
+      block_atimers ();
       atimers = stopped_atimers;
       stopped_atimers = NULL;
 
@@ -255,7 +270,7 @@ run_all_atimers (void)
           t = next;
         }
 
-      UNBLOCK_ATIMERS;
+      unblock_atimers ();
     }
 }
 
@@ -397,9 +412,9 @@ do_pending_atimers (void)
 {
   if (pending_atimers)
     {
-      BLOCK_ATIMERS;
+      block_atimers ();
       run_timers ();
-      UNBLOCK_ATIMERS;
+      unblock_atimers ();
     }
 }
 
@@ -412,7 +427,9 @@ turn_on_atimers (bool on)
 {
   if (on)
     {
-      signal (SIGALRM, deliver_alarm_signal);
+      struct sigaction action;
+      emacs_sigaction_init (&action, deliver_alarm_signal);
+      sigaction (SIGALRM, &action, 0);
       set_alarm ();
     }
   else
@@ -423,8 +440,10 @@ turn_on_atimers (bool on)
 void
 init_atimer (void)
 {
+  struct sigaction action;
   free_atimers = stopped_atimers = atimers = NULL;
   pending_atimers = 0;
   /* pending_signals is initialized in init_keyboard.*/
-  signal (SIGALRM, deliver_alarm_signal);
+  emacs_sigaction_init (&action, deliver_alarm_signal);
+  sigaction (SIGALRM, &action, 0);
 }