MS-Windows followup for 2012-09-07T01:27:44Z!eggert@cs.ucla.edu, signal-handler cleanup.

 src/w32proc.c (sigaction): New function, emulates Posix 'sigaction'.
 src/w32.c (sigemptyset): Empty the set.
 (sigsetmask, sigmask, sigblock, sigunblock): Remove unused functions.

 nt/inc/ms-w32.h (struct sigaction): Declare sa_handler __cdecl.

Fixes: debbugs:12327

3 files changed, 29 insertions, 25 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 1ff58232538..068584969f7 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,10 @@
 2012-09-07  Eli Zaretskii  <eliz@gnu.org>
 
+        * w32proc.c (sigaction): New function, emulates Posix 'sigaction'.
+
+        * w32.c (sigemptyset): Empty the set.
+        (sigsetmask, sigmask, sigblock, sigunblock): Remove unused functions.
+
         * alloc.c [ENABLE_CHECKING]: Include signal.h, since we need SIGABRT.
 
 2012-09-07  Dmitry Antipov  <dmantipov@yandex.ru>
diff --git a/src/w32.c b/src/w32.c
index 4505afc18b3..04f7471577c 100644
--- a/src/w32.c
+++ b/src/w32.c
@@ -1530,34 +1530,10 @@ is_unc_volume (const char *filename)
 }
 
 /* Routines that are no-ops on NT but are defined to get Emacs to compile.  */
-
-int
-sigsetmask (int signal_mask)
-{
-  return 0;
-}
-
-int
-sigmask (int sig)
-{
-  return 0;
-}
-
-int
-sigblock (int sig)
-{
-  return 0;
-}
-
-int
-sigunblock (int sig)
-{
-  return 0;
-}
-
 int
 sigemptyset (sigset_t *set)
 {
+  *set = 0;
   return 0;
 }
 
diff --git a/src/w32proc.c b/src/w32proc.c
index f83e81aedff..b9239cbb99a 100644
--- a/src/w32proc.c
+++ b/src/w32proc.c
@@ -103,6 +103,29 @@ sys_signal (int sig, signal_handler handler)
   return old;
 }
 
+/* Emulate sigaction. */
+int
+sigaction (int sig, const struct sigaction *act, struct sigaction *oact)
+{
+  signal_handler old;
+
+  if (sig != SIGCHLD)
+    {
+      errno = EINVAL;
+      return -1;
+    }
+  old = sig_handlers[sig];
+  if (act)
+    sig_handlers[sig] = act->sa_handler;
+  if (oact)
+    {
+      oact->sa_handler = old;
+      oact->sa_flags = 0;
+      oact->sa_mask = empty_mask;
+    }
+  return 0;
+}
+
 /* Defined in <process.h> which conflicts with the local copy */
 #define _P_NOWAIT 1