Improve sys_siglist detection.

* configure.ac (sys_siglist): Look for its decl in <signal.h>.
Otherwise, it's not found in either Fedora 17 or Solaris 11.
* src/sysdep.c (sys_siglist, init_signals): Use _sys_siglist if it's
defined as a macro, as is done in Solaris.
(sys_siglist_entries): New macro.
(save_strsignal): Use it.
* src/syssignal.h (safe_strsignal): Now ATTRIBUTE_CONST, to pacify
GCC 4.7.2 on Fedora 17 with the fixed sys_siglist detection.

3 files changed, 25 insertions, 5 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index b960837eaab..a30dde5e4ea 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,13 @@
+2012-10-07  Paul Eggert  <eggert@cs.ucla.edu>
+
+        Improve sys_siglist detection.
+        * sysdep.c (sys_siglist, init_signals): Use _sys_siglist if it's
+        defined as a macro, as is done in Solaris.
+        (sys_siglist_entries): New macro.
+        (save_strsignal): Use it.
+        * syssignal.h (safe_strsignal): Now ATTRIBUTE_CONST, to pacify
+        GCC 4.7.2 on Fedora 17 with the fixed sys_siglist detection.
+
 2012-10-06  Jan Djärv  <jan.h.d@swipnet.se>
 
         * nsfns.m (Fx_create_frame): Call x_default_parameter with
diff --git a/src/sysdep.c b/src/sysdep.c
index 74617fcaf0f..35beeaa7202 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -1545,8 +1545,18 @@ deliver_thread_signal (int sig, signal_handler_t handler)
 
 #if !HAVE_DECL_SYS_SIGLIST
 # undef sys_siglist
-# define sys_siglist my_sys_siglist
+# ifdef _sys_siglist
+#  define sys_siglist _sys_siglist
+# else
+#  define sys_siglist my_sys_siglist
 static char const *sys_siglist[NSIG];
+# endif
+#endif
+
+#ifdef _sys_nsig
+# define sys_siglist_entries _sys_nsig
+#else
+# define sys_siglist_entries NSIG
 #endif
 
 /* Handle bus errors, invalid instruction, etc.  */
@@ -1609,7 +1619,7 @@ init_signals (bool dumping)
   main_thread = pthread_self ();
 #endif
 
-#if !HAVE_DECL_SYS_SIGLIST
+#if !HAVE_DECL_SYS_SIGLIST && !defined _sys_siglist
   if (! initialized)
     {
       sys_siglist[SIGABRT] = "Aborted";
@@ -1757,7 +1767,7 @@ init_signals (bool dumping)
       sys_siglist[SIGXFSZ] = "File size limit exceeded";
 # endif
     }
-#endif /* !HAVE_DECL_SYS_SIGLIST */
+#endif /* !HAVE_DECL_SYS_SIGLIST && !_sys_siglist */
 
   /* Don't alter signal handlers if dumping.  On some machines,
      changing signal handlers sets static data that would make signals
@@ -2285,7 +2295,7 @@ safe_strsignal (int code)
 {
   char const *signame = 0;
 
-  if (0 <= code && code < NSIG)
+  if (0 <= code && code < sys_siglist_entries)
     signame = sys_siglist[code];
   if (! signame)
     signame = "Unknown signal";
diff --git a/src/syssignal.h b/src/syssignal.h
index 83ab19698dd..2bf2f046aa5 100644
--- a/src/syssignal.h
+++ b/src/syssignal.h
@@ -43,7 +43,7 @@ extern sigset_t empty_mask;
 typedef void (*signal_handler_t) (int);
 
 extern void emacs_sigaction_init (struct sigaction *, signal_handler_t);
-char const *safe_strsignal (int);
+char const *safe_strsignal (int) ATTRIBUTE_CONST;
 
 #if NSIG < NSIG_MINIMUM
 # undef NSIG