Fix logic bug introduced on 2007-05-06.

[gnulib.git] / lib / fatal-signal.c

diff --git a/lib/fatal-signal.c b/lib/fatal-signal.c
index 8718fd6..3862b79 100644 (file)
--- a/lib/fatal-signal.c
+++ b/lib/fatal-signal.c
@@ -1,5 +1,5 @@
 /* Emergency actions in case of a fatal signal.
-   Copyright (C) 2003 Free Software Foundation, Inc.
+   Copyright (C) 2003-2004, 2006-2007 Free Software Foundation, Inc.
    Written by Bruno Haible <bruno@clisp.org>, 2003.
 
    This program is free software; you can redistribute it and/or modify
@@ -14,12 +14,10 @@
 
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software Foundation,
-   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
 
 
-#ifdef HAVE_CONFIG_H
-# include "config.h"
-#endif
+#include <config.h>
 
 /* Specification.  */
 #include "fatal-signal.h"
@@ -27,10 +25,7 @@
 #include <stdbool.h>
 #include <stdlib.h>
 #include <signal.h>
-#include <string.h>
-#if HAVE_UNISTD_H
-# include <unistd.h>
-#endif
+#include <unistd.h>
 
 #include "xalloc.h"
 
@@ -54,7 +49,7 @@
    plus
      SIGXCPU, SIGXFSZ - because they are quite similar to SIGTERM.  */
 
-static const int fatal_signals[] =
+static int fatal_signals[] =
   {
     /* ISO C 99 signals.  */
 #ifdef SIGINT
@@ -77,11 +72,40 @@ static const int fatal_signals[] =
 #ifdef SIGXFSZ
     SIGXFSZ,
 #endif
+    /* Woe32 signals.  */
+#ifdef SIGBREAK
+    SIGBREAK,
+#endif
     0
   };
 
 #define num_fatal_signals (SIZEOF (fatal_signals) - 1)
 
+/* Eliminate signals whose signal handler is SIG_IGN.  */
+
+static void
+init_fatal_signals (void)
+{
+  static bool fatal_signals_initialized = false;
+  if (!fatal_signals_initialized)
+    {
+#if HAVE_SIGACTION
+      size_t i;
+
+      for (i = 0; i < num_fatal_signals; i++)
+       {
+         struct sigaction action;
+
+         if (sigaction (fatal_signals[i], NULL, &action) >= 0
+             && action.sa_handler == SIG_IGN)
+           fatal_signals[i] = -1;
+       }
+#endif
+
+      fatal_signals_initialized = true;
+    }
+}
+
 
 /* ========================================================================= */
 
@@ -111,7 +135,8 @@ uninstall_handlers ()
   size_t i;
 
   for (i = 0; i < num_fatal_signals; i++)
-    signal (fatal_signals[i], SIG_DFL);
+    if (fatal_signals[i] >= 0)
+      signal (fatal_signals[i], SIG_DFL);
 }
 
 
@@ -153,7 +178,8 @@ install_handlers ()
   size_t i;
 
   for (i = 0; i < num_fatal_signals; i++)
-    signal (fatal_signals[i], &fatal_signal_handler);
+    if (fatal_signals[i] >= 0)
+      signal (fatal_signals[i], &fatal_signal_handler);
 }
 
 
@@ -165,6 +191,7 @@ at_fatal_signal (action_t action)
   static bool cleanup_initialized = false;
   if (!cleanup_initialized)
     {
+      init_fatal_signals ();
       install_handlers ();
       cleanup_initialized = true;
     }
@@ -175,12 +202,17 @@ at_fatal_signal (action_t action)
         because then the cleanup() function could access an already
         deallocated array.  */
       actions_entry_t *old_actions = actions;
+      size_t old_actions_allocated = actions_allocated;
       size_t new_actions_allocated = 2 * actions_allocated;
       actions_entry_t *new_actions =
-       xmalloc (new_actions_allocated * sizeof (actions_entry_t));
-
-      memcpy (new_actions, old_actions,
-             actions_allocated * sizeof (actions_entry_t));
+       XNMALLOC (new_actions_allocated, actions_entry_t);
+      size_t k;
+
+      /* Don't use memcpy() here, because memcpy takes non-volatile arguments
+        and is therefore not guaranteed to complete all memory stores before
+        the next statement.  */
+      for (k = 0; k < old_actions_allocated; k++)
+       new_actions[k] = old_actions[k];
       actions = new_actions;
       actions_allocated = new_actions_allocated;
       /* Now we can free the old actions array.  */
@@ -199,8 +231,6 @@ at_fatal_signal (action_t action)
 /* ========================================================================= */
 
 
-#if HAVE_POSIX_SIGNALBLOCKING
-
 static sigset_t fatal_signal_set;
 
 static void
@@ -211,9 +241,12 @@ init_fatal_signal_set ()
     {
       size_t i;
 
+      init_fatal_signals ();
+
       sigemptyset (&fatal_signal_set);
       for (i = 0; i < num_fatal_signals; i++)
-       sigaddset (&fatal_signal_set, fatal_signals[i]);
+       if (fatal_signals[i] >= 0)
+         sigaddset (&fatal_signal_set, fatal_signals[i]);
 
       fatal_signal_set_initialized = true;
     }
@@ -234,20 +267,3 @@ unblock_fatal_signals ()
   init_fatal_signal_set ();
   sigprocmask (SIG_UNBLOCK, &fatal_signal_set, NULL);
 }
-
-#else
-
-/* Don't bother caring about the old systems which don't have POSIX signal
-   blocking.  */
-
-void
-block_fatal_signals ()
-{
-}
-
-void
-unblock_fatal_signals ()
-{
-}
-
-#endif