1 files changed, 76 insertions, 43 deletions

diff --git a/contrib/ntp/libntp/iosignal.c b/contrib/ntp/libntp/iosignal.c
index 3c78d48..cda5e96 100644
--- a/contrib/ntp/libntp/iosignal.c
+++ b/contrib/ntp/libntp/iosignal.c
@@ -27,6 +27,19 @@
 
 #if defined(HAVE_SIGNALED_IO)
 static int sigio_block_count = 0;
+# if defined(HAVE_SIGACTION)
+/*
+ * If sigaction() is used for signal handling and a signal is
+ * pending then the kernel blocks the signal before it calls
+ * the signal handler.
+ *
+ * The variable below is used to take care that the SIGIO signal
+ * is not unintentionally unblocked inside the sigio_handler()
+ * if the handler executes a piece of code that is normally
+ * bracketed by BLOCKIO()/UNBLOCKIO() calls.
+ */
+static int sigio_handler_active = 0;
+# endif
 extern	void	input_handler	P((l_fp *));
 
 /*
@@ -282,7 +295,21 @@ sigio_handler(
 	l_fp ts;
 
 	get_systime(&ts);
+
+# if defined(HAVE_SIGACTION)
+	sigio_handler_active++;
+	if (sigio_handler_active != 1)  /* This should never happen! */
+	    msyslog(LOG_ERR, "sigio_handler: sigio_handler_active != 1");
+# endif
+
 	(void)input_handler(&ts);
+
+# if defined(HAVE_SIGACTION)
+	sigio_handler_active--;
+	if (sigio_handler_active != 0)  /* This should never happen! */
+	    msyslog(LOG_ERR, "sigio_handler: sigio_handler_active != 0");
+# endif
+
 	errno = saved_errno;
 }
 
@@ -326,27 +353,30 @@ block_io_and_alarm(void)
 void
 block_sigio(void)
 {
-	sigset_t set;
-
-	++sigio_block_count;
-	if (sigio_block_count > 1)
-	    msyslog(LOG_INFO, "block_sigio: sigio_block_count > 1");
-	if (sigio_block_count < 1)
-	    msyslog(LOG_INFO, "block_sigio: sigio_block_count < 1");
-
-	if (sigemptyset(&set))
-	    msyslog(LOG_ERR, "block_sigio: sigemptyset() failed: %m");
-#  if defined(USE_SIGIO)
-	if (sigaddset(&set, SIGIO))
-	    msyslog(LOG_ERR, "block_sigio: sigaddset(SIGIO) failed: %m");
-#  endif
-#  if defined(USE_SIGPOLL)
-	if (sigaddset(&set, SIGPOLL))
-	    msyslog(LOG_ERR, "block_sigio: sigaddset(SIGPOLL) failed: %m");
-#  endif
-
-	if (sigprocmask(SIG_BLOCK, &set, NULL))
-	    msyslog(LOG_ERR, "block_sigio: sigprocmask() failed: %m");
+	if ( sigio_handler_active == 0 )  /* not called from within signal handler */
+	{
+		sigset_t set;
+
+		++sigio_block_count;
+		if (sigio_block_count > 1)
+		    msyslog(LOG_INFO, "block_sigio: sigio_block_count > 1");
+		if (sigio_block_count < 1)
+		    msyslog(LOG_INFO, "block_sigio: sigio_block_count < 1");
+
+		if (sigemptyset(&set))
+		    msyslog(LOG_ERR, "block_sigio: sigemptyset() failed: %m");
+#	if defined(USE_SIGIO)
+		if (sigaddset(&set, SIGIO))
+		    msyslog(LOG_ERR, "block_sigio: sigaddset(SIGIO) failed: %m");
+#	endif
+#	if defined(USE_SIGPOLL)
+		if (sigaddset(&set, SIGPOLL))
+		    msyslog(LOG_ERR, "block_sigio: sigaddset(SIGPOLL) failed: %m");
+#	endif
+
+		if (sigprocmask(SIG_BLOCK, &set, NULL))
+		    msyslog(LOG_ERR, "block_sigio: sigprocmask() failed: %m");
+	}
 }
 
 void
@@ -375,28 +405,31 @@ unblock_io_and_alarm(void)
 void
 unblock_sigio(void)
 {
-	sigset_t unset;
-
-	--sigio_block_count;
-	if (sigio_block_count > 0)
-	    msyslog(LOG_INFO, "unblock_sigio: sigio_block_count > 0");
-	if (sigio_block_count < 0)
-	    msyslog(LOG_INFO, "unblock_sigio: sigio_block_count < 0");
-
-	if (sigemptyset(&unset))
-	    msyslog(LOG_ERR, "unblock_sigio: sigemptyset() failed: %m");
-
-#  if defined(USE_SIGIO)
-	if (sigaddset(&unset, SIGIO))
-	    msyslog(LOG_ERR, "unblock_sigio: sigaddset(SIGIO) failed: %m");
-#  endif
-#  if defined(USE_SIGPOLL)
-	if (sigaddset(&unset, SIGPOLL))
-	    msyslog(LOG_ERR, "unblock_sigio: sigaddset(SIGPOLL) failed: %m");
-#  endif
-
-	if (sigprocmask(SIG_UNBLOCK, &unset, NULL))
-	    msyslog(LOG_ERR, "unblock_sigio: sigprocmask() failed: %m");
+	if ( sigio_handler_active == 0 )  /* not called from within signal handler */
+	{
+		sigset_t unset;
+
+		--sigio_block_count;
+		if (sigio_block_count > 0)
+		    msyslog(LOG_INFO, "unblock_sigio: sigio_block_count > 0");
+		if (sigio_block_count < 0)
+		    msyslog(LOG_INFO, "unblock_sigio: sigio_block_count < 0");
+
+		if (sigemptyset(&unset))
+		    msyslog(LOG_ERR, "unblock_sigio: sigemptyset() failed: %m");
+
+#	if defined(USE_SIGIO)
+		if (sigaddset(&unset, SIGIO))
+		    msyslog(LOG_ERR, "unblock_sigio: sigaddset(SIGIO) failed: %m");
+#	endif
+#	if defined(USE_SIGPOLL)
+		if (sigaddset(&unset, SIGPOLL))
+		    msyslog(LOG_ERR, "unblock_sigio: sigaddset(SIGPOLL) failed: %m");
+#	endif
+
+		if (sigprocmask(SIG_UNBLOCK, &unset, NULL))
+		    msyslog(LOG_ERR, "unblock_sigio: sigprocmask() failed: %m");
+	}
 }
 
 void