fatal-signal: Fatal signal handling for Windows.

Windows does not have a SIGHUP or SIGALRM. It does have
a SIGINT and SIGTERM. The documentation at msdn says that
SIGINT is not supported for win32 applications because
WIN32 operating systems generate a new thread to specifically
handle Ctrl+C.

This commit handles SIGTERM for Windows. The documentation also
states that nothing generates SIGTERM in Windows, but one can
use raise(SIGTERM) to manage it. The idea for handling SIGTERM
for Windows is to just have a place holder if there is need to
raise() a signal for some other purpose.

We use SIGALRM in timeval.c if we wake up from a sleep after
'deadline'. For Windows, print an error message and then
use SIGTERM.

There is an atexit() function for Windows, so we can call cleanup
functions during exit.

An upcoming commit separately handles Ctrl+C so that we can call
clean up functions for that use case.

Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>

diff --git a/lib/fatal-signal.c b/lib/fatal-signal.c
index b1a0341..1e63d48 100644 (file)
--- a/lib/fatal-signal.c
+++ b/lib/fatal-signal.c
@@ -41,7 +41,11 @@
 VLOG_DEFINE_THIS_MODULE(fatal_signal);
 
 /* Signals to catch. */
+#ifndef _WIN32
 static const int fatal_signals[] = { SIGTERM, SIGINT, SIGHUP, SIGALRM };
+#else
+static const int fatal_signals[] = { SIGTERM };
+#endif
 
 /* Hooks to call upon catching a signal */
 struct hook {
@@ -55,6 +59,7 @@ static struct hook hooks[MAX_HOOKS];
 static size_t n_hooks;
 
 static int signal_fds[2];
+HANDLE wevent;
 static volatile sig_atomic_t stored_sig_nr = SIG_ATOMIC_MAX;
 
 static struct ovs_mutex mutex;
@@ -78,10 +83,19 @@ fatal_signal_init(void)
         inited = true;
 
         ovs_mutex_init_recursive(&mutex);
+#ifndef _WIN32
         xpipe_nonblocking(signal_fds);
+#else
+        wevent = CreateEvent(NULL, TRUE, FALSE, NULL);
+        if (!wevent) {
+            char *msg_buf = ovs_lasterror_to_string();
+            VLOG_FATAL("Failed to create a event (%s).", msg_buf);
+        }
+#endif
 
         for (i = 0; i < ARRAY_SIZE(fatal_signals); i++) {
             int sig_nr = fatal_signals[i];
+#ifndef _WIN32
             struct sigaction old_sa;
 
             xsigaction(sig_nr, NULL, &old_sa);
@@ -89,6 +103,11 @@ fatal_signal_init(void)
                 && signal(sig_nr, fatal_signal_handler) == SIG_ERR) {
                 VLOG_FATAL("signal failed (%s)", ovs_strerror(errno));
             }
+#else
+            if (signal(sig_nr, fatal_signal_handler) == SIG_ERR) {
+                VLOG_FATAL("signal failed (%s)", ovs_strerror(errno));
+            }
+#endif
         }
         atexit(atexit_handler);
     }
@@ -136,7 +155,11 @@ fatal_signal_add_hook(void (*hook_cb)(void *aux), void (*cancel_cb)(void *aux),
 void
 fatal_signal_handler(int sig_nr)
 {
+#ifndef _WIN32
     ignore(write(signal_fds[1], "", 1));
+#else
+    SetEvent(wevent);
+#endif
     stored_sig_nr = sig_nr;
 }
 
@@ -164,8 +187,12 @@ fatal_signal_run(void)
 
         ovs_mutex_lock(&mutex);
 
+#ifndef _WIN32
         VLOG_WARN("terminating with signal %d (%s)",
                   (int)sig_nr, signal_name(sig_nr, namebuf, sizeof namebuf));
+#else
+        VLOG_WARN("terminating with signal %d", (int)sig_nr);
+#endif
         call_hooks(sig_nr);
 
         /* Re-raise the signal with the default handling so that the program
@@ -182,7 +209,7 @@ void
 fatal_signal_wait(void)
 {
     fatal_signal_init();
-    poll_fd_wait(signal_fds[0], POLLIN);
+    poll_fd_wait_event(signal_fds[0], wevent, POLLIN);
 }
 
 static void

diff --git a/lib/timeval.c b/lib/timeval.c
index 691cf74..3e7719f 100644 (file)
--- a/lib/timeval.c
+++ b/lib/timeval.c
@@ -282,7 +282,12 @@ time_poll(struct pollfd *pollfds, int n_pollfds, HANDLE *handles OVS_UNUSED,
 #endif
 
         if (deadline <= time_msec()) {
+#ifndef _WIN32
             fatal_signal_handler(SIGALRM);
+#else
+            VLOG_ERR("wake up from WaitForMultipleObjects after deadline");
+            fatal_signal_handler(SIGTERM);
+#endif
             if (retval < 0) {
                 retval = 0;
             }