ofp-util: Work on decoding OF1.1 flow_mods.

[openvswitch] / lib / signals.c

diff --git a/lib/signals.c b/lib/signals.c
index d8e51b644e541dba230e73d40103fdbf7aadc67b..b712f7e74da8bc819a6d9fd5d0b401aaee43d0d5 100644 (file)
--- a/lib/signals.c
+++ b/lib/signals.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2011, 2012 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,10 +20,15 @@
 #include <errno.h>
 #include <limits.h>
 #include <signal.h>
+#include <stdlib.h>
 #include <unistd.h>
 #include "poll-loop.h"
 #include "socket-util.h"
+#include "type-props.h"
 #include "util.h"
+#include "vlog.h"
+
+VLOG_DEFINE_THIS_MODULE(signals);
 
 #if defined(_NSIG)
 #define N_SIGNALS _NSIG
@@ -36,6 +41,7 @@
 #endif
 
 struct signal {
+    struct sigaction saved_sa;
     int signr;
 };
 
@@ -57,11 +63,9 @@ signal_init(void)
     static bool inited;
     if (!inited) {
         inited = true;
-        if (pipe(fds)) {
-            ovs_fatal(errno, "could not create pipe");
-        }
-        set_nonblocking(fds[0]);
-        set_nonblocking(fds[1]);
+        xpipe(fds);
+        xset_nonblocking(fds[0]);
+        xset_nonblocking(fds[1]);
     }
 }
 
@@ -76,29 +80,38 @@ signal_register(int signr)
 
     signal_init();
 
+    s = xmalloc(sizeof *s);
+    s->signr = signr;
+
     /* Set up signal handler. */
     assert(signr >= 1 && signr < N_SIGNALS);
     memset(&sa, 0, sizeof sa);
     sa.sa_handler = signal_handler;
     sigemptyset(&sa.sa_mask);
     sa.sa_flags = SA_RESTART;
-    if (sigaction(signr, &sa, NULL)) {
-        ovs_fatal(errno, "sigaction(%d) failed", signr);
-    }
+    xsigaction(signr, &sa, &s->saved_sa);
 
-    /* Return structure. */
-    s = xmalloc(sizeof *s);
-    s->signr = signr;
     return s;
 }
 
+/* Unregisters the handler for 's', restores the signal handler that was in
+ * effect before signal_register() was called, and frees 's'. */
+void
+signal_unregister(struct signal *s)
+{
+    if (s) {
+        xsigaction(s->signr, &s->saved_sa, NULL);
+        free(s);
+    }
+}
+
 /* Returns true if signal 's' has been received since the last call to this
  * function with argument 's'. */
 bool
 signal_poll(struct signal *s)
 {
     char buf[_POSIX_PIPE_BUF];
-    read(fds[0], buf, sizeof buf);
+    ignore(read(fds[0], buf, sizeof buf));
     if (signaled[s->signr]) {
         signaled[s->signr] = 0;
         return true;
@@ -122,7 +135,45 @@ static void
 signal_handler(int signr)
 {
     if (signr >= 1 && signr < N_SIGNALS) {
-        write(fds[1], "", 1);
+        ignore(write(fds[1], "", 1));
         signaled[signr] = true;
     }
 }
+
+/* Returns the name of signal 'signum' as a string.  The string may be in a
+ * static buffer that is reused from one call to the next.
+ *
+ * The string is probably a (possibly multi-word) description of the signal
+ * (e.g. "Hangup") instead of just the stringified version of the macro
+ * (e.g. "SIGHUP"). */
+const char *
+signal_name(int signum)
+{
+    const char *name = NULL;
+#ifdef HAVE_STRSIGNAL
+    name = strsignal(signum);
+#endif
+    if (!name) {
+        static char buffer[7 + INT_STRLEN(int) + 1];
+        sprintf(buffer, "signal %d", signum);
+        name = buffer;
+    }
+    return name;
+}
+
+void
+xsigaction(int signum, const struct sigaction *new, struct sigaction *old)
+{
+    if (sigaction(signum, new, old)) {
+        VLOG_FATAL("sigaction(%s) failed (%s)",
+                   signal_name(signum), strerror(errno));
+    }
+}
+
+void
+xsigprocmask(int how, const sigset_t *new, sigset_t *old)
+{
+    if (sigprocmask(how, new, old)) {
+        VLOG_FATAL("sigprocmask failed (%s)", strerror(errno));
+    }
+}