Replace all uses of strerror() by ovs_strerror(), for thread safety.

[sliver-openvswitch.git] / lib / signals.c

diff --git a/lib/signals.c b/lib/signals.c
index 37f0637..f11ed05 100644 (file)
--- a/lib/signals.c
+++ b/lib/signals.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009, 2011 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2011, 2012, 2013 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,10 +16,10 @@
 
 #include <config.h>
 #include "signals.h"
-#include <assert.h>
 #include <errno.h>
 #include <limits.h>
 #include <signal.h>
+#include <stdlib.h>
 #include <unistd.h>
 #include "poll-loop.h"
 #include "socket-util.h"
@@ -40,55 +40,36 @@ VLOG_DEFINE_THIS_MODULE(signals);
 #endif
 
 struct signal {
-    int signr;
+    int fds[2];
 };
 
-static volatile sig_atomic_t signaled[N_SIGNALS];
-
-static int fds[2];
+static struct signal signals[N_SIGNALS];
 
 static void signal_handler(int signr);
 
-/* Initializes the signals subsystem (if it is not already initialized).  Calls
- * exit() if initialization fails.
- *
- * Calling this function is optional; it will be called automatically by
- * signal_start() if necessary.  Calling it explicitly allows the client to
- * prevent the process from exiting at an unexpected time. */
-void
-signal_init(void)
-{
-    static bool inited;
-    if (!inited) {
-        inited = true;
-        xpipe(fds);
-        set_nonblocking(fds[0]);
-        set_nonblocking(fds[1]);
-    }
-}
-
 /* Sets up a handler for 'signr' and returns a structure that represents it.
  *
- * Only one handler for a given signal may be registered at a time. */
+ * Only one handler for a given signal may be registered. */
 struct signal *
 signal_register(int signr)
 {
     struct sigaction sa;
     struct signal *s;
 
-    signal_init();
+    ovs_assert(signr >= 1 && signr < N_SIGNALS);
+
+    /* Create a pipe. */
+    s = &signals[signr];
+    ovs_assert(!s->fds[0] && !s->fds[1]);
+    xpipe_nonblocking(s->fds);
 
-    /* Set up signal handler. */
-    assert(signr >= 1 && signr < N_SIGNALS);
+    /* Install signal handler. */
     memset(&sa, 0, sizeof sa);
     sa.sa_handler = signal_handler;
     sigemptyset(&sa.sa_mask);
     sa.sa_flags = SA_RESTART;
     xsigaction(signr, &sa, NULL);
 
-    /* Return structure. */
-    s = xmalloc(sizeof *s);
-    s->signr = signr;
     return s;
 }
 
@@ -98,12 +79,8 @@ bool
 signal_poll(struct signal *s)
 {
     char buf[_POSIX_PIPE_BUF];
-    ignore(read(fds[0], buf, sizeof buf));
-    if (signaled[s->signr]) {
-        signaled[s->signr] = 0;
-        return true;
-    }
-    return false;
+
+    return read(s->fds[0], buf, sizeof buf) > 0;
 }
 
 /* Causes the next call to poll_block() to wake up when signal_poll(s) would
@@ -111,56 +88,57 @@ signal_poll(struct signal *s)
 void
 signal_wait(struct signal *s)
 {
-    if (signaled[s->signr]) {
-        poll_immediate_wake();
-    } else {
-        poll_fd_wait(fds[0], POLLIN);
-    }
+    poll_fd_wait(s->fds[0], POLLIN);
 }
 \f
 static void
 signal_handler(int signr)
 {
     if (signr >= 1 && signr < N_SIGNALS) {
-        ignore(write(fds[1], "", 1));
-        signaled[signr] = true;
+        ignore(write(signals[signr].fds[1], "", 1));
     }
 }
 
-/* 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.
+/* Returns the name of signal 'signum' as a string.  The return value is either
+ * a statically allocated constant string or the 'bufsize'-byte buffer
+ * 'namebuf'.  'bufsize' should be at least SIGNAL_NAME_BUFSIZE.
  *
  * 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)
+signal_name(int signum, char *namebuf, size_t bufsize)
 {
-    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;
+#if HAVE_DECL_SYS_SIGLIST
+    if (signum >= 0 && signum < ARRAY_SIZE(sys_siglist)) {
+        const char *name = sys_siglist[signum];
+        if (name) {
+            return name;
+        }
     }
-    return name;
+#endif
+
+    snprintf(namebuf, bufsize, "signal %d", signum);
+    return namebuf;
 }
 
 void
 xsigaction(int signum, const struct sigaction *new, struct sigaction *old)
 {
     if (sigaction(signum, new, old)) {
+        char namebuf[SIGNAL_NAME_BUFSIZE];
+
         VLOG_FATAL("sigaction(%s) failed (%s)",
-                   signal_name(signum), strerror(errno));
+                   signal_name(signum, namebuf, sizeof namebuf),
+                   ovs_strerror(errno));
     }
 }
 
 void
-xsigprocmask(int how, const sigset_t *new, sigset_t *old)
+xpthread_sigmask(int how, const sigset_t *new, sigset_t *old)
 {
-    if (sigprocmask(how, new, old)) {
-        VLOG_FATAL("sigprocmask failed (%s)", strerror(errno));
+    int error = pthread_sigmask(how, new, old);
+    if (error) {
+        VLOG_FATAL("pthread_sigmask failed (%s)", ovs_strerror(error));
     }
 }