event/SignalMonitor: use signalfd() if available

src/system/SignalFD.cxx

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2003-2013 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#ifdef USE_SIGNALFD
+#include "SignalFD.hxx"
+#include "fd_util.h"
+#include "FatalError.hxx"
+
+#include <assert.h>
+#include <unistd.h>
+#include <sys/signalfd.h>
+
+void
+SignalFD::Create(const sigset_t &mask)
+{
+	fd = ::signalfd(fd, &mask, SFD_NONBLOCK|SFD_CLOEXEC);
+	if (fd < 0)
+		FatalSystemError("signalfd() failed");
+}
+
+void
+SignalFD::Close()
+{
+	if (fd >= 0) {
+		::close(fd);
+		fd = -1;
+	}
+}
+
+int
+SignalFD::Read()
+{
+	assert(fd >= 0);
+
+	signalfd_siginfo info;
+	return read(fd, &info, sizeof(info)) > 0
+		? info.ssi_signo
+		: -1;
+}
+
+#endif /* USE_SIGNALFD */

src/system/SignalFD.hxx

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2003-2013 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_SIGNAL_FD_HXX
+#define MPD_SIGNAL_FD_HXX
+
+#include "check.h"
+
+#include <signal.h>
+
+/**
+ * A class that wraps signalfd().
+ */
+class SignalFD {
+	int fd;
+
+public:
+	SignalFD():fd(-1) {}
+	~SignalFD() {
+		Close();
+	}
+
+	SignalFD(const SignalFD &other) = delete;
+	SignalFD &operator=(const SignalFD &other) = delete;
+
+	/**
+	 * Create the signalfd or update its mask.
+	 *
+	 * All errors are fatal.
+	 */
+	void Create(const sigset_t &mask);
+	void Close();
+
+	int Get() const {
+		return fd;
+	}
+
+	/**
+	 * Read the next signal from the file descriptor.  Returns the
+	 * signal number on success or -1 if there are no more
+	 * signals.
+	 */
+	int Read();
+};
+
+#endif