o check in simple daemonize code for slurm daemons

src/common/daemonize.c

+/*****************************************************************************\
+ * daemonize.c - daemonization routine
+ *****************************************************************************
+ *  Copyright (C) 2002 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Mark A. Grondona <mgrondona@llnl.gov>.
+ *  UCRL-CODE-2002-040.
+ *  
+ *  This file is part of SLURM, a resource management program.
+ *  For details, see <http://www.llnl.gov/linux/slurm/>.
+ *  
+ *  SLURM 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.
+ *  
+ *  SLURM 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 SLURM; if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+\*****************************************************************************/
+
+#if HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
+#include <unistd.h>
+
+#include <src/common/macros.h>
+#include <src/common/log.h>
+
+/* closeall FDs >= a specified value */
+static void
+closeall(int fd)
+{
+	int fdlimit = sysconf(_SC_OPEN_MAX);
+
+	while (fd < fdlimit) 
+		close(fd++);
+}
+
+/* detach and go into background.
+ * caller is responsible for umasks
+ *
+ * if chdir   != 0, will do a chdir to /
+ * if noclose == 0, will close all FDs
+ */
+int
+daemon(int nochdir, int noclose)
+{
+	switch (fork()) {
+		case  0 : break;        /* child */
+		case -1 : return -1;
+		default : _exit(0);     /* exit parent */
+	}
+
+	if (setsid() < 0)
+		return -1;
+
+	switch (fork()) {
+		case 0 : break;         /* child */
+		case -1: return -1;
+		default: _exit(0);      /* exit parent */
+	}
+
+	if(!nochdir && chdir("/") < 0)
+		fatal("chdir(/): %m");
+
+	if (!noclose) {
+		closeall(0);
+		open("/dev/null", O_RDWR);
+		dup(0);
+		dup(0);
+	}
+	return 0;
+
+}

src/common/daemonize.h

+/* src/common/daemonize.h
+ * $Id$
+ */
+
+#ifndef _HAVE_DAEMONIZE_H
+#define _HAVE_DAEMONIZE_H
+
+/* fork process into background and inherit new session
+ * if nochdir is 0, performs a chdir("/")
+ * if noclose is 0, closes all fds and dups stdout/err of daemon onto /dev/null
+ *
+ * returns -1 on error.
+ */
+int daemon(int nochdir, int noclose);
+
+#endif /* !_HAVE_DAEMONIZE_H */