Expand system into my_system, and add the necessary tidyness that we

need.  Close the pidfile.  Then close all descriptors >= 3 to avoid
information leakage to children.

This solves the problem of not being able to restart devd when you
have, for example, a dhclient forked to configure your network...

MFC after:	3 days

sbin/devd/devd.cc

@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 2002-2003 M. Warner Losh.
+ * Copyright (c) 2002-2010 M. Warner Losh.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -22,6 +22,35 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
+ *
+ * my_system is a variation on lib/libc/stdlib/system.c:
+ *
+ * Copyright (c) 1988, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
  */
 
 /*
@@ -41,6 +70,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/stat.h>
 #include <sys/sysctl.h>
 #include <sys/types.h>
+#include <sys/wait.h>
 #include <sys/un.h>
 
 #include <ctype.h>
@@ -49,6 +79,7 @@ __FBSDID("$FreeBSD$");
 #include <err.h>
 #include <fcntl.h>
 #include <libutil.h>
+#include <paths.h>
 #include <regex.h>
 #include <signal.h>
 #include <stdlib.h>
@@ -152,13 +183,67 @@ action::~action()
 	// nothing
 }
 
+static int
+my_system(const char *command)
+{
+	pid_t pid, savedpid;
+	int pstat;
+	struct sigaction ign, intact, quitact;
+	sigset_t newsigblock, oldsigblock;
+
+	if (!command)		/* just checking... */
+		return(1);
+
+	/*
+	 * Ignore SIGINT and SIGQUIT, block SIGCHLD. Remember to save
+	 * existing signal dispositions.
+	 */
+	ign.sa_handler = SIG_IGN;
+	::sigemptyset(&ign.sa_mask);
+	ign.sa_flags = 0;
+	::sigaction(SIGINT, &ign, &intact);
+	::sigaction(SIGQUIT, &ign, &quitact);
+	::sigemptyset(&newsigblock);
+	::sigaddset(&newsigblock, SIGCHLD);
+	::sigprocmask(SIG_BLOCK, &newsigblock, &oldsigblock);
+	switch (pid = ::fork()) {
+	case -1:			/* error */
+		break;
+	case 0:				/* child */
+		/*
+		 * Restore original signal dispositions and exec the command.
+		 */
+		::sigaction(SIGINT, &intact, NULL);
+		::sigaction(SIGQUIT,  &quitact, NULL);
+		::sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
+		/*
+		 * Close the PID file, and all other open descriptors.
+		 * Inherit std{in,out,err} only.
+		 */
+		cfg.close_pidfile();
+		::closefrom(3);
+		::execl(_PATH_BSHELL, "sh", "-c", command, (char *)NULL);
+		::_exit(127);
+	default:			/* parent */
+		savedpid = pid;
+		do {
+			pid = ::wait4(savedpid, &pstat, 0, (struct rusage *)0);
+		} while (pid == -1 && errno == EINTR);
+		break;
+	}
+	::sigaction(SIGINT, &intact, NULL);
+	::sigaction(SIGQUIT,  &quitact, NULL);
+	::sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
+	return (pid == -1 ? -1 : pstat);
+}
+
 bool
 action::do_action(config &c)
 {
 	string s = c.expand_string(_cmd);
 	if (Dflag)
 		fprintf(stderr, "Executing '%s'\n", s.c_str());
-	::system(s.c_str());
+	my_system(s.c_str());
 	return (true);
 }
 
@@ -390,6 +475,13 @@ config::write_pidfile()
 	pidfile_write(pfh);
 }
 
+void
+config::close_pidfile()
+{
+	
+	pidfile_close(pfh);
+}
+
 void
 config::remove_pidfile()
 {

sbin/devd/devd.hh

@@ -153,6 +153,7 @@ public:
 	void set_pidfile(const char *);
 	void reset();
 	void parse();
+	void close_pidfile();
 	void open_pidfile();
 	void write_pidfile();
 	void remove_pidfile();