From: Evan Hunt <each@isc.org>
Date: Sat, 27 Oct 2007 18:58:59 +0000 (+0000)
Subject: Don't delete PID files before writing to them. [rt17030]
X-Git-Tag: v4_0_0b3~12
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=182b187ea54b201b405561f342fecf674faf8b68;p=thirdparty%2Fdhcp.git

Don't delete PID files before writing to them. [rt17030]
---

diff --git a/client/dhclient.c b/client/dhclient.c
index 3a74269a7..9798119f2 100644
--- a/client/dhclient.c
+++ b/client/dhclient.c
@@ -138,7 +138,11 @@ main(int argc, char **argv) {
 	dhcp_interface_startup_hook = dhclient_interface_startup_hook;
 
 	for (i = 1; i < argc; i++) {
-		if (!strcmp(argv[i], "-4")) {
+                if (!strcmp(argv[i], "-r")) {
+			release_mode = 1;
+			no_daemon = 1;
+#ifdef DHCPv6
+		} else if (!strcmp(argv[i], "-4")) {
 			if (local_family_set && local_family != AF_INET)
 				log_fatal("Client can only do v4 or v6, not "
 					  "both.");
@@ -150,9 +154,7 @@ main(int argc, char **argv) {
 					  "both.");
 			local_family_set = 1;
 			local_family = AF_INET6;
-		} else if (!strcmp(argv[i], "-r")) {
-			release_mode = 1;
-			no_daemon = 1;
+#endif /* DHCPv6 */
                 } else if (!strcmp (argv [i], "-x")) { /* eXit, no release */
                         release_mode = 0;
                         no_daemon = 0;
@@ -306,10 +308,8 @@ main(int argc, char **argv) {
 			oldpid = (pid_t)temp;
 
 			if (e != 0 && e != EOF) {
-				if (oldpid) {
-					if (kill(oldpid, SIGTERM) == 0)
-						unlink(path_dhclient_pid);
-				}
+				if (oldpid)
+					kill(oldpid, SIGTERM);
 			}
 			fclose(pidfd);
 		}
@@ -555,7 +555,12 @@ static void usage ()
 	log_info (arr);
 	log_info (url);
 
-	log_error ("Usage: dhclient [-1dvrx] [-nw] [-p <port>] %s",
+	log_error ("Usage: dhclient %s %s",
+#ifdef DHCPv6
+                   "[-4|-6] [-1dvrx] [-nw] [-p <port>]",
+#else /* DHCPv6 */
+                   "[-1dvrx] [-nw] [-p <port>]",
+#endif /* DHCPv6 */
 		   "[-s server]");
 	log_error ("                [-cf config-file] [-lf lease-file]%s",
 		   "[-pf pid-file] [-e VAR=val]");
diff --git a/server/dhcpd.c b/server/dhcpd.c
index 744bbef12..d61e31b0c 100644
--- a/server/dhcpd.c
+++ b/server/dhcpd.c
@@ -202,7 +202,6 @@ main(int argc, char **argv) {
 	int cftest = 0;
 	int lftest = 0;
 #ifndef DEBUG
-	int pidfilewritten = 0;
 	int pid;
 	char pbuf [20];
 	int daemon = 1;
@@ -629,28 +628,32 @@ main(int argc, char **argv) {
 
 	/* Read previous pid file. */
 	if ((i = open (path_dhcpd_pid, O_RDONLY)) >= 0) {
-		status = read (i, pbuf, (sizeof pbuf) - 1);
+		status = read(i, pbuf, (sizeof pbuf) - 1);
 		close (i);
 		if (status > 0) {
-			pbuf [status] = 0;
-			pid = atoi (pbuf);
-
-			/* If the previous server process is not still running,
-			   write a new pid file immediately. */
-			if (pid && (pid == getpid() || kill (pid, 0) < 0)) {
-				unlink (path_dhcpd_pid);
-				if ((i = open (path_dhcpd_pid,
-					O_WRONLY | O_CREAT, 0644)) >= 0) {
-				    sprintf (pbuf, "%d\n", (int)getpid ());
-				    write (i, pbuf, strlen (pbuf));
-				    close (i);
-				    pidfilewritten = 1;
-				}
-			} else
-				log_fatal ("There's already a DHCP server running.");
+			pbuf[status] = 0;
+			pid = atoi(pbuf);
+
+			/*
+                         * If there was a previous server process and it's
+                         * is still running, abort
+                         */
+			if (!pid || (pid != getpid() && kill(pid, 0) == 0))
+				log_fatal("There's already a "
+                                          "DHCP server running.");
 		}
 	}
 
+        /* Write new pid file. */
+        if ((i = open(path_dhcpd_pid, O_WRONLY|O_CREAT|O_TRUNC, 0644)) >= 0) {
+                sprintf(pbuf, "%d\n", (int) getpid());
+                write(i, pbuf, strlen(pbuf));
+                close(i);
+        } else {
+                log_error("Can't create PID file %s: %m.", path_dhcpd_pid);
+        }
+
+
 	/* If we were requested to log to stdout on the command line,
 	   keep doing so; otherwise, stop. */
 	if (log_perror == -1)
@@ -658,21 +661,6 @@ main(int argc, char **argv) {
 	else
 		log_perror = 0;
 
-	/* If we didn't write the pid file earlier because we found a
-	   process running the logged pid, but we made it to here,
-	   meaning nothing is listening on the bootp port, then write
-	   the pid file out - what's in it now is bogus anyway. */
-	if (!pidfilewritten) {
-		unlink (path_dhcpd_pid);
-		if ((i = open (path_dhcpd_pid,
-			       O_WRONLY | O_CREAT, 0644)) >= 0) {
-			sprintf (pbuf, "%d\n", (int)getpid ());
-			write (i, pbuf, strlen (pbuf));
-			close (i);
-			pidfilewritten = 1;
-		}
-	}
-
 	if (daemon) {
 		/* Become session leader and get pid... */
 		pid = setsid();