Add assertions that kill() is never accidentally passed a non-positive

pid.  This follows a bug in rsync where it would accidentally
kill(-1), removing all the user's processes.  I can't see any way this
would directly happen in Samba, but having the assertions seems
beneficial.

http://cvs.samba.org/cgi-bin/cvsweb/rsync/util.c.diff?r1=1.108&r2=1.109&f=h
(This used to be commit 098905bea29c7d5b886809d431294ddf2fc1e152)

4 files changed, 15 insertions, 4 deletions

diff --git a/source3/lib/messages.c b/source3/lib/messages.c
index 642caafac4..b745cbaf8b 100644
--- a/source3/lib/messages.c
+++ b/source3/lib/messages.c
@@ -144,6 +144,9 @@ static TDB_DATA message_key_pid(pid_t pid)
 
 static BOOL message_notify(pid_t pid)
 {
+	/* Doing kill with a non-positive pid causes messages to be
+	 * sent to places we don't want. */
+	SMB_ASSERT(pid > 0);
 	if (kill(pid, SIGUSR1) == -1) {
 		if (errno == ESRCH) {
 			DEBUG(2,("pid %d doesn't exist - deleting messages record\n", (int)pid));
@@ -174,6 +177,10 @@ BOOL message_send_pid(pid_t pid, int msg_type, const void *buf, size_t len,
 	rec.src = sys_getpid();
 	rec.len = len;
 
+	/* Doing kill with a non-positive pid causes messages to be
+	 * sent to places we don't want. */
+	SMB_ASSERT(pid > 0);
+
 	kbuf = message_key_pid(pid);
 
 	/* lock the record for the destination */
diff --git a/source3/lib/util.c b/source3/lib/util.c
index 8867d37d57..a2f8c086e8 100644
--- a/source3/lib/util.c
+++ b/source3/lib/util.c
@@ -1034,6 +1034,9 @@ check if a process exists. Does this work on all unixes?
 
 BOOL process_exists(pid_t pid)
 {
+	/* Doing kill with a non-positive pid causes messages to be
+	 * sent to places we don't want. */
+	SMB_ASSERT(pid > 0);
 	return(kill(pid,0) == 0 || errno != ESRCH);
 }
 
diff --git a/source3/nmbd/asyncdns.c b/source3/nmbd/asyncdns.c
index c5ff718836..6c2f8de3b1 100644
--- a/source3/nmbd/asyncdns.c
+++ b/source3/nmbd/asyncdns.c
@@ -120,8 +120,9 @@ static void sig_term(int sig)
 
 void kill_async_dns_child(void)
 {
-  if(child_pid != 0 && child_pid != -1)
-    kill(child_pid, SIGTERM);
+	if (child_pid > 0) {
+		kill(child_pid, SIGTERM);
+	}
 }
 
 /***************************************************************************
diff --git a/source3/web/startstop.c b/source3/web/startstop.c
index 27ee7dd96e..c56320c962 100644
--- a/source3/web/startstop.c
+++ b/source3/web/startstop.c
@@ -75,7 +75,7 @@ void stop_smbd(void)
 
 	if (geteuid() != 0) return;
 
-	if (pid == 0) return;
+	if (pid <= 0) return;
 
 	kill(pid, SIGTERM);
 }
@@ -87,7 +87,7 @@ void stop_nmbd(void)
 
 	if (geteuid() != 0) return;
 
-	if (pid == 0) return;
+	if (pid <= 0) return;
 
 	kill(pid, SIGTERM);
 }