Don't check for NULL in cleanup routines, and don't pass NULL to them.

pcap_close() won't pass a null pointer - it'll crash long before that
when handed a null pointer, as the platforms on which we run map out
page 0.

Remove the null pointer checks, and, in cases where the cleanup routines
are called internally, make sure we don't pass them a null pointer.

3 files changed, 17 insertions, 22 deletions

diff --git a/pcap-dag.c b/pcap-dag.c
index 6a53ed86..77c03b36 100644
--- a/pcap-dag.c
+++ b/pcap-dag.c
@@ -144,28 +144,25 @@ delete_pcap_dag(pcap_t *p)
 static void
 dag_platform_cleanup(pcap_t *p)
 {
-	struct pcap_dag *pd;
+	struct pcap_dag *pd = p->pr;
 
-	if (p != NULL) {
-		pd = p->priv;
 #ifdef HAVE_DAG_STREAMS_API
-		if(dag_stop_stream(p->fd, pd->dag_stream) < 0)
-			fprintf(stderr,"dag_stop_stream: %s\n", strerror(errno));
+	if(dag_stop_stream(p->fd, pd->dag_stream) < 0)
+		fprintf(stderr,"dag_stop_stream: %s\n", strerror(errno));
 
-		if(dag_detach_stream(p->fd, pd->dag_stream) < 0)
-			fprintf(stderr,"dag_detach_stream: %s\n", strerror(errno));
+	if(dag_detach_stream(p->fd, pd->dag_stream) < 0)
+		fprintf(stderr,"dag_detach_stream: %s\n", strerror(errno));
 #else
-		if(dag_stop(p->fd) < 0)
-			fprintf(stderr,"dag_stop: %s\n", strerror(errno));
+	if(dag_stop(p->fd) < 0)
+		fprintf(stderr,"dag_stop: %s\n", strerror(errno));
 #endif /* HAVE_DAG_STREAMS_API */
-		if(p->fd != -1) {
-			if(dag_close(p->fd) < 0)
-				fprintf(stderr,"dag_close: %s\n", strerror(errno));
-			p->fd = -1;
-		}
-		delete_pcap_dag(p);
-		pcap_cleanup_live_common(p);
+	if(p->fd != -1) {
+		if(dag_close(p->fd) < 0)
+			fprintf(stderr,"dag_close: %s\n", strerror(errno));
+		p->fd = -1;
 	}
+	delete_pcap_dag(p);
+	pcap_cleanup_live_common(p);
 	/* Note: don't need to call close(p->fd) here as dag_close(p->fd) does this. */
 }
 
@@ -174,7 +171,8 @@ atexit_handler(void)
 {
 	while (pcap_dags != NULL) {
 		if (pcap_dags->pid == getpid()) {
-			dag_platform_cleanup(pcap_dags->p);
+			if (pcap_dags->p != NULL)
+				dag_platform_cleanup(pcap_dags->p);
 		} else {
 			delete_pcap_dag(pcap_dags->p);
 		}
diff --git a/pcap-dos.c b/pcap-dos.c
index bf4777da..c9a6a7c7 100644
--- a/pcap-dos.c
+++ b/pcap-dos.c
@@ -451,7 +451,7 @@ static void pcap_cleanup_dos (pcap_t *p)
 {
   struct pcap_dos *pd;
 
-  if (p && !exc_occured)
+  if (!exc_occured)
   {
     pd = p->priv;
     if (pcap_stats(p,NULL) < 0)
@@ -783,7 +783,7 @@ static void exc_handler (int sig)
          fprintf (stderr, "Catching signal %d.\n", sig);
   }
   exc_occured = 1;
-  pcap_cleanup_dos (NULL);
+  close_driver();
 }
 #endif  /* __DJGPP__ */
 
diff --git a/pcap-snf.c b/pcap-snf.c
index 2271fd66..a453b11c 100644
--- a/pcap-snf.c
+++ b/pcap-snf.c
@@ -66,9 +66,6 @@ snf_platform_cleanup(pcap_t *p)
 {
 	struct pcap_snf *ps = p->priv;
 
-	if (p == NULL)
-		return;
-
 #ifdef SNF_HAVE_INJECT_API
         if (ps->snf_inj)
                 snf_inject_close(ps->snf_inj);