P2P: Split p2p_channels_union() into two functions

The separate p2p_channels_union_inplace() makes the function easier for
static analyzers to see that the result buffer is always initialized.
(CID 74494)

Signed-off-by: Jouni Malinen <j@w1.fi>

src/p2p/p2p.c

@@ -1366,8 +1366,8 @@ int p2p_prepare_channel(struct p2p_data *p2p, struct p2p_device *dev,
 	if (go)
 		p2p_channels_remove_freqs(&p2p->channels, &p2p->no_go_freq);
 	else if (!force_freq)
-		p2p_channels_union(&p2p->channels, &p2p->cfg->cli_channels,
-				   &p2p->channels);
+		p2p_channels_union_inplace(&p2p->channels,
+					   &p2p->cfg->cli_channels);
 	p2p_channels_dump(p2p, "after go/cli filter/add", &p2p->channels);
 
 	p2p_dbg(p2p, "Own preference for operation channel: Operating Class %u Channel %u%s",

src/p2p/p2p_i.h

@@ -613,6 +613,8 @@ int p2p_freq_to_channel(unsigned int freq, u8 *op_class, u8 *channel);
 void p2p_channels_intersect(const struct p2p_channels *a,
 			    const struct p2p_channels *b,
 			    struct p2p_channels *res);
+void p2p_channels_union_inplace(struct p2p_channels *res,
+				const struct p2p_channels *b);
 void p2p_channels_union(const struct p2p_channels *a,
 			const struct p2p_channels *b,
 			struct p2p_channels *res);

src/p2p/p2p_utils.c

@@ -193,20 +193,15 @@ static void p2p_op_class_union(struct p2p_reg_class *cl,
 
 
 /**
- * p2p_channels_union - Union of channel lists
- * @a: First set of channels
+ * p2p_channels_union_inplace - Inplace union of channel lists
+ * @res: Input data and place for returning union of the channel sets
  * @b: Second set of channels
- * @res: Data structure for returning the union of channels
  */
-void p2p_channels_union(const struct p2p_channels *a,
-			const struct p2p_channels *b,
-			struct p2p_channels *res)
+void p2p_channels_union_inplace(struct p2p_channels *res,
+				const struct p2p_channels *b)
 {
 	size_t i, j;
 
-	if (a != res)
-		os_memcpy(res, a, sizeof(*res));
-
 	for (i = 0; i < res->reg_classes; i++) {
 		struct p2p_reg_class *cl = &res->reg_class[i];
 		for (j = 0; j < b->reg_classes; j++) {
@@ -236,6 +231,21 @@ void p2p_channels_union(const struct p2p_channels *a,
 }
 
 
+/**
+ * p2p_channels_union - Union of channel lists
+ * @a: First set of channels
+ * @b: Second set of channels
+ * @res: Data structure for returning the union of channels
+ */
+void p2p_channels_union(const struct p2p_channels *a,
+			const struct p2p_channels *b,
+			struct p2p_channels *res)
+{
+	os_memcpy(res, a, sizeof(*res));
+	p2p_channels_union_inplace(res, b);
+}
+
+
 void p2p_channels_remove_freqs(struct p2p_channels *chan,
 			       const struct wpa_freq_range_list *list)
 {