fix crash if no uci config file present

fix also possible null dereferenced pointers

Signed-off-by: Olivier Hardouin <olivier.hardouin@gmail.com>

uci.c

@@ -54,6 +54,9 @@ char* uci_get_option(struct uci_context *ctx, char *section, char *option)
 	char *value = NULL;
 	struct uci_ptr ptr;
 
+	if (!p)
+		return NULL;
+
 	memset(&ptr, 0, sizeof(ptr));
 	ptr.package = p->e.name;
 	ptr.section = section;
@@ -101,6 +104,9 @@ void uci_for_each_section_type(char *type, void (*cb)(char*, void*), void *priv)
 {
 	struct uci_element *e;
 
+	if (!p)
+		return;
+
 	uci_foreach_element(&p->sections, e)
 		if (!strcmp(type, uci_to_section(e)->type))
 			cb(e->name, priv);

ucix.c

@@ -18,6 +18,8 @@ static inline int ucix_get_ptr(struct uci_context *ctx, const char *p, const cha
 struct uci_context* ucix_init(const char *config_file)
 {
 	struct uci_context *ctx = uci_alloc_context();
+	if(!ctx)
+		return NULL;
 	uci_add_delta_path(ctx, "/var/state");
 	if(uci_load(ctx, config_file, NULL) != UCI_OK)
 	{
@@ -30,6 +32,8 @@ struct uci_context* ucix_init(const char *config_file)
 struct uci_context* ucix_init_path(const char *path, const char *config_file)
 {
 	struct uci_context *ctx = uci_alloc_context();
+	if(!ctx)
+		return NULL;
 	if(path)
 	{
 		uci_set_savedir(ctx, path);
@@ -44,7 +48,10 @@ struct uci_context* ucix_init_path(const char *path, const char *config_file)
 
 void ucix_cleanup(struct uci_context *ctx)
 {
-	uci_free_context(ctx);
+	if(ctx)
+	{
+		uci_free_context(ctx);
+	}
 }
 
 int ucix_save(struct uci_context *ctx, const char *p)