Start cleaning up dive accessors

I'm going to add a menu to import (and eventually export) dives, and so
we'd like to be able to start out with no dives at all.  Right now we
croak if that happens - it's not like the code has been written with
actual end users in mind.

So start cleaning things up.  First make the 'current_dive' macro work
right even for invalid dives.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 9 insertions, 2 deletions

diff --git a/display.h b/display.h
index b9de932cb..8f972e358 100644
--- a/display.h
+++ b/display.h
@@ -6,12 +6,12 @@
 #include <cairo.h>
 
 extern int selected_dive;
+#define current_dive (get_dive(selected_dive))
+
 extern GtkWidget *dive_profile_frame(void);
 extern GtkWidget *dive_info_frame(void);
 extern GtkWidget *create_dive_list(void);
 extern void update_dive_info(struct dive *dive);
 extern void repaint_dive(void);
 
-#define current_dive (dive_table.dives[selected_dive])
-
 #endif
diff --git a/dive.h b/dive.h
index a8e3c319a..23e2f544c 100644
--- a/dive.h
+++ b/dive.h
@@ -121,6 +121,13 @@ struct dive_table {
 
 extern struct dive_table dive_table;
 
+static inline struct dive *get_dive(unsigned int nr)
+{
+	if (nr >= dive_table.nr)
+		return NULL;
+	return dive_table.dives[nr];
+}
+
 extern void parse_xml_init(void);
 extern void parse_xml_file(const char *filename);