Fix setting of the dive_table.preexisting logic

The 'preexisting' value is used for downloading dives: we want to add
new dives but, but then compare those new dives against the
preexisting ones before we start sorting things and possibly merging
them.

However, the value was only updated sporadically, resulting in it
having stale information in it.  Which would cause problems
particularly if you deleted dives, so that the preexisting value would
point past the actual existing values!

So just update it unconditionally in dive_list_update_dives(), which
anything that changes the dive list is supposed to call in order to
display the changes anyway.

Also, just for safety, when removing a dive, put NULL in the last dive
table location.  Nobody should ever access past the end anyway (this
is enforced by 'get_dive()') but there are places that access the dive
list table directly, and the libdivecomputer download was one of
those.  No reason to leave stale dive pointers possibly around for
uses like that.

Reported-by: Henrik Brautaset Aronsen <subsurface@henrik.synth.no>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

3 files changed, 3 insertions, 3 deletions

diff --git a/divelist.c b/divelist.c
index 8aa957d1e..f9ca3ef41 100644
--- a/divelist.c
+++ b/divelist.c
@@ -1457,6 +1457,7 @@ static void fill_dive_list(void)
 
 void dive_list_update_dives(void)
 {
+	dive_table.preexisting = dive_table.nr;
 	gtk_tree_store_clear(TREESTORE(dive_list));
 	gtk_tree_store_clear(LISTSTORE(dive_list));
 	fill_dive_list();
@@ -2207,7 +2208,7 @@ void delete_single_dive(int idx)
 	remove_dive_from_trip(dive);
 	for (i = idx; i < dive_table.nr - 1; i++)
 		dive_table.dives[i] = dive_table.dives[i+1];
-	dive_table.nr--;
+	dive_table.dives[--dive_table.nr] = NULL;
 	if (dive->selected)
 		amount_selected--;
 	/* free all allocations */
diff --git a/gtk-gui.c b/gtk-gui.c
index e165012d5..3df6fbf70 100644
--- a/gtk-gui.c
+++ b/gtk-gui.c
@@ -242,7 +242,6 @@ static void file_close(GtkWidget *w, gpointer data)
 	/* free the dives and trips */
 	while (dive_table.nr)
 		delete_single_dive(0);
-	dive_table.preexisting = 0;
 	mark_divelist_changed(FALSE);
 
 	/* clear the selection and the statistics */
diff --git a/main.c b/main.c
index 307dd13c1..0e98d9059 100644
--- a/main.c
+++ b/main.c
@@ -181,6 +181,7 @@ void report_dives(gboolean is_imported, gboolean prefer_imported)
 		add_single_dive(i, merged);
 		delete_single_dive(i+1);
 		delete_single_dive(i+1);
+		mark_divelist_changed(TRUE);
 	}
 	/* make sure no dives are still marked as downloaded */
 	for (i = 1; i < dive_table.nr; i++)
@@ -195,7 +196,6 @@ void report_dives(gboolean is_imported, gboolean prefer_imported)
 		if (preexisting != dive_table.nr)
 			mark_divelist_changed(TRUE);
 	}
-	dive_table.preexisting = dive_table.nr;
 	dive_list_update_dives();
 }