From c1f61900360d9dcd17382f37f16a75184c99844a Mon Sep 17 00:00:00 2001
From: Bardur Arantsson <bardur@scientician.net>
Date: Mon, 20 Jun 2016 22:49:05 +0200
Subject: Fix store_top underflow when removing last item

---
 src/store.cc | 53 ++++++++++++++++++++++++++++++-----------------------
 1 file changed, 30 insertions(+), 23 deletions(-)

(limited to 'src')

diff --git a/src/store.cc b/src/store.cc
index 041cf74c..088de82a 100644
--- a/src/store.cc
+++ b/src/store.cc
@@ -1498,7 +1498,7 @@ static void display_entry(int pos)
  */
 static void display_inventory(void)
 {
-	int i, k;
+	int k;
 
 	/* Display the next 12 items */
 	for (k = 0; k < 12; k++)
@@ -1514,7 +1514,7 @@ static void display_inventory(void)
 	}
 
 	/* Erase the extra lines and the "more" prompt */
-	for (i = k; i < 13; i++) prt("", i + 6, 0);
+	for (int i = k; i < 13; i++) prt("", i + 6, 0);
 
 	/* Assume "no current page" */
 	put_str("         ", 5, 20);
@@ -1850,6 +1850,31 @@ static bool_ retire_owner_p(void)
 	return TRUE;
 }
 
+/*
+ * Adjust store_top to account for a removed item
+ */
+static void adjust_store_top_item_removed()
+{
+	/* Nothing left? */
+	if (st_ptr->stock.empty() == 0)
+	{
+		store_top = 0;
+	}
+
+	/* Already at the top beginning? */
+	else if (store_top == 0)
+	{
+		/* Nothing to do */
+	}
+
+	/* Nothing left on current screen? */
+	else if (store_top >= static_cast<int>(st_ptr->stock.size()))
+	{
+		store_top -= 12;
+	}
+}
+
+
 /*
  * Stole an item from a store                   -DG-
  */
@@ -2024,11 +2049,7 @@ void store_stole(void)
 		/* The item is gone */
 		else if (st_ptr->stock.size() != prev_stock_size)
 		{
-			/* Pick the correct screen */
-			if (store_top >= static_cast<int>(st_ptr->stock.size()))
-			{
-				store_top -= 12;
-			}
+			adjust_store_top_item_removed();
 
 			/* Redraw everything */
 			display_inventory();
@@ -2295,11 +2316,7 @@ void store_purchase(void)
 				/* The item is gone */
 				else if (st_ptr->stock.size() != prev_stock_size)
 				{
-					/* Pick the correct screen */
-					if (store_top >= static_cast<int>(st_ptr->stock.size()))
-					{
-						store_top -= 12;
-					}
+					adjust_store_top_item_removed();
 				}
 
 				/* Redraw everything */
@@ -2358,17 +2375,7 @@ void store_purchase(void)
 		/* The item is gone */
 		else
 		{
-			/* Nothing left */
-			if (st_ptr->stock.empty() == 0)
-			{
-				store_top = 0;
-			}
-
-			/* Nothing left on that screen */
-			else if (store_top >= static_cast<int>(st_ptr->stock.size()))
-			{
-				store_top -= 12;
-			}
+			adjust_store_top_item_removed();
 
 			/* Redraw everything */
 			display_inventory();
-- 
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