From dda0a4c82f730d08aa055a40354d2e0c6577f782 Mon Sep 17 00:00:00 2001
From: Markus Armbruster <armbru@pond.sub.org>
Date: Sat, 23 Aug 2008 15:17:44 -0400
Subject: [PATCH] Fix spy to reliably avoid spying same sector more than once

spy() stored coordinates of sectors successfully spied in an array.
Since it didn't bother to normalize coordinates, it could spy sectors
near the "seams" of the world more than once.  The array was also
wastefully large.

Fix by using a sector bitmap instead, like do_look().
---
 src/lib/commands/spy.c | 58 +++++++++---------------------------------
 1 file changed, 12 insertions(+), 46 deletions(-)

diff --git a/src/lib/commands/spy.c b/src/lib/commands/spy.c
index bc762240..4cd61b00 100644
--- a/src/lib/commands/spy.c
+++ b/src/lib/commands/spy.c
@@ -48,8 +48,6 @@
  * format:  spy <SECTS>
  */
 
-static int check(coord *table, int *len, coord x, coord y);
-static void insert(coord *table, int *len, coord x, coord y);
 static void spy_report(struct sctstr *sp);
 static void prplanes(int, int);
 static void prunits(int, int);
@@ -65,8 +63,7 @@ spy(void)
     int military;
     int btucost;
     int i;
-    coord *table;		/* sectors already seen */
-    int t_len = 0;
+    unsigned char *bitmap;
     int nrecon;
     struct nstr_sect nstr;
     struct nstr_item ni;
@@ -89,12 +86,13 @@ spy(void)
 	pr("You don't have the BTU's for spying on that scale!\n");
 	return RET_FAIL;
     }
-    /*
-     * set up all the goodies we need later
-     * 6 = neighbors, 2 = x,y
-     */
-    table = malloc((nsects + 1) * 6 * 2 * sizeof(coord));
-    memset(table, 0, (nsects + 1) * 6 * 2 * sizeof(coord));
+    bitmap = calloc(WORLD_SZ() / 8, 1);
+    if (!bitmap) {
+	logerror("malloc failed in do_look\n");
+	pr("Memory error.  Tell the deity.\n");
+	return RET_FAIL;
+    }
+
     pr("SPY report\n");
     prdate();
     pr("                 old sct rd  rl  def\n");
@@ -124,14 +122,8 @@ spy(void)
 		break;
 	    nx = x + diroff[i][0];
 	    ny = y + diroff[i][1];
-	    /*
-	     * if we've already seen the
-	     * sector, don't bother checking it
-	     * out.
-	     */
-	    if (check(table, &t_len, nx, ny)) {
-		continue;
-	    }
+	    if (emp_getbit(nx, ny, bitmap))
+		continue;	/* spied already */
 	    getsect(nx, ny, &dsect);
 	    if (player->owner || dsect.sct_type == SCT_WATER)
 		continue;
@@ -166,7 +158,7 @@ spy(void)
 	    }
 
 	    /* spy report */
-	    insert(table, &t_len, nx, ny);
+	    emp_setbit(nx, ny, bitmap);
 	    spy_report(&dsect);
 	    changed += map_set(player->cnum, dsect.sct_x, dsect.sct_y,
 			       dchr[dsect.sct_type].d_mnem, 0);
@@ -182,7 +174,7 @@ spy(void)
     if (changed)
 	writemap(player->cnum);
     player->btused += btucost;
-    free(table);
+    free(bitmap);
     return RET_OK;
 }
 
@@ -210,32 +202,6 @@ spy_report(struct sctstr *sp)
     prplanes(sp->sct_x, sp->sct_y);
 }
 
-/*
- * insert a key into the table.
- */
-static void
-insert(coord *table, int *len, coord x, coord y)
-{
-    if (!check(table, len, x, y)) {
-	table[(*len)++] = x;
-	table[(*len)++] = y;
-    }
-}
-
-/*
- * see if a key is in the bitmask table
- */
-static int
-check(coord *table, int *len, coord x, coord y)
-{
-    int i;
-
-    for (i = 0; i < *len; i += 2)
-	if (table[i] == x && table[i + 1] == y)
-	    return 1;
-    return 0;
-}
-
 static void
 prunits(int x, int y)
 {