Markus Armbruster
e1283b118a
The value of diffx() had the wrong sign when the arguments differed by
WORLD_X / 2. Same for diffy() and WORLD_Y / 2. satmap() used them to
find the vector from map center to ship or land unit to put on the
map, and got incorrect values for ships and land units directly
opposite to the center in x or y. The bug made satmap() read a
pointer out bounds of its malloced radbuf[], and then write through
that with unpredictable consequences.
Broken in 4.2.12. The original bug was in Empire 1.1: it
miscalculated where to put ships on the map (no crash). An incomplete
fix for radmap() and satmap() appeared in Chainsaw 2 (still no crash).
radmap() got fixed correctly in Chainsaw 3, but satmap() was
forgotten. That one got "fixed" in 4.2.7, and again in 4.2.12, but
both "fixes" were flawed and could crash.
Fix by backing out the flawed fixes and adopting the fix from radmap()
instead.
(cherry picked from commit 0cc474bd6d)
82 lines
1.9 KiB
C
82 lines
1.9 KiB
C
/*
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* Empire - A multi-player, client/server Internet based war game.
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* Copyright (C) 1986-2008, Dave Pare, Jeff Bailey, Thomas Ruschak,
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* Ken Stevens, Steve McClure
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* ---
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*
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* See files README, COPYING and CREDITS in the root of the source
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* tree for related information and legal notices. It is expected
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* that future projects/authors will amend these files as needed.
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*
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* ---
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*
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* mapdist.c: Return the distance between two sectors
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*
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* Known contributors to this file:
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*
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*/
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/*
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* mapdist returns (integer) distance between two sectors.
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*/
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#include <config.h>
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#include "misc.h"
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#include "optlist.h"
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#include "prototypes.h"
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int
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deltax(int x1, int x2)
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{
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int dx;
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dx = abs(x1 - x2);
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dx = dx % WORLD_X;
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if (dx > WORLD_X / 2)
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dx = WORLD_X - dx;
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return dx;
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}
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int
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deltay(int y1, int y2)
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{
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int dy;
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dy = abs(y1 - y2);
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dy = dy % WORLD_Y;
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if (dy > WORLD_Y / 2)
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dy = WORLD_Y - dy;
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return dy;
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}
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int
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mapdist(int x1, int y1, int x2, int y2)
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{
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int dx, dy;
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x1 = x1 % WORLD_X;
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y1 = y1 % WORLD_Y;
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x2 = x2 % WORLD_X;
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y2 = y2 % WORLD_Y;
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dx = deltax(x1, x2);
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dy = deltay(y1, y2);
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if (dx > dy)
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return (dx - dy) / 2 + dy;
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return dy;
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}
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