Wolfpack Empire - mirror of https://git.pond.sub.org/empserver
http://wolfpackempire.com/
Markus Armbruster
24000b4855
unit_move() is too big and has too many paths through its loop.
Maintenance of the (unspoken) loop invariant isn't obvious. In fact,
it isn't maintained on some paths. I found several bugs:
* We check prerequisite conditions for moving before the first move
and around prompts. When a condition becomes wrong on the move,
movement continues all the same until the next prompt. I believe
the only way this can happen is loss of crew due to hitting a mine.
* We cache ships and land units in a list of struct ulist. When a
ship or land unit gets left behind, its node is removed from the
list and freed.
We keep pointer flg pointing to the flagship in that list for
convenience. However, the pointer isn't updated until the next
prompt. It's referenced for automatic radar and all sub-commands
other than the six directions and 'h'. Use after free when such a
sub-command gets processed after a flagship change without a prompt.
Same for land units. For instance, navigating a pair of ships "jh"
where the flagship has no mobility leaves the flagship behind, then
attempts to radar automatically using the ship in the freed list
node. Likewise, marching a similar pair of land units "jl" examines
the land unit in the freed list node to figure out how to look.
* We cache mobility in the same list to support fractional mobility
during movement. Movement deducts from cached mobility and writes
the result back to the ship or land unit.
If something else charges it mobility while it's in this list, the
cache becomes stale. shp_nav() and lnd_nav() reload stale caches,
but don't run often enough. For instance, when a ship hits mines,
the mine damage makes the cache stale. If a direction or 'h'
follows directly, the stale mobility is written back, clobbering the
mine hit's mobility loss.
This mess dates back to Empire 2, where it replaced a different mess.
There may be more bugs.
unit_move()'s complex control flow makes reasoning about its loop
invariant too error-prone. Rewrite the mess instead, splitting off
sensible subroutines.
Also fixes a couple of minor annoyances:
* White-space can confuse the parser. For instance, "jg l" is
interpreted like "jgll". Fix to reject the space. Broken in commit
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| build-aux | ||
| doc | ||
| include | ||
| info | ||
| m4 | ||
| man | ||
| scripts | ||
| src | ||
| tests | ||
| .gitignore | ||
| .travis.yml | ||
| bootstrap | ||
| configure.ac | ||
| COPYING | ||
| CREDITS | ||
| GNUmakefile.in | ||
| INSTALL | ||
| Make.mk | ||
| README | ||
Welcome to Empire 4, code-named Wolfpack.
Empire is a multi-player, client/server Internet based war game.
Copyright (C) 1986-2015, Dave Pare, Jeff Bailey, Thomas Ruschak,
Ken Stevens, Steve McClure, Markus Armbruster
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License (in file
`COPYING'), or (at your option) any later version.
See file `CREDITS' for a list of contributors.
Directory `doc' has additional information. File `doc/README'
describes the files there and what they talk about.
To build the server and set up a game, follow the steps below.
(1) Unpacking the source tree
If you downloaded a tarball, unpack it.
If you cloned a git repository, run bootstrap. This requires
recent versions of Autoconf and Automake to be installed. See
also doc/contributing.
(2) Building a server
Prerequisites: IEEE Std 1003.1-2001 (POSIX.1-2001), GNU make, a
curses library, Perl, and either nroff or GNU troff (`groff').
See file `INSTALL' for detailed compilation and installation
instructions. Quick guide for the impatient: run configure; make;
make install. The last step is optional; everything runs fine
right from the build tree.
If configure reports "terminfo: no" in its configuration summary,
highlighting doesn't work in the client. Commonly caused by not
having development libraries installed. On Linux, try installing
ncurses-devel.
If make fails without doing anything, you're probably not using
GNU make. Some systems have it installed as `gmake'.
Solaris supports POSIX.1-2001, but you need to set up your
environment for that. Try passing
SHELL=/usr/xpg4/bin/sh PATH=/usr/xpg6/bin:/usr/xpg4/bin:$PATH
to make. See standards(5) for details.
(3) Creating a game
* Create a configuration for your game. make install installs one
in $prefix/etc/empire/econfig ($prefix is /usr/local unless you
chose something else with configure). You can use pconfig to
create another one.
* Edit your configuration file. See doc/econfig for more
information.
Unless you put your configuration file in the default location
(where make install installs it), you have to use -e with all
programs to make them use your configuration.
* Run files to set up your data directory.
* Run fairland to create a world. For a sample world, try
`fairland 10 30'. This creates file ./newcap_script, which will
be used below. You can edit it to change country names and
passwords.
Check out fairland's manual page for more information.
* Start the server. For development, you want to run it with -d
in a debugger, see doc/debugging. Do not use -d for a real
game!
* Log in as deity POGO with password peter. This guide assumes
you use the included client `empire', but other clients should
work as well.
For help, try `info'.
To change the deity password, use `change re <password>'.
* Create countries with `exec newcap_script'.
Your game is now up!
Naturally, there's more to running a real game than that, but that's
beyond the scope of this file.
Please report bugs to <wolfpack@wolfpackempire.com> or via SourceForge
<http://sourceforge.net/projects/empserver/> (registration required).
For more information or help, try rec.games.empire on Usenet, or send
e-mail to <wolfpack@wolfpackempire.com> and we'll try to answer if we
can. Also check out our web site at <http://www.wolfpackempire.com/>.
Have fun!
Wolfpack!