The capability to navigate ships spread over several sectors is
obscure and rarely useful. Accidental use is probably more frequent
than intentional use. Issues:
* Interactive prompts show only the flagship's position, and give no
clue that some ships are actually elsewhere.
* Path finding is supported only when all navigating ships are in
the same sector.
* Interdiction becomes rather complex. For each movement, every
sector entered is interdicted independently. This means the same
fort, ship, land unit or plane can interdict multiple times.
Interdiction order depends on the order the code examines
ships. which the player can control. This is all pretty much
undocumented.
* Complicates the code and its maintenance. Multiplies the number of
test cases needed to cover navigate.
I feel we're better off without this feature.
Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
The capability to march land units spread over several sectors is
obscure and rarely useful. Accidental use is probably more frequent
than intentional use. Issues:
* Interactive prompts show only the leader's position, and give no
clue that some land units are actually elsewhere.
* Path finding is supported only when all marching land units are in
the same sector.
* In each step, the bmap is updated for the leader's radar. The bmap
is not updated around other marching land units. Already odd when
all units are in the leader's sector, and odder still when some are
elsewhere.
* Interdiction becomes rather complex. For each movement, every
sector entered is interdicted independently. This means the same
ship, land unit or plane can interdict multiple times. Interdiction
order depends on the order the code examines land units. which the
player can control. This is all pretty much undocumented.
* Complicates the code and its maintenance. Multiplies the number of
test cases needed to cover march.
I feel we're better off without this feature.
Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
Unlike the move command, march checks sector abandonment before every
step.
If the player declines, the last land unit stays put and is removed
from the march.
Except when sectors or land units change while we're waiting for the
player's reply. Then the last unit is not removed from the march.
This can scatter land units. Screwed up when checking for abandoning
the sector was added in 4.2.2.
Change march to work like move, and to avoid scattering land units: if
the player declines to abandon the sector, the command simply fails.
Put the check into new lnd_abandon_askyn().
Extend would_abandon() and want_to_abandon() from a single land unit
to many. Rename the latter to abandon_askyn() for consistency.
Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
When a player moves more than 1023 sectors in a single navigate
command, we overrun the buffer holding the path taken. Remote hole,
but it requires a ship that can go that far, and even a ship with
speed 1000 would need a tech level well in excess of 1000 for that.
Thus, the hole is purely theoretical for even remotely sane game
configurations.
First known version with the flaw is 4.0.0.
Fix by going back the older behavior: don't print the total path
taken, but do print what the path finder does. Context diff of an
example:
[0:634] Command : nav 3 6,0
Flagship is od oil derrick (#3)
+Using path 'n'
h =
k . .
j d
<67.2:67.2: 6,0> h
od oil derrick (#3) stopped at 6,0
-Path taken: n
This is how march works.
Removes the only use of shp_nav_one_sector()'s unusual return value 2.
Return 1 instead.
Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
Commit e3cf1e32 (v4.3.27) created make_stale_if_command_arg() to
permit catching more potential yields on input. Unfortunately, the
implementation of navigate and march sub-commands 'r', 'l' and 's'
breaks it.
do_unit_move() reads units into a unit list at the beginning and at
each stop. It writes them back when they move or sweep. If a unit
changed in the file in between, the changes would get wiped out.
Therefore, do_unit_move() must not yield between stops.
do_unit_move() parses sub-commands into player->argp[], then supplies
defaults for missing arguments, so that code using them (radar(),
do_look(), sona(), mine(), landmine()) won't prompt for missing
arguments. Unclean and brittle. See also commit 28cc236e and commit
45106ab9.
Unfortunately, make_stale_if_command_arg() doesn't recognize the
difference between these defaulted arguments and parsed arguments, so
it makes objects stale, even though the defaulted arguments can't be
missing. If a move or sweep follows, it triggers a false positive
generation oops.
To fix, test "points into argument buffer" (only true for parsed
arguments) instead of "is in player->argp[]". Requires making the
argument buffer accessible: new struct player member argbuf[]. Use it
for parsing commands, in command(), execute(), do_unit_move(). Don't
use it in emp_config(), player_login(), move_ground(), because these
parse something else.
Destination arguments can be a path or sector coordinates.
do_unit_move() passes the argument buffer to unit_path() to convert
coordinates to a path. If unit_path() fails, do_unit_move() still
interprets the argument as path.
This is correct when unit_path() fails because the argument is not
coordinates. But it can also fail when it is coordinates, namely when
the destination isn't reachable, when the path to it is too long, or
when the ships or land units aren't together. Then do_unit_move()
interprets coordinates as path, and rejects them with "Legal
directions are:".
Except when a land unit's destination read from a march prompt isn't
reachable, because then unit_path() empties the argument buffer that
do_unit_move() uses.
Change unit_path() to succeed when the argument is not coordinates.
Make do_unit_move() discard the argument when unit_path() fails,
i.e. when it is bad coordinates. unit_path() emptying the argument no
longer has an effect, drop it.
Why upgrade? I'm not a lawyer, but here's my take on the differences
to version 2:
* Software patents: better protection against abuse of patents to
prevent users from exercising the rights under the GPL. I doubt
we'll get hit with a patent suit, but it's a good move just on
general principles.
* License compatibility: compatible with more free licenses, i.e. can
"steal" more free software for use in Empire. I don't expect to steal
much, but it's nice to have the option.
* Definition of "source code": modernization of some details for today's
networked world, to make it easier to distribute the software. Not
really relevant to us now, as we normally distribute full source code.
* Tivoization: this is about putting GPL-licensed software in hardware,
then make the hardware refuse to run modified software. "Neat" trick
to effectively deny its users their rights under the GPL. Abuse was
"pioneered" by TiVo (popular digital video recorders). GPLv3 forbids
it. Unlikely to become a problem for us.
* Internationalization: more careful wording, to harden the license
outside the US. The lawyers tell us it better be done that way.
* License violations: friendlier way to deal with license violations.
This has come out of past experience enforcing the GPL.
* Additional permissions: Probably not relevant to us.
Also include myself in the list of principal authors.
do_unit_move() reads the ships into a list. It re-reads them when it
prompts for sub-commands. shp_nav_one_sector() writes them back when
it moves ships.
Mine-laying (sub-command 'd') updates the minelayer, invalidating the
copy in the list. Any movement sub-command before the next prompt for
sub-commands wiped out this update, triggering a seno mismatch oops.
Happens only if 'd' is used without arguments, because remaining
sub-commands are discarded when there are arguments.
Broken when mine-laying was added in commits 2438fe7c, v4.3.7.
Same for march, commit 274c8e42, v4.3.7.
Fix by stopping after 'd' regardless of arguments.
When sub-command 'd' was used without arguments, do_unit_move() failed
to supply the second argument to mine(), which duly prompted for it.
This contracticted info, and could trigger a generation oops.
do_unit_move() reads the ships into a list. It re-reads them when it
prompts for sub-commands. shp_nav_one_sector() writes them back when
it moves ships.
The mine prompt made the list stale. Movement sub-commands before the
next prompt for sub-commands wrote back stale ships, triggering a
generation oops. Example: "nav 15 dg".
Broken when mine-laying was added in commits 2438fe7c, v4.3.7.
Same for march, commit 274c8e42, v4.3.7.
For an argument consisting of a valid path plus whitespace,
do_unit_move() eventually passed the whitespace suffix to parse(),
then dereferenced player->argp[0]. But that was null.
Broken in commit 0c12d837, v4.3.7. Trivial for players to trigger.
The old code used getstarg() to get an argument with a different
prompt than snxtitem() uses, then passed the value to snxtitem()
unchecked. If the player aborts, getstarg() returns a null pointer,
and snxtitem() prompts again. Affected:
* load/lload plane/land third argument; load_plane_ship(),
load_land_ship(), load_plane_land(), load_land_land()
* bomb, drop, fly, paradrop, recon and sweep second argument;
get_planes()
* tend and ltend second and fourth argument; ltend(), tend(),
tend_land()
* mission second argument; mission()
Fix by making snxtitem() taking a prompt argument, null pointer
requests the old prompt.
Use that to simplify multifire() and torp(). Change the other callers
to pass NULL.
land_unit as well.
(do_unit_move): Add view option for land units using unit_view().
Combine ship and land viewing using the unit_view().
(shp_view): Remove, not used any more, replaced by unit_view().
beginning of function instead using the leader. The leader
becomes unknown when stopping or unit list becomes
empty. This broke printing the path for ships. Broken
in rev 1.43.
