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(svn r23855) -Fix [FS#5007]: out of bounds read for slowdown parameter caused desync when railtype >= 4, vehicles were fast, and the original acceleration model was used

release/1.2
rubidium 2012-01-26 17:48:23 +00:00
parent a48e3cb891
commit 6045c9e383
1 changed files with 9 additions and 10 deletions
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19
src/train_cmd.cpp
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@ -2794,19 +2794,18 @@ static inline bool CheckCompatibleRail(const Train *v, TileIndex tile)
(!v->IsFrontEngine() || HasBit(v->compatible_railtypes, GetRailType(tile))); (!v->IsFrontEngine() || HasBit(v->compatible_railtypes, GetRailType(tile)));
} }
/** Data structure for storing engine speed changes of a rail type. */ /** Data structure for storing engine speed changes of an acceleration type. */
struct RailtypeSlowdownParams { struct AccelerationSlowdownParams {
byte small_turn; ///< Speed change due to a small turn. byte small_turn; ///< Speed change due to a small turn.
byte large_turn; ///< Speed change due to a large turn. byte large_turn; ///< Speed change due to a large turn.
byte z_up; ///< Fraction to remove when moving up. byte z_up; ///< Fraction to remove when moving up.
byte z_down; ///< Fraction to add when moving down. byte z_down; ///< Fraction to add when moving down.
}; };
/** Speed update fractions for each rail type. */ /** Speed update fractions for each acceleration type. */
static const RailtypeSlowdownParams _railtype_slowdown[] = { static const AccelerationSlowdownParams _accel_slowdown[] = {
/* normal accel */ /* normal accel */
{256 / 4, 256 / 2, 256 / 4, 2}, ///< normal {256 / 4, 256 / 2, 256 / 4, 2}, ///< normal
{256 / 4, 256 / 2, 256 / 4, 2}, ///< electrified
{256 / 4, 256 / 2, 256 / 4, 2}, ///< monorail {256 / 4, 256 / 2, 256 / 4, 2}, ///< monorail
{0, 256 / 2, 256 / 4, 2}, ///< maglev {0, 256 / 2, 256 / 4, 2}, ///< maglev
}; };
@ -2820,12 +2819,12 @@ static inline void AffectSpeedByZChange(Train *v, int old_z)
{ {
if (old_z == v->z_pos || _settings_game.vehicle.train_acceleration_model != AM_ORIGINAL) return; if (old_z == v->z_pos || _settings_game.vehicle.train_acceleration_model != AM_ORIGINAL) return;
const RailtypeSlowdownParams *rsp = &_railtype_slowdown[v->railtype]; const AccelerationSlowdownParams *asp = &_accel_slowdown[GetRailTypeInfo(v->railtype)->acceleration_type];
if (old_z < v->z_pos) { if (old_z < v->z_pos) {
v->cur_speed -= (v->cur_speed * rsp->z_up >> 8); v->cur_speed -= (v->cur_speed * asp->z_up >> 8);
} else { } else {
uint16 spd = v->cur_speed + rsp->z_down; uint16 spd = v->cur_speed + asp->z_down;
if (spd <= v->gcache.cached_max_track_speed) v->cur_speed = spd; if (spd <= v->gcache.cached_max_track_speed) v->cur_speed = spd;
} }
} }
@ -3242,9 +3241,9 @@ bool TrainController(Train *v, Vehicle *nomove, bool reverse)
if (chosen_dir != v->direction) { if (chosen_dir != v->direction) {
if (prev == NULL && _settings_game.vehicle.train_acceleration_model == AM_ORIGINAL) { if (prev == NULL && _settings_game.vehicle.train_acceleration_model == AM_ORIGINAL) {
const RailtypeSlowdownParams *rsp = &_railtype_slowdown[v->railtype]; const AccelerationSlowdownParams *asp = &_accel_slowdown[GetRailTypeInfo(v->railtype)->acceleration_type];
DirDiff diff = DirDifference(v->direction, chosen_dir); DirDiff diff = DirDifference(v->direction, chosen_dir);
v->cur_speed -= (diff == DIRDIFF_45RIGHT || diff == DIRDIFF_45LEFT ? rsp->small_turn : rsp->large_turn) * v->cur_speed >> 8; v->cur_speed -= (diff == DIRDIFF_45RIGHT || diff == DIRDIFF_45LEFT ? asp->small_turn : asp->large_turn) * v->cur_speed >> 8;
} }
direction_changed = true; direction_changed = true;
v->direction = chosen_dir; v->direction = chosen_dir;