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(svn r11724) -Fix: make it impossible (for users) to circumvent the length checking of the NewGRF 'allow wagon attach' callback by moving several wagons at a time.

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rubidium 2007-12-30 21:35:48 +00:00
parent 566a24d6ee
commit 1a70eed58c
1 changed files with 82 additions and 8 deletions
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86
src/train_cmd.cpp
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@ -1027,16 +1027,90 @@ CommandCost CmdMoveRailVehicle(TileIndex tile, uint32 flags, uint32 p1, uint32 p
if (flags & DC_EXEC) src->unitnumber = unit_num;
}
if (dst_head != NULL) {
/* Check NewGRF Callback 0x1D */
uint16 callback = GetVehicleCallbackParent(CBID_TRAIN_ALLOW_WAGON_ATTACH, 0, 0, dst_head->engine_type, src, dst_head);
/*
* Check whether the vehicles in the source chain are in the destination
* chain. This can easily be done by checking whether the first vehicle
* of the source chain is in the destination chain as the Next/Previous
* pointers always make a doubly linked list of it where the assumption
* v->Next()->Previous() == v holds (assuming v->Next() != NULL).
*/
bool src_in_dst = false;
for (Vehicle *v = dst_head; !src_in_dst && v != NULL; v = v->Next()) src_in_dst = v == src;
/*
* If the source chain is in the destination chain then the user is
* only reordering the vehicles, thus not attaching a new vehicle.
* Therefor the 'allow wagon attach' callback does not need to be
* called. If it would be called strange things would happen because
* one 'attaches' an already 'attached' vehicle causing more trouble
* than it actually solves (infinite loops and such).
*/
if (dst_head != NULL && !src_in_dst) {
/*
* When performing the 'allow wagon attach' callback, we have to check
* that for each and every wagon, not only the first one. This means
* that we have to test one wagon, attach it to the train and then test
* the next wagon till we have reached the end. We have to restore it
* to the state it was before we 'tried' attaching the train when the
* attaching fails or succeeds because we are not 'only' doing this
* in the DC_EXEC state.
*/
Vehicle *dst_tail = dst_head;
while (dst_tail->Next() != NULL) dst_tail = dst_tail->Next();
Vehicle *orig_tail = dst_tail;
Vehicle *next_to_attach = src;
Vehicle *src_previous = src->Previous();
while (next_to_attach != NULL) {
uint16 callback = GetVehicleCallbackParent(CBID_TRAIN_ALLOW_WAGON_ATTACH, 0, 0, dst_head->engine_type, next_to_attach, dst_head);
if (callback != CALLBACK_FAILED) {
if (callback == 0xFD) return_cmd_error(STR_INCOMPATIBLE_RAIL_TYPES);
if (callback < 0xFD) {
StringID error = GetGRFStringID(GetEngineGRFID(dst_head->engine_type), 0xD000 + callback);
StringID error = STR_NULL;
if (callback == 0xFD) error = STR_INCOMPATIBLE_RAIL_TYPES;
if (callback < 0xFD) error = GetGRFStringID(GetEngineGRFID(dst_head->engine_type), 0xD000 + callback);
if (error != STR_NULL) {
/*
* The attaching is not allowed. In this case 'next_to_attach'
* can contain some vehicles of the 'source' and the destination
* train can have some too. We 'just' add the to-be added wagons
* to the chain and then split it where it was previously
* separated, i.e. the tail of the original destination train.
* Furthermore the 'previous' link of the original source vehicle needs
* to be restored, otherwise the train goes missing in the depot.
*/
dst_tail->SetNext(next_to_attach);
orig_tail->SetNext(NULL);
if (src_previous != NULL) src_previous->SetNext(src);
return_cmd_error(error);
}
}
/*
* Adding a next wagon to the chain so we can test the other wagons.
* First 'take' the first wagon from 'next_to_attach' and move it
* to the next wagon. Then add that to the tail of the destination
* train and update the tail with the new vehicle.
*/
Vehicle *to_add = next_to_attach;
next_to_attach = next_to_attach->Next();
to_add->SetNext(NULL);
dst_tail->SetNext(to_add);
dst_tail = dst_tail->Next();
}
/*
* When we reach this the attaching is allowed. It also means that the
* chain of vehicles to attach is empty, so we do not need to merge that.
* This means only the splitting needs to be done.
* Furthermore the 'previous' link of the original source vehicle needs
* to be restored, otherwise the train goes missing in the depot.
*/
orig_tail->SetNext(NULL);
if (src_previous != NULL) src_previous->SetNext(src);
}
/* do it? */