Fix #8453: [Script] Don't truncate loan variation to 32bit

2 files changed, 22 insertions, 15 deletions

diff --git a/src/misc_cmd.cpp b/src/misc_cmd.cpp
index 2b32c06bf..c1c81535a 100644
--- a/src/misc_cmd.cpp
+++ b/src/misc_cmd.cpp
@@ -25,14 +25,18 @@
 
 #include "safeguards.h"
 
+/* Make sure we can discard lower 2 bits of 64bit amount when passing it to Cmd[In|De]creaseLoan() */
+static_assert((LOAN_INTERVAL & 3) == 0);
+
 /**
  * Increase the loan of your company.
  * @param tile unused
  * @param flags operation to perform
- * @param p1 amount to increase the loan with, multitude of LOAN_INTERVAL. Only used when p2 == 2.
- * @param p2 when 0: loans LOAN_INTERVAL
- *           when 1: loans the maximum loan permitting money (press CTRL),
- *           when 2: loans the amount specified in p1
+ * @param p1 higher half of amount to increase the loan with, multitude of LOAN_INTERVAL. Only used when (p2 & 3) == 2.
+ * @param p2 (bit 2-31) - lower half of amount (lower 2 bits assumed to be 0)
+ *           (bit 0-1)  - when 0: loans LOAN_INTERVAL
+ *                        when 1: loans the maximum loan permitting money (press CTRL),
+ *                        when 2: loans the amount specified in p1 and p2
  * @param text unused
  * @return the cost of this operation or an error
  */
@@ -46,7 +50,7 @@ CommandCost CmdIncreaseLoan(TileIndex tile, DoCommandFlag flags, uint32 p1, uint
 	}
 
 	Money loan;
-	switch (p2) {
+	switch (p2 & 3) {
 		default: return CMD_ERROR; // Invalid method
 		case 0: // Take some extra loan
 			loan = LOAN_INTERVAL;
@@ -55,8 +59,8 @@ CommandCost CmdIncreaseLoan(TileIndex tile, DoCommandFlag flags, uint32 p1, uint
 			loan = _economy.max_loan - c->current_loan;
 			break;
 		case 2: // Take the given amount of loan
-			if ((int32)p1 < LOAN_INTERVAL || c->current_loan + (int32)p1 > _economy.max_loan || p1 % LOAN_INTERVAL != 0) return CMD_ERROR;
-			loan = p1;
+			loan = ((uint64)p1 << 32) | (p2 & 0xFFFFFFFC);
+			if (loan < LOAN_INTERVAL || c->current_loan + loan > _economy.max_loan || loan % LOAN_INTERVAL != 0) return CMD_ERROR;
 			break;
 	}
 
@@ -76,10 +80,11 @@ CommandCost CmdIncreaseLoan(TileIndex tile, DoCommandFlag flags, uint32 p1, uint
  * Decrease the loan of your company.
  * @param tile unused
  * @param flags operation to perform
- * @param p1 amount to decrease the loan with, multitude of LOAN_INTERVAL. Only used when p2 == 2.
- * @param p2 when 0: pays back LOAN_INTERVAL
- *           when 1: pays back the maximum loan permitting money (press CTRL),
- *           when 2: pays back the amount specified in p1
+ * @param p1 higher half of amount to decrease the loan with, multitude of LOAN_INTERVAL. Only used when (p2 & 3) == 2.
+ * @param p2 (bit 2-31) - lower half of amount (lower 2 bits assumed to be 0)
+ *           (bit 0-1)  - when 0: pays back LOAN_INTERVAL
+ *                        when 1: pays back the maximum loan permitting money (press CTRL),
+ *                        when 2: pays back the amount specified in p1 and p2
  * @param text unused
  * @return the cost of this operation or an error
  */
@@ -90,7 +95,7 @@ CommandCost CmdDecreaseLoan(TileIndex tile, DoCommandFlag flags, uint32 p1, uint
 	if (c->current_loan == 0) return_cmd_error(STR_ERROR_LOAN_ALREADY_REPAYED);
 
 	Money loan;
-	switch (p2) {
+	switch (p2 & 3) {
 		default: return CMD_ERROR; // Invalid method
 		case 0: // Pay back one step
 			loan = min(c->current_loan, (Money)LOAN_INTERVAL);
@@ -100,8 +105,8 @@ CommandCost CmdDecreaseLoan(TileIndex tile, DoCommandFlag flags, uint32 p1, uint
 			loan -= loan % LOAN_INTERVAL;
 			break;
 		case 2: // Repay the given amount of loan
-			if (p1 % LOAN_INTERVAL != 0 || (int32)p1 < LOAN_INTERVAL || p1 > c->current_loan) return CMD_ERROR; // Invalid amount to loan
-			loan = p1;
+			loan = ((uint64)p1 << 32) | (p2 & 0xFFFFFFFC);
+			if (loan % LOAN_INTERVAL != 0 || loan < LOAN_INTERVAL || loan > c->current_loan) return CMD_ERROR; // Invalid amount to loan
 			break;
 	}
 
diff --git a/src/script/api/script_company.cpp b/src/script/api/script_company.cpp
index 5769c97fa..93bba6332 100644
--- a/src/script/api/script_company.cpp
+++ b/src/script/api/script_company.cpp
@@ -204,8 +204,10 @@
 
 	if (loan == GetLoanAmount()) return true;
 
+	Money amount = abs(loan - GetLoanAmount());
+
 	return ScriptObject::DoCommand(0,
-			abs(loan - GetLoanAmount()), 2,
+			amount >> 32, (amount & 0xFFFFFFFC) | 2,
 			(loan > GetLoanAmount()) ? CMD_INCREASE_LOAN : CMD_DECREASE_LOAN);
 }