[Scummvm-git-logs] scummvm master -> 591d2a801e47d0a0fc3b38c44a8ae8564d41e12d

[sluicebox]

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Summary:
591d2a801e SCI32: Fix PHANT1 basement fast-forward lockup


Commit: 591d2a801e47d0a0fc3b38c44a8ae8564d41e12d
    https://github.com/scummvm/scummvm/commit/591d2a801e47d0a0fc3b38c44a8ae8564d41e12d
Author: sluicebox (22204938+sluicebox at users.noreply.github.com)
Date: 2023-04-05T16:07:59-07:00

Commit Message:
SCI32: Fix PHANT1 basement fast-forward lockup

Fixes bug #14368

Changed paths:
    engines/sci/engine/script_patches.cpp


diff --git a/engines/sci/engine/script_patches.cpp b/engines/sci/engine/script_patches.cpp
index 60f66b0e49d..9f72f56b7c9 100644
--- a/engines/sci/engine/script_patches.cpp
+++ b/engines/sci/engine/script_patches.cpp
@@ -11723,6 +11723,51 @@ static const uint16 phant1RatPatch[] = {
 	PATCH_END
 };
 
+// In the basement there is a moment where clicking the fast-forward button
+//  locks up the game. Fast-forward changes the current room script to state
+//  zero and sets global 115. Most scripts' changeState methods start by testing
+//  this global to implement fast-forward behavior. They then reset the global
+//  when disposing before calling handsOn. scaryHandsOnCode:doit enables input,
+//  empties the event queue, and then polls and processes one final event.
+//  This creates a window where handsOn can process a fast-forward click and
+//  re-enter the room script while it's in the middle of disposing itself.
+//
+// Most room scripts have a structure that survives this re-entrancy, but room
+//  20100's sEnterFrom20200 is unusual. It doesn't test the fast-forward global
+//  in state zero. Instead, it unconditionally calls handsOff, causing the
+//  original handsOn call to undo its work before it returns.
+//
+// We fix this by swapping two function calls in sEnterFrom20200:dispose:
+//  handsOn and super:dispose. Now the script is fully disposed before handsOn.
+//  If a fast-forward click occurs it will no longer have any effect, because
+//  the room no longer has a script. If other scripts are discovered with this
+//  same problem, this patch will probably apply.
+//
+// Applies to: All versions
+// Responsible method: sEnterFrom20200:dispose
+// Fixes bug: #14368
+static const uint16 phant1BasementFastForwardSignature[] = {
+	0x35, 0x00,                     // ldi 00
+	0xa1, SIG_MAGICDWORD, 0x73,     // lag 73 [ fast-forward = 0 ]
+	0x38, SIG_SELECTOR16(handsOn),  // pushi handsOn
+	0x76,                           // push0
+	0x81, 0x01,                     // lag 01
+	0x4a, SIG_UINT16(0x0004),       // send 04 [ Scary handsOn: ]
+	0x38, SIG_SELECTOR16(dispose),  // pushi dispose
+	0x76,                           // push0
+	0x59, 0x01,                     // &rest 01
+	0x57, SIG_ADDTOOFFSET(+1),      // super 04 [ super dispose: &rest ]
+	      SIG_UINT16(0x0004),
+	SIG_END
+};
+
+static const uint16 phant1BasementFastForwardPatch[] = {
+	PATCH_ADDTOOFFSET(+4),          // [ fast-forward = 0 ]
+	PATCH_GETORIGINALBYTES(13, 10), // [ super dispose: &rest ]
+	PATCH_GETORIGINALBYTES(4, 9),   // [ Scary handsOn: ]
+	PATCH_END
+};
+
 // In Phantasmagoria the cursor's hover state will not trigger on any of the
 // buttons in the main menu after returning to the main menu from a game, or
 // when choosing "Quit" on the main menu and then cancelling the quit in the
@@ -12127,6 +12172,7 @@ static const SciScriptPatcherEntry phantasmagoriaSignatures[] = {
 	{  true,   901, "fix invalid array construction",              1, sci21IntArraySignature,          sci21IntArrayPatch },
 	{  true,   901, "fix delete save",                             1, phant1DeleteSaveSignature,       phant1DeleteSavePatch },
 	{  true,  1111, "ignore audio settings from save game",        1, phant1SavedVolumeSignature,      phant1SavedVolumePatch },
+	{  true, 20100, "fix basement fast-forward",                   1, phant1BasementFastForwardSignature, phant1BasementFastForwardPatch },
 	{  true, 20200, "fix broken rat init in sEnterFromAlcove",     1, phant1RatSignature,              phant1RatPatch },
 	{  true, 20200, "fix chapter 5 wine cask hotspot",             1, phant1WineCaskHotspotSignature,  phant1WineCaskHotspotPatch },
 	{  true, 45950, "fix chase file deletion",                     1, phant1DeleteChaseFileSignature,  phant1DeleteChaseFilePatch },