From c309ca331ec25bf65ad4ad3fe38109ffa12a0db6 Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Sat, 19 Sep 2026 15:48:07 +1000
Subject: [PATCH] CDROM: Fix possible incorrect restart track when playing

If the readahead passes a track boundary.
---
 src/core/cdrom.cpp  | 22 ++++++++++++++--------
 src/util/cd_image.h |  5 ++---
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/src/core/cdrom.cpp b/src/core/cdrom.cpp
index 9535124e7..6f311c855 100644
--- a/src/core/cdrom.cpp
+++ b/src/core/cdrom.cpp
@@ -2894,7 +2894,10 @@ void CDROM::BeginPlaying(u8 track, bool after_seek)
     if (track > media->GetTrackCount())
     {
       // restart current track
-      track = Truncate8(media->GetTrackNumber());
+      const u32 track_count = media->GetTrackCount();
+      const CDImage::Index* const index = media->GetIndexForDiscPosition(s_state.current_lba);
+      track = Truncate8(std::min(index ? index->track_number : track_count, track_count));
+      s_state.play_track_number_bcd = BinaryToBCD(track);
     }
 
     s_state.setloc_position = media->GetTrackStartMSFPosition(track);
@@ -4197,15 +4200,16 @@ void CDROM::DrawDebugWindow(float scale)
       ImGui::Text("Disc Position: MSF[%02u:%02u:%02u] LBA[%u]", disc_position.minute, disc_position.second,
                   disc_position.frame, disc_position.ToLBA());
 
-      if (media->GetTrackNumber() > media->GetTrackCount())
+      const CDImage::Index* index = media->GetIndexForDiscPosition(s_state.current_lba);
+      if (!index || index->track_number > media->GetTrackCount())
       {
         ImGui::Text("Track Position: Lead-out");
       }
       else
       {
         const CDImage::Position track_position = CDImage::Position::FromLBA(
-          s_state.current_lba - media->GetTrackStartPosition(static_cast<u8>(media->GetTrackNumber())));
-        ImGui::Text("Track Position: Number[%u] MSF[%02u:%02u:%02u] LBA[%u]", media->GetTrackNumber(),
+          s_state.current_lba - media->GetTrackStartPosition(Truncate8(index->track_number)));
+        ImGui::Text("Track Position: Number[%u] MSF[%02u:%02u:%02u] LBA[%u]", index->track_number,
                     track_position.minute, track_position.second, track_position.frame, track_position.ToLBA());
       }
 
@@ -4215,14 +4219,16 @@ void CDROM::DrawDebugWindow(float scale)
 
       if (s_state.show_current_file)
       {
-        if (media->GetTrackNumber() == 1)
+        if (index && index->track_number == 1)
         {
           if (!s_state.file_map_created)
-            CreateFileMap();
+          {
+            Host::RunOnCoreThread(static_cast<void (*)()>(&CDROM::CreateFileMap));
+            return;
+          }
 
           u32 current_file_start_lba, current_file_end_lba;
-          const u32 track_lba =
-            s_state.current_lba - media->GetTrackStartPosition(static_cast<u8>(media->GetTrackNumber()));
+          const u32 track_lba = s_state.current_lba - media->GetTrackStartPosition(Truncate8(index->track_number));
           const std::string* current_file = LookupFileMap(track_lba, &current_file_start_lba, &current_file_end_lba);
           if (current_file)
           {
diff --git a/src/util/cd_image.h b/src/util/cd_image.h
index 5ef3cc880..535bb5aa2 100644
--- a/src/util/cd_image.h
+++ b/src/util/cd_image.h
@@ -233,6 +233,8 @@ public:
   u32 GetFirstTrackNumber() const { return m_tracks.front().track_number; }
   u32 GetLastTrackNumber() const { return m_tracks.back().track_number; }
   u32 GetIndexCount() const { return static_cast<u32>(m_indices.size()); }
+  const Index* GetIndexForDiscPosition(LBA pos) const;
+  const Index* GetIndexForTrackPosition(u32 track_number, LBA track_pos) const;
   const std::vector<Track>& GetTracks() const { return m_tracks; }
   const std::vector<Index>& GetIndices() const { return m_indices; }
   const Track& GetTrack(u32 track) const;
@@ -298,9 +300,6 @@ protected:
   void ClearTOC();
   void CopyTOC(const CDImage* image);
 
-  const Index* GetIndexForDiscPosition(LBA pos) const;
-  const Index* GetIndexForTrackPosition(u32 track_number, LBA track_pos) const;
-
   /// Synthesis of lead-out data.
   void AddLeadOutIndex();