From 18c930c1b209eb24edd4081ce31804821902ae48 Mon Sep 17 00:00:00 2001
From: emoose <abc@cock.li>
Date: Sun, 5 Jan 2020 20:18:14 +0000
Subject: [PATCH] [VFS] Port new BlockToOffsetSTFS algo from stfs-headers

https://github.com/emoose/xenia/commit/65ca664fdb5dc75d8585a2ca8f19f2f13b676e74
This should give better compatibility with CON packages - ie. profiles taken from actual consoles should hopefully extract properly without errors, now there's shouldn't be any need for extracting them with Velocity/Horizon first.
---
 .../vfs/devices/stfs_container_device.cc      | 35 ++++++++++++++++++-
 src/xenia/vfs/devices/stfs_container_device.h |  3 ++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/src/xenia/vfs/devices/stfs_container_device.cc b/src/xenia/vfs/devices/stfs_container_device.cc
index 8b180e91d..29e069df5 100644
--- a/src/xenia/vfs/devices/stfs_container_device.cc
+++ b/src/xenia/vfs/devices/stfs_container_device.cc
@@ -591,10 +591,43 @@ StfsContainerDevice::Error StfsContainerDevice::ReadSTFS() {
     }
   }
 
-  return Error::kSuccess;
+  if (all_entries.size() > 0) {
+    return Error::kSuccess;
+  }
+
+  // Failed to load any entries, try with old algo if we haven't already
+  if (!use_old_algorithm_) {
+    use_old_algorithm_ = true;
+    return ReadSTFS();
+  }
+
+  // Tried with old algo and still no entries... return failure
+  return Error::kErrorReadError;
 }
 
 size_t StfsContainerDevice::BlockToOffsetSTFS(uint64_t block_index) {
+  if (use_old_algorithm_) {
+    return BlockToOffsetSTFS_Old(block_index);
+  }
+
+  uint32_t num_tables = 1;  // num hashtables per block? or maybe backingblocks?
+  if (((header_.header_size + 0xFFF) & 0xB000) == 0xB000 ||
+      (header_.stfs_volume_descriptor.flags & 0x1) == 0x0) {
+    num_tables++;
+  }
+
+  uint64_t dataBlock = block_index + num_tables * ((block_index + 0xAA) / 0xAA);
+  if (block_index >= 170) {
+    dataBlock += num_tables * ((block_index + 0x70E4) / 0x70E4);
+    if (block_index >= 28900) {
+      dataBlock += num_tables * ((block_index + 0x4AF768) / 0x4AF768);
+    }
+  }
+
+  return xe::round_up(header_.header_size, 0x1000) + (dataBlock * 0x1000);
+}
+
+size_t StfsContainerDevice::BlockToOffsetSTFS_Old(uint64_t block_index) {
   uint64_t block;
   uint32_t block_shift = 0;
   if (((header_.header_size + 0x0FFF) & 0xB000) == 0xB000 ||
diff --git a/src/xenia/vfs/devices/stfs_container_device.h b/src/xenia/vfs/devices/stfs_container_device.h
index e77674a3a..658844f84 100644
--- a/src/xenia/vfs/devices/stfs_container_device.h
+++ b/src/xenia/vfs/devices/stfs_container_device.h
@@ -217,6 +217,7 @@ class StfsContainerDevice : public Device {
 
   Error ReadSTFS();
   size_t BlockToOffsetSTFS(uint64_t block);
+  size_t BlockToOffsetSTFS_Old(uint64_t block);
 
   BlockHash GetBlockHash(const uint8_t* map_ptr, uint32_t block_index,
                          uint32_t table_offset);
@@ -231,6 +232,8 @@ class StfsContainerDevice : public Device {
   StfsPackageType package_type_;
   StfsHeader header_;
   uint32_t table_size_shift_;
+
+  bool use_old_algorithm_ = false;
 };
 
 }  // namespace vfs