From 4e0db1719237385fb210ddc24dc76c4b5e38fb75 Mon Sep 17 00:00:00 2001
From: Alex Barney <thealexbarney@gmail.com>
Date: Mon, 13 May 2024 23:07:24 -0700
Subject: [PATCH] Limit the hash target size to the file size when building a
 hashed PFS

---
 .../Tools/FsSystem/PartitionFileSystemBuilder.cs       | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/LibHac/Tools/FsSystem/PartitionFileSystemBuilder.cs b/src/LibHac/Tools/FsSystem/PartitionFileSystemBuilder.cs
index b9858d21..2e8ec276 100644
--- a/src/LibHac/Tools/FsSystem/PartitionFileSystemBuilder.cs
+++ b/src/LibHac/Tools/FsSystem/PartitionFileSystemBuilder.cs
@@ -23,6 +23,7 @@ public enum PartitionFileSystemType
 public class PartitionFileSystemBuilder
 {
     private const int HeaderSize = 0x10;
+    private const int DefaultHashTargetSize = 0x200;
 
     private List<Entry> Entries { get; } = new List<Entry>();
     private long CurrentOffset { get; set; }
@@ -58,7 +59,7 @@ public class PartitionFileSystemBuilder
             Offset = CurrentOffset,
             NameLength = Encoding.UTF8.GetByteCount(filename),
             HashOffset = 0,
-            HashLength = 0x200
+            HashLength = (int)Math.Min(DefaultHashTargetSize, fileSize)
         };
 
         CurrentOffset += entry.Length;
@@ -163,7 +164,10 @@ public class PartitionFileSystemBuilder
 
         foreach (Entry entry in Entries)
         {
-            if (entry.HashLength == 0) entry.HashLength = 0x200;
+            if (entry.HashLength == 0)
+            {
+                entry.HashLength = (int)Math.Min(DefaultHashTargetSize, entry.Length);
+            }
 
             byte[] data = new byte[entry.HashLength];
             entry.File.Read(out long bytesRead, entry.HashOffset, data);
@@ -180,7 +184,7 @@ public class PartitionFileSystemBuilder
             sha.GetHash(entry.Hash);
         }
     }
-    
+
     public static int GetEntrySize(PartitionFileSystemType type)
     {
         switch (type)