From 2380a4bd8a01ea5b9c719b32f222a2cf53df800b Mon Sep 17 00:00:00 2001
From: atom0s <atom0s@live.com>
Date: Sat, 26 Mar 2022 02:25:36 -0700
Subject: [PATCH] Unpackers: (x86) - Ensure all unpacked files default to a
 checksum of 0.

---
 Steamless.Unpacker.Variant10.x86/Main.cs | 3 +--
 Steamless.Unpacker.Variant20.x86/Main.cs | 1 +
 Steamless.Unpacker.Variant21.x86/Main.cs | 1 +
 Steamless.Unpacker.Variant30.x86/Main.cs | 3 ++-
 Steamless.Unpacker.Variant31.x86/Main.cs | 3 ++-
 5 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/Steamless.Unpacker.Variant10.x86/Main.cs b/Steamless.Unpacker.Variant10.x86/Main.cs
index f8a96bd..a96bc19 100644
--- a/Steamless.Unpacker.Variant10.x86/Main.cs
+++ b/Steamless.Unpacker.Variant10.x86/Main.cs
@@ -36,7 +36,6 @@ namespace Steamless.Unpacker.Variant10.x86
     using System.IO;
     using System.Linq;
     using System.Reflection;
-    using System.Runtime.InteropServices;
 
     [SteamlessApiVersion(1, 0)]
     public class Main : SteamlessPlugin
@@ -275,7 +274,7 @@ namespace Steamless.Unpacker.Variant10.x86
                 if (this.File.DosStubSize > 0)
                     fStream.WriteBytes(this.File.DosStubData);
 
-                // Update the entry point and checksum of the file..
+                // Update the NT headers..
                 var ntHeaders = this.File.NtHeaders;
                 ntHeaders.OptionalHeader.AddressOfEntryPoint = this.OriginalEntryPoint;
                 ntHeaders.OptionalHeader.CheckSum = 0;
diff --git a/Steamless.Unpacker.Variant20.x86/Main.cs b/Steamless.Unpacker.Variant20.x86/Main.cs
index 382c24e..35ae77e 100644
--- a/Steamless.Unpacker.Variant20.x86/Main.cs
+++ b/Steamless.Unpacker.Variant20.x86/Main.cs
@@ -335,6 +335,7 @@ namespace Steamless.Unpacker.Variant20.x86
                 var ntHeaders = this.File.NtHeaders;
                 var lastSection = this.File.Sections[this.File.Sections.Count - 1];
                 ntHeaders.OptionalHeader.AddressOfEntryPoint = this.File.GetRvaFromVa(this.StubHeader.OEP);
+                ntHeaders.OptionalHeader.CheckSum = 0;
                 ntHeaders.OptionalHeader.SizeOfImage = this.File.GetAlignment(lastSection.VirtualAddress + lastSection.VirtualSize, this.File.NtHeaders.OptionalHeader.SectionAlignment);
                 this.File.NtHeaders = ntHeaders;
 
diff --git a/Steamless.Unpacker.Variant21.x86/Main.cs b/Steamless.Unpacker.Variant21.x86/Main.cs
index 4f5e58d..df4cedf 100644
--- a/Steamless.Unpacker.Variant21.x86/Main.cs
+++ b/Steamless.Unpacker.Variant21.x86/Main.cs
@@ -462,6 +462,7 @@ namespace Steamless.Unpacker.Variant21.x86
                 var lastSection = this.File.Sections[this.File.Sections.Count - 1];
                 var originalEntry = BitConverter.ToUInt32(this.PayloadData.Skip(this.SteamDrmpOffsets[2]).Take(4).ToArray(), 0);
                 ntHeaders.OptionalHeader.AddressOfEntryPoint = this.File.GetRvaFromVa(originalEntry);
+                ntHeaders.OptionalHeader.CheckSum = 0;
                 ntHeaders.OptionalHeader.SizeOfImage = this.File.GetAlignment(lastSection.VirtualAddress + lastSection.VirtualSize, this.File.NtHeaders.OptionalHeader.SectionAlignment);
                 this.File.NtHeaders = ntHeaders;
 
diff --git a/Steamless.Unpacker.Variant30.x86/Main.cs b/Steamless.Unpacker.Variant30.x86/Main.cs
index c93e26d..e526e7e 100644
--- a/Steamless.Unpacker.Variant30.x86/Main.cs
+++ b/Steamless.Unpacker.Variant30.x86/Main.cs
@@ -463,9 +463,10 @@ namespace Steamless.Unpacker.Variant30.x86
                 if (this.File.DosStubSize > 0)
                     fStream.WriteBytes(this.File.DosStubData);
 
-                // Update the entry point of the file..
+                // Update the NT headers..
                 var ntHeaders = this.File.NtHeaders;
                 ntHeaders.OptionalHeader.AddressOfEntryPoint = this.StubHeader.OriginalEntryPoint;
+                ntHeaders.OptionalHeader.CheckSum = 0;
                 this.File.NtHeaders = ntHeaders;
 
                 // Write the NT headers to the file..
diff --git a/Steamless.Unpacker.Variant31.x86/Main.cs b/Steamless.Unpacker.Variant31.x86/Main.cs
index 980cc7f..2089850 100644
--- a/Steamless.Unpacker.Variant31.x86/Main.cs
+++ b/Steamless.Unpacker.Variant31.x86/Main.cs
@@ -459,9 +459,10 @@ namespace Steamless.Unpacker.Variant31.x86
                 if (this.File.DosStubSize > 0)
                     fStream.WriteBytes(this.File.DosStubData);
 
-                // Update the entry point of the file..
+                // Update the NT headers..
                 var ntHeaders = this.File.NtHeaders;
                 ntHeaders.OptionalHeader.AddressOfEntryPoint = (uint)this.StubHeader.OriginalEntryPoint;
+                ntHeaders.OptionalHeader.CheckSum = 0;
                 this.File.NtHeaders = ntHeaders;
 
                 // Write the NT headers to the file..