From 20d5d480fb215e8fa5d50108749a95f692cde788 Mon Sep 17 00:00:00 2001
From: Matt Bilker <me@mbilker.us>
Date: Fri, 13 Mar 2020 05:30:18 +0000
Subject: [PATCH] mu3hook/unity.c: hook Unity plugin DLLs

- Unity loads plugin DLLs and Mono dynamically.

- Ongeki uses Criware for videos so hook the Criware plugin DLL so the
  path hooks load the videos from the hooked paths.
---
 mu3hook/dllmain.c   |  2 +
 mu3hook/meson.build |  2 +
 mu3hook/unity.c     | 95 +++++++++++++++++++++++++++++++++++++++++++++
 mu3hook/unity.h     |  3 ++
 4 files changed, 102 insertions(+)
 create mode 100644 mu3hook/unity.c
 create mode 100644 mu3hook/unity.h

diff --git a/mu3hook/dllmain.c b/mu3hook/dllmain.c
index c34bc51..cc6a980 100644
--- a/mu3hook/dllmain.c
+++ b/mu3hook/dllmain.c
@@ -11,6 +11,7 @@
 
 #include "mu3hook/config.h"
 #include "mu3hook/io4.h"
+#include "mu3hook/unity.h"
 
 #include "platform/platform.h"
 
@@ -33,6 +34,7 @@ static DWORD CALLBACK mu3_pre_startup(void)
     /* Hook Win32 APIs */
 
     serial_hook_init();
+    unity_hook_init();
 
     /* Initialize emulation hooks */
 
diff --git a/mu3hook/meson.build b/mu3hook/meson.build
index 66293dc..4f3ba71 100644
--- a/mu3hook/meson.build
+++ b/mu3hook/meson.build
@@ -24,5 +24,7 @@ shared_library(
         'dllmain.c',
         'io4.c',
         'io4.h',
+        'unity.h',
+        'unity.c',
     ],
 )
diff --git a/mu3hook/unity.c b/mu3hook/unity.c
new file mode 100644
index 0000000..efefc32
--- /dev/null
+++ b/mu3hook/unity.c
@@ -0,0 +1,95 @@
+#include <stdbool.h>
+
+#include <windows.h>
+
+#include "hook/table.h"
+
+#include "hooklib/dll.h"
+#include "hooklib/path.h"
+
+#include "util/dprintf.h"
+
+static void dll_hook_insert_hooks(HMODULE target);
+
+static HMODULE WINAPI my_LoadLibraryW(const wchar_t *name);
+static HMODULE (WINAPI *next_LoadLibraryW)(const wchar_t *name);
+
+static const struct hook_symbol unity_kernel32_syms[] = {
+    {
+        .name = "LoadLibraryW",
+        .patch = my_LoadLibraryW,
+        .link = (void **) &next_LoadLibraryW,
+    },
+};
+
+static const wchar_t *target_modules[] = {
+    L"mono.dll",
+    L"cri_ware_unity.dll",
+};
+static const size_t target_modules_len = _countof(target_modules);
+
+void unity_hook_init(void)
+{
+    dll_hook_insert_hooks(NULL);
+}
+
+static void dll_hook_insert_hooks(HMODULE target)
+{
+    hook_table_apply(
+            target,
+            "kernel32.dll",
+            unity_kernel32_syms,
+            _countof(unity_kernel32_syms));
+}
+
+static HMODULE WINAPI my_LoadLibraryW(const wchar_t *name)
+{
+    const wchar_t *name_end;
+    const wchar_t *target_module;
+    bool already_loaded;
+    HMODULE result;
+    size_t name_len;
+    size_t target_module_len;
+
+    if (name == NULL) {
+        SetLastError(ERROR_INVALID_PARAMETER);
+
+        return NULL;
+    }
+
+    // Check if the module is already loaded
+    already_loaded = GetModuleHandleW(name) != NULL;
+
+    // Must call the next handler so the DLL reference count is incremented
+    result = next_LoadLibraryW(name);
+
+    if (!already_loaded && result != NULL) {
+        name_len = wcslen(name);
+
+        for (size_t i = 0; i < target_modules_len; i++) {
+            target_module = target_modules[i];
+            target_module_len = wcslen(target_module);
+
+            // Check if the newly loaded library is at least the length of
+            // the name of the target module
+            if (name_len < target_module_len) {
+                continue;
+            }
+
+            name_end = &name[name_len - target_module_len];
+
+            // Check if the name of the newly loaded library is one of the
+            // modules the path hooks should be injected into
+            if (_wcsicmp(name_end, target_module) != 0) {
+                continue;
+            }
+
+            dprintf("Unity: Loaded %S\n", target_module);
+
+            dll_hook_insert_hooks(result);
+            path_hook_insert_hooks(result);
+        }
+    }
+
+    return result;
+}
diff --git a/mu3hook/unity.h b/mu3hook/unity.h
new file mode 100644
index 0000000..99c3bd9
--- /dev/null
+++ b/mu3hook/unity.h
@@ -0,0 +1,3 @@
+#pragma once
+
+void unity_hook_init(void);