From 434382ce4b848c1768407703c03ff8be024c86f8 Mon Sep 17 00:00:00 2001
From: Kevin Trocolli <pitok236@gmail.com>
Date: Sun, 7 Apr 2024 17:55:38 -0400
Subject: [PATCH] vfs: hook System_getAppRootPath for unity games

---
 platform/platform.c |  2 +-
 platform/vfs.c      | 34 +++++++++++++++++++++++++++++++++-
 platform/vfs.h      |  2 +-
 3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/platform/platform.c b/platform/platform.c
index bf44800..51279f9 100644
--- a/platform/platform.c
+++ b/platform/platform.c
@@ -75,7 +75,7 @@ HRESULT platform_hook_init(
         return hr;
     }
 
-    hr = vfs_hook_init(&cfg->vfs);
+    hr = vfs_hook_init(&cfg->vfs, game_id);
 
     if (FAILED(hr)) {
         return hr;
diff --git a/platform/vfs.c b/platform/vfs.c
index befc87d..e02114f 100644
--- a/platform/vfs.c
+++ b/platform/vfs.c
@@ -8,6 +8,8 @@
 
 #include "hooklib/path.h"
 #include "hooklib/reg.h"
+#include "hook/procaddr.h"
+#include "hook/table.h"
 
 #include "platform/vfs.h"
 
@@ -31,6 +33,18 @@ static HRESULT vfs_path_hook_option(
 static HRESULT vfs_reg_read_amfs(void *bytes, uint32_t *nbytes);
 static HRESULT vfs_reg_read_appdata(void *bytes, uint32_t *nbytes);
 
+static wchar_t* my_System_getAppRootPath();
+static wchar_t* (*next_System_getAppRootPath)();
+
+static const struct hook_symbol amdaemon_syms[] = {
+    {
+        .name = "System_getAppRootPath",
+        .patch = my_System_getAppRootPath,
+        .link = (void **) &next_System_getAppRootPath,
+    },
+};
+
+static wchar_t game[5] = {0};
 static wchar_t vfs_nthome_real[MAX_PATH];
 static const wchar_t vfs_nthome[] = L"C:\\Documents and Settings\\AppUser";
 static const size_t vfs_nthome_len = _countof(vfs_nthome) - 1;
@@ -55,7 +69,7 @@ static const struct reg_hook_val vfs_reg_vals[] = {
 
 static struct vfs_config vfs_config;
 
-HRESULT vfs_hook_init(const struct vfs_config *config)
+HRESULT vfs_hook_init(const struct vfs_config *config, const char* game_id)
 {
     wchar_t temp[MAX_PATH];
     size_t nthome_len;
@@ -68,6 +82,8 @@ HRESULT vfs_hook_init(const struct vfs_config *config)
         return S_FALSE;
     }
 
+    mbstowcs(game, game_id, 4);
+
     if (config->amfs[0] == L'\0') {
         dprintf("Vfs: FATAL: AMFS path not specified in INI file\n");
 
@@ -175,6 +191,13 @@ HRESULT vfs_hook_init(const struct vfs_config *config)
         return hr;
     }
 
+    proc_addr_table_push(
+        NULL,
+        "amdaemon_api.dll",
+        amdaemon_syms,
+        _countof(amdaemon_syms)
+    );
+
     return S_OK;
 }
 
@@ -473,3 +496,12 @@ static HRESULT vfs_reg_read_appdata(void *bytes, uint32_t *nbytes)
 {
     return reg_hook_read_wstr(bytes, nbytes, vfs_config.appdata);
 }
+
+static wchar_t* my_System_getAppRootPath()
+{
+    wchar_t *path = malloc(sizeof(wchar_t) * MAX_PATH);
+    wcscpy_s(path, MAX_PATH, vfs_config.appdata);
+    wcscat_s(path, MAX_PATH, game);
+    wcscat_s(path, MAX_PATH, L"\\");
+    return path;
+}
diff --git a/platform/vfs.h b/platform/vfs.h
index 8767305..a7e513f 100644
--- a/platform/vfs.h
+++ b/platform/vfs.h
@@ -12,4 +12,4 @@ struct vfs_config {
     wchar_t option[MAX_PATH];
 };
 
-HRESULT vfs_hook_init(const struct vfs_config *config);
+HRESULT vfs_hook_init(const struct vfs_config *config, const char* game_id);