From 8f92c60a0bf01a78c190a4477260ff11defcc3e7 Mon Sep 17 00:00:00 2001
From: "Dr. Chat" <arkolbed@gmail.com>
Date: Thu, 17 Dec 2015 17:14:43 -0600
Subject: [PATCH] ObCreateSymbolicLink/ObDeleteSymbolicLink

---
 src/xenia/kernel/xboxkrnl/xboxkrnl_ob.cc | 31 +++++++++++++++++++
 src/xenia/vfs/virtual_file_system.cc     | 38 ++++++++++++++++++++----
 src/xenia/vfs/virtual_file_system.h      |  1 +
 3 files changed, 64 insertions(+), 6 deletions(-)

diff --git a/src/xenia/kernel/xboxkrnl/xboxkrnl_ob.cc b/src/xenia/kernel/xboxkrnl/xboxkrnl_ob.cc
index 057b27297..15ee29804 100644
--- a/src/xenia/kernel/xboxkrnl/xboxkrnl_ob.cc
+++ b/src/xenia/kernel/xboxkrnl/xboxkrnl_ob.cc
@@ -169,6 +169,37 @@ SHIM_CALL ObDereferenceObject_shim(PPCContext* ppc_context,
   SHIM_SET_RETURN_32(0);
 }
 
+dword_result_t ObCreateSymbolicLink(pointer_t<X_ANSI_STRING> path,
+                                    pointer_t<X_ANSI_STRING> target) {
+  auto path_str = path->to_string(kernel_memory()->virtual_membase());
+  auto target_str = target->to_string(kernel_memory()->virtual_membase());
+  path_str = filesystem::CanonicalizePath(path_str);
+  target_str = filesystem::CanonicalizePath(target_str);
+
+  auto pos = path_str.find("\\??\\");
+  if (pos != path_str.npos && pos == 0) {
+    path_str = path_str.substr(4);  // Strip the full qualifier
+  }
+
+  if (!kernel_state()->file_system()->RegisterSymbolicLink(path_str,
+                                                           target_str)) {
+    return X_STATUS_UNSUCCESSFUL;
+  }
+
+  return X_STATUS_SUCCESS;
+}
+DECLARE_XBOXKRNL_EXPORT(ObCreateSymbolicLink, ExportTag::kImplemented);
+
+dword_result_t ObDeleteSymbolicLink(pointer_t<X_ANSI_STRING> path) {
+  auto path_str = path->to_string(kernel_memory()->virtual_membase());
+  if (!kernel_state()->file_system()->UnregisterSymbolicLink(path_str)) {
+    return X_STATUS_UNSUCCESSFUL;
+  }
+
+  return X_STATUS_SUCCESS;
+}
+DECLARE_XBOXKRNL_EXPORT(ObDeleteSymbolicLink, ExportTag::kImplemented);
+
 dword_result_t NtDuplicateObject(dword_t handle, lpdword_t new_handle_ptr,
                                  dword_t options) {
   // NOTE: new_handle_ptr can be zero to just close a handle.
diff --git a/src/xenia/vfs/virtual_file_system.cc b/src/xenia/vfs/virtual_file_system.cc
index 5806c0824..3f3c3d638 100644
--- a/src/xenia/vfs/virtual_file_system.cc
+++ b/src/xenia/vfs/virtual_file_system.cc
@@ -36,6 +36,8 @@ bool VirtualFileSystem::RegisterSymbolicLink(std::string path,
                                              std::string target) {
   auto global_lock = global_critical_region_.Acquire();
   symlinks_.insert({path, target});
+  XELOGD("Registered symbolic link: %s => %s", path.c_str(), target.c_str());
+
   return true;
 }
 
@@ -45,10 +47,22 @@ bool VirtualFileSystem::UnregisterSymbolicLink(std::string path) {
   if (it == symlinks_.end()) {
     return false;
   }
+  XELOGD("Unregistered symbolic link: %s => %s", it->first.c_str(),
+         it->second.c_str());
+
   symlinks_.erase(it);
   return true;
 }
 
+bool VirtualFileSystem::IsSymbolicLink(const std::string& path) {
+  auto global_lock = global_critical_region_.Acquire();
+  auto it = symlinks_.find(path);
+  if (it == symlinks_.end()) {
+    return false;
+  }
+  return true;
+}
+
 Entry* VirtualFileSystem::ResolvePath(std::string path) {
   auto global_lock = global_critical_region_.Acquire();
 
@@ -58,17 +72,29 @@ Entry* VirtualFileSystem::ResolvePath(std::string path) {
   // Resolve symlinks.
   std::string device_path;
   std::string relative_path;
-  for (const auto& it : symlinks_) {
-    if (xe::find_first_of_case(normalized_path, it.first) == 0) {
-      // Found symlink!
-      device_path = it.second;
-      relative_path = normalized_path.substr(it.first.size());
+  for (int i = 0; i < 2; i++) {
+    for (const auto& it : symlinks_) {
+      if (xe::find_first_of_case(normalized_path, it.first) == 0) {
+        // Found symlink!
+        device_path = it.second;
+        if (relative_path.empty()) {
+          relative_path = normalized_path.substr(it.first.size());
+        }
+
+        // Bit of a cheaty move here, but allows double symlinks to be resolved.
+        normalized_path = device_path;
+        break;
+      }
+    }
+
+    // Break as soon as we've completely resolved the symlinks to a device.
+    if (!IsSymbolicLink(device_path)) {
       break;
     }
   }
 
-  // Not to fret, check to see if the path is fully qualified.
   if (device_path.empty()) {
+    // Symlink wasn't passed in - Check if we've received a raw device name.
     for (auto& device : devices_) {
       if (xe::find_first_of_case(normalized_path, device->mount_path()) == 0) {
         device_path = device->mount_path();
diff --git a/src/xenia/vfs/virtual_file_system.h b/src/xenia/vfs/virtual_file_system.h
index f9f3eff62..f7d23190a 100644
--- a/src/xenia/vfs/virtual_file_system.h
+++ b/src/xenia/vfs/virtual_file_system.h
@@ -32,6 +32,7 @@ class VirtualFileSystem {
 
   bool RegisterSymbolicLink(std::string path, std::string target);
   bool UnregisterSymbolicLink(std::string path);
+  bool IsSymbolicLink(const std::string& path);
 
   Entry* ResolvePath(std::string path);
   Entry* ResolveBasePath(std::string path);