FileUtils: Implement RecursiveRemoveDirectory and WalkDirectory with NT syscalls

A bit messy but it basically duplicates the Linux side. We don't have a
way to include NT internal defines in to FEXCore currently so the two
required symbols are just forward declared.

FEXCore/Source/CMakeLists.txt

@@ -262,6 +262,10 @@ endfunction()
 # Build FEXCore_Base static library
 add_library(FEXCore_Base STATIC ${FEXCORE_BASE_SRCS})
 target_link_libraries(FEXCore_Base PUBLIC ${LIBS})
+if (MINGW)
+  target_link_libraries(FEXCore_Base PUBLIC ntdll)
+endif()
+
 AddDefaultOptionsToTarget(FEXCore_Base)
 
 if (ENABLE_FEXCORE_PROFILER AND FEXCORE_PROFILER_BACKEND STREQUAL "TRACY")

FEXCore/Source/Utils/FileUtils.cpp

@@ -9,6 +9,18 @@
 #include <dirent.h>
 #include <fcntl.h>
 #include <unistd.h>
+#else
+#include <windows.h>
+#include <winnt.h>
+#include <winternl.h>
+#include <ntstatus.h>
+
+// FEX today doesn't have Windows include in FEXCore.
+extern "C" NTSTATUS WINAPI NtQueryDirectoryFile(HANDLE, HANDLE, PIO_APC_ROUTINE, PVOID, PIO_STATUS_BLOCK, PVOID, ULONG,
+                                                FILE_INFORMATION_CLASS, BOOLEAN, PUNICODE_STRING, BOOLEAN);
+
+extern "C" NTSTATUS RtlUnicodeToUTF8N(OUT PCHAR UTF8StringDestination, IN ULONG UTF8StringMaxByteCount,
+                                      OUT PULONG UTF8StringActualByteCount, IN PCWCH UnicodeStringSource, IN ULONG UnicodeStringByteCount);
 #endif
 
 namespace FEXCore::FileUtils {
@@ -190,17 +202,165 @@ end:
 }
 
 #else
-FEX_DEFAULT_VISIBILITY bool RecursiveRemoveDirectory(const fextl::string& Directory) {
-  std::error_code ec;
-  return std::filesystem::remove_all(Directory, ec) != ~0ULL;
+static inline std::optional<UNICODE_STRING> PathToNTPath(std::string_view Path) {
+  UNICODE_STRING PathW;
+  if (!RtlCreateUnicodeStringFromAsciiz(&PathW, fextl::string(Path).c_str())) {
+    return std::nullopt;
+  }
+  UNICODE_STRING NTPath;
+  bool Success = RtlDosPathNameToNtPathName_U(PathW.Buffer, &NTPath, nullptr, nullptr);
+  RtlFreeUnicodeString(&PathW);
+  if (!Success) {
+    return std::nullopt;
+  }
+
+  return NTPath;
+}
+
+static inline void FreeNTPath(UNICODE_STRING Path) {
+  RtlFreeUnicodeString(&Path);
 }
 
 FEX_DEFAULT_VISIBILITY void WalkDirectory(std::string_view Directory,
                                           fextl::move_only_function<void(std::string_view name, bool is_dir, const void* user_data)> Callback,
                                           const void* user_data) {
-  for (const auto& iter : std::filesystem::directory_iterator(Directory)) {
-    Callback(iter.path().string(), iter.is_directory(), user_data);
+  auto NTPath = PathToNTPath(Directory);
+  if (!NTPath) {
+    return;
   }
+
+  NTSTATUS Status {};
+
+  HANDLE dir_fd {};
+  OBJECT_ATTRIBUTES attr {};
+  IO_STATUS_BLOCK io {};
+
+  InitializeObjectAttributes(&attr, &*NTPath, OBJ_CASE_INSENSITIVE, nullptr, nullptr);
+  Status = NtOpenFile(&dir_fd, FILE_LIST_DIRECTORY | SYNCHRONIZE, &attr, &io, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+                      FILE_DIRECTORY_FILE | FILE_SYNCHRONOUS_IO_NONALERT);
+
+  FreeNTPath(*NTPath);
+
+  if (!NT_SUCCESS(Status)) {
+    return;
+  }
+
+  BOOLEAN FirstQuery = TRUE;
+  size_t dirent_size = 4096 * 4;
+  uint8_t* dirent_buffer = reinterpret_cast<uint8_t*>(FEXCore::Allocator::malloc(dirent_size));
+
+  if (!dirent_buffer) {
+    // Ran out of memory?
+    goto end;
+  }
+
+  while (true) {
+    Status = NtQueryDirectoryFile(dir_fd,
+                                  nullptr, // Event
+                                  nullptr, // ApcRoutine
+                                  nullptr, // ApcContext
+                                  &io, dirent_buffer, dirent_size, FileDirectoryInformation,
+                                  FALSE,   // ReturnSingleEntry
+                                  nullptr, // FileName
+                                  FirstQuery);
+    FirstQuery = FALSE;
+
+    if (Status == STATUS_NO_MORE_FILES) {
+      // No more files
+      break;
+    }
+
+    if (!NT_SUCCESS(Status)) {
+      if (Status == STATUS_BUFFER_TOO_SMALL || Status == STATUS_INFO_LENGTH_MISMATCH) {
+        // Buffer too small? Scale and try again.
+        dirent_size *= 2;
+        FEXCore::Allocator::free(dirent_buffer);
+        uint8_t* dirent_buffer = reinterpret_cast<uint8_t*>(FEXCore::Allocator::malloc(dirent_size));
+
+        if (!dirent_buffer) {
+          // Ran out of memory?
+          goto end;
+        }
+
+        continue;
+      }
+
+      // Any other failure, exit loop.
+      break;
+    }
+
+    // Iterate the entries returned.
+    for (size_t dirent_offset = 0;;) {
+      auto Info = reinterpret_cast<FILE_DIRECTORY_INFORMATION*>(dirent_buffer + dirent_offset);
+
+      std::wstring_view EntryName(Info->FileName, Info->FileNameLength / sizeof(wchar_t));
+
+      if (EntryName != L"." && EntryName != L"..") {
+        ULONG utf8_bytes_needed = 0;
+        ULONG actual_utf8_bytes = 0;
+        RtlUnicodeToUTF8N(nullptr, 0, &utf8_bytes_needed, Info->FileName, Info->FileNameLength);
+        char* dynamic_buf = reinterpret_cast<char*>(FEXCore::Allocator::malloc(utf8_bytes_needed + 1));
+        if (dynamic_buf) {
+          RtlUnicodeToUTF8N(dynamic_buf, utf8_bytes_needed + 1, &actual_utf8_bytes, Info->FileName, Info->FileNameLength);
+          std::string_view name_view(dynamic_buf, actual_utf8_bytes);
+          bool is_dir = (Info->FileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
+          Callback(name_view, is_dir, user_data);
+          FEXCore::Allocator::free(dynamic_buf);
+        }
+      }
+
+      if (Info->NextEntryOffset == 0) {
+        break;
+      }
+
+      dirent_offset += Info->NextEntryOffset;
+    }
+  }
+
+end:
+  if (dirent_buffer) {
+    FEXCore::Allocator::free(dirent_buffer);
+  }
+
+  NtClose(dir_fd);
 }
+
+FEX_DEFAULT_VISIBILITY bool RecursiveRemoveDirectory(const fextl::string& Directory) {
+  using CallbackType = void (*)(std::string_view name, bool is_dir, const void* user_data);
+  struct UserData {
+    CallbackType RemoveFile {};
+    std::string_view base_path;
+  };
+
+  CallbackType RemoveFile = [](std::string_view name, bool is_dir, const void* user_data) {
+    auto Data = reinterpret_cast<const UserData*>(user_data);
+
+    auto full_path = std::format("{}/{}", Data->base_path, name);
+    if (is_dir) {
+      UserData NewData {
+        .RemoveFile = Data->RemoveFile,
+        .base_path = full_path,
+      };
+
+      WalkDirectory(full_path, Data->RemoveFile, &NewData);
+    }
+
+    if (is_dir) {
+      RemoveDirectoryA(full_path.c_str());
+    } else {
+      DeleteFileA(full_path.c_str());
+    }
+  };
+
+  UserData Data {
+    .RemoveFile = RemoveFile,
+    .base_path = Directory,
+  };
+
+  WalkDirectory(Directory, RemoveFile, &Data);
+
+  return RemoveDirectoryA(Directory.c_str()) != 0;
+}
+
 #endif
 } // namespace FEXCore::FileUtils