global_object.cpp

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// Copyright (c) 2015-2017, Satoshi Tanda. All rights reserved.
// Use of this source code is governed by a MIT-style license that can be
// found in the LICENSE file.


#include "global_object.h"

// .CRT section is required to invoke ctors and dtors. This pragma embeds a .CRT
// section into the .rdata section. Or else, a LNK warning would be raised.
#pragma comment(linker, "/merge:.CRT=.rdata")

// Create two sections that are used by MSVC to place an array of ctors at a
// compile time. It is important to be ordered in alphabetical order.
#pragma section(".CRT$XCA", read)
#pragma section(".CRT$XCZ", read)

extern "C" {
//
// macro utilities
//

//
// constants and macros
//

static const ULONG kGlobalObjectpPoolTag = 'jbOG';

//
// types
//

using Destructor = void(__cdecl *)();

struct DestructorEntry {
  Destructor dtor;
  SINGLE_LIST_ENTRY list_entry;
};

//
// prototypes
//

#if defined(ALLOC_PRAGMA)
#pragma alloc_text(INIT, GlobalObjectInitialization)
#pragma alloc_text(INIT, atexit)
#pragma alloc_text(PAGE, GlobalObjectTermination)
#endif

//
// variables
//

// Place markers pointing to the beginning and end of the ctors arrays embedded
// by MSVC.
__declspec(allocate(".CRT$XCA")) static Destructor g_gop_ctors_begin[1] = {};
__declspec(allocate(".CRT$XCZ")) static Destructor g_gop_ctors_end[1] = {};

// Stores pointers to dtors to be called at the exit.
static SINGLE_LIST_ENTRY g_gop_dtors_list_head = {};

//
// implementations
//

// Calls all constructors and register all destructor
_Use_decl_annotations_ NTSTATUS GlobalObjectInitialization() {
  PAGED_CODE();

  // Call all constructors
  for (auto ctor = g_gop_ctors_begin + 1; ctor < g_gop_ctors_end; ++ctor) {
    (*ctor)();
  }
  return STATUS_SUCCESS;
}

// Calls all registered destructors
_Use_decl_annotations_ void GlobalObjectTermination() {
  PAGED_CODE();

  auto entry = PopEntryList(&g_gop_dtors_list_head);
  while (entry) {
    const auto element = CONTAINING_RECORD(entry, DestructorEntry, list_entry);
    element->dtor();
    ExFreePoolWithTag(element, kGlobalObjectpPoolTag);
    entry = PopEntryList(&g_gop_dtors_list_head);
  }
}

// Registers destructor; this is called through a call to constructor
_IRQL_requires_max_(PASSIVE_LEVEL) int __cdecl atexit(_In_ Destructor dtor) {
  PAGED_CODE();

  const auto element =
      reinterpret_cast<DestructorEntry *>(ExAllocatePoolWithTag(
          PagedPool, sizeof(DestructorEntry), kGlobalObjectpPoolTag));
  if (!element) {
    return 1;
  }
  element->dtor = dtor;
  PushEntryList(&g_gop_dtors_list_head, &element->list_entry);
  return 0;
}

}  // extern "C"