/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <windows.h>

#include "shared-libraries.h"
#include "nsWindowsHelpers.h"
#include "mozilla/NativeNt.h"
#include "mozilla/WindowsEnumProcessModules.h"
#include "mozilla/WindowsProcessMitigations.h"
#include "nsPrintfCString.h"

static bool IsModuleUnsafeToLoad(const nsAString& aModuleName) {
  // Hackaround for Bug 1723868.  There is no safe way to prevent the module
  // Microsoft's VP9 Video Decoder from being unloaded because mfplat.dll may
  // have posted more than one task to unload the module in the work queue
  // without calling LoadLibrary.
  if (aModuleName.LowerCaseEqualsLiteral("msvp9dec_store.dll")) {
    return true;
  }

  return false;
}

void AddSharedLibraryFromModuleInfo(SharedLibraryInfo& sharedLibraryInfo,
                                    const wchar_t* aModulePath,
                                    mozilla::Maybe<HMODULE> aModule) {
  nsDependentSubstring moduleNameStr(
      mozilla::nt::GetLeafName(nsDependentString(aModulePath)));

  // If the module is unsafe to call LoadLibraryEx for, we skip.
  if (IsModuleUnsafeToLoad(moduleNameStr)) {
    return;
  }

  // If EAF+ is enabled, parsing ntdll's PE header causes a crash.
  if (mozilla::IsEafPlusEnabled() &&
      moduleNameStr.LowerCaseEqualsLiteral("ntdll.dll")) {
    return;
  }

  // Load the module again - to make sure that its handle will remain valid as
  // we attempt to read the PDB information from it - or for the first time if
  // we only have a path. We want to load the DLL without running the newly
  // loaded module's DllMain function, but not as a data file because we want
  // to be able to do RVA computations easily. Hence, we use the flag
  // LOAD_LIBRARY_AS_IMAGE_RESOURCE which ensures that the sections (not PE
  // headers) will be relocated by the loader. Otherwise GetPdbInfo() and/or
  // GetVersionInfo() can cause a crash. If the original handle |aModule| is
  // valid, LoadLibraryEx just increments its refcount.
  nsModuleHandle handleLock(
      ::LoadLibraryExW(aModulePath, NULL, LOAD_LIBRARY_AS_IMAGE_RESOURCE));
  if (!handleLock) {
    return;
  }

  mozilla::nt::PEHeaders headers(handleLock.get());
  if (!headers) {
    return;
  }

  mozilla::Maybe<mozilla::Range<const uint8_t>> bounds = headers.GetBounds();
  if (!bounds) {
    return;
  }

  // Put the original |aModule| into SharedLibrary, but we get debug info
  // from |handleLock| as |aModule| might be inaccessible.
  const uintptr_t modStart =
      aModule.isSome() ? reinterpret_cast<uintptr_t>(*aModule)
                       : reinterpret_cast<uintptr_t>(handleLock.get());
  const uintptr_t modEnd = modStart + bounds->length();

  nsAutoCString breakpadId;
  nsAutoString pdbPathStr;
  if (const auto* debugInfo = headers.GetPdbInfo()) {
    MOZ_ASSERT(breakpadId.IsEmpty());
    const GUID& pdbSig = debugInfo->pdbSignature;
    breakpadId.AppendPrintf(
        "%08lX"                             // m0
        "%04X%04X"                          // m1,m2
        "%02X%02X%02X%02X%02X%02X%02X%02X"  // m3
        "%X",                               // pdbAge
        pdbSig.Data1, pdbSig.Data2, pdbSig.Data3, pdbSig.Data4[0],
        pdbSig.Data4[1], pdbSig.Data4[2], pdbSig.Data4[3], pdbSig.Data4[4],
        pdbSig.Data4[5], pdbSig.Data4[6], pdbSig.Data4[7], debugInfo->pdbAge);

    // The PDB file name could be different from module filename,
    // so report both
    // e.g. The PDB for C:\Windows\SysWOW64\ntdll.dll is wntdll.pdb
    pdbPathStr = NS_ConvertUTF8toUTF16(debugInfo->pdbFileName);
  }

  nsAutoCString codeId;
  DWORD timestamp;
  DWORD imageSize;
  if (headers.GetTimeStamp(timestamp) && headers.GetImageSize(imageSize)) {
    codeId.AppendPrintf(
        "%08lX"  // Uppercase 8 digits of hex timestamp with leading zeroes.
        "%lx",   // Lowercase hex image size
        timestamp, imageSize);
  }

  nsAutoCString versionStr;
  uint64_t version;
  if (headers.GetVersionInfo(version)) {
    versionStr.AppendPrintf("%u.%u.%u.%u",
                            static_cast<uint32_t>((version >> 48) & 0xFFFFu),
                            static_cast<uint32_t>((version >> 32) & 0xFFFFu),
                            static_cast<uint32_t>((version >> 16) & 0xFFFFu),
                            static_cast<uint32_t>(version & 0xFFFFu));
  }

  const nsString& pdbNameStr =
      PromiseFlatString(mozilla::nt::GetLeafName(pdbPathStr));
  SharedLibrary shlib(modStart, modEnd,
                      0,  // DLLs are always mapped at offset 0 on Windows
                      breakpadId, codeId, PromiseFlatString(moduleNameStr),
                      nsDependentString(aModulePath), pdbNameStr, pdbPathStr,
                      versionStr, "");
  sharedLibraryInfo.AddSharedLibrary(shlib);
}

SharedLibraryInfo SharedLibraryInfo::GetInfoForSelf() {
  SharedLibraryInfo sharedLibraryInfo;

  auto addSharedLibraryFromModuleInfo =
      [&sharedLibraryInfo](const wchar_t* aModulePath, HMODULE aModule) {
        AddSharedLibraryFromModuleInfo(sharedLibraryInfo, aModulePath,
                                       mozilla::Some(aModule));
      };

  mozilla::EnumerateProcessModules(addSharedLibraryFromModuleInfo);
  return sharedLibraryInfo;
}

SharedLibraryInfo SharedLibraryInfo::GetInfoFromPath(const wchar_t* aPath) {
  SharedLibraryInfo sharedLibraryInfo;
  AddSharedLibraryFromModuleInfo(sharedLibraryInfo, aPath, mozilla::Nothing());
  return sharedLibraryInfo;
}

void SharedLibraryInfo::Initialize() { /* do nothing */
}