gecko-dev/ipc/glue/FileDescriptor.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "FileDescriptor.h"

#include "mozilla/Assertions.h"
#include "nsDebug.h"

#ifdef XP_WIN
#  include <windows.h>
#  include "ProtocolUtils.h"
#else  // XP_WIN
#  include <unistd.h>
#endif  // XP_WIN

namespace mozilla {
namespace ipc {

FileDescriptor::FileDescriptor() = default;

FileDescriptor::FileDescriptor(const FileDescriptor& aOther)
    : mHandle(Clone(aOther.mHandle.get())) {}

FileDescriptor::FileDescriptor(FileDescriptor&& aOther)
    : mHandle(std::move(aOther.mHandle)) {}

FileDescriptor::FileDescriptor(PlatformHandleType aHandle)
    : mHandle(Clone(aHandle)) {}

FileDescriptor::FileDescriptor(UniquePlatformHandle&& aHandle)
    : mHandle(std::move(aHandle)) {}

FileDescriptor::FileDescriptor(const IPDLPrivate&, const PickleType& aPickle) {
#ifdef XP_WIN
  mHandle.reset(aPickle);
#else
  mHandle.reset(aPickle.fd);
#endif
}

FileDescriptor::~FileDescriptor() = default;

FileDescriptor& FileDescriptor::operator=(const FileDescriptor& aOther) {
  if (this != &aOther) {
    mHandle = Clone(aOther.mHandle.get());
  }
  return *this;
}

FileDescriptor& FileDescriptor::operator=(FileDescriptor&& aOther) {
  if (this != &aOther) {
    mHandle = std::move(aOther.mHandle);
  }
  return *this;
}

FileDescriptor::PickleType FileDescriptor::ShareTo(
    const FileDescriptor::IPDLPrivate&,
    FileDescriptor::ProcessId aTargetPid) const {
  PlatformHandleType newHandle;
#ifdef XP_WIN
  if (IsValid()) {
    if (mozilla::ipc::DuplicateHandle(mHandle.get(), aTargetPid, &newHandle, 0,
                                      DUPLICATE_SAME_ACCESS)) {
      return newHandle;
    }
    NS_WARNING("Failed to duplicate file handle for other process!");
  }
  return INVALID_HANDLE_VALUE;
#else  // XP_WIN
  if (IsValid()) {
    newHandle = dup(mHandle.get());
    if (newHandle >= 0) {
      return base::FileDescriptor(newHandle, /* auto_close */ true);
    }
    NS_WARNING("Failed to duplicate file handle for other process!");
  }
  return base::FileDescriptor();
#endif

  MOZ_CRASH("Must not get here!");
}

bool FileDescriptor::IsValid() const { return mHandle != nullptr; }

FileDescriptor::UniquePlatformHandle FileDescriptor::ClonePlatformHandle()
    const {
  return Clone(mHandle.get());
}

FileDescriptor::UniquePlatformHandle FileDescriptor::TakePlatformHandle() {
  return UniquePlatformHandle(mHandle.release());
}

bool FileDescriptor::operator==(const FileDescriptor& aOther) const {
  return mHandle == aOther.mHandle;
}

// static
FileDescriptor::UniquePlatformHandle FileDescriptor::Clone(
    PlatformHandleType aHandle) {
  FileDescriptor::PlatformHandleType newHandle;

#ifdef XP_WIN
  if (aHandle == INVALID_HANDLE_VALUE || aHandle == nullptr) {
    return UniqueFileHandle();
  }
  if (::DuplicateHandle(GetCurrentProcess(), aHandle, GetCurrentProcess(),
                        &newHandle, 0, FALSE, DUPLICATE_SAME_ACCESS)) {
    return UniqueFileHandle(newHandle);
  }
#else  // XP_WIN
  if (aHandle < 0) {
    return UniqueFileHandle();
  }
  newHandle = dup(aHandle);
  if (newHandle >= 0) {
    return UniqueFileHandle(newHandle);
  }
#endif
  NS_WARNING("Failed to duplicate file handle for current process!");
  return UniqueFileHandle();
}

void IPDLParamTraits<FileDescriptor>::Write(IPC::Message* aMsg,
                                            IProtocol* aActor,
                                            const FileDescriptor& aParam) {
#ifdef XP_WIN
  FileDescriptor::PickleType pfd =
      aParam.ShareTo(FileDescriptor::IPDLPrivate(), aActor->OtherPid());
#else
  // The pid returned by OtherPID() is only required for Windows to
  // send file descriptors.  For the use case of the fork server,
  // aActor is always null.  Since it is only for the special case of
  // Windows, here we skip it for other platforms.
  FileDescriptor::PickleType pfd =
      aParam.ShareTo(FileDescriptor::IPDLPrivate(), 0);
#endif
  WriteIPDLParam(aMsg, aActor, pfd);
}

bool IPDLParamTraits<FileDescriptor>::Read(const IPC::Message* aMsg,
                                           PickleIterator* aIter,
                                           IProtocol* aActor,
                                           FileDescriptor* aResult) {
  FileDescriptor::PickleType pfd;
  if (!ReadIPDLParam(aMsg, aIter, aActor, &pfd)) {
    return false;
  }

  *aResult = FileDescriptor(FileDescriptor::IPDLPrivate(), pfd);
  if (!aResult->IsValid()) {
    printf_stderr("IPDL protocol Error: Received an invalid file descriptor\n");
  }
  return true;
}

}  // namespace ipc
}  // namespace mozilla