public/lib/fsl/vmo/sized_vmo.h

// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef LIB_FSL_VMO_SIZED_VMO_H_
#define LIB_FSL_VMO_SIZED_VMO_H_

#include <cstddef>

#include <fuchsia/mem/cpp/fidl.h>

#include <lib/zx/vmo.h>

namespace fsl {

// A VMO along with an associated size. The associated size may be smaller than
// the actual size of the VMO, which allows to represent data that is not
// page-aligned.
class SizedVmo {
 public:
  SizedVmo(std::nullptr_t = nullptr);
  SizedVmo(zx::vmo vmo, uint64_t size);
  SizedVmo(SizedVmo&& other);
  ~SizedVmo();

  // Builds a SizedVmo from a fuchsia::mem::Buffer. Returns false if the
  // transport is not valid. For the object to be valid, it must either be null,
  // or the vmo must be valid and the size must be inferior or equal to the
  // physical size of the vmo.
  static bool FromTransport(fuchsia::mem::Buffer transport, SizedVmo* out);

  static bool IsSizeValid(const zx::vmo& vmo, uint64_t size);

  SizedVmo& operator=(SizedVmo&& other);

  operator bool() const { return static_cast<bool>(vmo_); }

  zx::vmo& vmo() { return vmo_; }
  const zx::vmo& vmo() const { return vmo_; }

  uint64_t size() const { return size_; }

  // Builds a fuchsia::mem::Buffer from this object. This will null this object
  // vmo.
  fuchsia::mem::Buffer ToTransport() &&;

  zx_status_t Duplicate(zx_rights_t rights, SizedVmo* output) const;

 private:
  zx::vmo vmo_;
  uint64_t size_;
};

}  // namespace fsl

#endif  // LIB_FSL_VMO_SIZED_VMO_H_