js/src/ds/FixedLengthVector.h
author Nika Layzell <nika@thelayzells.com>
Wed, 16 Sep 2020 20:47:55 +0000
changeset 549331 ab7d302fd3186b10ada9264528c80f6840e44571
parent 518950 e4d136fe97331f4f66b78ecb8f725948a7b7e845
permissions -rw-r--r--
Bug 1659696 - Check PendingInitialization before targeting in window.open, r=kmag This requires adding the flag as a synced field on the BrowsingContext, and checking it in a few more places. Attempts to open a new window in this racy manner will now raise an exception. This should avoid the issue from bug 1658854 by blocking the buggy attempts to load before the nested event loop has been exited. Differential Revision: https://phabricator.services.mozilla.com/D87927

/* -*- 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/. */

#ifndef ds_FixedLengthVector_h
#define ds_FixedLengthVector_h

#include "mozilla/Assertions.h"             // MOZ_ASSERT
#include "mozilla/Attributes.h"             // MOZ_MUST_USE
#include "mozilla/OperatorNewExtensions.h"  // mozilla::KnownNotNull

#include <stddef.h>  // size_t

#include "js/Utility.h"    // js_free
#include "vm/JSContext.h"  // JSContext

namespace js {

// A dynamically-allocated fixed-length vector with bounds checking assertions.
template <typename T>
class FixedLengthVector {
  // The pointer to the storage.
  T* data_ = nullptr;

  // The size of the storage.
  size_t length_ = 0;

 public:
  FixedLengthVector() = default;

  FixedLengthVector(FixedLengthVector&) = delete;
  FixedLengthVector(FixedLengthVector&&) = default;

  ~FixedLengthVector() {
    if (initialized()) {
      js_free(data_);
    }
  }

  size_t length() const { return length_; }

  bool initialized() const { return !!data_; }

  // Allocate the storage with the given size, wihtout calling constructor.
  //
  // If the allocation fails, this returns false and sets the
  // pending exception on the given context.
  MOZ_MUST_USE bool allocateUninitialized(JSContext* cx, size_t length) {
    MOZ_ASSERT(!initialized());

    length_ = length;
    data_ = cx->pod_malloc<T>(length);
    if (MOZ_UNLIKELY(!data_)) {
      return false;
    }

    return true;
  }

  // Allocate the storage with the given size and call default constructor.
  //
  // If the allocation fails, this returns false and sets the
  // pending exception on the given context.
  MOZ_MUST_USE bool allocate(JSContext* cx, size_t length) {
    if (!allocateUninitialized(cx, length)) {
      return false;
    }

    for (size_t i = 0; i < length; i++) {
      new (mozilla::KnownNotNull, &data_[i]) T();
    }
    return true;
  }

  T* begin() {
    MOZ_ASSERT(initialized());
    return data_;
  }

  const T* begin() const {
    MOZ_ASSERT(initialized());
    return data_;
  }

  T* end() {
    MOZ_ASSERT(initialized());
    return data_ + length_;
  }

  const T* end() const {
    MOZ_ASSERT(initialized());
    return data_ + length_;
  }

  T& operator[](size_t index) {
    MOZ_ASSERT(initialized());
    MOZ_ASSERT(index < length_);
    return begin()[index];
  }

  const T& operator[](size_t index) const {
    MOZ_ASSERT(initialized());
    MOZ_ASSERT(index < length_);
    return begin()[index];
  }
};

}  // namespace js

#endif  // ds_FixedLengthVector_h