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// Copyright 2014 The Crashpad Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef CRASHPAD_UTIL_MISC_INITIALIZATION_INITIALIZATION_STATE_H_
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#define CRASHPAD_UTIL_MISC_INITIALIZATION_INITIALIZATION_STATE_H_
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#include <stdint.h>
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#include "base/macros.h"
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namespace crashpad {
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//! \brief Tracks whether data are initialized.
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//!
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//! Objects of this type track whether the data they’re guarding are
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//! initialized. The three possible states are uninitialized (the initial
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//! state), initializing, and valid. As the guarded data are initialized, an
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//! InitializationState object will normally transition through these three
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//! states. A fourth state corresponds to the destruction of objects of this
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//! type, making it less likely that a use-after-free of an InitializationState
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//! object will appear in the valid state.
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//!
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//! If the only purpose for tracking the initialization state of guarded data is
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//! to DCHECK when the object is in an unexpected state, use
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//! InitializationStateDcheck instead.
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class InitializationState {
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public:
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//! \brief The object’s state.
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enum State : uint8_t {
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//! \brief The object has not yet been initialized.
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kStateUninitialized = 0,
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//! \brief The object is being initialized.
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//!
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//! This state protects against attempted reinitializaton of
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//! partially-initialized objects whose initial initialization attempt
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//! failed. This state is to be used while objects are initializing, but are
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//! not yet fully initialized.
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kStateInvalid,
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//! \brief The object has been initialized.
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kStateValid,
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//! \brief The object has been destroyed.
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kStateDestroyed,
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};
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InitializationState() : state_(kStateUninitialized) {}
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~InitializationState() { state_ = kStateDestroyed; }
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//! \brief Returns `true` if the object’s state is #kStateUninitialized and it
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//! is safe to begin initializing it.
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bool is_uninitialized() const { return state_ == kStateUninitialized; }
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//! \brief Sets the object’s state to #kStateInvalid, marking initialization
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//! as being in process.
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void set_invalid() { state_ = kStateInvalid; }
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//! \brief Sets the object’s state to #kStateValid, marking it initialized.
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void set_valid() { state_ = kStateValid; }
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//! \brief Returns `true` if the the object’s state is #kStateValid and it has
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//! been fully initialized and may be used.
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bool is_valid() const { return state_ == kStateValid; }
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protected:
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//! \brief Returns the object’s state.
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//!
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//! Consumers of this class should use an is_state_*() method instead.
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State state() const { return state_; }
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//! \brief Sets the object’s state.
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//!
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//! Consumers of this class should use a set_state_*() method instead.
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void set_state(State state) { state_ = state; }
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private:
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// state_ is volatile to ensure that it’ll be set by the destructor when it
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// runs. Otherwise, optimizations might prevent it from ever being set to
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// kStateDestroyed, limiting this class’ ability to catch use-after-free
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// errors.
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volatile State state_;
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DISALLOW_COPY_AND_ASSIGN(InitializationState);
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};
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} // namespace crashpad
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#endif // CRASHPAD_UTIL_MISC_INITIALIZATION_INITIALIZATION_STATE_H_
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