mirror of
https://github.com/facebook/react-native.git
synced 2025-11-01 09:14:26 +00:00
Nick Gerleman
c2a089fddf
Summary: Pull Request resolved: https://github.com/facebook/react-native/pull/36258 This fixes a few instances where YogaLayoutableShadowNode (or general shadownode casting) could offer better memory safety. 1. The reference form of traitCast() now terminates on invalid cast, instead of debug assert, since it is better to crash in production than to corrupt memory (which will crash somewhere later, in a much more confusing way). 2. We use traitCast() in more places where we previously would static_cast. This means needing to formally add a mutable version. 3. We bounds-check yoga children access in a single place by using `std::vector` `at()` instead of `[]`. 4. Removed `Trait::UnreservedTrait1` API, since multiple libraries using it can collide and we lose the memory safety benefits of `traitCast`. This change is in response to a bug where `YogaLayoutableShadowNode` may perform an invalid `static_cast` of `RawTextShadowNode` if a text or number is rendered directly inside of a `<View>` (instead of a `<Text>` element). This does not yet fix the underlying logic of YogaLayoutableShadowNode to act gracefully when a RawTextShadowNode makes its way into children. We just terminate, instead of corrupting memory. Changelog: [General][Breaking] - Better Fabric ShadowNode Memory Safety (Removes `Trait::UnreservedTrait` API) Reviewed By: javache Differential Revision: D43271779 fbshipit-source-id: 727c1230f72664bf4d261871c66ca61ddf0d5ffa
124 lines
3.5 KiB
C++
124 lines
3.5 KiB
C++
/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#pragma once
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#include <cstdint>
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namespace facebook {
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namespace react {
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/*
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* A set of predefined traits associated with a particular `ShadowNode` class
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* and an instance of that class. Used for efficient checking for interface
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* conformance for and storing important flags.
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*/
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class ShadowNodeTraits {
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public:
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/*
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* Underlying type for the traits.
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* The first 23 bits are reserved for Core.
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*/
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enum Trait : int32_t {
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None = 0,
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// Note:
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// Not all traits are used yet (but all will be used in the near future).
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// Inherits `LayoutableShadowNode`.
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LayoutableKind = 1 << 0,
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// Inherits `YogaLayoutableShadowNode`.
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YogaLayoutableKind = 1 << 1,
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// Inherits `ConcreteViewShadowNode<>` template.
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ViewKind = 1 << 2,
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// Inherits `BaseTextShadowNode`.
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TextKind = 1 << 3,
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// Used when calculating relative layout in
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// LayoutableShadowNode::getRelativeLayoutMetrics. This trait marks node as
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// root, so when calculating relative layout, the calculation will not
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// traverse beyond this node. See T61257516 for details.
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RootNodeKind = 1 << 4,
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// `ViewShadowNode` (exact!) class.
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View = 1 << 5,
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// The node is hidden.
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// Nodes with this trait (and all their descendants) will not produce views.
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Hidden = 1 << 6,
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// Indicates that the `YogaLayoutableShadowNode` must set `isDirty` flag for
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// Yoga node when a `ShadowNode` is being cloned. `ShadowNode`s that modify
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// Yoga styles in the constructor (or later) *after* the `ShadowNode`
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// is cloned must set this trait.
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// Any Yoga node (not only Leaf ones) can have this trait.
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DirtyYogaNode = 1 << 7,
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// Inherits `YogaLayoutableShadowNode` and enforces that the `YGNode` is a
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// leaf.
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LeafYogaNode = 1 << 8,
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// Inherits `YogaLayoutableShadowNode` and has a custom measure function.
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// Only Leaf nodes can have this trait.
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MeasurableYogaNode = 1 << 9,
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// Indicates that the `ShadowNode` must form a stacking context.
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// A Stacking Context forms a level of a `ShadowView` hierarchy (in contrast
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// with a level of a `ShadowNode` hierarchy).
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// See W3C standard for more details: https://www.w3.org/TR/CSS2/zindex.html
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FormsStackingContext = 1 << 10,
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// Indicates that the node must form a `ShadowView`.
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FormsView = 1 << 11,
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// Internal to `ShadowNode`; do not use it outside.
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// Indicates that `children` list is shared between nodes and need
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// to be cloned before the first mutation.
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ChildrenAreShared = 1 << 12,
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// Inherits 'RawTextShadowNode'
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RawText = 1 << 13,
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// Inherits 'TextShadowNode'
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Text = 1 << 14,
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// Temporary (?) to indicate MapBuffer support on Android
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AndroidMapBufferPropsSupported = 1 << 15,
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// Inherits 'ArtBaseShadowNode' (previously built into RN)
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Art = 1 << 16,
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};
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/*
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* Sets, unsets, and checks individual traits.
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*/
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inline void set(Trait trait) {
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traits_ = ShadowNodeTraits::Trait(traits_ | trait);
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}
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inline void unset(Trait trait) {
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traits_ = ShadowNodeTraits::Trait(traits_ & ~trait);
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}
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inline bool check(Trait traits) const {
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return ShadowNodeTraits::Trait(traits_ & traits) == traits;
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}
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inline Trait get() const {
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return traits_;
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}
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private:
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Trait traits_{Trait::None};
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};
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} // namespace react
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} // namespace facebook
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