Mitigate device info main queue modules crash#51662
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This pull request was exported from Phabricator. Differential Revision: D75537894 |
Summary:
## Changes
DeviceInfo: Deafult fontScale to 1 when accessibility manager isn't available
# Analysis
**The problem:** For reasons that we don't understand, accessibility manager is sometimes nil, when deviceinfo needs it. This is a long-standing issue in react native.
```
_constants = @{
@"Dimensions" : [self _exportedDimensions],
// Note:
// This prop is deprecated and will be removed in a future release.
// Please use this only for a quick and temporary solution.
// Use <SafeAreaView> instead.
@"isIPhoneX_deprecated" : @(RCTIsIPhoneNotched()),
};
```
```
- (NSDictionary *)_exportedDimensions
{
RCTAssert(!_invalidated, @"Failed to get exported dimensions: RCTDeviceInfo has been invalidated");
RCTAssert(_moduleRegistry, @"Failed to get exported dimensions: RCTModuleRegistry is nil");
RCTAccessibilityManager *accessibilityManager =
(RCTAccessibilityManager *)[_moduleRegistry moduleForName:"AccessibilityManager"];
if (!accessibilityManager) {
return nil;
}
CGFloat fontScale = accessibilityManager ? accessibilityManager.multiplier : 1.0;
return RCTExportedDimensions(fontScale);
}
```
**The crash:** When accessibility manager is nil, device info tries to insert nil into an NSDictionary, and crashes.
We found a possible repro of this issue: [launch facebook, log out, and log back in](https://www.internalfb.com/diff/D72020801?transaction_fbid=982516293994114).
**Why this surged now:** Recently, we started initializing device info during react native init. That means this code-path just runs much more often.
# Mitigation
Remove the return nil in `[self _exportedDimensions]`. Instead, just default the fontScale to 1 when the accessibility manager isn't available.
**This should be safe:** If we assume that accessibility manager eventually becomes available, the fontScale will eventually become correct. Device info will send the updated fontScale to js when it becomes available: [native](https://www.internalfb.com/code/fbsource/[ec6fd664a9cd]/xplat/js/react-native-github/packages/react-native/React/CoreModules/RCTDeviceInfo.mm?lines=231-232), [js](https://www.internalfb.com/code/fbsource/[ec6fd664a9cd]/xplat/js/react-native-github/packages/react-native/Libraries/Utilities/Dimensions.js?lines=120-125).
# Long-term fix
Understand why accessibility manager is nil.
Changelog: [Internal]
Differential Revision: D75537894
Contributor
|
This pull request was exported from Phabricator. Differential Revision: D75537894 |
Collaborator
|
This pull request was successfully merged by @RSNara in 0b8db7e When will my fix make it into a release? | How to file a pick request? |
Contributor
|
This pull request has been merged in 0b8db7e. |
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Summary:
Changes
DeviceInfo: Deafult fontScale to 1 when accessibility manager isn't available
Analysis
The problem: For reasons that we don't understand, accessibility manager is sometimes nil, when deviceinfo needs it. This is a long-standing issue in react native.
The crash: When accessibility manager is nil, device info tries to insert nil into an NSDictionary, and crashes.
We found a possible repro of this issue: launch facebook, log out, and log back in.
Why this surged now: Recently, we started initializing device info during react native init. That means this code-path just runs much more often.
Mitigation
Remove the return nil in
[self _exportedDimensions]. Instead, just default the fontScale to 1 when the accessibility manager isn't available.This should be safe: If we assume that accessibility manager eventually becomes available, the fontScale will eventually become correct. Device info will send the updated fontScale to js when it becomes available: native, js.
Long-term fix
Understand why accessibility manager is nil.
Changelog: [Internal]
Differential Revision: D75537894