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fix(image): fix data race in imageURLLoaderForURL: and imageDataDecoderForData: #57297

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mfazekas wants to merge 2 commits into from
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fix(image): fix data race in imageURLLoaderForURL: and imageDataDecoderForData: #57297

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fix(image): fix data race in imageURLLoaderForURL and imageDataDecode…
Jun 20, 2026
8226219
refactor(image): extract -loaders and -decoders accessors, fix canHan…
Jun 22, 2026
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93 changes: 55 additions & 38 deletions packages/react-native/Libraries/Image/RCTImageLoader.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -73,7 +73,9 @@ @implementation RCTImageLoader {
NSArray<id<RCTImageURLLoader>> * (^_loadersProvider)(RCTModuleRegistry *);
NSArray<id<RCTImageDataDecoder>> * (^_decodersProvider)(RCTModuleRegistry *);
NSArray<id<RCTImageURLLoader>> *_loaders;
std::atomic<BOOL> _loadersReady;
NSArray<id<RCTImageDataDecoder>> *_decoders;
std::atomic<BOOL> _decodersReady;
NSOperationQueue *_imageDecodeQueue;
dispatch_queue_t _URLRequestQueue;
id<RCTImageCache> _imageCache;
Expand Down Expand Up @@ -161,23 +163,17 @@ - (void)setImageCache:(id<RCTImageCache>)cache
_imageCache = cache;
}

- (id<RCTImageURLLoader>)imageURLLoaderForURL:(NSURL *)URL
- (NSArray<id<RCTImageURLLoader>> *)loaders
{
if (!_isLoaderSetup) {
[self setUp];
}

if (!_loaders) {
std::unique_lock<std::mutex> guard(_loadersMutex);
if (!_loaders) {
// Get loaders, sorted in reverse priority order (highest priority first)
if (!_loadersReady.load(std::memory_order_acquire)) {
std::lock_guard<std::mutex> guard(_loadersMutex);
if (!_loadersReady.load(std::memory_order_relaxed)) {
if (_loadersProvider) {
_loaders = _loadersProvider(self.moduleRegistry);
} else {
RCTAssert(_bridge, @"Trying to find RCTImageURLLoaders and bridge not set.");
_loaders = [_bridge modulesConformingToProtocol:@protocol(RCTImageURLLoader)];
}

_loaders =
[_loaders sortedArrayUsingComparator:^NSComparisonResult(id<RCTImageURLLoader> a, id<RCTImageURLLoader> b) {
float priorityA = [a respondsToSelector:@selector(loaderPriority)] ? [a loaderPriority] : 0;
Expand All @@ -190,14 +186,54 @@ - (void)setImageCache:(id<RCTImageCache>)cache
return NSOrderedSame;
}
}];
_loadersReady.store(YES, std::memory_order_release);
}
}
return _loaders;
}

- (NSArray<id<RCTImageDataDecoder>> *)decoders
{
if (!_decodersReady.load(std::memory_order_acquire)) {
std::lock_guard<std::mutex> guard(_loadersMutex);
if (!_decodersReady.load(std::memory_order_relaxed)) {
if (_decodersProvider) {
_decoders = _decodersProvider(self.moduleRegistry);
} else {
RCTAssert(_bridge, @"Trying to find RCTImageDataDecoders and bridge not set.");
_decoders = [_bridge modulesConformingToProtocol:@protocol(RCTImageDataDecoder)];
}
_decoders = [_decoders
sortedArrayUsingComparator:^NSComparisonResult(id<RCTImageDataDecoder> a, id<RCTImageDataDecoder> b) {
float priorityA = [a respondsToSelector:@selector(decoderPriority)] ? [a decoderPriority] : 0;
float priorityB = [b respondsToSelector:@selector(decoderPriority)] ? [b decoderPriority] : 0;
if (priorityA > priorityB) {
return NSOrderedAscending;
} else if (priorityA < priorityB) {
return NSOrderedDescending;
} else {
return NSOrderedSame;
}
}];
_decodersReady.store(YES, std::memory_order_release);
}
}
return _decoders;
}

- (id<RCTImageURLLoader>)imageURLLoaderForURL:(NSURL *)URL
{
if (!_isLoaderSetup) {
[self setUp];
}

NSArray<id<RCTImageURLLoader>> *loaders = [self loaders];

if (RCT_DEBUG) {
// Check for handler conflicts
float previousPriority = 0;
id<RCTImageURLLoader> previousLoader = nil;
for (id<RCTImageURLLoader> loader in _loaders) {
for (id<RCTImageURLLoader> loader in loaders) {
float priority = [loader respondsToSelector:@selector(loaderPriority)] ? [loader loaderPriority] : 0;
if (previousLoader && priority < previousPriority) {
return previousLoader;
Expand All @@ -224,7 +260,7 @@ - (void)setImageCache:(id<RCTImageCache>)cache
}

// Normal code path
for (id<RCTImageURLLoader> loader in _loaders) {
for (id<RCTImageURLLoader> loader in loaders) {
if ([loader canLoadImageURL:URL]) {
return loader;
}
Expand All @@ -240,35 +276,13 @@ - (void)setImageCache:(id<RCTImageCache>)cache
[self setUp];
}

if (!_decoders) {
// Get decoders, sorted in reverse priority order (highest priority first)

if (_decodersProvider) {
_decoders = _decodersProvider(self.moduleRegistry);
} else {
RCTAssert(_bridge, @"Trying to find RCTImageDataDecoders and bridge not set.");
_decoders = [_bridge modulesConformingToProtocol:@protocol(RCTImageDataDecoder)];
}

_decoders = [_decoders
sortedArrayUsingComparator:^NSComparisonResult(id<RCTImageDataDecoder> a, id<RCTImageDataDecoder> b) {
float priorityA = [a respondsToSelector:@selector(decoderPriority)] ? [a decoderPriority] : 0;
float priorityB = [b respondsToSelector:@selector(decoderPriority)] ? [b decoderPriority] : 0;
if (priorityA > priorityB) {
return NSOrderedAscending;
} else if (priorityA < priorityB) {
return NSOrderedDescending;
} else {
return NSOrderedSame;
}
}];
}
NSArray<id<RCTImageDataDecoder>> *decoders = [self decoders];

if (RCT_DEBUG) {
// Check for handler conflicts
float previousPriority = 0;
id<RCTImageDataDecoder> previousDecoder = nil;
for (id<RCTImageDataDecoder> decoder in _decoders) {
for (id<RCTImageDataDecoder> decoder in decoders) {
float priority = [decoder respondsToSelector:@selector(decoderPriority)] ? [decoder decoderPriority] : 0;
if (previousDecoder && priority < previousPriority) {
return previousDecoder;
Expand Down Expand Up @@ -297,7 +311,7 @@ - (void)setImageCache:(id<RCTImageCache>)cache
}

// Normal code path
for (id<RCTImageDataDecoder> decoder in _decoders) {
for (id<RCTImageDataDecoder> decoder in decoders) {
if ([decoder canDecodeImageData:data]) {
return decoder;
}
Expand Down Expand Up @@ -1173,7 +1187,10 @@ - (BOOL)canHandleRequest:(NSURLRequest *)request
return NO;
}

for (id<RCTImageURLLoader> loader in _loaders) {
if (!_isLoaderSetup) {
[self setUp];
}
for (id<RCTImageURLLoader> loader in [self loaders]) {
// Don't use RCTImageURLLoader protocol for modules that already conform to
// RCTURLRequestHandler as it's inefficient to decode an image and then
// convert it back into data
Expand Down
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