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Fix HmrServer crash when entry point uses virtual URL prefix #1709

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Fix HmrServer crash when entry point uses virtual URL prefix #1709

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e76c212
Add integration tests for virtual-prefix URL routing
motiz88 May 11, 2026
f33ff47
Extract `ProjectRouteMap`, refactor path<-->URL mappings in Server (#…
motiz88 May 11, 2026
bdc26e4
Fix _getEntryPointAbsolutePath conflating disk paths with URL pathnames
motiz88 May 11, 2026
8974b20
Fix HmrServer crash when entry point uses virtual URL prefix
motiz88 May 11, 2026
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29 changes: 15 additions & 14 deletions packages/metro/src/HmrServer.js
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@ import debounceAsyncQueue from './lib/debounceAsyncQueue';
import formatBundlingError from './lib/formatBundlingError';
import getGraphId from './lib/getGraphId';
import parseBundleOptionsFromBundleRequestUrl from './lib/parseBundleOptionsFromBundleRequestUrl';
import ProjectRouteMap from './lib/ProjectRouteMap';
import splitBundleOptions from './lib/splitBundleOptions';
import * as transformHelpers from './lib/transformHelpers';
import {Logger} from 'metro-core';
Expand Down Expand Up @@ -71,6 +72,7 @@ export default class HmrServer<TClient extends Client> {
_bundler: IncrementalBundler;
_createModuleId: (path: string) => number;
_clientGroups: Map<RevisionId, ClientGroup>;
_routeMap: ProjectRouteMap;

constructor(
bundler: IncrementalBundler,
Expand All @@ -81,6 +83,7 @@ export default class HmrServer<TClient extends Client> {
this._bundler = bundler;
this._createModuleId = createModuleId;
this._clientGroups = new Map();
this._routeMap = new ProjectRouteMap(config);
}

onClientConnect: (
Expand Down Expand Up @@ -121,19 +124,18 @@ export default class HmrServer<TClient extends Client> {
transformOptions.platform,
resolverOptions,
);
const resolvedEntryFilePath = resolutionFn(
(this._config.server.unstable_serverRoot ?? this._config.projectRoot) +
'/.',
{
name: entryFile,
data: {
key: entryFile,
asyncType: null,
isESMImport: false,
locs: [],
},
const absolutePath = this._routeMap.filePathOfUrlDecodedPathname(entryFile);
const rootDir = absolutePath != null ? '/' : this._routeMap.serverRootDir;
const resolvedEntryFile = absolutePath ?? entryFile;
const resolvedEntryFilePath = resolutionFn(rootDir + '/.', {
name: resolvedEntryFile,
data: {
key: resolvedEntryFile,
asyncType: null,
isESMImport: false,
locs: [],
},
).filePath;
}).filePath;
const graphId = getGraphId(resolvedEntryFilePath, transformOptions, {
resolverOptions,
shallow: graphOptions.shallow,
Expand Down Expand Up @@ -379,8 +381,7 @@ export default class HmrServer<TClient extends Client> {
createModuleId: this._createModuleId,
includeAsyncPaths: group.graphOptions.lazy,
projectRoot: this._config.projectRoot,
serverRoot:
this._config.server.unstable_serverRoot ?? this._config.projectRoot,
serverRoot: this._routeMap.serverRootDir,
});

logger?.point('serialize_end');
Expand Down
138 changes: 30 additions & 108 deletions packages/metro/src/Server.js
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,7 @@ import formatBundlingError from './lib/formatBundlingError';
import getGraphId from './lib/getGraphId';
import parseBundleOptionsFromBundleRequestUrl from './lib/parseBundleOptionsFromBundleRequestUrl';
import parseJsonBody from './lib/parseJsonBody';
import ProjectRouteMap from './lib/ProjectRouteMap';
import splitBundleOptions from './lib/splitBundleOptions';
import * as transformHelpers from './lib/transformHelpers';
import {UnableToResolveError} from './node-haste/DependencyGraph/ModuleResolution';
Expand Down Expand Up @@ -149,9 +150,7 @@ export default class Server {
_reporter: Reporter;
_serverOptions: ServerOptions | void;
_allowedSuffixesForSourceRequests: ReadonlyArray<string>;
_sourceRequestRoutingMap: ReadonlyArray<
[pathnamePrefix: string, normalizedRootDir: string],
>;
_routeMap: ProjectRouteMap;
_fetchTimings: Array<FetchTiming>;
_activeFetchCount: number;

Expand All @@ -178,13 +177,7 @@ export default class Server {
].map(ext => '.' + ext),
),
];
this._sourceRequestRoutingMap = [
['/[metro-project]/', path.resolve(this._config.projectRoot)],
...this._config.watchFolders.map((watchFolder, index) => [
`/[metro-watchFolders]/${index}/`,
path.resolve(watchFolder),
]),
];
this._routeMap = new ProjectRouteMap(config);
this._isEnded = false;
this._fetchTimings = [];
this._activeFetchCount = 0;
Expand Down Expand Up @@ -260,8 +253,7 @@ export default class Server {
sourceMapUrl: serializerOptions.sourceMapUrl,
sourceUrl: serializerOptions.sourceUrl,
inlineSourceMap: serializerOptions.inlineSourceMap,
serverRoot:
this._config.server.unstable_serverRoot ?? this._config.projectRoot,
serverRoot: this._routeMap.serverRootDir,
shouldAddToIgnoreList: (module: Module<>) =>
this._shouldAddModuleToIgnoreList(module),
getSourceUrl: (module: Module<>) =>
Expand Down Expand Up @@ -365,6 +357,8 @@ export default class Server {
transformOptions,
} = splitBundleOptions(options);

const entryPoint = this._getEntryPointAbsolutePath(entryFile);

const {prepend, graph} = await this._bundler.buildGraph(
entryFile,
transformOptions,
Expand All @@ -376,8 +370,6 @@ export default class Server {
},
);

const entryPoint = this._getEntryPointAbsolutePath(entryFile);

return await getRamBundleInfo(entryPoint, prepend, graph, {
asyncRequireModulePath: await this._resolveRelativePath(
this._config.transformer.asyncRequireModulePath,
Expand Down Expand Up @@ -406,8 +398,7 @@ export default class Server {
sourceMapUrl: serializerOptions.sourceMapUrl,
sourceUrl: serializerOptions.sourceUrl,
inlineSourceMap: serializerOptions.inlineSourceMap,
serverRoot:
this._config.server.unstable_serverRoot ?? this._config.projectRoot,
serverRoot: this._routeMap.serverRootDir,
shouldAddToIgnoreList: (module: Module<>) =>
this._shouldAddModuleToIgnoreList(module),
getSourceUrl: (module: Module<>) =>
Expand Down Expand Up @@ -440,7 +431,7 @@ export default class Server {
processModuleFilter: this._config.serializer.processModuleFilter,
assetPlugins: this._config.transformer.assetPlugins,
platform,
projectRoot: this._getServerRootDir(),
projectRoot: this._routeMap.serverRootDir,
publicPath: this._config.transformer.publicPath,
});
}
Expand Down Expand Up @@ -700,52 +691,38 @@ export default class Server {
} else if (pathname === '/symbolicate') {
await this._symbolicate(req, res);
} else {
let handled = false;
for (const [pathnamePrefix, normalizedRootDir] of this
._sourceRequestRoutingMap) {
if (filePathname.startsWith(pathnamePrefix)) {
const relativeFilePathname = filePathname.substr(
pathnamePrefix.length,
);
await this._processSourceRequest(
relativeFilePathname,
normalizedRootDir,
res,
);
handled = true;
break;
}
}
if (!handled) {
const sourceFilePath =
this._routeMap.filePathOfUrlDecodedPathname(filePathname);
if (sourceFilePath != null) {
await this._processSourceRequest(sourceFilePath, res);
} else {
next();
}
}
}

async _processSourceRequest(
relativeFilePathname: string,
rootDir: string,
filePath: string,
res: ServerResponse,
): Promise<void> {
if (
!this._allowedSuffixesForSourceRequests.some(suffix =>
relativeFilePathname.endsWith(suffix),
filePath.endsWith(suffix),
)
) {
res.writeHead(404);
res.end();
return;
}
const depGraph = await this._bundler.getBundler().getDependencyGraph();
const filePath = path.join(rootDir, relativeFilePathname);
try {
await depGraph.getOrComputeSha1(filePath);
} catch {
res.writeHead(404);
res.end();
return;
}
const mimeType = mime.lookup(path.basename(relativeFilePathname));
const mimeType = mime.lookup(path.basename(filePath));
res.setHeader('Content-Type', mimeType);
const stream = fs.createReadStream(filePath);
stream.pipe(res);
Expand Down Expand Up @@ -1150,8 +1127,7 @@ export default class Server {
sourceMapUrl: serializerOptions.sourceMapUrl,
sourceUrl: serializerOptions.sourceUrl,
inlineSourceMap: serializerOptions.inlineSourceMap,
serverRoot:
this._config.server.unstable_serverRoot ?? this._config.projectRoot,
serverRoot: this._routeMap.serverRootDir,
shouldAddToIgnoreList: (module: Module<>) =>
this._shouldAddModuleToIgnoreList(module),
getSourceUrl: (module: Module<>) =>
Expand Down Expand Up @@ -1622,33 +1598,6 @@ export default class Server {
);
}

_resolveWatchFolderPrefix(
filePath: string,
): {rootDir: string, filePath: string} | null {
const watchFolderMatch = filePath.match(
/^\.\/\[metro-watchFolders\]\/(\d+)\/(.*)/,
);
if (watchFolderMatch != null) {
const index = parseInt(watchFolderMatch[1], 10);
const watchFolder = this._config.watchFolders[index];
if (watchFolder != null) {
return {
rootDir: path.resolve(watchFolder),
filePath:
'.' + path.sep + watchFolderMatch[2].split('/').join(path.sep),
};
}
}
const projectMatch = filePath.match(/^\.\/\[metro-project\]\/(.*)/);
if (projectMatch != null) {
return {
rootDir: path.resolve(this._config.projectRoot),
filePath: '.' + path.sep + projectMatch[1].split('/').join(path.sep),
};
}
return null;
}

async _resolveRelativePath(
filePath: string,
{
Expand All @@ -1666,14 +1615,17 @@ export default class Server {
transformOptions.platform,
resolverOptions,
);
const resolved = this._resolveWatchFolderPrefix(filePath);
const rootDir =
resolved != null
? resolved.rootDir
: relativeTo === 'server'
? this._getServerRootDir()
: this._config.projectRoot;
const resolvedFilePath = resolved != null ? resolved.filePath : filePath;
let rootDir;
let resolvedFilePath;
if (relativeTo === 'project') {
rootDir = this._config.projectRoot;
resolvedFilePath = filePath;
} else {
const absolutePath =
this._routeMap.filePathOfUrlDecodedPathname(filePath);
rootDir = absolutePath != null ? '/' : this._routeMap.serverRootDir;
resolvedFilePath = absolutePath ?? filePath;
}
return resolutionFn(`${rootDir}/.`, {
name: resolvedFilePath,
data: {
Expand Down Expand Up @@ -1737,16 +1689,8 @@ export default class Server {
sourcePaths: SourcePathsMode.Absolute,
};

_getServerRootDir(): string {
return this._config.server.unstable_serverRoot ?? this._config.projectRoot;
}

_getEntryPointAbsolutePath(entryFile: string): string {
const resolved = this._resolveWatchFolderPrefix(entryFile);
if (resolved != null) {
return path.resolve(resolved.rootDir, resolved.filePath);
}
return path.resolve(this._getServerRootDir(), entryFile);
return path.resolve(this._routeMap.serverRootDir, entryFile);
}

// Wait for the server to finish initializing.
Expand All @@ -1771,29 +1715,7 @@ export default class Server {
_getModuleSourceUrl(module: Module<>, mode: SourcePathsMode): string {
switch (mode) {
case SourcePathsMode.ServerUrl:
for (const [pathnamePrefix, normalizedRootDir] of this
._sourceRequestRoutingMap) {
if (module.path.startsWith(normalizedRootDir + path.sep)) {
const relativePath = module.path.slice(
normalizedRootDir.length + 1,
);
const relativePathPosix = relativePath
.split(path.sep)
.map(segment => encodeURIComponent(segment))
.join('/');
return pathnamePrefix + relativePathPosix;
}
}
// Ordinarily all files should match one of the roots above. If they
// don't, try to preserve useful information, even if fetching the path
// from Metro might fail.
const modulePathPosix = module.path
.split(path.sep)
.map(segment => encodeURIComponent(segment))
.join('/');
return modulePathPosix.startsWith('/')
? modulePathPosix
: '/' + modulePathPosix;
return this._routeMap.urlPathnameOfFilePath(module.path);
case SourcePathsMode.Absolute:
return module.path;
}
Expand Down
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