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// Copyright (c) 2026 Cloudflare, Inc.
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// Licensed under the Apache 2.0 license found in the LICENSE file or at:
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//     https://opensource.org/licenses/Apache-2.0
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import { default as MetadataReader } from 'pyodide-internal:runtime-generated/metadata';
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import { createReadonlyFS } from 'pyodide-internal:readOnlyFS';
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import { PythonWorkersInternalError } from 'pyodide-internal:util';
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function createTree(paths: string[]): MetadataDirInfo {
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  const tree: MetadataFSInfo = new Map();
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  paths.forEach((elt: string, idx: number) => {
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    let subTree: MetadataFSInfo = tree;
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    const parts = elt.split('/');
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    const name = parts.pop()!;
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    for (const part of parts) {
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      if (typeof subTree === 'number') {
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        throw new PythonWorkersInternalError(
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          'expected subtree to not be a number'
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        );
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      }
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      let next: MetadataFSInfo | undefined = subTree.get(part);
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      if (!next) {
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        next = new Map();
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        subTree.set(part, next);
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      }
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      subTree = next;
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    }
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    if (typeof subTree === 'number') {
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      throw new PythonWorkersInternalError(
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        'expected subtree to not be a number'
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      );
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    }
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    subTree.set(name, idx);
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  });
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  return tree;
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}
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export function createMetadataFS(Module: Module): object {
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  // TODO: Make this type more specific
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  const TIMESTAMP = Date.now();
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  const names = MetadataReader.getNames();
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  const sizes = MetadataReader.getSizes();
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  const rootInfo = createTree(names);
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  const FSOps: FSOps<MetadataFSInfo> = {
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    getNodeMode(_parent, _name, info) {
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      return {
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        permissions: 0o555, // read and execute but not write
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        isDir: typeof info !== 'number',
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      };
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    },
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    setNodeAttributes(node, info, isDir) {
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      node.modtime = TIMESTAMP;
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      node.usedBytes = 0;
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      if (info === undefined) {
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        info = rootInfo;
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      }
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      if (isDir) {
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        node.tree = info as MetadataDirInfo;
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      } else {
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        node.index = info as number;
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        node.usedBytes = sizes[info as number]!;
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      }
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    },
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    readdir(node) {
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      if (node.tree == undefined) {
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        throw new PythonWorkersInternalError(
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          'cannot read directory, tree is undefined'
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        );
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      }
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      return Array.from(node.tree.keys());
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    },
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    lookup(parent, name) {
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      // Parent is not a directory so we always raise ENOENT (44)
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      if (parent.tree == undefined) {
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        throw new Module.FS.ErrnoError(44);
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      }
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      const res = parent.tree.get(name);
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      if (res === undefined) {
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        throw new Module.FS.ErrnoError(44);
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      }
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      return res;
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    },
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    read(stream, position, buffer) {
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      return MetadataReader.read(stream.node.index!, position, buffer);
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    },
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  };
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  return createReadonlyFS(FSOps, Module);
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}