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nexe/src/fs/patch.ts
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import { ZipFS, getLibzipSync } from "@yarnpkg/libzip";
import { patchFs, PosixFS, NodeFS } from "@yarnpkg/fslib";
import { SnapshotZipFS } from "./SnapshotZipFS";
import * as assert from "assert";
import * as constants from "constants";
import { dirname, relative, sep } from "path";
export interface NexeHeader {
blobPath: string;
layout: {
resourceStart: number;
resourceSize: number;
contentSize: number;
contentStart: number;
};
}
let originalFsMethods: any = null;
let lazyRestoreFs = () => {};
const patches = (process as any).nexe.patches || {};
const originalPatches = { ...patches };
delete (process as any).nexe;
function shimFs(binary: NexeHeader, fs: typeof import("fs") = require("fs")) {
if (originalFsMethods !== null) {
return;
}
originalFsMethods = Object.assign({}, fs);
const realFs: typeof fs = { ...fs };
const nodeFs = new NodeFS(realFs);
const blob = Buffer.allocUnsafe(binary.layout.resourceSize);
const blobFd = realFs.openSync(binary.blobPath, "r");
const bytesRead = realFs.readSync(
blobFd,
blob,
0,
binary.layout.resourceSize,
binary.layout.resourceStart
);
assert.equal(bytesRead, binary.layout.resourceSize);
const zipFs = new ZipFS(blob, { readOnly: true });
const snapshotZipFS = new SnapshotZipFS({
libzip: getLibzipSync(),
zipFs,
baseFs: nodeFs,
root: dirname(process.argv[0]), // executable directory = original project root
});
const posixSnapshotZipFs = new PosixFS(snapshotZipFS);
patchFs(fs, posixSnapshotZipFs); // patches global fs
// Capture the project root for path mapping
const projectRoot = dirname(process.argv[0]);
const drive = projectRoot.slice(0, 2); // e.g., "C:"
// Enable logging with DEBUG=nexe:require
let log = (_: string) => true;
if ((process.env.DEBUG || "").toLowerCase().includes("nexe:require")) {
process.stderr.write(
`[nexe] - FILES ${JSON.stringify(
// @ts-ignore - accessing private property for debugging
Array.from(zipFs.entries.keys()),
null,
4
)}\n`
);
process.stderr.write(
`[nexe] - DIRECTORIES ${JSON.stringify(
// @ts-ignore - accessing private property for debugging
Array.from(zipFs.listings.keys()),
null,
4
)}\n`
);
log = (text: string) => process.stderr.write(`[nexe] - ${text}\n`);
}
/**
* Convert a Windows path to the snapshot POSIX path.
* Handles:
* - Paths under the original project root (e.g., C:\Users\oxmc\Desktop\src\entry.js → /snapshot/src/entry.js)
* - Paths that have been converted to C:\snapshot\... (from _findPath returning /snapshot/...)
* - Already POSIX /snapshot/... paths (return as-is)
*/
function toSnapshotPath(filePath: string): string {
// Already a POSIX snapshot path
if (filePath.startsWith("/snapshot/")) {
return filePath;
}
// Handle Windows-style snapshot path: e.g., C:\snapshot\src\entry.js
if (filePath.startsWith(drive + "\\snapshot\\")) {
return "/snapshot/" + filePath.slice(drive.length + 9).replace(/\\/g, "/");
}
// Path under original project root
if (filePath.startsWith(projectRoot)) {
const rel = relative(projectRoot, filePath);
return "/snapshot/" + rel.replace(/\\/g, "/");
}
// Not mappable return unchanged (will likely fail)
return filePath;
}
// --- Internal Module Patches (unconditionally assigned) ---
function internalModuleReadFile(this: any, original: any, ...args: any[]) {
// Strip Windows extended-length path prefix if present
let filePath = typeof args[0] === "string" ? args[0] : "";
if (filePath.startsWith("\\\\?\\")) {
filePath = filePath.slice(4);
}
const mappedPath = toSnapshotPath(filePath);
log(`internalModuleReadFile ${filePath} -> ${mappedPath}`);
try {
// Use the patched fs (which already sees the zip)
return fs.readFileSync(mappedPath, "utf-8");
} catch (e) {
return "";
}
}
patches.internalModuleReadFile = internalModuleReadFile;
// internalModuleReadJSON should return a string (or undefined) in Node 22
patches.internalModuleReadJSON = function (this: any, original: any, ...args: any[]) {
const content = internalModuleReadFile.call(this, original, ...args);
return content === "" ? undefined : content;
};
// Handle Node 22+ signature: first arg is context (non-string), second is path
function internalModuleStat(this: any, original: any, ...args: any[]) {
const target = args[0];
let statPath: string;
// Node 22+: args[0] is context (often a buffer), args[1] is the path string
if (typeof target === "number") {
// file descriptor case unchanged
try {
originalFsMethods.fstatSync(target);
return 0;
} catch (e) {
return -constants.ENOENT;
}
}
if (typeof target === "string") {
// Node <22 or when a string is passed directly
statPath = target;
} else {
// Node 22+: path is the second argument
statPath = args[1];
}
if (typeof statPath !== "string") {
// Unexpected: fallback to original
return original.call(this, ...args);
}
// Strip Windows extended-length prefix
if (statPath.startsWith("\\\\?\\")) {
statPath = statPath.slice(4);
}
const mappedPath = toSnapshotPath(statPath);
log(`internalModuleStat ${statPath} -> ${mappedPath}`);
try {
const stat = fs.statSync(mappedPath);
return stat.isDirectory() ? 1 : 0;
} catch (e) {
return -constants.ENOENT;
}
}
patches.internalModuleStat = internalModuleStat;
// --- Patch Module._findPath with a correct exports resolver ---
// Helper to check if a path exists and is a file
function isFile(p: string): boolean {
try {
const stat = fs.statSync(p);
return stat.isFile();
} catch {
return false;
}
}
// Recursive exports resolver following Node's conditional exports
function resolvePackageExports(exports: any, conditions: string[]): string | null {
if (typeof exports === "string") {
return exports;
}
if (!exports || typeof exports !== "object") {
return null;
}
// Handle "." subpath first (for bare module, we always start with ".")
const subExports = exports["."] ?? exports;
return resolveExportsObject(subExports, conditions);
}
function resolveExportsObject(obj: any, conditions: string[]): string | null {
if (typeof obj === "string") {
return obj;
}
if (!obj || typeof obj !== "object") {
return null;
}
// Iterate over keys in order; if a key matches a condition, take that branch
for (const key of Object.keys(obj)) {
if (conditions.includes(key)) {
const value = obj[key];
if (typeof value === "string") {
return value;
}
if (value && typeof value === "object") {
const nested = resolveExportsObject(value, conditions);
if (nested) return nested;
}
}
}
// If no matching condition, try "default" if not already tried
if (!conditions.includes("default") && obj.default) {
const def = obj.default;
if (typeof def === "string") return def;
if (def && typeof def === "object") {
return resolveExportsObject(def, conditions);
}
}
return null;
}
let _origFindPath: ((...args: any[]) => any) | null = null;
try {
const Module = require("module");
const nodePath = require("path");
const capturedOrigFindPath = (Module as any)._findPath;
if (typeof capturedOrigFindPath === "function") {
_origFindPath = capturedOrigFindPath;
(Module as any)._findPath = function nexeFindPath(this: any, ...args: any[]) {
// Try original first
let result: any;
try {
result = capturedOrigFindPath.apply(this, args);
} catch (_) {
result = false;
}
if (result) return result;
const request: string = args[0];
// Only handle bare module specifiers
if (!request || request[0] === "." || nodePath.isAbsolute(request)) {
return result;
}
// Use snapshot node_modules as the base for all bare modules
const basePath = "/snapshot/node_modules";
const pkgJsonPath = nodePath.posix.join(basePath, request, "package.json");
log(`_findPath trying snapshot package.json: ${pkgJsonPath}`);
let pkg: any;
try {
pkg = JSON.parse(fs.readFileSync(pkgJsonPath, "utf8") as string);
} catch (e) {
return result; // not found in snapshot
}
// 1. Try exports field with appropriate conditions (CJS, Node)
if (pkg.exports) {
const conditions = ["require", "node", "default"];
const exportTarget = resolvePackageExports(pkg.exports, conditions);
if (exportTarget) {
const candidate = nodePath.posix.join(basePath, request, exportTarget);
log(`_findPath trying exports target: ${candidate}`);
if (isFile(candidate)) return candidate;
// Try with extensions if the export target doesn't have one
for (const ext of [".js", ".json", ".node"]) {
const withExt = candidate + ext;
if (isFile(withExt)) return withExt;
}
}
}
// 2. Fallback to main field
let main = "index.js";
if (typeof pkg.main === "string") {
main = pkg.main;
}
// Normalize main path
if (main.startsWith("./")) main = main.slice(2);
if (!main || main === ".") main = "index.js";
if (main.endsWith("/")) main += "index.js";
const mainPath = nodePath.posix.join(basePath, request, main);
log(`_findPath trying main: ${mainPath}`);
// Detailed check for main
try {
const st = fs.statSync(mainPath);
if (st.isFile()) return mainPath;
if (st.isDirectory()) {
const idxPath = nodePath.posix.join(mainPath, "index.js");
if (isFile(idxPath)) return idxPath;
}
} catch (e) {
// mainPath may not exist; proceed to extension checks
}
// 3. Try with extensions
for (const ext of [".js", ".json", ".node"]) {
const withExt = mainPath + ext;
if (isFile(withExt)) return withExt;
}
// 4. Common patterns: if main is missing, look for index.js in the package root
const fallbackIndex = nodePath.posix.join(basePath, request, "index.js");
if (isFile(fallbackIndex)) return fallbackIndex;
// 5. If package uses a dist subdirectory (like axios), try dist/index.js or dist/<name>.js
const distIndex = nodePath.posix.join(basePath, request, "dist", "index.js");
if (isFile(distIndex)) return distIndex;
const distMain = nodePath.posix.join(basePath, request, "dist", request + ".js");
if (isFile(distMain)) return distMain;
return result;
};
}
} catch (_) {
// Patching _findPath failed, ignore
}
lazyRestoreFs = () => {
Object.assign(fs, originalFsMethods);
Object.assign(patches, originalPatches);
if (_origFindPath !== null) {
try {
const Module = require("module");
(Module as any)._findPath = _origFindPath;
} catch (_) {}
_origFindPath = null;
}
lazyRestoreFs = () => {};
};
}
function restoreFs() {
lazyRestoreFs();
}
export { shimFs, restoreFs };