basant307/AI_Governance_Project

1const {AbortError} = require('./error.js');2const {FSReqCallback} = process.binding('fs');3 4/**5 * This is a workaround for getting access to the ReadFileContext6 * prototype, which we need to be able to patch its methods.7 * @return {Object} The prototype.8 */9exports.getReadFileContextPrototype = function () {10  const fs = require('fs');11  const fsBinding = process.binding('fs');12 13  const originalOpen = fsBinding.open;14 15  let proto;16  fsBinding.open = (_path, _flags, _mode, req) => {17    proto = Object.getPrototypeOf(req.context);18    return originalOpen.apply(fsBinding, [_path, _flags, _mode, req]);19  };20 21  fs.readFile('/ignored.txt', () => {});22 23  fsBinding.open = originalOpen;24 25  return proto;26};27 28/**29 * This patches the ReadFileContext prototype to use mocked bindings30 * when available. This entire implementation is more or less fully31 * copied over from Node.js's /lib/internal/fs/read_file_context.js32 *33 * This patch is required to support Node.js v16+, where the ReadFileContext34 * closes directly over the internal fs bindings, and is also eagerly loader.35 *36 * See https://github.com/tschaub/mock-fs/issues/332 for more information.37 * @param {Object} prototype The ReadFileContext prototype object to patch.38 */39exports.patchReadFileContext = function (prototype) {40  const origRead = prototype.read;41  const origClose = prototype.close;42 43  const kReadFileUnknownBufferLength = 64 * 1024;44  const kReadFileBufferLength = 512 * 1024;45 46  function readFileAfterRead(err, bytesRead) {47    const context = this.context;48 49    if (err) {50      return context.close(err);51    }52    context.pos += bytesRead;53 54    if (context.pos === context.size || bytesRead === 0) {55      context.close();56    } else {57      if (context.size === 0) {58        // Unknown size, just read until we don't get bytes.59        const buffer =60          bytesRead === kReadFileUnknownBufferLength61            ? context.buffer62            : context.buffer.slice(0, bytesRead);63        context.buffers.push(buffer);64      }65      context.read();66    }67  }68 69  function readFileAfterClose(err) {70    const context = this.context;71    const callback = context.callback;72    let buffer = null;73 74    if (context.err || err) {75      // This is a simplification from Node.js, where we don't bother merging the errors76      return callback(context.err || err);77    }78 79    try {80      if (context.size === 0) {81        buffer = Buffer.concat(context.buffers, context.pos);82      } else if (context.pos < context.size) {83        buffer = context.buffer.slice(0, context.pos);84      } else {85        buffer = context.buffer;86      }87 88      if (context.encoding) {89        buffer = buffer.toString(context.encoding);90      }91    } catch (err) {92      return callback(err);93    }94 95    callback(null, buffer);96  }97 98  prototype.read = function read() {99    if (!prototype._mockedBinding) {100      return origRead.apply(this, arguments);101    }102 103    let buffer;104    let offset;105    let length;106 107    if (this.signal && this.signal.aborted) {108      return this.close(new AbortError());109    }110    if (this.size === 0) {111      buffer = Buffer.allocUnsafeSlow(kReadFileUnknownBufferLength);112      offset = 0;113      length = kReadFileUnknownBufferLength;114      this.buffer = buffer;115    } else {116      buffer = this.buffer;117      offset = this.pos;118      length = Math.min(kReadFileBufferLength, this.size - this.pos);119    }120 121    const req = new FSReqCallback();122    req.oncomplete = readFileAfterRead;123    req.context = this;124 125    // This call and the one in close() is what we want to change, the126    // rest is pretty much the same as Node.js except we don't have access127    // to some of the internal optimizations.128    prototype._mockedBinding.read(this.fd, buffer, offset, length, -1, req);129  };130 131  prototype.close = function close(err) {132    if (!prototype._mockedBinding) {133      return origClose.apply(this, arguments);134    }135 136    if (this.isUserFd) {137      process.nextTick(function tick(context) {138        readFileAfterClose.apply({context}, [null]);139      }, this);140      return;141    }142 143    const req = new FSReqCallback();144    req.oncomplete = readFileAfterClose;145    req.context = this;146    this.err = err;147 148    prototype._mockedBinding.close(this.fd, req);149  };150};151