basant307/AI_Governance_Project

1/**2 * @license3 * Copyright 2025 Google LLC4 * SPDX-License-Identifier: Apache-2.05 */6 7import { writeStderrLine } from './stdioHelpers.js';8 9function takeUtf8Prefix(value: string, maxBytes: number): string {10  let bytes = 0;11  let end = 0;12 13  for (const char of value) {14    const charBytes = Buffer.byteLength(char, 'utf8');15    if (bytes + charBytes > maxBytes) {16      break;17    }18    bytes += charBytes;19    end += char.length;20  }21 22  return value.slice(0, end);23}24 25export async function readStdin(): Promise<string> {26  const MAX_STDIN_SIZE = 8 * 1024 * 1024; // 8MB27  return new Promise((resolve, reject) => {28    let data = '';29    let totalSize = 0;30    let settled = false;31    process.stdin.setEncoding('utf8');32 33    const pipedInputShouldBeAvailableInMs = 500;34    let pipedInputTimerId: null | NodeJS.Timeout = setTimeout(() => {35      // stop reading if input is not available yet, this is needed36      // in terminals where stdin is never TTY and nothing's piped37      // which causes the program to get stuck expecting data from stdin38      onEnd();39    }, pipedInputShouldBeAvailableInMs);40 41    const onReadable = () => {42      let chunk;43      while ((chunk = process.stdin.read()) !== null) {44        if (pipedInputTimerId) {45          clearTimeout(pipedInputTimerId);46          pipedInputTimerId = null;47        }48 49        const chunkSize = Buffer.byteLength(chunk, 'utf8');50        if (totalSize + chunkSize > MAX_STDIN_SIZE) {51          const remainingSize = MAX_STDIN_SIZE - totalSize;52          const prefix = takeUtf8Prefix(chunk, remainingSize);53          data += prefix;54          totalSize += Buffer.byteLength(prefix, 'utf8');55          writeStderrLine(56            `Warning: stdin input truncated to ${MAX_STDIN_SIZE} bytes.`,57          );58          finish();59          process.stdin.destroy(); // Stop reading further60          return;61        }62        data += chunk;63        totalSize += chunkSize;64      }65    };66 67    const finish = () => {68      if (settled) return;69      settled = true;70      cleanup();71      resolve(data);72    };73 74    const onEnd = () => {75      finish();76    };77 78    const onError = (err: Error) => {79      if (settled) return;80      settled = true;81      cleanup();82      reject(err);83    };84 85    const cleanup = () => {86      if (pipedInputTimerId) {87        clearTimeout(pipedInputTimerId);88        pipedInputTimerId = null;89      }90      process.stdin.removeListener('readable', onReadable);91      process.stdin.removeListener('end', onEnd);92      process.stdin.removeListener('error', onError);93    };94 95    process.stdin.on('readable', onReadable);96    process.stdin.on('end', onEnd);97    process.stdin.on('error', onError);98  });99}100