ztrace/bin/cli.js

strace for node

#!/usr/bin/env node
'use strict';

const argv = require('yargs')
  .usage('Usage: $0 ... program args')
  .demand(1)
  .boolean('b').default('b', undefined)
  .alias('b', 'bindings').alias('b', 'binding')
  .describe('b', 'Trace native bindings')
  .boolean('m').default('m', undefined)
  .alias('m', 'modules').alias('m', 'module')
  .describe('m', 'Trace builtin modules')
  .boolean('g').default('g', undefined)
  .alias('g', 'globals').alias('g', 'global')
  .describe('g', 'Trace globals (Buffer, process)')
  .boolean('a').default('a', undefined)
  .alias('a', 'arguments').alias('a', 'argument')
  .describe('a', 'Trace arguments to traced functions')
  .boolean('r').default('r', undefined)
  .alias('r', 'returned').alias('r', 'ret')
  .describe('r', 'Trace return values of traced functions')
  .boolean('l').default('l', undefined)
  .alias('l', 'loading')
  .describe('l', 'Trace module loading internals')
  .string('s').default('s', undefined)
  .alias('s', 'object-display-size')
  .describe('s', 'Object display length')
  .alias('color', 'colour').alias('color', 'colors').alias('color', 'colours')
  .describe('color', 'Toggle color output (always/never/auto)')
  .boolean('z').describe('z', 'Provide the __ztrace__ global')
  .describe('e', 'An expression for selective hooking')
  .describe('p', 'An expression for selective printing')
  .describe('S', 'An expression for selective stack\u00a0trace printing')
  .example('$0 -- npm --version')
  .argv;

const fs = require('fs');
const Module = require('module');
const path = require('path');
const which = require('which');
const arrify = require('arrify');
const chalk = require('chalk');
const regexify = require('../lib/regexify.js');
const output = require('../lib/output.js');

if (argv.color !== undefined && argv.color !== 'auto') {
  chalk.enabled = !['never', 'no'].includes(argv.color);
} else {
  chalk.enabled = require('tty').isatty(output.fd);
}

try {
  argv._[0] = which.sync(argv._[0]);
} catch(e) {}

const resolved = path.resolve(argv._[0]);
if (fs.existsSync(resolved))
  argv._[0] = resolved;

const { ZTraceWriter } = require('../lib/writer.js');
const trace = {};

if (argv.b !== undefined) trace.binding = !!argv.b;
if (argv.m !== undefined) trace.module = !!argv.m;
if (argv.g !== undefined) trace.global = !!argv.g;
if (argv.a !== undefined) trace.passed = !!argv.a;
if (argv.r !== undefined) trace.ret = !!argv.r;
if (argv.l !== undefined) trace.moduleLoading = !!argv.l;

const hookExpressions = arrify(argv.e).map(e => regexify(e));
const printExpressions = arrify(argv.p).map(e => regexify(e));
const stackExpressions = arrify(argv.S).map(e => regexify(e));

let objectDisplayLength = undefined;
if (!isNaN(argv.s)) {
  objectDisplayLength = +argv.s;
} else if (argv.s === 'unlimited') {
  objectDisplayLength = Infinity;
}

const options = {
  trace,
  provideGlobal: argv.z,
  hookExpressions,
  printExpressions,
  stackExpressions,
  output,
  objectDisplayLength
};

if (argv.startupWarnings !== undefined)
  options.suppressStartupWarnings = !argv.startupWarnings;

new ZTraceWriter().init(options);

process.argv = [process.argv[0]].concat(argv._);
Module.runMain(); // inspects process.argv[1]