node.js

// Hello, and welcome to hacking node.js!
//
// This file is invoked by node::Load in src/node.cc, and responsible for
// bootstrapping the node.js core. Special caution is given to the performance
// of the startup process, so many dependencies are invoked lazily.

'use strict';

(function(process) {
  this.global = this;

  function startup() {
    var EventEmitter = NativeModule.require('events').EventEmitter;

    process.__proto__ = Object.create(EventEmitter.prototype, {
      constructor: {
        value: process.constructor
      }
    });
    EventEmitter.call(process);

    process.EventEmitter = EventEmitter; // process.EventEmitter is deprecated

    // do this good and early, since it handles errors.
    startup.processFatal();

    startup.globalVariables();
    startup.globalTimeouts();
    startup.globalConsole();

    startup.processAssert();
    startup.processConfig();
    startup.processNextTick();
    startup.processStdio();
    startup.processKillAndExit();
    startup.processSignalHandlers();

    // Do not initialize channel in debugger agent, it deletes env variable
    // and the main thread won't see it.
    if (process.argv[1] !== '--debug-agent')
      startup.processChannel();

    startup.processRawDebug();

    startup.resolveArgv0();

    // There are various modes that Node can run in. The most common two
    // are running from a script and running the REPL - but there are a few
    // others like the debugger or running --eval arguments. Here we decide
    // which mode we run in.

    if (NativeModule.exists('_third_party_main')) {
      // To allow people to extend Node in different ways, this hook allows
      // one to drop a file lib/_third_party_main.js into the build
      // directory which will be executed instead of Node's normal loading.
      process.nextTick(function() {
        NativeModule.require('_third_party_main');
      });

    } else if (process.argv[1] == 'debug') {
      // Start the debugger agent
      var d = NativeModule.require('_debugger');
      d.start();

    } else if (process.argv[1] == '--debug-agent') {
      // Start the debugger agent
      var d = NativeModule.require('_debug_agent');
      d.start();

    } else if (process._eval != null) {
      // User passed '-e' or '--eval' arguments to Node.
      evalScript('[eval]');
    } else if (process.argv[1]) {
      // make process.argv[1] into a full path
      var path = NativeModule.require('path');
      process.argv[1] = path.resolve(process.argv[1]);

      // If this is a worker in cluster mode, start up the communication
      // channel.
      if (process.env.NODE_UNIQUE_ID) {
        var cluster = NativeModule.require('cluster');
        cluster._setupWorker();

        // Make sure it's not accidentally inherited by child processes.
        delete process.env.NODE_UNIQUE_ID;
      }

      var Module = NativeModule.require('module');

      if (global.v8debug &&
          process.execArgv.some(function(arg) {
            return arg.match(/^--debug-brk(=[0-9]*)?$/);
          })) {

        // XXX Fix this terrible hack!
        //
        // Give the client program a few ticks to connect.
        // Otherwise, there's a race condition where `node debug foo.js`
        // will not be able to connect in time to catch the first
        // breakpoint message on line 1.
        //
        // A better fix would be to somehow get a message from the
        // global.v8debug object about a connection, and runMain when
        // that occurs.  --isaacs

        var debugTimeout = +process.env.NODE_DEBUG_TIMEOUT || 50;
        setTimeout(Module.runMain, debugTimeout);

      } else {
        // Main entry point into most programs:
        Module.runMain();
      }

    } else {
      var Module = NativeModule.require('module');

      // If -i or --interactive were passed, or stdin is a TTY.
      if (process._forceRepl || NativeModule.require('tty').isatty(0)) {
        var history;
        var path = NativeModule.require('path');
        var fs = NativeModule.require('fs');
        // This code comes from Sindre Sorhus `user-home` module
        // https://github.com/sindresorhus/user-home
        var home = (function getUserHome() {
          var env = process.env;
          var home = env.HOME;
          var user = env.LOGNAME || env.USER || env.LNAME || env.USERNAME;

          if (process.platform === 'win32') {
            return env.USERPROFILE || env.HOMEDRIVE + env.HOMEPATH || home || null;
          } else if (process.platform === 'darwin') {
            return home || (user ? '/Users/' + user : null);
          } else if (process.platform === 'linux') {
            return home ||
              (user ? (process.getuid() === 0 ? '/root' : '/home/' + user) : null);
          }
          return home || null;
        })()
        var HISTORY_PATH = home ? path.join(home,'.iojs_history') : null;

        // REPL
        var opts = {
          useGlobal: true,
          ignoreUndefined: false
        };

        // If we got user-home dir
        if(HISTORY_PATH) {
          // Get history if exist
          try {
            history = fs.readFileSync(HISTORY_PATH, 'utf8')
              .replace(/\n$/, '') // Ignore the last \n
              .split('\n');
          } catch(e) {
            history = [];
          }
          opts.history = history;
        }

        if (parseInt(process.env['NODE_NO_READLINE'], 10)) {
          opts.terminal = false;
        }
        if (parseInt(process.env['NODE_DISABLE_COLORS'], 10)) {
          opts.useColors = false;
        }
        var repl = Module.requireRepl().start(opts);
        repl
          .on('line', function(line) {
            if(HISTORY_PATH)
              try {
                fs.appendFileSync(HISTORY_PATH, line + '\n');
              } catch(e) {}
          })
          .on('exit', function() {
            if(HISTORY_PATH && repl.history)
              try {
                fs.writeFileSync(HISTORY_PATH, repl.history
                  .join('\n'));
              } catch(e) {}

            process.exit();
          });

      } else {
        // Read all of stdin - execute it.
        process.stdin.setEncoding('utf8');

        var code = '';
        process.stdin.on('data', function(d) {
          code += d;
        });

        process.stdin.on('end', function() {
          process._eval = code;
          evalScript('[stdin]');
        });
      }
    }
  }

  startup.globalVariables = function() {
    global.process = process;
    global.global = global;
    global.GLOBAL = global;
    global.root = global;
    global.Buffer = NativeModule.require('buffer').Buffer;
    process.domain = null;
    process._exiting = false;
  };

  startup.globalTimeouts = function() {
    global.setTimeout = function() {
      var t = NativeModule.require('timers');
      return t.setTimeout.apply(this, arguments);
    };

    global.setInterval = function() {
      var t = NativeModule.require('timers');
      return t.setInterval.apply(this, arguments);
    };

    global.clearTimeout = function() {
      var t = NativeModule.require('timers');
      return t.clearTimeout.apply(this, arguments);
    };

    global.clearInterval = function() {
      var t = NativeModule.require('timers');
      return t.clearInterval.apply(this, arguments);
    };

    global.setImmediate = function() {
      var t = NativeModule.require('timers');
      return t.setImmediate.apply(this, arguments);
    };

    global.clearImmediate = function() {
      var t = NativeModule.require('timers');
      return t.clearImmediate.apply(this, arguments);
    };
  };

  startup.globalConsole = function() {
    global.__defineGetter__('console', function() {
      return NativeModule.require('console');
    });
  };


  startup._lazyConstants = null;

  startup.lazyConstants = function() {
    if (!startup._lazyConstants) {
      startup._lazyConstants = process.binding('constants');
    }
    return startup._lazyConstants;
  };

  startup.processFatal = function() {
    process._fatalException = function(er) {
      var caught;

      if (process.domain && process.domain._errorHandler)
        caught = process.domain._errorHandler(er) || caught;

      if (!caught)
        caught = process.emit('uncaughtException', er);

      // If someone handled it, then great.  otherwise, die in C++ land
      // since that means that we'll exit the process, emit the 'exit' event
      if (!caught) {
        try {
          if (!process._exiting) {
            process._exiting = true;
            process.emit('exit', 1);
          }
        } catch (er) {
          // nothing to be done about it at this point.
        }

      // if we handled an error, then make sure any ticks get processed
      } else {
        NativeModule.require('timers').setImmediate(process._tickCallback);
      }

      return caught;
    };
  };

  var assert;
  startup.processAssert = function() {
    assert = process.assert = function(x, msg) {
      if (!x) throw new Error(msg || 'assertion error');
    };
  };

  startup.processConfig = function() {
    // used for `process.config`, but not a real module
    var config = NativeModule._source.config;
    delete NativeModule._source.config;

    // strip the gyp comment line at the beginning
    config = config.split('\n')
        .slice(1)
        .join('\n')
        .replace(/"/g, '\\"')
        .replace(/'/g, '"');

    process.config = JSON.parse(config, function(key, value) {
      if (value === 'true') return true;
      if (value === 'false') return false;
      return value;
    });
  };

  startup.processNextTick = function() {
    var nextTickQueue = [];
    var microtasksScheduled = false;

    // Used to run V8's micro task queue.
    var _runMicrotasks = {};

    // This tickInfo thing is used so that the C++ code in src/node.cc
    // can have easy accesss to our nextTick state, and avoid unnecessary
    var tickInfo = {};

    // *Must* match Environment::TickInfo::Fields in src/env.h.
    var kIndex = 0;
    var kLength = 1;

    process.nextTick = nextTick;
    // Needs to be accessible from beyond this scope.
    process._tickCallback = _tickCallback;
    process._tickDomainCallback = _tickDomainCallback;

    process._setupNextTick(tickInfo, _tickCallback, _runMicrotasks);

    _runMicrotasks = _runMicrotasks.runMicrotasks;

    function tickDone() {
      if (tickInfo[kLength] !== 0) {
        if (tickInfo[kLength] <= tickInfo[kIndex]) {
          nextTickQueue = [];
          tickInfo[kLength] = 0;
        } else {
          nextTickQueue.splice(0, tickInfo[kIndex]);
          tickInfo[kLength] = nextTickQueue.length;
        }
      }
      tickInfo[kIndex] = 0;
    }

    function scheduleMicrotasks() {
      if (microtasksScheduled)
        return;

      nextTickQueue.push({
        callback: runMicrotasksCallback,
        domain: null
      });

      tickInfo[kLength]++;
      microtasksScheduled = true;
    }

    function runMicrotasksCallback() {
      microtasksScheduled = false;
      _runMicrotasks();

      if (tickInfo[kIndex] < tickInfo[kLength])
        scheduleMicrotasks();
    }

    // Run callbacks that have no domain.
    // Using domains will cause this to be overridden.
    function _tickCallback() {
      var callback, threw, tock;

      scheduleMicrotasks();

      while (tickInfo[kIndex] < tickInfo[kLength]) {
        tock = nextTickQueue[tickInfo[kIndex]++];
        callback = tock.callback;
        threw = true;
        try {
          callback();
          threw = false;
        } finally {
          if (threw)
            tickDone();
        }
        if (1e4 < tickInfo[kIndex])
          tickDone();
      }

      tickDone();
    }

    function _tickDomainCallback() {
      var callback, domain, threw, tock;

      scheduleMicrotasks();

      while (tickInfo[kIndex] < tickInfo[kLength]) {
        tock = nextTickQueue[tickInfo[kIndex]++];
        callback = tock.callback;
        domain = tock.domain;
        if (domain)
          domain.enter();
        threw = true;
        try {
          callback();
          threw = false;
        } finally {
          if (threw)
            tickDone();
        }
        if (1e4 < tickInfo[kIndex])
          tickDone();
        if (domain)
          domain.exit();
      }

      tickDone();
    }

    function nextTick(callback) {
      // on the way out, don't bother. it won't get fired anyway.
      if (process._exiting)
        return;

      var obj = {
        callback: callback,
        domain: process.domain || null
      };

      nextTickQueue.push(obj);
      tickInfo[kLength]++;
    }
  };

  function evalScript(name) {
    var Module = NativeModule.require('module');
    var path = NativeModule.require('path');
    var cwd = process.cwd();

    var module = new Module(name);
    module.filename = path.join(cwd, name);
    module.paths = Module._nodeModulePaths(cwd);
    var script = process._eval;
    if (!Module._contextLoad) {
      var body = script;
      script = 'global.__filename = ' + JSON.stringify(name) + ';\n' +
               'global.exports = exports;\n' +
               'global.module = module;\n' +
               'global.__dirname = __dirname;\n' +
               'global.require = require;\n' +
               'return require("vm").runInThisContext(' +
               JSON.stringify(body) + ', { filename: ' +
               JSON.stringify(name) + ' });\n';
    }
    var result = module._compile(script, name + '-wrapper');
    if (process._print_eval) console.log(result);
  }

  function createWritableStdioStream(fd) {
    var stream;
    var tty_wrap = process.binding('tty_wrap');

    // Note stream._type is used for test-module-load-list.js

    switch (tty_wrap.guessHandleType(fd)) {
      case 'TTY':
        var tty = NativeModule.require('tty');
        stream = new tty.WriteStream(fd);
        stream._type = 'tty';

        // Hack to have stream not keep the event loop alive.
        // See https://github.com/joyent/node/issues/1726
        if (stream._handle && stream._handle.unref) {
          stream._handle.unref();
        }
        break;

      case 'FILE':
        var fs = NativeModule.require('fs');
        stream = new fs.SyncWriteStream(fd, { autoClose: false });
        stream._type = 'fs';
        break;

      case 'PIPE':
      case 'TCP':
        var net = NativeModule.require('net');
        stream = new net.Socket({
          fd: fd,
          readable: false,
          writable: true
        });

        // FIXME Should probably have an option in net.Socket to create a
        // stream from an existing fd which is writable only. But for now
        // we'll just add this hack and set the `readable` member to false.
        // Test: ./node test/fixtures/echo.js < /etc/passwd
        stream.readable = false;
        stream.read = null;
        stream._type = 'pipe';

        // FIXME Hack to have stream not keep the event loop alive.
        // See https://github.com/joyent/node/issues/1726
        if (stream._handle && stream._handle.unref) {
          stream._handle.unref();
        }
        break;

      default:
        // Probably an error on in uv_guess_handle()
        throw new Error('Implement me. Unknown stream file type!');
    }

    // For supporting legacy API we put the FD here.
    stream.fd = fd;

    stream._isStdio = true;

    return stream;
  }

  startup.processStdio = function() {
    var stdin, stdout, stderr;

    process.__defineGetter__('stdout', function() {
      if (stdout) return stdout;
      stdout = createWritableStdioStream(1);
      stdout.destroy = stdout.destroySoon = function(er) {
        er = er || new Error('process.stdout cannot be closed.');
        stdout.emit('error', er);
      };
      if (stdout.isTTY) {
        process.on('SIGWINCH', function() {
          stdout._refreshSize();
        });
      }
      return stdout;
    });

    process.__defineGetter__('stderr', function() {
      if (stderr) return stderr;
      stderr = createWritableStdioStream(2);
      stderr.destroy = stderr.destroySoon = function(er) {
        er = er || new Error('process.stderr cannot be closed.');
        stderr.emit('error', er);
      };
      return stderr;
    });

    process.__defineGetter__('stdin', function() {
      if (stdin) return stdin;

      var tty_wrap = process.binding('tty_wrap');
      var fd = 0;

      switch (tty_wrap.guessHandleType(fd)) {
        case 'TTY':
          var tty = NativeModule.require('tty');
          stdin = new tty.ReadStream(fd, {
            highWaterMark: 0,
            readable: true,
            writable: false
          });
          break;

        case 'FILE':
          var fs = NativeModule.require('fs');
          stdin = new fs.ReadStream(null, { fd: fd, autoClose: false });
          break;

        case 'PIPE':
        case 'TCP':
          var net = NativeModule.require('net');

          // It could be that process has been started with an IPC channel
          // sitting on fd=0, in such case the pipe for this fd is already
          // present and creating a new one will lead to the assertion failure
          // in libuv.
          if (process._channel && process._channel.fd === fd) {
            stdin = new net.Socket({
              handle: process._channel,
              readable: true,
              writable: false
            });
          } else {
            stdin = new net.Socket({
              fd: fd,
              readable: true,
              writable: false
            });
          }
          break;

        default:
          // Probably an error on in uv_guess_handle()
          throw new Error('Implement me. Unknown stdin file type!');
      }

      // For supporting legacy API we put the FD here.
      stdin.fd = fd;

      // stdin starts out life in a paused state, but node doesn't
      // know yet.  Explicitly to readStop() it to put it in the
      // not-reading state.
      if (stdin._handle && stdin._handle.readStop) {
        stdin._handle.reading = false;
        stdin._readableState.reading = false;
        stdin._handle.readStop();
      }

      // if the user calls stdin.pause(), then we need to stop reading
      // immediately, so that the process can close down.
      stdin.on('pause', function() {
        if (!stdin._handle)
          return;
        stdin._readableState.reading = false;
        stdin._handle.reading = false;
        stdin._handle.readStop();
      });

      return stdin;
    });

    process.openStdin = function() {
      process.stdin.resume();
      return process.stdin;
    };
  };

  startup.processKillAndExit = function() {

    process.exit = function(code) {
      if (code || code === 0)
        process.exitCode = code;

      if (!process._exiting) {
        process._exiting = true;
        process.emit('exit', process.exitCode || 0);
      }
      process.reallyExit(process.exitCode || 0);
    };

    process.kill = function(pid, sig) {
      var err;

      if (pid != (pid | 0)) {
        throw new TypeError('invalid pid');
      }

      // preserve null signal
      if (0 === sig) {
        err = process._kill(pid, 0);
      } else {
        sig = sig || 'SIGTERM';
        if (startup.lazyConstants()[sig] &&
            sig.slice(0, 3) === 'SIG') {
          err = process._kill(pid, startup.lazyConstants()[sig]);
        } else {
          throw new Error('Unknown signal: ' + sig);
        }
      }

      if (err) {
        var errnoException = NativeModule.require('util')._errnoException;
        throw errnoException(err, 'kill');
      }

      return true;
    };
  };

  startup.processSignalHandlers = function() {
    // Load events module in order to access prototype elements on process like
    // process.addListener.
    var signalWraps = {};
    var addListener = process.addListener;
    var removeListener = process.removeListener;

    function isSignal(event) {
      return event.slice(0, 3) === 'SIG' &&
             startup.lazyConstants().hasOwnProperty(event);
    }

    // Wrap addListener for the special signal types
    process.on = process.addListener = function(type, listener) {
      if (isSignal(type) &&
          !signalWraps.hasOwnProperty(type)) {
        var Signal = process.binding('signal_wrap').Signal;
        var wrap = new Signal();

        wrap.unref();

        wrap.onsignal = function() { process.emit(type); };

        var signum = startup.lazyConstants()[type];
        var err = wrap.start(signum);
        if (err) {
          wrap.close();
          var errnoException = NativeModule.require('util')._errnoException;
          throw errnoException(err, 'uv_signal_start');
        }

        signalWraps[type] = wrap;
      }

      return addListener.apply(this, arguments);
    };

    process.removeListener = function(type, listener) {
      var ret = removeListener.apply(this, arguments);
      if (isSignal(type)) {
        assert(signalWraps.hasOwnProperty(type));

        if (NativeModule.require('events').listenerCount(this, type) === 0) {
          signalWraps[type].close();
          delete signalWraps[type];
        }
      }

      return ret;
    };
  };


  startup.processChannel = function() {
    // If we were spawned with env NODE_CHANNEL_FD then load that up and
    // start parsing data from that stream.
    if (process.env.NODE_CHANNEL_FD) {
      var fd = parseInt(process.env.NODE_CHANNEL_FD, 10);
      assert(fd >= 0);

      // Make sure it's not accidentally inherited by child processes.
      delete process.env.NODE_CHANNEL_FD;

      var cp = NativeModule.require('child_process');

      // Load tcp_wrap to avoid situation where we might immediately receive
      // a message.
      // FIXME is this really necessary?
      process.binding('tcp_wrap');

      cp._forkChild(fd);
      assert(process.send);
    }
  };


  startup.processRawDebug = function() {
    var format = NativeModule.require('util').format;
    var rawDebug = process._rawDebug;
    process._rawDebug = function() {
      rawDebug(format.apply(null, arguments));
    };
  };


  startup.resolveArgv0 = function() {
    var cwd = process.cwd();
    var isWindows = process.platform === 'win32';

    // Make process.argv[0] into a full path, but only touch argv[0] if it's
    // not a system $PATH lookup.
    // TODO: Make this work on Windows as well.  Note that "node" might
    // execute cwd\node.exe, or some %PATH%\node.exe on Windows,
    // and that every directory has its own cwd, so d:node.exe is valid.
    var argv0 = process.argv[0];
    if (!isWindows && argv0.indexOf('/') !== -1 && argv0.charAt(0) !== '/') {
      var path = NativeModule.require('path');
      process.argv[0] = path.join(cwd, process.argv[0]);
    }
  };

  // Below you find a minimal module system, which is used to load the node
  // core modules found in lib/*.js. All core modules are compiled into the
  // node binary, so they can be loaded faster.

  var ContextifyScript = process.binding('contextify').ContextifyScript;
  function runInThisContext(code, options) {
    var script = new ContextifyScript(code, options);
    return script.runInThisContext();
  }

  function NativeModule(id) {
    this.filename = id + '.js';
    this.id = id;
    this.exports = {};
    this.loaded = false;
  }

  NativeModule._source = process.binding('natives');
  NativeModule._cache = {};

  NativeModule.require = function(id) {
    if (id == 'native_module') {
      return NativeModule;
    }

    var cached = NativeModule.getCached(id);
    if (cached) {
      return cached.exports;
    }

    if (!NativeModule.exists(id)) {
      throw new Error('No such native module ' + id);
    }

    process.moduleLoadList.push('NativeModule ' + id);

    var nativeModule = new NativeModule(id);

    nativeModule.cache();
    nativeModule.compile();

    return nativeModule.exports;
  };

  NativeModule.getCached = function(id) {
    return NativeModule._cache[id];
  };

  NativeModule.exists = function(id) {
    return NativeModule._source.hasOwnProperty(id);
  };

  NativeModule.getSource = function(id) {
    return NativeModule._source[id];
  };

  NativeModule.wrap = function(script) {
    return NativeModule.wrapper[0] + script + NativeModule.wrapper[1];
  };

  NativeModule.wrapper = [
    '(function (exports, require, module, __filename, __dirname) { ',
    '\n});'
  ];

  NativeModule.prototype.compile = function() {
    var source = NativeModule.getSource(this.id);
    source = NativeModule.wrap(source);

    var fn = runInThisContext(source, { filename: this.filename });
    fn(this.exports, NativeModule.require, this, this.filename);

    this.loaded = true;
  };

  NativeModule.prototype.cache = function() {
    NativeModule._cache[this.id] = this;
  };

  startup();
});