stdForkStart.js

/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

var net = require('net'),
	fs = require('fs'),
	stream = require('stream'),
	util = require('util');

var ENABLE_LOGGING = false;

var log = (function() {
	if (!ENABLE_LOGGING) {
		return function() {};
	}
	var isFirst = true;
	var LOG_LOCATION = 'C:\\stdFork.log';
	return function log(str) {
		if (isFirst) {
			isFirst = false;
			fs.writeFileSync(LOG_LOCATION, str + '\n');
			return;
		}
		fs.appendFileSync(LOG_LOCATION, str + '\n');
	}
})();

var stdInPipeName = process.env['STDIN_PIPE_NAME'];
var stdOutPipeName = process.env['STDOUT_PIPE_NAME'];
var stdErrPipeName = process.env['STDERR_PIPE_NAME'];

log('STDIN_PIPE_NAME: ' + stdInPipeName);
log('STDOUT_PIPE_NAME: ' + stdOutPipeName);
log('STDERR_PIPE_NAME: ' + stdErrPipeName);
log('ATOM_SHELL_INTERNAL_RUN_AS_NODE: ' + process.env['ATOM_SHELL_INTERNAL_RUN_AS_NODE']);

// stdout redirection to named pipe
(function() {
	log('Beginning stdout redirection...');

	// Create a writing stream to the stdout pipe
	var stdOutStream = net.connect(stdOutPipeName);

	// unref stdOutStream to behave like a normal standard out
	stdOutStream.unref();

	// handle process.stdout
	process.__defineGetter__('stdout', function() { return stdOutStream; });

	// Create a writing stream to the stderr pipe
	var stdErrStream = net.connect(stdErrPipeName);

	// unref stdErrStream to behave like a normal standard out
	stdErrStream.unref();

	// handle process.stderr
	process.__defineGetter__('stderr', function() { return stdErrStream; });

	var fsWriteSyncString = function(fd, str, position, encoding) {
		//  fs.writeSync(fd, string[, position[, encoding]]);
		var buf = new Buffer(str, encoding || 'utf8');
		return fsWriteSyncBuffer(fd, buf, 0, buf.length);
	};

	var fsWriteSyncBuffer = function(fd, buffer, off, len, position) {
		off = Math.abs(off | 0);
		len = Math.abs(len | 0);

		//  fs.writeSync(fd, buffer, offset, length[, position]);
		var buffer_length = buffer.length;

		if (off > buffer_length) {
			throw new Error('offset out of bounds');
		}
		if (len > buffer_length) {
			throw new Error('length out of bounds');
		}
		if (((off + len) | 0) < off) {
			throw new Error('off + len overflow');
		}
		if (buffer_length - off < len) {
			// Asking for more than is left over in the buffer
			throw new Error('off + len > buffer.length');
		}

		var slicedBuffer = buffer;
		if (off !== 0 || len !== buffer_length) {
			slicedBuffer = buffer.slice(off, off + len);
		}

		if (fd === 1) {
			stdOutStream.write(slicedBuffer);
		} else {
			stdErrStream.write(slicedBuffer);
		}
		return slicedBuffer.length;
	};

	// handle fs.writeSync(1, ...) and fs.writeSync(2, ...)
	var originalWriteSync = fs.writeSync;
	fs.writeSync = function(fd, data, position, encoding) {
		if (fd !== 1 && fd !== 2) {
			return originalWriteSync.apply(fs, arguments);
		}
		// usage:
		//  fs.writeSync(fd, buffer, offset, length[, position]);
		// OR
		//  fs.writeSync(fd, string[, position[, encoding]]);

		if (data instanceof Buffer) {
			return fsWriteSyncBuffer.apply(null, arguments);
		}

		// For compatibility reasons with fs.writeSync, writing null will write "null", etc
		if (typeof data !== 'string') {
			data += '';
		}

		return fsWriteSyncString.apply(null, arguments);
	};

	log('Finished defining process.stdout, process.stderr and fs.writeSync');
})();

// stdin redirection to named pipe
(function() {

	// Begin listening to stdin pipe
	var server = net.createServer(function(stream) {
		// Stop accepting new connections, keep the existing one alive
		server.close();

		log('Parent process has connected to my stdin. All should be good now.');

		// handle process.stdin
		process.__defineGetter__('stdin', function() {
			return stream;
		});

		// Remove myself from process.argv
		process.argv.splice(1, 1);

		// Load the actual program
		var program = process.argv[1];
		log('Loading program: ' + program);

		// Unset the custom environmental variables that should not get inherited
		delete process.env['STDIN_PIPE_NAME'];
		delete process.env['STDOUT_PIPE_NAME'];
		delete process.env['STDERR_PIPE_NAME'];
		delete process.env['ATOM_SHELL_INTERNAL_RUN_AS_NODE'];

		require(program);

		log('Finished loading program.');

		var stdinIsReferenced = true;
		var timer = setInterval(function() {
			var listenerCount = (
				stream.listeners('data').length +
				stream.listeners('end').length +
				stream.listeners('close').length +
				stream.listeners('error').length
			);
			// log('listenerCount: ' + listenerCount);
			if (listenerCount <= 1) {
				// No more "actual" listeners, only internal node
				if (stdinIsReferenced) {
					stdinIsReferenced = false;
					// log('unreferencing stream!!!');
					stream.unref();
				}
			} else {
				// There are "actual" listeners
				if (!stdinIsReferenced) {
					stdinIsReferenced = true;
					stream.ref();
				}
			}
			// log(
			// 	'' + stream.listeners('data').length +
			// 	' ' + stream.listeners('end').length +
			// 	' ' + stream.listeners('close').length +
			// 	' ' + stream.listeners('error').length
			// );
		}, 1000);
		timer.unref();
	});


	server.listen(stdInPipeName, function() {
		// signal via stdout that the parent process can now begin writing to stdin pipe
		process.stdout.write('ready');
	});

})();