react/packages/react-devtools-core/src/launchEditor.js

// @flow

import { existsSync } from 'fs';
import { basename, join, isAbsolute } from 'path';
import { execSync, spawn } from 'child_process';
import { parse } from 'shell-quote';

function isTerminalEditor(editor: string): boolean {
  switch (editor) {
    case 'vim':
    case 'emacs':
    case 'nano':
      return true;
    default:
      return false;
  }
}

// Map from full process name to binary that starts the process
// We can't just re-use full process name, because it will spawn a new instance
// of the app every time
const COMMON_EDITORS = {
  '/Applications/Atom.app/Contents/MacOS/Atom': 'atom',
  '/Applications/Atom Beta.app/Contents/MacOS/Atom Beta':
    '/Applications/Atom Beta.app/Contents/MacOS/Atom Beta',
  '/Applications/Sublime Text.app/Contents/MacOS/Sublime Text':
    '/Applications/Sublime Text.app/Contents/SharedSupport/bin/subl',
  '/Applications/Sublime Text 2.app/Contents/MacOS/Sublime Text 2':
    '/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl',
  '/Applications/Visual Studio Code.app/Contents/MacOS/Electron': 'code',
};

function getArgumentsForLineNumber(
  editor: string,
  filePath: string,
  lineNumber: number
): Array<string> {
  switch (basename(editor)) {
    case 'vim':
    case 'mvim':
      return [filePath, '+' + lineNumber];
    case 'atom':
    case 'Atom':
    case 'Atom Beta':
    case 'subl':
    case 'sublime':
    case 'wstorm':
    case 'appcode':
    case 'charm':
    case 'idea':
      return [filePath + ':' + lineNumber];
    case 'joe':
    case 'emacs':
    case 'emacsclient':
      return ['+' + lineNumber, filePath];
    case 'rmate':
    case 'mate':
    case 'mine':
      return ['--line', lineNumber + '', filePath];
    case 'code':
      return ['-g', filePath + ':' + lineNumber];
    default:
      // For all others, drop the lineNumber until we have
      // a mapping above, since providing the lineNumber incorrectly
      // can result in errors or confusing behavior.
      return [filePath];
  }
}

function guessEditor(): Array<string> {
  // Explicit config always wins
  if (process.env.REACT_EDITOR) {
    return parse(process.env.REACT_EDITOR);
  }

  // Using `ps x` on OSX we can find out which editor is currently running.
  // Potentially we could use similar technique for Windows and Linux
  if (process.platform === 'darwin') {
    try {
      const output = execSync('ps x').toString();
      const processNames = Object.keys(COMMON_EDITORS);
      for (let i = 0; i < processNames.length; i++) {
        const processName = processNames[i];
        if (output.indexOf(processName) !== -1) {
          return [COMMON_EDITORS[processName]];
        }
      }
    } catch (error) {
      // Ignore...
    }
  }

  // Last resort, use old skool env vars
  if (process.env.VISUAL) {
    return [process.env.VISUAL];
  } else if (process.env.EDITOR) {
    return [process.env.EDITOR];
  }

  return [];
}

let childProcess = null;

export default function launchEditor(
  maybeRelativePath: string,
  lineNumber: number,
  absoluteProjectRoots: Array<string>
) {
  // We use relative paths at Facebook with deterministic builds.
  // This is why our internal tooling calls React DevTools with absoluteProjectRoots.
  // If the filename is absolute then we don't need to care about this.
  let filePath;
  if (isAbsolute(maybeRelativePath)) {
    if (existsSync(maybeRelativePath)) {
      filePath = maybeRelativePath;
    }
  } else {
    for (let i = 0; i < absoluteProjectRoots.length; i++) {
      const projectRoot = absoluteProjectRoots[i];
      const joinedPath = join(projectRoot, maybeRelativePath);
      if (existsSync(joinedPath)) {
        filePath = joinedPath;
        break;
      }
    }
  }

  if (!filePath) {
    return;
  }

  // Sanitize lineNumber to prevent malicious use on win32
  // via: https://github.com/nodejs/node/blob/c3bb4b1aa5e907d489619fb43d233c3336bfc03d/lib/child_process.js#L333
  if (lineNumber && isNaN(lineNumber)) {
    return;
  }

  let [editor, ...args] = guessEditor();
  if (!editor) {
    return;
  }

  if (lineNumber) {
    args = args.concat(getArgumentsForLineNumber(editor, filePath, lineNumber));
  } else {
    args.push(filePath);
  }

  if (childProcess && isTerminalEditor(editor)) {
    // There's an existing editor process already and it's attached
    // to the terminal, so go kill it. Otherwise two separate editor
    // instances attach to the stdin/stdout which gets confusing.
    childProcess.kill('SIGKILL');
  }

  if (process.platform === 'win32') {
    // On Windows, launch the editor in a shell because spawn can only
    // launch .exe files.
    childProcess = spawn('cmd.exe', ['/C', editor].concat(args), {
      stdio: 'inherit',
    });
  } else {
    childProcess = spawn(editor, args, { stdio: 'inherit' });
  }
  childProcess.on('error', function() {});
  childProcess.on('exit', function(errorCode) {
    childProcess = null;
  });
}