src/emrun_postjs.js

/**
 * @license
 * Copyright 2013 The Emscripten Authors
 * SPDX-License-Identifier: MIT
 */

if (typeof window === "object" && (typeof ENVIRONMENT_IS_PTHREAD === 'undefined' || !ENVIRONMENT_IS_PTHREAD)) {
  var emrun_register_handlers = function() {
    // When C code exit()s, we may still have remaining stdout and stderr messages in flight. In that case, we can't close
    // the browser until all those XHRs have finished, so the following state variables track that all communication is done,
    // after which we can close.
    var emrun_num_post_messages_in_flight = 0;
    var emrun_should_close_itself = false;
    var postExit = function(msg) {
      var http = new XMLHttpRequest();
      // Don't do this immediately, this may race with the notification about the return code reaching the
      // server. Send a *sync* xhr so that we know for sure that the server has gotten the return code
      // before we continue.
      http.open("POST", "stdio.html", false);
      http.send(msg);
      try {
        // Try closing the current browser window, since it exit()ed itself. This can shut down the browser process
        // and then emrun does not need to kill the whole browser process.
        window.close();
      } catch(e) {}
    };
    var post = function(msg) {
      var http = new XMLHttpRequest();
      ++emrun_num_post_messages_in_flight;
      http.onreadystatechange = function() {
        if (http.readyState == 4 /*DONE*/) {
          if (--emrun_num_post_messages_in_flight == 0 && emrun_should_close_itself) postExit('^exit^'+EXITSTATUS);
        }
      }
      http.open("POST", "stdio.html", true);
      http.send(msg);
    };
    // If the address contains localhost, or we are running the page from port 6931, we can assume we're running the test runner and should post stdout logs.
    if (document.URL.search("localhost") != -1 || document.URL.search(":6931/") != -1) {
      var emrun_http_sequence_number = 1;
      var prevPrint = out;
      var prevErr = err;
      Module['addOnExit'](function() { if (emrun_num_post_messages_in_flight == 0) postExit('^exit^'+EXITSTATUS); else emrun_should_close_itself = true; });
      out = function(text) { post('^out^'+(emrun_http_sequence_number++)+'^'+encodeURIComponent(text)); prevPrint(text); };
      err = function(text) { post('^err^'+(emrun_http_sequence_number++)+'^'+encodeURIComponent(text)); prevErr(text); };

      // Notify emrun web server that this browser has successfully launched the page. Note that we may need to
      // wait for the server to be ready.
      var tryToSendPageload = function() {
        try {
          post('^pageload^');
        } catch (e) {
          setTimeout(tryToSendPageload, 50);
        }
      };
      tryToSendPageload();
    }
  };

  // POSTs the given binary data represented as a (typed) array data back to the emrun-based web server.
  // To use from C code, call e.g. EM_ASM({emrun_file_dump("file.dat", HEAPU8.subarray($0, $0 + $1));}, my_data_pointer, my_data_pointer_byte_length);
  var emrun_file_dump = function(filename, data) {
    var http = new XMLHttpRequest();
    out('Dumping out file "' + filename + '" with ' + data.length + ' bytes of data.');
    http.open("POST", "stdio.html?file=" + filename, true);
    http.send(data); // XXX  this does not work in workers, for some odd reason (issue #2681)
  };

  if (typeof Module !== 'undefined' && typeof document !== 'undefined') emrun_register_handlers();
}