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<!DOCTYPE html>
<html>
<!--
Copyright (c) 2012 The Chromium Authors. All rights reserved.
Use of this source code is governed by a BSD-style license that can be
found in the LICENSE file.
-->
<head>
<meta http-equiv="Pragma" content="no-cache" />
<meta http-equiv="Expires" content="-1" />
<title>Logging and Stack Trace</title>
<script type="text/javascript">
statusText = 'NO-STATUS';
tick = '';
boomTime = null;
crashed = false;
// Handle a message coming from the NaCl module.
function handleMessage(message_event) {
msg_type = message_event.data.substring(0,4)
msg_data = message_event.data.substring(5, message_event.data.length)
if (msg_type == 'POP:') {
alert(message_event.data);
return
}
if (msg_type == 'LOG:') {
document.Logging.log.value += msg_data + '\n';
return
}
if (msg_type == 'TRC:') {
crashed = true;
updateStatus('Crash Reported')
xmlhttp = new XMLHttpRequest();
xmlhttp.open('POST',document.nacl_module.src,false);
xmlhttp.send(msg_data)
document.Logging.trace.value = xmlhttp.responseText + '\n';
return
}
}
function pageDidLoad() {
updateStatus("Page Loaded")
heartBeat();
updateStatus("Page Submitted")
}
// Indicate success when the NaCl module has loaded.
function moduleDidLoad() {
updateStatus('LOADED');
t=setTimeout('boom()', 4000);
}
// Set the global status message. If the element with id 'statusField'
// exists, then set its HTML to the status message as well.
// opt_message The message test. If this is null or undefined, then
// attempt to set the element with id 'statusField' to the value of
// |statusText|.
function updateStatus(opt_message) {
if (opt_message)
statusText = opt_message;
document.Logging.log.value += opt_message + '\n'
var statusField = document.getElementById('statusField');
if (statusField) {
statusField.innerHTML = statusText;
}
}
function boom() {
if (!crashed) {
updateStatus('Send BOOM');
document.nacl_module.postMessage('BOOM');
t=setTimeout('boom()', 1000);
}
}
function heartBeat() {
if (document.nacl_module.lastError) {
if (tick != document.nacl_module.lastError) {
tick = document.nacl_module.lastError;
updateStatus('Missed heartbeat: ' + document.nacl_module.lastError);
crashed = true;
}
}
else { t=setTimeout('heartBeat()', 1000); }
}
</script>
<form name="Status">
<input type="hidden" name="Data" value="">
</form>
</head>
<body onload="pageDidLoad()">
<h1>Native Client Debugging Example: Generating a Stack Trace.</h1>
<h2>How the example works</h2>
<p>This example shows how to trap an untrusted exception (such as a illegal
memory reference in the NEXE). This debugging technique can only be used
for development since it requires several command-line switches, and
environment variables. The test works by loading the module and communicating
with it through PostMessage. Messages from the module are sent to the Status
line and/or the Log window in the page. Four seconds after the module is
loaded, the JavaScript on this page sends a 'BOOM' message to the module that
causes the module to dereference an illegal location in memory.</p>
<p>If your setup is correct (you launched Chrome with the appropriate
command-line arguments and environment variables), the Log window bellow should
show that the crash dump facilities are turn on. When the crash data arrives
from the module, the data is forwarded to the HTTP server, which drives
a decoder and sends back a stack trace to the web page.</p>
<p>If setup incorrectly, the NaCl module may or may not load. If the module
loads, it sends a "LOADED" message to the log and crash after four seconds.
Since the stack trace facilities are not enables, the script will determine that
the module has crashed by detecting a missed heartbeat which the application
would normally send.
</p>
<h2>Running the example</h2>
In one terminal window, to start the server:
<ul>
<li>Set the CHROME_PATH environment variable to the fully qualified path of your
Chrome executable.</li>
<li>From the example directory type: <b>make RUN</b></li>
</ul>
In another terminal window, to automatically start Chrome with the correct
environment variables and command-line switches:
<ul>
<li>Set the CHROME_PATH environment variable to the fully qualified path of your
Chrome executable.</li>
<li>From the example directory type: <b>make TRACE</b></li>
</ul>
<div id="listener">
<script type="text/javascript">
var listener = document.getElementById('listener')
listener.addEventListener('load', moduleDidLoad, true);
listener.addEventListener('message', handleMessage, true);
</script>
<embed name="nacl_module"
id="hello_world"
width=100 height=100
src="<tc>/debugging.nmf"
type="application/x-nacl" />
</div>
<hr>
<h2>Status: <code id="statusField">NO-STATUS</code></h2>
<form name="Logging">
<h2>Log</h2>
<textarea rows="10" cols="130" name="log" readonly="readonly"></textarea>
<br />
<h2>Stack Trace</h2>
<textarea rows="10" cols="130" name="trace" readonly="readonly"></textarea>
</form>
</body>
</html>
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