<?xml version="1.0"?>
<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
<?xml-stylesheet type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
<!--
https://bugzilla.mozilla.org/show_bug.cgi?id=732665
-->
<window title="Mozilla Bug 732665"
xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
<script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
<!-- test results are displayed in the html:body -->
<body xmlns="http://www.w3.org/1999/xhtml">
<a href="https://bugzilla.mozilla.org/show_bug.cgi?id=732665"
target="_blank">Mozilla Bug 732665</a>
</body>
<!-- test code goes here -->
<script type="application/javascript">
<![CDATA[
//
// Important! If this test starts failing after a tricky platform-y change,
// the stack quota numbers in XPCJSContext probably need twiddling. We want
// to maintain the invariants in this test (at least to some approximation)
// for security reasons.
//
// Executes f() d steps from the probed native stack limit, and returns
// the number of steps to the recursion limit from the caller.
function nearNativeStackLimit(d, f) {
f = f || function() {};
function inner() {
try {
with ({}) { // keep things predictable -- stay in the interpreter
var stepsFromLimit = eval("inner()"); // Use eval to force a number of native stackframes to be created.
}
if (stepsFromLimit == d) {
try { f(); } catch(e) { ok(false, 'nearNativeStackLimit callback threw: ' + e); }
}
return stepsFromLimit + 1;
} catch(e) {
// It would be nice to check here that the exception is actually an
// over-recursion here. But doing so would require toString()ing the
// exception, which we may not have the stack space to do.
return 0;
}
}
return inner();
}
const Cu = Components.utils;
var contentSb = new Cu.Sandbox('http://www.example.com');
var chromeSb = new Cu.Sandbox(window);
chromeSb.ok = contentSb.ok = ok;
Cu.evalInSandbox(nearNativeStackLimit.toSource(), chromeSb);
Cu.evalInSandbox(nearNativeStackLimit.toSource(), contentSb);
var chromeLimit = Cu.evalInSandbox("nearNativeStackLimit(0);", chromeSb);
var contentLimit = Cu.evalInSandbox("nearNativeStackLimit(0)", contentSb);
ok(chromeLimit >= contentLimit + 10,
"Chrome should be able to have at least 10 heavy frames more stack than content: " + chromeLimit + ", " + contentLimit);
// Exhaust the stack space in content, and then make sure we can still get 10
// heavy frames in chrome.
//
// Note that sometimes, if we pass |0| to nearNativeStackLimit, we can end up
// so close to the border in content that we can't even get ourselves together
// enough to make the cross-compartment call. So rather than exhausting the
// stack entirely and then checking for 10 chrome frames, we leave ourselves
// one frame's worth, and check for 11.
//
// If this assertion fails, the current work-around so far is to measure
// again the worst frame size, by using the JS Shell to run
// test_bug732665_meta.js . This script will output numbers to update
// XPCJSContext.cpp comment, as well as the kTrustedScriptBuffer constant.
contentSb.nnslChrome = chromeSb.nearNativeStackLimit;
var nestedLimit = Cu.evalInSandbox("nearNativeStackLimit(1, function() { nestedLimit = nnslChrome(0);}); nestedLimit;", contentSb);
ok(nestedLimit >= 11, "Chrome should be invokable from content script with an exhausted stack: " + nestedLimit);
]]>
</script>
</window>