js/xpconnect/tests/chrome/test_bug732665.xhtml

   1 <?xml version="1.0"?>
   2 <?xml-stylesheet type="text/css" href="chrome://global/skin"?>
   3 <?xml-stylesheet type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
   4 <!--
   5 https://bugzilla.mozilla.org/show_bug.cgi?id=732665
   6 -->
   7 <window title="Mozilla Bug 732665"
   8         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
   9   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
  10
  11   <!-- test results are displayed in the html:body -->
  12   <body xmlns="http://www.w3.org/1999/xhtml">
  13   <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=732665"
  14      target="_blank">Mozilla Bug 732665</a>
  15   </body>
  16
  17   <!-- test code goes here -->
  18   <script type="application/javascript">
  19   <![CDATA[
  20
  21 add_task(async () => {
  22   await SpecialPowers.pushPrefEnv({"set": [["security.allow_eval_with_system_principal",
  23                                             true]]});
  24   //
  25   // Important! If this test starts failing after a tricky platform-y change,
  26   // the stack quota numbers in XPCJSContext probably need twiddling. We want
  27   // to maintain the invariants in this test (at least to some approximation)
  28   // for security reasons.
  29   //
  30
  31   // Executes f() d steps from the probed native stack limit, and returns
  32   // the number of steps to the recursion limit from the caller.
  33   function nearNativeStackLimit(d, f) {
  34     f = f || function() {};
  35     let failed = null;
  36     function inner() {
  37       try {
  38         // eslint-disable-next-line no-eval
  39         var stepsFromLimit = eval("inner()"); // Use eval to force a number of native stackframes to be created.
  40         if (stepsFromLimit == d) {
  41           try {
  42             f();
  43           } catch(e) {
  44             // If we didn't have enough stack space to call the (possibly
  45             // trivial) test function above, we obviously can't expect to call
  46             // into the test harness assertion code successfully.
  47             failed = e;
  48           }
  49         }
  50         return stepsFromLimit + 1;
  51       } catch(e) {
  52       // It would be nice to check here that the exception is actually an
  53       // over-recursion here. But doing so would require toString()ing the
  54       // exception, which we may not have the stack space to do.
  55         return 0;
  56       }
  57     }
  58     let result = inner();
  59     ok(!failed, `nearNativeStackLimit callback threw: ${failed}`);
  60     return result;
  61   }
  62
  63   var contentSb = new Cu.Sandbox("https://www.example.com");
  64   var chromeSb = new Cu.Sandbox(window);
  65   chromeSb.ok = contentSb.ok = ok;
  66   Cu.evalInSandbox(nearNativeStackLimit.toSource(), chromeSb);
  67   Cu.evalInSandbox(nearNativeStackLimit.toSource(), contentSb);
  68   var chromeLimit = Cu.evalInSandbox("nearNativeStackLimit(0);", chromeSb);
  69   var contentLimit = Cu.evalInSandbox("nearNativeStackLimit(0)", contentSb);
  70   ok(chromeLimit >= contentLimit + 10,
  71      "Chrome should be able to have at least 10 heavy frames more stack than content: " + chromeLimit + ", " + contentLimit);
  72
  73   // Exhaust the stack space in content, and then make sure we can still get 10
  74   // heavy frames in chrome.
  75   //
  76   // Note that sometimes, if we pass |0| to nearNativeStackLimit, we can end up
  77   // so close to the border in content that we can't even get ourselves together
  78   // enough to make the cross-compartment call. So rather than exhausting the
  79   // stack entirely and then checking for 10 chrome frames, we leave ourselves
  80   // one frame's worth, and check for 11.
  81   //
  82   // If this assertion fails, the current work-around so far is to measure
  83   // again the worst frame size, by using the JS Shell to run
  84   // test_bug732665_meta.js . This script will output numbers to update
  85   // XPCJSContext.cpp comment, as well as the kTrustedScriptBuffer constant.
  86   contentSb.nnslChrome = chromeSb.nearNativeStackLimit;
  87   var nestedLimit = Cu.evalInSandbox("nearNativeStackLimit(1, function() { nestedLimit = nnslChrome(0);}); nestedLimit;", contentSb);
  88   ok(nestedLimit >= 11, "Chrome should be invokable from content script with an exhausted stack: " + nestedLimit);
  89 });
  90   ]]>
  91   </script>
  92 </window>