The Tor Browser: js/src/tests/ecma_6/Math/shell.js@129ffea94266 (annotated)

js/src/tests/ecma_6/Math/shell.js@129ffea94266 (annotated)

js/src/tests/ecma_6/Math/shell.js

Sat, 03 Jan 2015 20:18:00 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Sat, 03 Jan 2015 20:18:00 +0100
branch: TOR_BUG_3246
changeset 7: 129ffea94266
permissions: -rw-r--r--

Conditionally enable double key logic according to:
private browsing mode or privacy.thirdparty.isolate preference and
implement in GetCookieStringCommon and FindCookie where it counts...
With some reservations of how to convince FindCookie users to test
condition and pass a nullptr when disabling double key logic.

 // The nearest representable values to +1.0.
 const ONE_PLUS_EPSILON = 1 + Math.pow(2, -52);  // 0.9999999999999999
 const ONE_MINUS_EPSILON = 1 - Math.pow(2, -53);  // 1.0000000000000002
 {
     var fail = function (msg) {
         var exc = new Error(msg);
         try {
             // Try to improve on exc.fileName and .lineNumber; leave exc.stack
             // alone. We skip two frames: fail() and its caller, an assertX()
             // function.
             var frames = exc.stack.trim().split("\n");
             if (frames.length > 2) {
                 var m = /@([^@:]*):([0-9]+)$/.exec(frames[2]);
                 if (m) {
                     exc.fileName = m[1];
                     exc.lineNumber = +m[2];
                 }
             }
         } catch (ignore) { throw ignore;}
         throw exc;
     };
     var ENDIAN;  // 0 for little-endian, 1 for big-endian.
     // Return the difference between the IEEE 754 bit-patterns for a and b.
     //
     // This is meaningful when a and b are both finite and have the same
     // sign. Then the following hold:
     //
     //   * If a === b, then diff(a, b) === 0.
     //
     //   * If a !== b, then diff(a, b) === 1 + the number of representable values
     //                                         between a and b.
     //
     var f = new Float64Array([0, 0]);
     var u = new Uint32Array(f.buffer);
     var diff = function (a, b) {
         f[0] = a;
         f[1] = b;
         //print(u[1].toString(16) + u[0].toString(16) + " " + u[3].toString(16) + u[2].toString(16));
         return Math.abs((u[3-ENDIAN] - u[1-ENDIAN]) * 0x100000000 + u[2+ENDIAN] - u[0+ENDIAN]);
     };
     // Set ENDIAN to the platform's endianness.
     ENDIAN = 0;  // try little-endian first
     if (diff(2, 4) === 0x100000)  // exact wrong answer we'll get on a big-endian platform
         ENDIAN = 1;
     assertEq(diff(2,4), 0x10000000000000);
     assertEq(diff(0, Number.MIN_VALUE), 1);
     assertEq(diff(1, ONE_PLUS_EPSILON), 1);
     assertEq(diff(1, ONE_MINUS_EPSILON), 1);
     var assertNear = function assertNear(a, b, tolerance=1) {
         if (!Number.isFinite(b)) {
             fail("second argument to assertNear (expected value) must be a finite number");
         } else if (Number.isNaN(a)) {
             fail("got NaN, expected a number near " + b);
         } else if (!Number.isFinite(a)) {
             if (b * Math.sign(a) < Number.MAX_VALUE)
                 fail("got " + a + ", expected a number near " + b);
         } else {
             // When the two arguments do not have the same sign bit, diff()
             // returns some huge number. So if b is positive or negative 0,
             // make target the zero that has the same sign bit as a.
             var target = b === 0 ? a * 0 : b;
             var err = diff(a, target);
             if (err > tolerance) {
                 fail("got " + a + ", expected a number near " + b +
                      " (relative error: " + err + ")");
             }
         }
     };
 }