tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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test_largeItems.js (2466B)

      1 /**
      2 * Any copyright is dedicated to the Public Domain.
      3 * http://creativecommons.org/publicdomain/zero/1.0/
      4 */
      5 
      6 /**
      7 * Test repeatedly setting values that are just under the LocalStorage quota
      8 * limit without yielding control flow in order to verify that the write
      9 * optimizer is present / works. If there was no write optimizer present, the
     10 * IPC message size limit would be exceeded, resulting in a crash.
     11 */
     12 
     13 add_task(async function testSteps() {
     14  const globalLimitKB = 5 * 1024;
     15 
     16  // 18 and more iterations would produce an IPC message with size greater than
     17  // 256 MB if write optimizer was not present. This number was determined
     18  // experimentally by running the test with disabled write optimizer.
     19  const numberOfIterations = 18;
     20 
     21  const randomStringBlockSize = 65536;
     22 
     23  // We need to use a random string because LS internally tries to compress
     24  // values.
     25  function getRandomString(size) {
     26    let crypto = this.window ? this.window.crypto : this.crypto;
     27    let decoder = new TextDecoder("ISO-8859-2");
     28 
     29    function getRandomStringBlock(array) {
     30      crypto.getRandomValues(array);
     31      return decoder.decode(array);
     32    }
     33 
     34    let string = "";
     35 
     36    let quotient = size / randomStringBlockSize;
     37    if (quotient) {
     38      let array = new Uint8Array(randomStringBlockSize);
     39      for (let i = 1; i <= quotient; i++) {
     40        string += getRandomStringBlock(array);
     41      }
     42    }
     43 
     44    let remainder = size % randomStringBlockSize;
     45    if (remainder) {
     46      let array = new Uint8Array(remainder);
     47      string += getRandomStringBlock(array);
     48    }
     49 
     50    return string;
     51  }
     52 
     53  const data = {};
     54  data.key = "foo";
     55  data.value = getRandomString(
     56    globalLimitKB * 1024 -
     57      data.key.length -
     58      numberOfIterations.toString().length
     59  );
     60 
     61  info("Setting pref");
     62 
     63  // By disabling snapshot reusing, we guarantee that the snapshot will be
     64  // checkpointed once control returns to the event loop.
     65  if (this.window) {
     66    await SpecialPowers.pushPrefEnv({
     67      set: [["dom.storage.snapshot_reusing", false]],
     68    });
     69  } else {
     70    Services.prefs.setBoolPref("dom.storage.snapshot_reusing", false);
     71  }
     72 
     73  info("Getting storage");
     74 
     75  let storage = getLocalStorage();
     76 
     77  info("Adding/updating item");
     78 
     79  for (var i = 0; i < numberOfIterations; i++) {
     80    storage.setItem(data.key, data.value + i);
     81  }
     82 
     83  info("Returning to event loop");
     84 
     85  await returnToEventLoop();
     86 
     87  ok(!storage.hasSnapshot, "Snapshot successfully finished");
     88 });