author Rob Wu <rob@robwu.nl>
Sun, 25 Feb 2018 17:30:13 +0100
changeset 461636 a9eca77bd638babb8de38824f1e61b4bbd8424f6
parent 460693 7bbd1a09eacb8a31f4caef5c1e526d8d32569ae9
child 462028 87a34b1b1ad782b2aae304b7d14b2150f1b2ba4f
permissions -rw-r--r--
Bug 335545 - Count FD instead of looking for clipboardcache in test_bug1123480.xul r=mstange - Count open file descriptors instead of testing the existence of a file (because the clipboard is now only reachable through file descriptors, and not through a file path). - Use a fixed string instead of a random string. The previous way of generating a string was non-deterministic, and there was a very small chance that the generated string was not large enough to trigger the cache-to-disk-mode. - Use "text/unicode" instead of "text/plain", because JavaScript strings use two bytes, not one bytes each. - The cache file is already created when the Transferable is created, so check the cache file after assigning data to the nsITransferable, but before copying it to the clipboard. MozReview-Commit-ID: KOkYOm280Oh

<?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"?>
<window title="Mozilla Bug 1123480"
  <title>nsTransferable PBM Overflow Selection Test</title>
  <script type="application/javascript"

  <script type="application/javascript">
  // Create over 1 MB of sample garbage text. JavaScript strings are represented by
  // UTF16 strings, so the size is twice as much as the actual string length.
  // This value is chosen such that the size of the memory for the string exceeds
  // the kLargeDatasetSize threshold in nsTransferable.h.
  // It is also not a round number to reduce the odds of having an accidental
  // collisions with another file (since the test below looks at the file size
  // to identify the file).
  var Ipsum = "0123456789".repeat(1234321);
  var IpsumByteLength = Ipsum.length * 2;
  var SHORT_STRING_NO_CACHE = "short string that will never be cached to the disk";

  function isWindows() {
    return AppConstants.platform === 'win';

  // Get a list of open file descriptors that refer to a file with the same size as
  // the expected data (and assume that any mutations in file descriptor counts
  // are caused by our test).
  function getClipboardCacheFDCount() {
    var dir;
    if (isWindows()) {
      // On Windows, nsAnonymousTemporaryFile does not immediately delete the file.
      // Instead, the Windows-specific FILE_FLAG_DELETE_ON_CLOSE flag is used,
      // which means that the file is deleted when the last handle is closed.
      // Apparently, this flag is unreliable (e.g. when the application crashes),
      // so nsAnonymousTemporaryFile stores the temporary files in a subdirectory,
      // which is cleaned up some time after start-up.

      // This is just a test, and during the test we deterministically close the
      // handles, so if FILE_FLAG_DELETE_ON_CLOSE does the thing it promises, the
      // file is actually removed when the handle is closed.

      // Path from nsAnonymousTemporaryFile.cpp, GetTempDir.
      dir = FileUtils.getFile("TmpD", ["mozilla-temp-files"]);
    } else {
      dir = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsIFile);
    var count = 0;
    for (var de = dir.directoryEntries; de.hasMoreElements(); ) {
      var fdFile = de.getNext().QueryInterface(Ci.nsIFile);
      var fileSize;
      try {
        fileSize = fdFile.fileSize;
      } catch (e) {
        // This can happen on macOS.
      if (fileSize === IpsumByteLength) {
        // Assume that the file was created by us if the size matches.
    return count;

  function RunTest() {
    const gClipboardHelper = Cc["@mozilla.org/widget/clipboardhelper;1"].getService(Ci.nsIClipboardHelper);

    // Sanitize environment

    var initialFdCount = getClipboardCacheFDCount();

    // Overflow a nsTransferable region by using the clipboard helper

    // Undefined private browsing mode should not cache to disk
    is(getClipboardCacheFDCount(), initialFdCount, "should avoid caching to disk when PBM is undefined");

    // Sanitize environment again.
    is(getClipboardCacheFDCount(), initialFdCount, "should have cleared the clipboard data");

    // Repeat procedure of plain text selection with private browsing
    // disabled and enabled
    for (let private of [false, true]) {
      var win = window.open("about:blank", "_blank", "chrome, width=500, height=200" + (private ? ", private" : ""));
      ok(win, private ? "should open private window" : "should open non-private window");
      is(PrivateBrowsingUtils.isContentWindowPrivate(win), private, "used correct window context");

      // Select plaintext in private/non-private channel
      const nsTransferable = Components.Constructor("@mozilla.org/widget/transferable;1", "nsITransferable");
      const nsSupportsString = Components.Constructor("@mozilla.org/supports-string;1", "nsISupportsString");
      var Loadctx = PrivateBrowsingUtils.privacyContextFromWindow(win);
      var Transfer = nsTransferable();
      var Suppstr = nsSupportsString();
      Suppstr.data = Ipsum;
      Transfer.setTransferData("text/unicode", Suppstr, IpsumByteLength);

      // Enabled private browsing mode should not cache any selection to disk; disabled should
      if (private) {
        is(getClipboardCacheFDCount(), initialFdCount, "did not violate private browsing mode");
      } else {
        is(getClipboardCacheFDCount(), initialFdCount + 1, "should save memory by caching non-private clipboard data to disk");

      // Share the transferable with the system.
      Services.clipboard.setData(Transfer, null, Services.clipboard.kGlobalClipboard);
      if (private) {
        is(getClipboardCacheFDCount(), initialFdCount, "did not violate private browsing mode");
      } else {
        is(getClipboardCacheFDCount(), initialFdCount + 1, "should save memory by caching non-private clipboard data to disk");

      // Sanitize the environment.
      Suppstr = nsSupportsString();
      Suppstr.data = SHORT_STRING_NO_CACHE;
      Transfer.setTransferData("text/unicode", Suppstr, SHORT_STRING_NO_CACHE.length * 2);
      is(getClipboardCacheFDCount(), initialFdCount, "should drop the cache file, if any.");

      Services.clipboard.setData(Transfer, null, Services.clipboard.kGlobalClipboard);
      is(getClipboardCacheFDCount(), initialFdCount, "should postsanitize the environment");

  <!-- 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=1123480"
     target="_blank">Mozilla Bug 1123480</a>