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Test Info: Warnings
- This test gets skipped with pattern: os == 'android' OR verify && apple_catalina OR verify && os == 'linux'
- Manifest: widget/tests/chrome.toml
<?xml version="1.0"?>
<window title="nsTransferable with large string"
onload="RunTest();">
<title>nsTransferable with large string</title>
<script type="application/javascript">
<![CDATA[
// This value is chosen such that the size of the memory for the string exceeds
// the kLargeDatasetSize threshold in nsTransferable.h (one million).
// Each character of a JS string is internally represented by two bytes,
// so the following string of length 500 001 uses 1 000 002 bytes.
const BIG_STRING = "x" + "BIGGY".repeat(100000);
// Some value with a length that is exactly kLargeDatasetSize (1 000 000).
const SMALL_STRING = "small".repeat(100000);
const nsTransferable = Components.Constructor("@mozilla.org/widget/transferable;1", "nsITransferable");
const nsSupportsString = Components.Constructor("@mozilla.org/supports-string;1", "nsISupportsString");
function assignTextToTransferable(transferable, string) {
var Suppstr = nsSupportsString();
Suppstr.data = string;
transferable.setTransferData("text/plain", Suppstr);
}
function checkTransferableText(transferable, expectedString, description) {
var data = {};
transferable.getTransferData("text/plain", data);
var actualValue = data.value.QueryInterface(Ci.nsISupportsString).data;
// Use ok + shortenString instead of is(...) to avoid dumping millions of characters in the output.
ok(actualValue === expectedString, description + ": text should match. " +
"Expected " + shortenString(expectedString) + ", got " + shortenString(actualValue));
function shortenString(str) {
return str && str.length > 30 ? str.slice(0, 10) + "..." + str.slice(-10) : String(str);
}
}
function isFDCountingSupported() {
// On on-Windows we can count the number of file handles for the current process,
// while on Windows we need to count the number of files in ${TempD}\mozilla-temp-files\,
// which can be unreliable, especially because nsAnonymousTemporaryFile has documented
// that the deletion might not be immediate.
//
// To avoid intermittents, we only check the file descriptor counts on non-Windows.
// test_bug1123480.xhtml will do some basic testing for Windows.
const {AppConstants} = ChromeUtils.importESModule(
"resource://gre/modules/AppConstants.sys.mjs"
);
return AppConstants.platform !== 'win';
}
function getClipboardCacheFDCount() {
var dir = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsIFile);
dir.initWithPath("/dev/fd");
var count = 0;
for (var de = dir.directoryEntries; de.hasMoreElements(); ) {
var fdFile = de.nextFile;
var fileSize;
try {
fileSize = fdFile.fileSize;
} catch (e) {
// This can happen on macOS.
continue;
}
if (fileSize === BIG_STRING.length * 2 ||
// We are not expecting files of this small size,
// but include them in the count anyway
// in case the files are unexpectedly created.
fileSize === SMALL_STRING.length * 2) {
// Assume that the file was created by us if the size matches.
++count;
}
}
return count;
}
function RunTest() {
const {PrivateBrowsingUtils} = ChromeUtils.importESModule(
"resource://gre/modules/PrivateBrowsingUtils.sys.mjs"
);
var win = window.browsingContext.topChromeWindow.open("about:blank", "_blank", "chrome, width=500, height=200");
ok(win, "should open window");
is(PrivateBrowsingUtils.isContentWindowPrivate(win), false, "used correct window context");
// ### Part 1 - Writing to the clipboard.
var Loadctx = PrivateBrowsingUtils.privacyContextFromWindow(win);
var Transfer = nsTransferable();
Transfer.init(Loadctx);
Transfer.addDataFlavor("text/plain");
var initialFdCount = isFDCountingSupported() ? getClipboardCacheFDCount() : -1;
assignTextToTransferable(Transfer, BIG_STRING);
checkTransferableText(Transfer, BIG_STRING, "transferable after assigning BIG_STRING");
if (isFDCountingSupported()) {
is(getClipboardCacheFDCount(), initialFdCount + 1, "should use a file for BIG_STRING");
}
// Share the transferable with the system.
Services.clipboard.setData(Transfer, null, Services.clipboard.kGlobalClipboard);
// Sanity check: Copying to the clipboard should not have altered the transferable.
checkTransferableText(Transfer, BIG_STRING, "transferable after copying to clipboard");
if (isFDCountingSupported()) {
// We are only counting file descriptors for the current process,
// so even if the test were to be multi-process and the parent process creates another
// nsTransferable, then the count should still be the same.
is(getClipboardCacheFDCount(), initialFdCount + 1, "should still be using files for previously stored BIG_STRING");
// Re-establish baseline for the second part of the test below.
initialFdCount = getClipboardCacheFDCount();
}
// ### Part 2 - Reading from the clipboard.
var Transfer2 = nsTransferable();
Transfer2.init(Loadctx);
Transfer2.addDataFlavor("text/plain");
// Iniitalize with a small string, so we can see that mData -> mCacheFD works.
assignTextToTransferable(Transfer2, SMALL_STRING);
checkTransferableText(Transfer2, SMALL_STRING, "transferable after assigning SMALL_STRING");
if (isFDCountingSupported()) {
is(getClipboardCacheFDCount(), initialFdCount, "should not use file to store SMALL_STRING.");
}
// Check whether the clipboard data can be read, and simulatenously trigger mData -> mCacheFD.
Services.clipboard.getData(Transfer2, Services.clipboard.kGlobalClipboard, SpecialPowers.wrap(window).browsingContext.currentWindowContext);
checkTransferableText(Transfer2, BIG_STRING, "transferable after retrieving from clipboard");
if (isFDCountingSupported()) {
is(getClipboardCacheFDCount(), initialFdCount + 1, "should use a file for BIG_STRING (read from clipboard).");
}
// Store a small string, to exercise the code path from mCacheFD -> mData.
assignTextToTransferable(Transfer2, SMALL_STRING);
checkTransferableText(Transfer2, SMALL_STRING, "transferable after assigning SMALL_STRING");
if (isFDCountingSupported()) {
is(getClipboardCacheFDCount(), initialFdCount, "should release the file after clearing the transferable.");
}
}
]]>
</script>
<!-- test results are displayed in the html:body -->
This test checks whether a big string can be copied to the clipboard, and then retrieved in the same form.
On non-Windows, the test also checks whether the data of the transferable is really stored in a file.
</body>
</window>