Bug 1854747 - Stop exposing the image data as file to clipboard; r=evilpie

Differential Revision: https://phabricator.services.mozilla.com/D189242

dom/base/nsCopySupport.cpp

@@ -40,6 +40,7 @@
 #include "nsContentCID.h"
 
 #ifdef XP_WIN
+#  include "mozilla/StaticPrefs_clipboard.h"
 #  include "nsCExternalHandlerService.h"
 #  include "nsEscape.h"
 #  include "nsIMIMEInfo.h"
@@ -502,8 +503,10 @@ nsresult nsCopySupport::ImageCopy(nsIImageLoadingContent* aImageElement,
     }
 
 #ifdef XP_WIN
-    rv = AppendImagePromise(trans, imgRequest, aImageElement);
-    NS_ENSURE_SUCCESS(rv, rv);
+    if (StaticPrefs::clipboard_imageAsFile_enabled()) {
+      rv = AppendImagePromise(trans, imgRequest, aImageElement);
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
 #endif
 
     // copy the image data onto the transferable

dom/events/moz.build

@@ -16,6 +16,7 @@ BROWSER_CHROME_MANIFESTS += [
 ]
 
 MOCHITEST_MANIFESTS += [
+    "test/clipboard/mochitest.toml",
     "test/mochitest.toml",
     "test/pointerevents/mochitest.toml",
 ]

dom/events/test/clipboard/mochitest.toml

@@ -0,0 +1,7 @@
+[DEFAULT]
+
+["test_paste_image.html"]
+skip-if = [
+  "headless", # Bug 1405869
+  "os == 'android'", # Image type isn't supported
+]

dom/events/test/clipboard/test_paste_image.html

@@ -14,9 +14,9 @@
       images.push(aFile);
     };
 
-    this.test = function() {
+    this.test = async function() {
       for (var i = 0; i < images.length; i++) {
-        testImageSize(images[i]);
+        await testImageSize(images[i]);
       }
     };
 
@@ -25,28 +25,31 @@
       info("returned=" + counter + " images.length=" + images.length);
       if (counter == images.length) {
         info("test finish");
-        SimpleTest.finish();
       }
     };
 
-    function testImageSize(aFile) {
+    async function testImageSize(aFile) {
       var source = window.URL.createObjectURL(aFile);
       var image = new Image();
       image.src = source;
       var imageTester = that;
-      image.onload = function() {
-        is(this.width, 62, "Check generated image width");
-        is(this.height, 71, "Check generated image height");
+      let promise = new Promise(resolve => {
+        image.addEventListener("load", function(e) {
+          is(this.width, 62, "Check generated image width");
+          is(this.height, 71, "Check generated image height");
 
-        // This fails on OSX only.
-        if (!navigator.platform.includes("Mac")) {
-          testImageCanvas(image);
-        }
+          // This fails on OSX only.
+          if (!navigator.platform.includes("Mac")) {
+            testImageCanvas(image);
+          }
 
-        imageTester.returned();
-      }
+          imageTester.returned();
+          resolve();
+        }, { once: true });
+      });
 
       document.body.appendChild(image);
+      await promise;
     };
 
     function testImageCanvas(aImage) {
@@ -80,8 +83,10 @@
     documentViewer.copyImage(documentViewer.COPY_IMAGE_ALL);
   }
 
-  function doTest() {
-    SimpleTest.waitForExplicitFinish();
+  async function doTest(imageAsFileEnabled) {
+    await SpecialPowers.pushPrefEnv({
+      set: [["clipboard.imageAsFile.enabled", imageAsFileEnabled]],
+    });
 
     copyImage('image');
 
@@ -98,18 +103,30 @@
     ok(clipboard.hasDataMatchingFlavors(["image/png"], clipboard.kGlobalClipboard),
        "clipboard contains image");
 
-    window.addEventListener("paste", onPaste);
+    let promise = new Promise(resolve => {
+      window.addEventListener("paste", async (e) => {
+        isDeeply(e.clipboardData.types,
+                 (navigator.platform.includes("Win") && imageAsFileEnabled) ?
+                    ["application/x-moz-file", "Files"] : ["text/html", "text/plain", "Files"]);
+        await onPaste(e, imageAsFileEnabled);
+        resolve();
+      }, { once: true });
+    });
 
     var textarea = SpecialPowers.wrap(document.getElementById('textarea'));
     textarea.focus();
     textarea.editor.paste(clipboard.kGlobalClipboard);
+
+    await promise;
+
+    clipboard.emptyClipboard(clipboard.kGlobalClipboard);
   }
 
-  function onPaste(e) {
+  async function onPaste(e, imageAsFileEnabled) {
     var imageTester = new ImageTester;
-    testFiles(e, imageTester);
+    testFiles(e, imageTester, imageAsFileEnabled);
     testItems(e, imageTester);
-    imageTester.test();
+    await imageTester.test();
   }
 
   function testItems(e, imageTester) {
@@ -131,7 +148,7 @@
     }
   }
 
-  function testFiles(e, imageTester) {
+  function testFiles(e, imageTester, imageAsFileEnabled) {
     var files = e.clipboardData.files;
 
     is(files, e.clipboardData.files,
@@ -141,15 +158,12 @@
       var file = files[i];
       ok(file instanceof File, ".files should contain only File objects");
       ok(file.size > 0, "This file shouldn't have size 0");
-      if (navigator.platform.includes("Win")) {
-        // On Windows the pasted file is (sometimes?) produced from the Windows only
-        // file promise added by AppendImagePromise.
-        ok(file.name == "image.png" || (file.name.startsWith("Untitled") && file.name.endsWith(".png")),
-           `Correct filename, got "${file.name}"`);
+      if (navigator.platform.includes("Win") && imageAsFileEnabled) {
+        ok(file.name.startsWith("Untitled") && file.name.endsWith(".png"),
+           `Check filename, got "${file.name}"`);
       } else {
-        is(file.name, "image.png", "Correct filename");
+        is(file.name, "image.png", "Check filename");
       }
-      is(file.type, "image/png", "This file should be a image/png");
 
       testSlice(file);
       imageTester.add(file);
@@ -177,8 +191,16 @@
     is(blob.type, "image/png", ".slice @type check");
   }
 
+  add_task(async function test_imageAsFile_enabled() {
+    await doTest(true);
+  });
+
+  add_task(async function test_imageAsFile_disabled() {
+    await doTest(false);
+  });
+
 </script>
-<body onload="doTest();">
+<body>
   <img id="image" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAD4AAABHCA
   IAAADQjmMaAAAACXBIWXMAAAsTAAALEwEAmpwYAAAAB3RJTUUH3goUAwAgSAORBwAAABl0RVh0Q29
   tbWVudABDcmVhdGVkIHdpdGggR0lNUFeBDhcAAABPSURBVGje7c4BDQAACAOga//OmuMbJGAurTbq

dom/events/test/mochitest.toml

@@ -483,12 +483,6 @@ support-files = ["window_empty_document.html"]
 
 ["test_passive_listeners.html"]
 
-["test_paste_image.html"]
-skip-if = [
-  "headless", # Bug 1405869
-  "os == 'android'", # Image type isn't supported
-]
-
 ["test_scroll_per_page.html"]
 support-files = ["window_empty_document.html"]
 skip-if = ["os == 'android'"] # fail

modules/libpref/init/StaticPrefList.yaml

@@ -1857,6 +1857,12 @@
     type: bool
     value: false
     mirror: always
+
+  # Whether to put a file promise onto the clipboard when copying images on Windows
+-   name: clipboard.imageAsFile.enabled
+    type: bool
+    value: @IS_NOT_EARLY_BETA_OR_EARLIER@
+    mirror: always
 #endif
 
 #---------------------------------------------------------------------------

uriloader/exthandler/tests/mochitest/browser_save_filenames.js

@@ -372,7 +372,10 @@ if (AppConstants.platform != "macosx") {
 
 // This test checks that copying an image provides the right filename
 // for pasting to the local file system. This is only implemented on Windows.
-if (AppConstants.platform == "win") {
+const imageAsFileEnabled = SpecialPowers.getBoolPref(
+  "clipboard.imageAsFile.enabled"
+);
+if (AppConstants.platform == "win" && imageAsFileEnabled) {
   add_task(async function copy_image() {
     for (let idx = 0; idx < expectedItems.length; idx++) {
       if (!expectedItems[idx].draggable) {