Bug 1180715 (2/4) - Provide a nsIFileURL interface for thumbnails. review=ttaubert

Use nsISubstitutingProtocolHandler to return a SubstitutingURL and to
resolve the thumbnail URL to the backing nsIFile.

Now the image loader code will realise that moz-page-thumb:// URLs are
backed by a file and will be able to use the file mtime to evaluate
whether the cached imgRequest has expired.

* Implement the nsISubstitutingProtocolHandler methods in the thumbnail
protocol handler. The resolveURI method does all the work, the other
methods are just stubs.

* moz-page-thumb:// is now an URL rather than an URI, so update the
signature accordingly.

* Add xpcshell-test to affirm that SubstitutingURL::EnsureFile()
resolves the backing file correctly.

* Adjust the mochitest to account for the one second granularity of the
mtime tracking.

toolkit/components/thumbnails/PageThumbs.jsm

@@ -158,7 +158,7 @@ this.PageThumbs = {
    */
   getThumbnailURL: function PageThumbs_getThumbnailURL(aUrl) {
     return this.scheme + "://" + this.staticHost +
-           "?url=" + encodeURIComponent(aUrl);
+           "/?url=" + encodeURIComponent(aUrl);
   },
 
    /**

toolkit/components/thumbnails/PageThumbsProtocol.js

@@ -10,7 +10,7 @@
  *
  * URL structure:
  *
- * moz-page-thumb://thumbnail?url=http%3A%2F%2Fwww.mozilla.org%2F
+ * moz-page-thumb://thumbnail/?url=http%3A%2F%2Fwww.mozilla.org%2F
  *
  * This URL requests an image for 'http://www.mozilla.org/'.
  */
@@ -24,14 +24,17 @@ const Ci = Components.interfaces;
 
 Cu.import("resource://gre/modules/PageThumbs.jsm");
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/osfile.jsm", this);
 
 XPCOMUtils.defineLazyModuleGetter(this, "Services",
   "resource://gre/modules/Services.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "FileUtils",
   "resource://gre/modules/FileUtils.jsm");
 
+const SUBSTITUTING_URL_CID = "{dea9657c-18cf-4984-bde9-ccef5d8ab473}";
+
 /**
- * Implements the thumbnail protocol handler responsible for moz-page-thumb: URIs.
+ * Implements the thumbnail protocol handler responsible for moz-page-thumb: URLs.
  */
 function Protocol() {
 }
@@ -68,7 +71,7 @@ Protocol.prototype = {
    * @return The newly created URI.
    */
   newURI: function Proto_newURI(aSpec, aOriginCharset) {
-    let uri = Cc["@mozilla.org/network/simple-uri;1"].createInstance(Ci.nsIURI);
+    let uri = Components.classesByID[SUBSTITUTING_URL_CID].createInstance(Ci.nsIURL);
     uri.spec = aSpec;
     return uri;
   },
@@ -98,8 +101,37 @@ Protocol.prototype = {
    */
   allowPort: () => false,
 
+  // nsISubstitutingProtocolHandler methods
+
+  /*
+   * Substituting the scheme and host isn't enough, we also transform the path.
+   * So declare no-op implementations for (get|set|has)Substitution methods and
+   * do all the work in resolveURI.
+   */
+
+  setSubstitution(root, baseURI) {},
+
+  getSubstitution(root) {
+    throw Cr.NS_ERROR_NOT_AVAILABLE;
+  },
+
+  hasSubstitution(root) {
+    return false;
+  },
+
+  resolveURI(resURI) {
+    if (resURI.host != PageThumbs.staticHost)
+      throw Cr.NS_ERROR_NOT_AVAILABLE;
+
+    let {url} = parseURI(resURI);
+    let path = PageThumbsStorage.getFilePathForURL(url);
+    return OS.Path.toFileURI(path);
+  },
+
+  // xpcom machinery
   classID: Components.ID("{5a4ae9b5-f475-48ae-9dce-0b4c1d347884}"),
-  QueryInterface: XPCOMUtils.generateQI([Ci.nsIProtocolHandler])
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIProtocolHandler,
+                                         Ci.nsISubstitutingProtocolHandler])
 };
 
 this.NSGetFactory = XPCOMUtils.generateNSGetFactory([Protocol]);

toolkit/components/thumbnails/moz.build

@@ -5,6 +5,7 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']
+XPCSHELL_TESTS_MANIFESTS += ['test/xpcshell.ini']
 
 EXTRA_COMPONENTS += [
     'BrowserPageThumbs.manifest',

toolkit/components/thumbnails/test/browser_thumbnails_update.js

@@ -88,6 +88,11 @@ function capIfStaleErrorResponseUpdateTest() {
   yield addTab(URL);
 
   yield captureAndCheckColor(0, 255, 0, "we have a green thumbnail");
+
+  // image cache entry timestamps have second resolution
+  // so make sure the second part of this test takes part in a different second.
+  yield wait(2000);
+
   // update the thumbnail to be stale, then re-request it.  The server will
   // return a 400 response and a red thumbnail.
   // The service should not save the thumbnail - so we (a) check the thumbnail
@@ -119,6 +124,11 @@ function capIfStaleGoodResponseUpdateTest() {
   let browser = gBrowser.selectedBrowser;
 
   yield captureAndCheckColor(0, 255, 0, "we have a green thumbnail");
+
+  // image cache entry timestamps have second resolution
+  // so make sure the second part of this test takes part in a different second.
+  yield wait(2000);
+
   // update the thumbnail to be stale, then re-request it.  The server will
   // return a 200 response and a red thumbnail - so that new thumbnail should
   // end up captured.
@@ -148,6 +158,11 @@ function regularCapErrorResponseUpdateTest() {
   yield addTab(URL);
   yield captureAndCheckColor(0, 255, 0, "we have a green thumbnail");
   gBrowser.removeTab(gBrowser.selectedTab);
+
+  // image cache entry timestamps have second resolution
+  // so make sure the second part of this test takes part in a different second.
+  yield wait(2000);
+
   // do it again - the server will return a 400, so the foreground service
   // should not update it.
   yield addTab(URL);
@@ -162,6 +177,11 @@ function regularCapGoodResponseUpdateTest() {
   yield addTab(URL);
   yield captureAndCheckColor(0, 255, 0, "we have a green thumbnail");
   gBrowser.removeTab(gBrowser.selectedTab);
+
+  // image cache entry timestamps have second resolution
+  // so make sure the second part of this test takes part in a different second.
+  yield wait(2000);
+
   // do it again - the server will return a 200, so the foreground service
   // should  update it.
   yield addTab(URL);

toolkit/components/thumbnails/test/test_thumbnails_interfaces.js

@@ -0,0 +1,31 @@
+// tests to check that moz-page-thumb URLs correctly resolve as file:// URLS
+"use strict";
+
+const Cu = Components.utils;
+const Cc = Components.classes;
+const Cr = Components.results;
+const Ci = Components.interfaces;
+
+Cu.import("resource://gre/modules/Services.jsm");
+
+// need profile so that PageThumbsStorage can resolve the path to the underlying file
+do_get_profile();
+
+function run_test() {
+  // first check the protocol handler implements the correct interface
+  let handler = Services.io.getProtocolHandler("moz-page-thumb");
+  ok(handler instanceof Ci.nsISubstitutingProtocolHandler,
+     "moz-page-thumb handler provides substituting interface");
+
+  // then check that the file URL resolution works
+  let uri = Services.io.newURI("moz-page-thumb://thumbnail/?url=http%3A%2F%2Fwww.mozilla.org%2F",
+                               null, null);
+  ok(uri instanceof Ci.nsIFileURL, "moz-page-thumb:// is a FileURL");
+  ok(uri.file, "This moz-page-thumb:// object is backed by a file");
+
+  // and check that the error case works as specified
+  let bad = Services.io.newURI("moz-page-thumb://wronghost/?url=http%3A%2F%2Fwww.mozilla.org%2F",
+                               null, null);
+  Assert.throws(() => handler.resolveURI(bad), /NS_ERROR_NOT_AVAILABLE/i,
+                "moz-page-thumb object with wrong host must not resolve to a file path");
+}

toolkit/components/thumbnails/test/xpcshell.ini

@@ -0,0 +1,6 @@
+[DEFAULT]
+head =
+tail =
+
+[test_thumbnails_interfaces.js]
+skip-if = os == 'b2g' || os == 'android' # xpcom interface not packaged