Merge pull request #17363 from Snuffleupagus/issue-17353

[Firefox] Restore opening of PDF attachments (issue 17353, bug 1867764)

web/firefoxcom.js

@@ -112,9 +112,11 @@ class DownloadManager {
         this.#openBlobUrls.set(data, blobUrl);
       }
       // Let Firefox's content handler catch the URL and display the PDF.
-      let viewerUrl = blobUrl + "?filename=" + encodeURIComponent(filename);
+      // NOTE: This cannot use a query string for the filename, see
+      //       https://bugzilla.mozilla.org/show_bug.cgi?id=1632644#c5
+      let viewerUrl = blobUrl + "#filename=" + encodeURIComponent(filename);
       if (dest) {
-        viewerUrl += `#${escape(dest)}`;
+        viewerUrl += `&filedest=${escape(dest)}`;
       }
 
       try {

web/pdf_link_service.js

@@ -431,7 +431,19 @@ class PDFLinkService {
       if (params.has("nameddest")) {
         this.goToDestination(params.get("nameddest"));
       }
-    } else {
+
+      if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("MOZCENTRAL")) {
+        return;
+      }
+      // Support opening of PDF attachments in the Firefox PDF Viewer,
+      // which uses a couple of non-standard hash parameters; refer to
+      // `DownloadManager.openOrDownloadData` in the firefoxcom.js file.
+      if (!params.has("filename") || !params.has("filedest")) {
+        return;
+      }
+      hash = params.get("filedest");
+    }
+
     // Named (or explicit) destination.
     dest = unescape(hash);
     try {
@@ -452,12 +464,9 @@ class PDFLinkService {
       return;
     }
     console.error(
-        `PDFLinkService.setHash: "${unescape(
+      `PDFLinkService.setHash: "${unescape(hash)}" is not a valid destination.`
-          hash
-        )}" is not a valid destination.`
     );
   }
-  }
 
   /**
    * @param {string} action