[api-minor] Support the Content-Disposition filename in the Firefox PDF Viewer (bug 1694556, PR 9379 follow-up)

As can be seen [in the mozilla-central code](https://searchfox.org/mozilla-central/rev/a6db3bd67367aa9ddd9505690cab09b47e65a762/toolkit/components/pdfjs/content/PdfStreamConverter.jsm#1222-1225), we're already getting the Content-Disposition filename. However, that data isn't passed through to the viewer nor to the `PDFDataTransportStream`-implementation, which explains why it's currently being ignored.

*Please note:* This will also require a small mozilla-central patch, see https://bugzilla.mozilla.org/show_bug.cgi?id=1694556, to forward the necessary data to the viewer.

src/display/api.js

@@ -334,6 +334,7 @@ function getDocument(src) {
               length: params.length,
               initialData: params.initialData,
               progressiveDone: params.progressiveDone,
+              contentDispositionFilename: params.contentDispositionFilename,
               disableRange: params.disableRange,
               disableStream: params.disableStream,
             },
@@ -401,6 +402,8 @@ function _fetchDocument(worker, source, pdfDataRangeTransport, docId) {
     source.length = pdfDataRangeTransport.length;
     source.initialData = pdfDataRangeTransport.initialData;
     source.progressiveDone = pdfDataRangeTransport.progressiveDone;
+    source.contentDispositionFilename =
+      pdfDataRangeTransport.contentDispositionFilename;
   }
   return worker.messageHandler
     .sendWithPromise("GetDocRequest", {
@@ -554,11 +557,18 @@ class PDFDataRangeTransport {
    * @param {number} length
    * @param {Uint8Array} initialData
    * @param {boolean} [progressiveDone]
+   * @param {string} [contentDispositionFilename]
    */
-  constructor(length, initialData, progressiveDone = false) {
+  constructor(
+    length,
+    initialData,
+    progressiveDone = false,
+    contentDispositionFilename = null
+  ) {
     this.length = length;
     this.initialData = initialData;
     this.progressiveDone = progressiveDone;
+    this.contentDispositionFilename = contentDispositionFilename;
 
     this._rangeListeners = [];
     this._progressListeners = [];

src/display/display_utils.js

@@ -451,6 +451,10 @@ function addLinkAttributes(link, { url, target, rel, enabled = true } = {}) {
   link.rel = typeof rel === "string" ? rel : DEFAULT_LINK_REL;
 }
 
+function isPdfFile(filename) {
+  return typeof filename === "string" && /\.pdf$/i.test(filename);
+}
+
 /**
  * Gets the file name from a given URL.
  * @param {string} url
@@ -652,6 +656,7 @@ export {
   DOMSVGFactory,
   getFilenameFromUrl,
   isFetchSupported,
+  isPdfFile,
   isValidFetchUrl,
   LinkTarget,
   loadScript,

src/display/network_utils.js

@@ -19,6 +19,7 @@ import {
   UnexpectedResponseException,
 } from "../shared/util.js";
 import { getFilenameFromContentDispositionHeader } from "./content_disposition.js";
+import { isPdfFile } from "./display_utils.js";
 
 function validateRangeRequestCapabilities({
   getResponseHeader,
@@ -70,7 +71,7 @@ function extractFilenameFromHeader(getResponseHeader) {
         filename = decodeURIComponent(filename);
       } catch (ex) {}
     }
-    if (/\.pdf$/i.test(filename)) {
+    if (isPdfFile(filename)) {
       return filename;
     }
   }
@@ -82,11 +83,7 @@ function createResponseStatusError(status, url) {
     return new MissingPDFException('Missing PDF "' + url + '".');
   }
   return new UnexpectedResponseException(
-    "Unexpected server response (" +
-      status +
-      ') while retrieving PDF "' +
-      url +
-      '".',
+    `Unexpected server response (${status}) while retrieving PDF "${url}".`,
     status
   );
 }

src/display/transport_stream.js

@@ -14,6 +14,7 @@
  */
 
 import { assert, createPromiseCapability } from "../shared/util.js";
+import { isPdfFile } from "./display_utils.js";
 
 /** @implements {IPDFStream} */
 class PDFDataTransportStream {
@@ -25,6 +26,8 @@ class PDFDataTransportStream {
 
     this._queuedChunks = [];
     this._progressiveDone = params.progressiveDone || false;
+    this._contentDispositionFilename =
+      params.contentDispositionFilename || null;
 
     const initialData = params.initialData;
     if (initialData?.length > 0) {
@@ -125,7 +128,8 @@ class PDFDataTransportStream {
     return new PDFDataTransportStreamReader(
       this,
       queuedChunks,
-      this._progressiveDone
+      this._progressiveDone,
+      this._contentDispositionFilename
     );
   }
 
@@ -153,10 +157,17 @@ class PDFDataTransportStream {
 
 /** @implements {IPDFStreamReader} */
 class PDFDataTransportStreamReader {
-  constructor(stream, queuedChunks, progressiveDone = false) {
+  constructor(
+    stream,
+    queuedChunks,
+    progressiveDone = false,
+    contentDispositionFilename = null
+  ) {
     this._stream = stream;
     this._done = progressiveDone || false;
-    this._filename = null;
+    this._filename = isPdfFile(contentDispositionFilename)
+      ? contentDispositionFilename
+      : null;
     this._queuedChunks = queuedChunks || [];
     this._loaded = 0;
     for (const chunk of this._queuedChunks) {

src/pdf.js

@@ -18,6 +18,7 @@ import {
   addLinkAttributes,
   getFilenameFromUrl,
   isFetchSupported,
+  isPdfFile,
   isValidFetchUrl,
   LinkTarget,
   loadScript,
@@ -128,6 +129,7 @@ export {
   // From "./display/display_utils.js":
   addLinkAttributes,
   getFilenameFromUrl,
+  isPdfFile,
   LinkTarget,
   loadScript,
   PDFDateString,