Move and re-use the stripPath helper function more

There's a couple of spots that essentially re-implement that function.

src/core/file_spec.js

@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-import { stringToPDFString, warn } from "../shared/util.js";
+import { stringToPDFString, stripPath, warn } from "../shared/util.js";
 import { BaseStream } from "./base_stream.js";
 import { Dict } from "./primitives.js";
 
@@ -29,10 +29,6 @@ function pickPlatformItem(dict) {
   return null;
 }
 
-function stripPath(str) {
-  return str.substring(str.lastIndexOf("/") + 1);
-}
-
 /**
  * "A PDF file can refer to the contents of another file by using a File
  * Specification (PDF 1.1)", see the spec (7.11) for more details.

src/display/display_utils.js

@@ -19,6 +19,7 @@ import {
   FeatureTest,
   MathClamp,
   shadow,
+  stripPath,
   Util,
   warn,
 } from "../shared/util.js";
@@ -325,7 +326,7 @@ function isPdfFile(filename) {
  */
 function getFilenameFromUrl(url) {
   [url] = url.split(/[#?]/, 1);
-  return url.substring(url.lastIndexOf("/") + 1);
+  return stripPath(url);
 }
 
 /**
@@ -375,7 +376,7 @@ function getPdfFilenameFromUrl(url, defaultFilename = "document.pdf") {
     try {
       let decoded = decodeURIComponent(name);
       if (decoded.includes("/")) {
-        decoded = decoded.split("/").at(-1);
+        decoded = stripPath(decoded);
         if (decoded.test(/^\.pdf$/i)) {
           return decoded;
         }
@@ -388,7 +389,7 @@ function getPdfFilenameFromUrl(url, defaultFilename = "document.pdf") {
   };
 
   const pdfRegex = /\.pdf$/i;
-  const filename = newURL.pathname.split("/").at(-1);
+  const filename = stripPath(newURL.pathname);
   if (pdfRegex.test(filename)) {
     return decode(filename);
   }

src/shared/util.js

@@ -475,6 +475,11 @@ function updateUrlHash(url, hash, allowRel = false) {
   return "";
 }
 
+// Extract the final component from a path string.
+function stripPath(str) {
+  return str.substring(str.lastIndexOf("/") + 1);
+}
+
 function shadow(obj, prop, value, nonSerializable = false) {
   if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
     assert(
@@ -1343,6 +1348,7 @@ export {
   stringToBytes,
   stringToPDFString,
   stringToUTF8String,
+  stripPath,
   TextRenderingMode,
   UnknownErrorException,
   unreachable,