Handle JPX wasm fetch-response errors correctly (PR 19329 follow-up)

Currently we're not checking that the response is actually OK before getting the data, which means that rather than throwing an error we can get an empty `ArrayBuffer`.

To avoid duplicating code we can move an existing helper into `src/core/core_utils.js` and re-use it when fetching the JPX wasm-file as well.

src/core/core_utils.js

@@ -103,6 +103,16 @@ function arrayBuffersToBytes(arr) {
   return data;
 }
 
+async function fetchBinaryData(url) {
+  const response = await fetch(url);
+  if (!response.ok) {
+    throw new Error(
+      `Failed to fetch file "${url}" with "${response.statusText}".`
+    );
+  }
+  return new Uint8Array(await response.arrayBuffer());
+}
+
 /**
  * Get the value of an inheritable property.
  *
@@ -701,6 +711,7 @@ export {
   encodeToXmlString,
   escapePDFName,
   escapeString,
+  fetchBinaryData,
   getInheritableProperty,
   getLookupTableFactory,
   getNewAnnotationsMap,

src/core/evaluator.js

@@ -32,6 +32,12 @@ import {
 import { CMapFactory, IdentityCMap } from "./cmap.js";
 import { Cmd, Dict, EOF, isName, Name, Ref, RefSet } from "./primitives.js";
 import { ErrorFont, Font } from "./fonts.js";
+import {
+  fetchBinaryData,
+  isNumberArray,
+  lookupMatrix,
+  lookupNormalRect,
+} from "./core_utils.js";
 import {
   getEncoding,
   MacRomanEncoding,
@@ -51,7 +57,6 @@ import {
 import { getTilingPatternIR, Pattern } from "./pattern.js";
 import { getXfaFontDict, getXfaFontName } from "./xfa_fonts.js";
 import { IdentityToUnicodeMap, ToUnicodeMap } from "./to_unicode_map.js";
-import { isNumberArray, lookupMatrix, lookupNormalRect } from "./core_utils.js";
 import { isPDFFunction, PDFFunctionFactory } from "./function.js";
 import { Lexer, Parser } from "./parser.js";
 import {
@@ -382,16 +387,6 @@ class PartialEvaluator {
     return false;
   }
 
-  async #fetchData(url) {
-    const response = await fetch(url);
-    if (!response.ok) {
-      throw new Error(
-        `Failed to fetch file "${url}" with "${response.statusText}".`
-      );
-    }
-    return new Uint8Array(await response.arrayBuffer());
-  }
-
   async fetchBuiltInCMap(name) {
     const cachedData = this.builtInCMapCache.get(name);
     if (cachedData) {
@@ -401,7 +396,7 @@ class PartialEvaluator {
 
     if (this.options.cMapUrl !== null) {
       // Only compressed CMaps are (currently) supported here.
-      const cMapData = await this.#fetchData(
+      const cMapData = await fetchBinaryData(
         `${this.options.cMapUrl}${name}.bcmap`
       );
       data = { cMapData, isCompressed: true };
@@ -437,7 +432,7 @@ class PartialEvaluator {
 
     try {
       if (this.options.standardFontDataUrl !== null) {
-        data = await this.#fetchData(
+        data = await fetchBinaryData(
           `${this.options.standardFontDataUrl}${filename}`
         );
       } else {

src/core/jpx.js

@@ -14,6 +14,7 @@
  */
 
 import { BaseException, warn } from "../shared/util.js";
+import { fetchBinaryData } from "./core_utils.js";
 import OpenJPEG from "../../external/openjpeg/openjpeg.js";
 import { Stream } from "./stream.js";
 
@@ -44,14 +45,14 @@ class JpxImage {
   }
 
   static async #instantiateWasm(imports, successCallback) {
+    const filename = "openjpeg.wasm";
     try {
       if (!this.#buffer) {
         if (this.#wasmUrl !== null) {
-          const response = await fetch(`${this.#wasmUrl}openjpeg.wasm`);
+          this.#buffer = await fetchBinaryData(`${this.#wasmUrl}${filename}`);
-          this.#buffer = await response.arrayBuffer();
         } else {
           this.#buffer = await this.#handler.sendWithPromise("FetchWasm", {
-            filename: "openjpeg.wasm",
+            filename,
           });
         }
       }
@@ -59,7 +60,7 @@ class JpxImage {
       return successCallback(results.instance);
     } catch (e) {
       this.#instantiationFailed = true;
-      warn(`Cannot load openjpeg.wasm: "${e}".`);
+      warn(`Cannot load ${filename}: "${e}".`);
       return false;
     } finally {
       this.#handler = null;