From c4c72161718f87bd5bce96a396f55c5c8db75fc6 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Tue, 16 Mar 2021 11:56:39 +0100
Subject: [PATCH] Improve memory usage around the `BasePdfManager.docBaseUrl`
 parameter (PR 7689 follow-up)

While there is nothing *outright* wrong with the existing implementation, it can however lead to increased memory usage in one particular case (that I completely overlooked when implementing this):
For "data:"-URLs, which by definition contains the entire PDF document and can thus be arbitrarily large, we obviously want to avoid sending, storing, and/or logging the "raw" docBaseUrl in that case.

To address this, this patch makes the following changes:
 - Ignore any non-string in the `docBaseUrl` option passed to `getDocument`, since those are unsupported anyway, already on the main-thread.

 - Ignore "data:"-URLs in the `docBaseUrl` option passed to `getDocument`, to avoid having to send what could potentially be a *very* long string to the worker-thread.

 - Parse the `docBaseUrl` option *directly* in the `BasePdfManager`-constructors, on the worker-thread, to avoid having to store the "raw" docBaseUrl in the first place.
---
 src/core/pdf_manager.js      | 33 +++++++++++++++------------------
 src/display/api.js           | 10 ++++++++++
 src/display/display_utils.js |  1 +
 3 files changed, 26 insertions(+), 18 deletions(-)

diff --git a/src/core/pdf_manager.js b/src/core/pdf_manager.js
index 1cdcc03fa..33dee308c 100644
--- a/src/core/pdf_manager.js
+++ b/src/core/pdf_manager.js
@@ -13,17 +13,23 @@
  * limitations under the License.
  */
 
-import {
-  createValidAbsoluteUrl,
-  shadow,
-  unreachable,
-  warn,
-} from "../shared/util.js";
+import { createValidAbsoluteUrl, unreachable, warn } from "../shared/util.js";
 import { ChunkedStreamManager } from "./chunked_stream.js";
 import { MissingDataException } from "./core_utils.js";
 import { PDFDocument } from "./document.js";
 import { Stream } from "./stream.js";
 
+function parseDocBaseUrl(url) {
+  if (url) {
+    const absoluteUrl = createValidAbsoluteUrl(url);
+    if (absoluteUrl) {
+      return absoluteUrl.href;
+    }
+    warn(`Invalid absolute docBaseUrl: "${url}".`);
+  }
+  return null;
+}
+
 class BasePdfManager {
   constructor() {
     if (this.constructor === BasePdfManager) {
@@ -40,16 +46,7 @@ class BasePdfManager {
   }
 
   get docBaseUrl() {
-    let docBaseUrl = null;
-    if (this._docBaseUrl) {
-      const absoluteUrl = createValidAbsoluteUrl(this._docBaseUrl);
-      if (absoluteUrl) {
-        docBaseUrl = absoluteUrl.href;
-      } else {
-        warn(`Invalid absolute docBaseUrl: "${this._docBaseUrl}".`);
-      }
-    }
-    return shadow(this, "docBaseUrl", docBaseUrl);
+    return this._docBaseUrl;
   }
 
   onLoadedStream() {
@@ -111,7 +108,7 @@ class LocalPdfManager extends BasePdfManager {
 
     this._docId = docId;
     this._password = password;
-    this._docBaseUrl = docBaseUrl;
+    this._docBaseUrl = parseDocBaseUrl(docBaseUrl);
     this.evaluatorOptions = evaluatorOptions;
 
     const stream = new Stream(data);
@@ -146,7 +143,7 @@ class NetworkPdfManager extends BasePdfManager {
 
     this._docId = docId;
     this._password = args.password;
-    this._docBaseUrl = docBaseUrl;
+    this._docBaseUrl = parseDocBaseUrl(docBaseUrl);
     this.msgHandler = args.msgHandler;
     this.evaluatorOptions = evaluatorOptions;
 
diff --git a/src/display/api.js b/src/display/api.js
index 690193ade..9f779214b 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -40,6 +40,7 @@ import {
   deprecated,
   DOMCanvasFactory,
   DOMCMapReaderFactory,
+  isDataScheme,
   loadScript,
   PageViewport,
   RenderingCancelledException,
@@ -285,6 +286,15 @@ function getDocument(src) {
   params.fontExtraProperties = params.fontExtraProperties === true;
   params.pdfBug = params.pdfBug === true;
 
+  if (
+    typeof params.docBaseUrl !== "string" ||
+    isDataScheme(params.docBaseUrl)
+  ) {
+    // Ignore "data:"-URLs, since they can't be used to recover valid absolute
+    // URLs anyway. We want to avoid sending them to the worker-thread, since
+    // they contain the *entire* PDF document and can thus be arbitrarily long.
+    params.docBaseUrl = null;
+  }
   if (!Number.isInteger(params.maxImageSize)) {
     params.maxImageSize = -1;
   }
diff --git a/src/display/display_utils.js b/src/display/display_utils.js
index 3cb0da278..4e23ec876 100644
--- a/src/display/display_utils.js
+++ b/src/display/display_utils.js
@@ -708,6 +708,7 @@ export {
   DOMSVGFactory,
   getFilenameFromUrl,
   getPdfFilenameFromUrl,
+  isDataScheme,
   isFetchSupported,
   isPdfFile,
   isValidFetchUrl,