From 17f65908aee7a2e581b2cfd5d7766454e9b9fc1d Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sun, 15 Jul 2018 18:32:05 +0200
Subject: [PATCH] Add more validation of the /Filter entry, in image
 dictionaries, to the `PDFImage` constructor

Given that the code is currently assuming that the /Filter entry is a `Name`, it cannot hurt to actually ensure that's the case.

Also fixes an error message, for JPEG 2000 images with unsupported ColorSpaces, since `this.numComps` hasn't been initialized when it's accessed during the `throw new Error()` invocation.
---
 src/core/image.js | 31 +++++++++++++++++++------------
 src/core/jpx.js   |  2 +-
 2 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/src/core/image.js b/src/core/image.js
index 32a26d157..fd87b4271 100644
--- a/src/core/image.js
+++ b/src/core/image.js
@@ -14,7 +14,7 @@
  */
 
 import { assert, FormatError, ImageKind, info, warn } from '../shared/util';
-import { isStream, Name } from './primitives';
+import { isName, isStream, Name } from './primitives';
 import { ColorSpace } from './colorspace';
 import { DecodeStream } from './stream';
 import { JpegStream } from './jpeg_stream';
@@ -84,16 +84,23 @@ var PDFImage = (function PDFImageClosure() {
     this.image = image;
     var dict = image.dict;
     if (dict.has('Filter')) {
-      var filter = dict.get('Filter').name;
-      if (filter === 'JPXDecode') {
-        var jpxImage = new JpxImage();
-        jpxImage.parseImageProperties(image.stream);
-        image.stream.reset();
-        image.bitsPerComponent = jpxImage.bitsPerComponent;
-        image.numComps = jpxImage.componentsCount;
-      } else if (filter === 'JBIG2Decode') {
-        image.bitsPerComponent = 1;
-        image.numComps = 1;
+      const filter = dict.get('Filter');
+      if (isName(filter)) {
+        switch (filter.name) {
+          case 'JPXDecode':
+            var jpxImage = new JpxImage();
+            jpxImage.parseImageProperties(image.stream);
+            image.stream.reset();
+            image.bitsPerComponent = jpxImage.bitsPerComponent;
+            image.numComps = jpxImage.componentsCount;
+            break;
+          case 'JBIG2Decode':
+            image.bitsPerComponent = 1;
+            image.numComps = 1;
+            break;
+        }
+      } else {
+        warn(`PDFImage - invalid /Filter entry in dictionary: "${filter}".`);
       }
     }
     // TODO cache rendered images?
@@ -139,7 +146,7 @@ var PDFImage = (function PDFImageClosure() {
             colorSpace = Name.get('DeviceCMYK');
             break;
           default:
-            throw new Error(`JPX images with ${this.numComps} ` +
+            throw new Error(`JPX images with ${image.numComps} ` +
                             'color components not supported.');
         }
       }
diff --git a/src/core/jpx.js b/src/core/jpx.js
index b484f5ba4..da80ad2a3 100644
--- a/src/core/jpx.js
+++ b/src/core/jpx.js
@@ -142,7 +142,7 @@ var JpxImage = (function JpxImageClosure() {
           this.width = Xsiz - XOsiz;
           this.height = Ysiz - YOsiz;
           this.componentsCount = Csiz;
-          // Results are always returned as Uint8Arrays
+          // Results are always returned as `Uint8ClampedArray`s.
           this.bitsPerComponent = 8;
           return;
         }