From 107eaef45efce970fe3942ed4153fd2f55610faf Mon Sep 17 00:00:00 2001
From: Tilman Hausherr <tilman@apache.org>
Date: Sun, 25 Aug 2024 10:54:03 +0000
Subject: [PATCH] =?UTF-8?q?PDFBOX-5872:=20avoid=20NPE=20on=20image=20libra?=
 =?UTF-8?q?ry=20/=20allow=20JPEG2000=20library=20that=20doesn't=20support?=
 =?UTF-8?q?=20raster,=20by=20G=C3=83=C2=A1bor=20Stefanik;=20closes=20#197?=
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git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1920175 13f79535-47bb-0310-9956-ffa450edef68
---
 .../org/apache/pdfbox/filter/DCTFilter.java   |  2 +-
 .../java/org/apache/pdfbox/filter/Filter.java | 32 +++++++++++++++++--
 .../pdmodel/graphics/image/JPEGFactory.java   |  4 +--
 3 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/pdfbox/src/main/java/org/apache/pdfbox/filter/DCTFilter.java b/pdfbox/src/main/java/org/apache/pdfbox/filter/DCTFilter.java
index b69822054a3..cb8b3322044 100644
--- a/pdfbox/src/main/java/org/apache/pdfbox/filter/DCTFilter.java
+++ b/pdfbox/src/main/java/org/apache/pdfbox/filter/DCTFilter.java
@@ -59,7 +59,7 @@ final class DCTFilter extends Filter
     public DecodeResult decode(InputStream encoded, OutputStream decoded, COSDictionary
             parameters, int index, DecodeOptions options) throws IOException
     {
-        ImageReader reader = findImageReader("JPEG", "a suitable JAI I/O image filter is not installed");
+        ImageReader reader = findRasterReader("JPEG", "a suitable JAI I/O image filter is not installed");
         try (ImageInputStream iis = ImageIO.createImageInputStream(encoded))
         {
 
diff --git a/pdfbox/src/main/java/org/apache/pdfbox/filter/Filter.java b/pdfbox/src/main/java/org/apache/pdfbox/filter/Filter.java
index b6f521cd061..8e9824d88fc 100644
--- a/pdfbox/src/main/java/org/apache/pdfbox/filter/Filter.java
+++ b/pdfbox/src/main/java/org/apache/pdfbox/filter/Filter.java
@@ -149,7 +149,7 @@ else if (obj != null && !(filter instanceof COSArray || obj instanceof COSArray)
     }
 
     /**
-     * Finds a suitable image raster reader for an image format.
+     * Finds a suitable image reader for an image format.
      *
      * @param formatName The image format to search for.
      * @param errorCause The probably cause if something goes wrong.
@@ -163,11 +163,37 @@ public static final ImageReader findImageReader(String formatName, String errorC
         while (readers.hasNext())
         {
             ImageReader reader = readers.next();
-            if (reader.canReadRaster())
+            if (reader != null)
             {
                 return reader;
             }
-            reader.dispose();
+        }
+        throw new MissingImageReaderException("Cannot read " + formatName + " image: " + errorCause);
+    }
+
+    /**
+     * Finds a suitable image raster reader for an image format.
+     *
+     * @param formatName The image format to search for.
+     * @param errorCause The probably cause if something goes wrong.
+     * @return The image reader for the format.
+     * @throws MissingImageReaderException if no image reader is found.
+     */
+    public static final ImageReader findRasterReader(String formatName, String errorCause)
+            throws MissingImageReaderException
+    {
+        Iterator<ImageReader> readers = ImageIO.getImageReadersByFormatName(formatName);
+        while (readers.hasNext())
+        {
+            ImageReader reader = readers.next();
+            if (reader != null)
+            {
+                if (reader.canReadRaster())
+                {
+                    return reader;
+                }
+                reader.dispose();
+            }
         }
         throw new MissingImageReaderException("Cannot read " + formatName + " image: " + errorCause);
     }
diff --git a/pdfbox/src/main/java/org/apache/pdfbox/pdmodel/graphics/image/JPEGFactory.java b/pdfbox/src/main/java/org/apache/pdfbox/pdmodel/graphics/image/JPEGFactory.java
index 9c9563363eb..f71e3c08b35 100644
--- a/pdfbox/src/main/java/org/apache/pdfbox/pdmodel/graphics/image/JPEGFactory.java
+++ b/pdfbox/src/main/java/org/apache/pdfbox/pdmodel/graphics/image/JPEGFactory.java
@@ -148,7 +148,7 @@ private static class Dimensions
     private static Dimensions retrieveDimensions(ByteArrayInputStream stream) throws IOException
     {
         ImageReader reader =
-                Filter.findImageReader("JPEG", "a suitable JAI I/O image filter is not installed");
+                Filter.findRasterReader("JPEG", "a suitable JAI I/O image filter is not installed");
         try (ImageInputStream iis = ImageIO.createImageInputStream(stream))
         {
             reader.setInput(iis);
@@ -169,7 +169,7 @@ private static Dimensions retrieveDimensions(ByteArrayInputStream stream) throws
             catch (IOException ex)
             {
                 LOG.warn("Error reading image metadata, will decode image and use raster size");
-            }            
+            }
 
             // Old method: get from raster (slower)
             ImageIO.setUseCache(false);