Craig Kelly created IMAGING-88:
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Summary: Method lowerBound in
org.apache.commons.imaging.common.itu_t4.T4AndT6Compression has a division error
Key: IMAGING-88
URL: https://issues.apache.org/jira/browse/IMAGING-88
Project: Commons Imaging
Issue Type: Bug
Components: Format: TIFF
Affects Versions: 1.0
Reporter: Craig Kelly
In method lowerBound in the class
org.apache.commons.imaging.common.itu_t4.T4AndT6Compression, the binary search
loop uses:
int middle = (first + last) >>> 2;
To find a mid-point for the search. However, the bit-shift is causing a divide
by 4. At best this produces bad results, and at worst causes an infinite loop
(which is how I found the error). A simple patch to fix is:
Index:
src/main/java/org/apache/commons/imaging/common/itu_t4/T4AndT6Compression.java
===================================================================
---
src/main/java/org/apache/commons/imaging/common/itu_t4/T4AndT6Compression.java
(revision 1363019)
+++
src/main/java/org/apache/commons/imaging/common/itu_t4/T4AndT6Compression.java
(working copy)
@@ -720,7 +720,7 @@
int first = 0;
int last = entries.length - 1;
do {
- int middle = (first + last) >>> 2;
+ int middle = (first + last) >>> 1; //2;
if (entries[middle].value.intValue() <= value
&& ((middle + 1) >= entries.length || value <
entries[middle + 1].value
.intValue())) {
--
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