(tomcat) 02/02: Replace the unused buffer with a zero length, static instance.

[ma...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

markt pushed a commit to branch 10.1.x
in repository https://gitbox.apache.org/repos/asf/tomcat.git

commit 152c5259ef48a0ad768193d90c974125c59ac089
Author: Mark Thomas <ma...@apache.org>
AuthorDate: Thu Jan 9 15:19:00 2025 +0000

    Replace the unused buffer with a zero length, static instance.
---
 java/org/apache/catalina/connector/InputBuffer.java | 19 ++++++++++++++-----
 webapps/docs/changelog.xml                          |  5 +++++
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/java/org/apache/catalina/connector/InputBuffer.java b/java/org/apache/catalina/connector/InputBuffer.java
index b5e6a38088..2de7d243af 100644
--- a/java/org/apache/catalina/connector/InputBuffer.java
+++ b/java/org/apache/catalina/connector/InputBuffer.java
@@ -60,6 +60,8 @@ public class InputBuffer extends Reader implements ByteChunk.ByteInputChannel, A
 
     private static final Log log = LogFactory.getLog(InputBuffer.class);
 
+    private static final ByteBuffer EMPTY_BUFFER = ByteBuffer.allocate(0);
+
     public static final int DEFAULT_BUFFER_SIZE = 8 * 1024;
 
     // The buffer can be used for byte[] and char[] reading
@@ -76,8 +78,11 @@ public class InputBuffer extends Reader implements ByteChunk.ByteInputChannel, A
 
     // ----------------------------------------------------- Instance Variables
 
-    /**
-     * The byte buffer.
+    /*
+     * The byte buffer. Data is always injected into this class by calling {@link #setByteBuffer(ByteBuffer)} rather
+     * than copying data into any existing buffer. It is initialised to an empty buffer as there are code paths that
+     * access the buffer when it is expected to be empty and an empty buffer gives cleaner code than lots of null
+     * checks.
      */
     private ByteBuffer bb;
 
@@ -151,8 +156,8 @@ public class InputBuffer extends Reader implements ByteChunk.ByteInputChannel, A
     public InputBuffer(int size) {
 
         this.size = size;
-        bb = ByteBuffer.allocate(size);
-        clear(bb);
+        // Will be replaced when there is data to read so initialise to empty buffer.
+        bb = EMPTY_BUFFER;
         cb = CharBuffer.allocate(size);
         clear(cb);
         readLimit = size;
@@ -191,7 +196,11 @@ public class InputBuffer extends Reader implements ByteChunk.ByteInputChannel, A
         }
         readLimit = size;
         markPos = -1;
-        clear(bb);
+        /*
+         * This buffer will have been replaced if there was data to read so re-initialise to an empty buffer to clear
+         * any reference to an injected buffer.
+         */
+        bb = EMPTY_BUFFER;
         closed = false;
 
         if (conv != null) {
diff --git a/webapps/docs/changelog.xml b/webapps/docs/changelog.xml
index f6e77ef9bf..4424d5e404 100644
--- a/webapps/docs/changelog.xml
+++ b/webapps/docs/changelog.xml
@@ -133,6 +133,11 @@
         <pr>843</pr>: Fix off by one validation logic for partial PUT ranges
         and associated test case. Submitted by Chenjp. (remm)
       </fix>
+      <scode>
+        Replace the unused buffer in
+        <code>org.apache.catalina.connector.InputBuffer</code> with a static,
+        zero length buffer. (markt)
+      </scode>
     </changelog>
   </subsection>
   <subsection name="Coyote">


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