(commons-io) branch master updated: [IO-871] IOUtils.contentEquals is incorrect when InputStream.available under-reports

[ggregory]

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ggregory pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/commons-io.git


The following commit(s) were added to refs/heads/master by this push:
     new bda102e36 [IO-871] IOUtils.contentEquals is incorrect when 
InputStream.available under-reports
bda102e36 is described below

commit bda102e36114d1dac58504c03b658f43a295c662
Author: Gary D. Gregory <garydgreg...@gmail.com>
AuthorDate: Sun Mar 23 09:15:42 2025 -0400

    [IO-871] IOUtils.contentEquals is incorrect when InputStream.available
    under-reports
---
 src/main/java/org/apache/commons/io/channels/FileChannels.java | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/main/java/org/apache/commons/io/channels/FileChannels.java 
b/src/main/java/org/apache/commons/io/channels/FileChannels.java
index f4d611493..3c731aba9 100644
--- a/src/main/java/org/apache/commons/io/channels/FileChannels.java
+++ b/src/main/java/org/apache/commons/io/channels/FileChannels.java
@@ -135,7 +135,7 @@ public static boolean contentEquals(final 
SeekableByteChannel channel1, final Se
      *
      * @param channel The source channel.
      * @param dst     The buffer into which bytes are to be transferred.
-     * @return The number of bytes read, possibly zero, or {@code-1} if the 
channel has reached end-of-stream
+     * @return The number of bytes read, <em>never</em> zero, or {@code -1} if 
the channel has reached end-of-stream
      * @throws IOException              If some other I/O error occurs.
      * @throws IllegalArgumentException If there is room in the given buffer.
      */
@@ -143,18 +143,20 @@ private static int readToLimit(final ReadableByteChannel 
channel, final ByteBuff
         if (!dst.hasRemaining()) {
             throw new IllegalArgumentException();
         }
-        int numRead = 0;
         int totalRead = 0;
         while (dst.hasRemaining()) {
-            if ((totalRead += numRead = channel.read(dst)) == IOUtils.EOF) {
+            final int numRead;
+            if ((numRead = channel.read(dst)) == IOUtils.EOF) {
                 break;
             }
             if (numRead == 0) {
                 // 0 may be returned from a non-blocking channel.
                 Thread.yield();
+            } else {
+                totalRead += numRead;
             }
         }
-        return totalRead;
+        return totalRead != 0 ? totalRead : IOUtils.EOF;
     }
 
     private static long size(final SeekableByteChannel channel) throws 
IOException {