Infinite loop on Content.copy() with Content.Source.from(... , Path, ) when Path has size 0.

[pyraca]

Jetty version(s)
12.1.2

Jetty Environment
Jetty-12

HTTP version
N/A

Java version/vendor (use: java -version)
java version "21.0.2" 2024-01-16 LTS
Java(TM) SE Runtime Environment Oracle GraalVM 21.0.2+13.1 (build 21.0.2+13-LTS-jvmci-23.1-b30)

OS type/version
Linux 6.8.0-79-generic #79-Ubuntu SMP PREEMPT_DYNAMIC Tue Aug 12 14:42:46 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux

Description

Content.copy(source,sink,cb) does not come back when a Content.Source.from(path) is given on a file that has 0 length (org.eclipse.jetty.io.internal.ByteChannelContentSource$PathContentSource).

The same is true when PathContentSource is used as the source (org.eclipse.jetty.io.content.PathContentSource).

The same does not happen on String or Byte sources.

When PathContentSource is a part on a MultiPart ContentSource the same issue happens.

Off by 1 someplace.

How to reproduce?

import org.eclipse.jetty.io.Content;
import org.eclipse.jetty.util.BufferUtil;
import org.eclipse.jetty.util.Callback;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

public class PathContentSourceBug {

    static void p (String msg, Object ... args) {
        System.out.printf(msg,args);
        System.out.flush();
    }

    void ok () {
        p("Callback OK\n");
    }
    void fail(Throwable t) {
        p("Fault: \n");
        t.printStackTrace( System.out );
    }

    Content.Sink stdout () {
        return (last, byteBuffer, callback) -> {
            try
            {
                BufferUtil.writeTo(byteBuffer, System.out);
                callback.succeeded();
            }
            catch (Throwable t)
            {
                callback.failed(t);
            }
        };
    }

    void run(String[] args) throws IOException {
        Content.Sink sink = stdout();
        for(var next : args) {
            Path path = Paths.get(next);

            Content.Source source = Content.Source.from( path );
            p("Contents of: %s (size: %d bytes)\n", path, Files.size(path));
            Content.copy(source,sink,Callback.from(this::ok, this::fail));
            p("----------\n");
        }
    }

    public static void main(String[] args) throws IOException {
        new PathContentSourceBug().run(args);
    }
}

[gregw]

The problem is that we try to read bytes max by the length of the file. So we try to read 0 byte and succeed in reading 0 bytes and then loop forever afterwards.
Should be and easy fix....