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Do not report a channel closed underneath us as EBADF on close #9723

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Do not report a channel closed underneath us as EBADF on close #9723

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abced19
Do not report a channel closed underneath us as EBADF on close
aminmansuri Sep 20, 2026
87d12b8
Keep the fileno bookkeeping when the channel is already closed
aminmansuri Sep 20, 2026
64ec6bc
Guard the channel close and evict the wrapper only if it is ours
aminmansuri Sep 21, 2026
913668c
Test the close after Thread#kill instead of JRuby internals
aminmansuri Sep 23, 2026
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14 changes: 6 additions & 8 deletions core/src/main/java/org/jruby/util/io/ChannelFD.java
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Original file line number Diff line number Diff line change
Expand Up @@ -136,24 +136,22 @@ private void finish() throws IOException {
throw new ClosedChannelException();
}

// if channel is already closed, we're no longer valid
if (!ch.isOpen()) {
throw new ClosedChannelException();
}

// otherwise decrement and possibly close as normal
int count = refs.decrementAndGet();

if (count <= 0) {
// if we're the last referrer, close the channel
try {
ch.close();
// The JDK closes an interruptible channel when the thread blocked on it is
// interrupted, which is how Thread#kill unblocks IO, so Ruby never closed
// that stream and there is nothing left for us to close.
if (ch.isOpen()) ch.close();
if (needsClosing) {
filenoUtil.closeFilenoHandle(realFileno);
}
} finally {
filenoUtil.unregisterWrapper(realFileno);
filenoUtil.unregisterWrapper(fakeFileno);
filenoUtil.unregisterWrapper(realFileno, this);
filenoUtil.unregisterWrapper(fakeFileno, this);
}
}
}
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7 changes: 7 additions & 0 deletions core/src/main/java/org/jruby/util/io/FilenoUtil.java
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Expand Up @@ -119,6 +119,13 @@ public void unregisterWrapper(int fileno) {
filenoMap.remove(fileno);
}

// Remove only if the fileno still maps to this wrapper, so a stale close cannot evict a
// live wrapper that has taken over a recycled descriptor number.
public void unregisterWrapper(int fileno, ChannelFD wrapper) {
if (fileno == -1) return;
filenoMap.remove(fileno, wrapper);
}

// Used by testing. See test/jruby/test_io.rb, test_io_copy_stream_does_not_leak_io_like_objects
public int getNumberOfWrappers() {
return filenoMap.size();
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25 changes: 25 additions & 0 deletions test/jruby/test_io.rb
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Expand Up @@ -698,4 +698,29 @@ def test_accept_on_closed_server_raises_ioerror
assert true
end

# Thread#kill unblocks a write by interrupting the thread, and the JDK closes the
# interruptible channel in response. Ruby never closed the stream, so the close in
# the ensure must succeed rather than report the vanished channel as Errno::EBADF.
def test_close_after_kill_during_blocking_write
read, write = IO.pipe
@to_close << read
@to_close << write

started = Queue.new
thread = Thread.new do
begin
started << true
write.write('x' * 1_000_000) # larger than the pipe buffer, so it blocks
ensure
write.close
end
end

started.pop
sleep 0.2 # let the write fill the buffer and block
thread.kill

assert_nothing_raised { thread.join }
end

end
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