Core: Fix ByteBufferInputStream.read() to return -1 at EOF

[sachinnn99]

Fixes #16127.

SingleBufferInputStream.read() and MultiBufferInputStream.read() throw EOFException when the stream is exhausted. This violates the java.io.InputStream contract, which requires the no-arg read() to return -1 at EOF.

The multi-byte read(byte[], int, int) in both classes already correctly returns -1 at EOF — the two overloads were inconsistent.

Changes:

• SingleBufferInputStream.read(): return -1 instead of throwing EOFException
• MultiBufferInputStream.read(): return -1 at both EOF entry points instead of throwing EOFException
• Update testReadByte() to assert -1 return (including idempotency check)

Other EOFException-throwing methods (slice(), sliceBuffers(), skipFully()) are unchanged — they request specific byte counts where EOFException is the correct signal.

[steveloughran]

looks good for read(); looking at read(buffer[], offset, len), it seems ok too.

slice() probably needs attention at the same time

[sachinnn99]

Thanks for the review! I looked at slice() — its EOFException is intentional since it's a "read exactly N bytes" operation (not part of the InputStream contract). Callers expect either the full slice or a failure, so throwing there is the correct behavior.

The fix here is scoped to the no-arg read(), which has a clear contract violation per InputStream.read() javadoc.

[Baunsgaard]

src LGTM.

But i would suggest a few additional test cases, just to ensure future coverage:

1. invariants after the first -1 is encountered:
2. an explicit empty case:

we can simply add a utility function to call with any stream to verify:

private static void assertAtEOF(ByteBufferInputStream stream) {
  long pos = stream.getPos();
  assertThat(stream.read()).as("read() at EOF").isEqualTo(-1);
  assertThat(stream.read()).as("read() should keep returning -1 at EOF").isEqualTo(-1);
  assertThat(stream.getPos()).as("Position should not advance past EOF").isEqualTo(pos);
  assertThat(stream.available()).as("available() should be 0 at EOF").isEqualTo(0);
}

To make full coverage of all paths you can add an additional test that calls the assertAtEOF with empty streams that are empty from the beginning.

[sachinnn99]

Thanks for the suggestions @Baunsgaard! Added in the latest push:

• assertAtEOF helper matching your snippet
• Called it after EOF is first encountered in testReadAll, testSmallReads, testPartialBufferReads, and testReadByte
• Added testEmptyStream covering single empty buffer, multiple empty buffers, and an empty buffer list

[Baunsgaard]

LGTM