Aliyun, Dell: Handle EOF in OSS and ECS InputStream read() variants

[jbbqqf]

Summary

OSSInputStream (aliyun) and EcsSeekableInputStream (dell) had the same EOF-handling bug fixed in #16055 for GCSInputStream / S3InputStream / ADLSInputStream: when the underlying read() returns -1, the wrapper still advanced pos (and next, in OSS's case) and incremented the readBytes / readOperations metric counters by -1.

This PR applies the same one-shape fix the maintainers picked in #16055 to the two modules left out of that PR, plus regression tests covering both overloads.

Resolves #16062 for aliyun and dell. The remaining pieces (GCS, S3, ADLS) are still tracked by the in-flight #16055.

Context

The original issue body for #16062 explicitly enumerates the four affected files; #16055 covers GCS/S3/ADLS and the issue comment confirms OSSInputStream and EcsSeekableInputStream are still pending.

In Iceberg's hot path, files are read via known-offset range reads rather than sequential reads-to-EOF, so the bug is latent in production today. It still matters because:

1. Any future caller that does loop until read() == -1 would silently corrupt pos/next and the metric counters.
2. The behavior diverges from InputStream's contract — every other Iceberg *InputStream already returns -1 cleanly after GCS, S3, ADLS: Handle EOF in inputStreams #16055.
3. The metric drift is observable today via FileIOMetricsContext snapshots that overshoot the file size.

Changes

• aliyun/src/main/java/org/apache/iceberg/aliyun/oss/OSSInputStream.java
  • read() and read(byte[], int, int) now check the underlying return value and, if -1, return immediately without mutating pos / next or incrementing readBytes / readOperations. Same pattern as GCS, S3, ADLS: Handle EOF in inputStreams #16055's S3InputStream change.
  • Inline comments explain the why and reference both GCS, S3, ADLS: Handle EOF in inputStreams #16055 (the canonical fix) and EOF not handled correctly in single byte read in cloud storage InputStream implementations #16062 (this issue), so a reviewer reading the diff cold doesn't have to re-derive the reasoning.
• dell/src/main/java/org/apache/iceberg/dell/ecs/EcsSeekableInputStream.java — same shape.
• aliyun/src/test/java/org/apache/iceberg/aliyun/oss/TestOSSInputStream.java — adds testReadSingleByteAtEof and testReadBufferAtEof. Both run against the in-process AliyunOSSMockExtension (no live OSS access required).
• dell/src/test/java/org/apache/iceberg/dell/ecs/TestEcsSeekableInputStream.java — same two tests against the existing EcsS3MockRule.

All four new tests fail on origin/main and pass with this change.

Reproduce BEFORE/AFTER yourself (copy-paste)

# --- one-time setup ---
git clone https://github.com/apache/iceberg.git /tmp/repro && cd /tmp/repro

# --- BEFORE (origin/main) ---
git checkout origin/main
# Pull in only the new test methods so the regression is visible against
# the unmodified production code in main:
git fetch https://github.com/jbbqqf/iceberg.git feat/16062-fix-eof-handling-oss-ecs-streams
git checkout FETCH_HEAD -- \
  aliyun/src/test/java/org/apache/iceberg/aliyun/oss/TestOSSInputStream.java \
  dell/src/test/java/org/apache/iceberg/dell/ecs/TestEcsSeekableInputStream.java
./gradlew :iceberg-dell:test --tests "org.apache.iceberg.dell.ecs.TestEcsSeekableInputStream"
./gradlew :iceberg-aliyun:test --tests "org.apache.iceberg.aliyun.oss.TestOSSInputStream"
# Expected: 2 failures in each test class —
#   testReadSingleByteAtEof  (pos / readBytes shifted by -1 at EOF)
#   testReadBufferAtEof      (same, for the buffered overload)

# --- AFTER (this PR) ---
git checkout FETCH_HEAD
./gradlew :iceberg-dell:test --tests "org.apache.iceberg.dell.ecs.TestEcsSeekableInputStream"
./gradlew :iceberg-aliyun:test --tests "org.apache.iceberg.aliyun.oss.TestOSSInputStream"
# Expected: all tests green in both modules.

The only thing that changes between BEFORE and AFTER is the checked-out ref of the production InputStream classes; the test files are the same in both runs.

What I ran locally

• ./gradlew :iceberg-dell:test --tests "...TestEcsSeekableInputStream" on origin/main with the new tests imported → 6 tests, 2 failures (regression visible).
• Same on this branch → 6/6 pass.
• ./gradlew :iceberg-aliyun:test --tests "...TestOSSInputStream" on origin/main with the new tests imported → 5 tests, 2 failures.
• Same on this branch → 5/5 pass.
• ./gradlew :iceberg-aliyun:spotlessCheck :iceberg-dell:spotlessCheck → PASS.

Edge cases tested

#	Module	Scenario	Expected	Verified by
1	dell	Single-byte read() past the last byte of a 4-byte object	returns -1; getPos() stays at file size; idempotent on a second call	TestEcsSeekableInputStream#testReadSingleByteAtEof
2	dell	Buffered read(byte[], 0, len) past EOF	returns -1; getPos() stays at file size	TestEcsSeekableInputStream#testReadBufferAtEof
3	aliyun	Single-byte read() past EOF on an 8-byte object	returns -1; getPos() stays; idempotent	TestOSSInputStream#testReadSingleByteAtEof
4	aliyun	Buffered read(byte[], 0, dataSize+1) followed by another EOF buffered read	first read returns dataSize, second returns -1; getPos() stays at dataSize	TestOSSInputStream#testReadBufferAtEof

Risk / blast radius

• Two-line guard in two *InputStream classes, mirroring the GCS/S3/ADLS shape that was already chosen by maintainers in GCS, S3, ADLS: Handle EOF in inputStreams #16055.
• No public API surface modified.
• Behavioral change is strictly more contract-compliant: InputStream.read() is documented to return -1 at EOF without side effects, and that is now what these wrappers do.
• Metrics: readBytes/readOperations no longer drift on EOF reads. Pre-fix snapshots overcounted reads; post-fix they don't. This is observable but should be considered a fix, not a regression.

Release note

Fix OSS (aliyun) and ECS (dell) InputStreams to return -1 at EOF without advancing the position counter or skewing read metrics, matching the GCS/S3/ADLS fix in #16055.

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PR drafted with assistance from Claude Code. The change was reviewed manually against apache/iceberg's source on main and against the corresponding fix shape in #16055. The reproducer block above was used during development; it is the same one a reviewer can paste verbatim.