fix(go): ensure physical buffer space for unsafe varint fast-paths#3613
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chaokunyang merged 2 commits intoapache:mainfrom Apr 24, 2026
Merged
fix(go): ensure physical buffer space for unsafe varint fast-paths#3613chaokunyang merged 2 commits intoapache:mainfrom
chaokunyang merged 2 commits intoapache:mainfrom
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@chaokunyang have a look. |
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Apr 24, 2026
| // TestUnsafePutVarUint32PhysicalWriteWidth verifies that UnsafePutVarUint32 performs | ||
| // an 8-byte physical write for 5-byte varints and that Reserve(8) (as required by | ||
| // buffer.go:661) keeps those 8 bytes within the backing array. | ||
| func TestUnsafePutVarUint32PhysicalWriteWidth(t *testing.T) { |
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Please add another test to cover struct.go change
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@chaokunyang please have a look. |
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Why?
The Go runtime's struct serialization fast-path in
struct.goviolates the documented contract ofUnsafePutVarUint32andUnsafeReadVarUint32inbuffer.go.UnsafePutVarUint32documents that the caller must callReserve(8)(because it performs an 8-byte bulk write for 5-byte varints), butstruct.goonly callsReserve(MaxVarintSize), which is 5 for uint32/int32 varint fields.UnsafeReadVarUint32physically reads 8 bytes, but the fast-path guard instruct.goonly checksremaining() >= MaxVarintSize(which can be 5).What does this PR do?
Add +8 byte padding to struct varint reservation and remaining-check guardrails in struct.go. This ensures that the underlying unsafe bulk memory operations (8-byte loads/stores) always stay within the allocated backing array, even when the logical varint size is smaller (e.g., 5 bytes).
Includes a regression test in buffer_test.go verifying the physical write width of
UnsafePutVarUint32.Related issues
Closes #3612
AI Contribution Checklist
yes/noyes, I included a completed AI Contribution Checklist in this PR description and the requiredAI Usage Disclosure.yes, my PR description includes the requiredai_reviewsummary and screenshot evidence of the final clean AI review results from both fresh reviewers on the current PR diff or current HEAD after the latest code changes.Does this PR introduce any user-facing change?
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