Fix native heap corruption in GitPackIndexMappedReaderTests#1360
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The test was double-closing the FileStream: once via the explicit 'using' block on the FileStream variable, and again inside GitPackIndexMappedReader.Dispose() which calls MemoryMappedFile.Dispose() (created with leaveOpen: false). On Linux/net10 this caused non-deterministic native heap corruption (free(): invalid pointer, double free or corruption, malloc_consolidate(): invalid chunk size) that crashed the test host with exit code 134 — the pattern seen in 4 consecutive ubuntu-24.04 CI failures. Additionally, the GetOffsetFromPartialTest assertions compared a GitObjectId? (Nullable<GitObjectId>) against a GitObjectId value type using Assert.Equal. On .NET Framework (net472/x86) the boxed struct equality check could fail even when the underlying bytes matched. Switch to comparing the string representation instead. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
This was referenced Jun 19, 2026
This was referenced Jun 25, 2026
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Problem
The ubuntu-24.04 CI build has been failing non-deterministically with native heap corruption errors during test execution:
free(): invalid pointer(runs #24475017484, #24474758609)double free or corruption (out)(run #24474464353)malloc_consolidate(): invalid chunk size(run #24475399839)All four failures show the test host crashing with exit code 134 (SIGABRT) and zero actual test failures — the process dies during cleanup. A separate Windows build (#24473836691) also failed in the same test class (
GetOffsetFromPartialTest) with a value-equality assertion failure on net472/x86.Root Cause
Double-free of FileStream:
GitPackIndexMappedReaderTestswrapped theFileStreamin an explicitusingblock and passed it toGitPackIndexMappedReader, which takes ownership viaMemoryMappedFile.CreateFromFile(..., leaveOpen: false). When the outerusingblock then tried to dispose the already-closed stream, the native file handle was freed twice — causing heap corruption on Linux.Nullable struct equality:
GetOffsetFromPartialTestcomparedGitObjectId?(boxed nullable) withGitObjectId(value type) usingAssert.Equal. On .NET Framework x86, the boxing path could produce a false negative even when the underlying bytes matched.Fix
usingonFileStreamsoGitPackIndexMappedReaderis the sole ownerobjectId.Value.ToString()instead of comparing boxed nullable structs