Keep guest creation-mask state in libc behind C-linkage helpers so NID
patching preserves the shared exports. Reject a pinned descriptor whose
file identity differs from the snapshot taken before classification.
Exercise close and reuse from another thread at both acquisition windows
for writes, resize and seek, and create temporary ordinary-file fixtures
so runtime tests work without the source tree.
Constraint: NID exemptions require the literal suffix at the end of the exported symbol
Confidence: high
Scope-risk: narrow
Tested: 18 targeted Linux runtime tests with zero skips; patched_libraries for libc/libkernel/libkernel_sys; standalone ASan/UBSan with warnings as errors; source-prefix-remapped fixtures; Clang analyzer and conventions
Not-tested: Full project build and library set, Windows runtime, console hardware and titles
Directive: Device/inode validation establishes file identity, not open-file-description identity
Pin the descriptor before mmap validation so guest descriptor reuse cannot
redirect the eventual mapping. Apply the canonical guest creation mask when
creating named objects, distinguishing new objects before setting permissions
without changing the host process umask. Add regressions that reproduce both
failures and document the remaining host requirements.
Constraint: Guest umask must not mutate the process-wide host mask
Confidence: high
Scope-risk: narrow
Tested: 17 targeted Linux runtime tests passed with zero skips; conventions and diff checks; Clang analyzer on three changed production translation units
Not-tested: Full project build and suite, Windows runtime, console hardware and titles
bilel