ABI Layer 2: prove linear-pointer memory safety (no use-after-free/double-free) — flagship Idris2 proof#44
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Flagship semantic proof: a pointer with explicit Live/Freed state; an `Accessible` permission with a constructor only for Live pointers, so use-after-free and double-free are unrepresentable. `free` consumes a Live pointer (with its witness) into a Freed one. Sound+complete Dec, certifier soundness, positive + negative controls. Verified with idris2 0.7.0 (build clean, zero warnings) + adversarial false-proof rejection. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
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Summary
Raises atsiser's Idris2 ABI to Layer 2 with its first flagship semantic proof. atsiser's headline is wrapping C in ATS linear types for zero-cost memory safety; this proves the defining guarantee: a pointer carries an explicit
Live/Freedstate, theAccessiblepermission (to dereference or free) has a constructor only forLivepointers, andfreeconsumes aLivepointer with its witness into aFreedone — so use-after-free and double-free are unrepresentable.Mirrors the estate flagship-proof pattern: state model, proposition uninhabited on the bad case, sound+complete
Dec, certifier proven sound, positive + negative controls.Changes
src/interface/abi/Atsiser/ABI/Semantics.idr—Ptr/PtrState,Accessible,free,decAccessible,certifyAccessSound, and negative controlfreedNotAccessible.atsiser-abi.ipkg.RSR Quality Checklist
Required
As Applicable
Testing
Verified with Idris2 0.7.0:
idris2 --build atsiser-abi.ipkg→ exit 0, zero warnings. Adversarial check: a deliberately-false proof (Accessible (MkPtr 4096 Freed)) was rejected.build/removed.🤖 Generated with Claude Code
https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
Generated by Claude Code