Decode instructions without reading past the bytecode buffer
A truncated PUSH instruction reads its operand from bytes beyond the supplied program.
- Focused work estimate
- 1h 30m + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Binary parsing · Bounds checking
Estimated field mix
- Systems programming70%
- Compiler and language tooling30%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
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Project context
A fictional rules engine executes a tiny arithmetic bytecode over synthetic integers. Its interpreter trusts jump offsets and can run forever. Build a local Rust runtime; it has no filesystem, network, dynamic loading, host calls, or candidate-source execution.
Setup prerequisites
- Stacks
- Instruction decoding
- Control flow
Preceding work
No earlier ticket is required. Complete the project setup above.
Acceptance criteria
- Decoder checks opcode and operand length before advancing
- Unknown opcodes return a stable offset and code
- Failure exposes no partially decoded instruction
Implementation constraints
- Keep bytecode length bounded before parsing.
Verification to include
- Decode a program containing every documented instruction.
- Truncate at every byte and confirm deterministic errors without panic.
Deliverables
- Checked decoder and truncation matrix
Rollout and recovery
Reject programs not validated by the new decoder.
Value of the work
For the engineer: Practice runtime invariants, validation, resource accounting and compatibility.
For the team: Review a constrained execution component whose malformed programs fail deterministically without gaining host capabilities.
Evidence boundaries
Outcome Evidence: Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.
Ownership Evidence: Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence.