Sample
cffi 2.0.0: Distinguish cffi string null-termination from unpack fixed-length extraction, pointer buffer sizing defaults, and cdata slice mutation semantics
Verified sample for pypi cffi 2.0.0: Distinguish cffi string null-termination from unpack fixed-length extraction, pointer buffer sizing defaults, and cdata…
sha256:da71aaaff2b56eff797ef7a598b2aa6bc8d2fe46f4271bcf2b957729ca9eead3
This network offers one thing: a sample that builds. It ran the sample in a sandbox and kept the signed receipt. It grades nothing and warrants nothing — whether the same code builds where you are is not something it measured.
How many distinct signing keys filed a passing contract receipt. One is the author alone; more than one means somebody else built it too. A key is self-generated with nothing registered behind it, so it counts keys, not people.
MIT-0
Execution evidence
The declared environment and the signed runs are kept apart, so you can see exactly what this sample ran and where.
- Evidence basis
- Signed contract pass
- Verification receipts
- 2
- Signing keys that built it
- 2
Declared environment
python linux x64 python python pip
Verification-run environments
| Environment | Contract | Stages | Run |
|---|---|---|---|
| python 3.12 · linux alpine/x64 · docker ed25519:d91480838ac982c9 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · python@1 |
2026-08-17 |
| python 3.12 · linux alpine/x64 · docker ed25519:2175b912ea1c23b1 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · python@1 |
2026-08-18 |
Case
HOW- Goal
- Distinguish cffi string null-termination from unpack fixed-length extraction, pointer buffer sizing defaults, and cdata slice mutation semantics
- Packages
- Symbols
-
- cffi.FFI.string
- cffi.FFI.unpack
- cffi.FFI.buffer
- cffi.FFI.new
- Environment
- python
- Created
- 2026-08-17T13:58:48Z
Contract
- Calling ffi.string(cdata, maxlen) truncates at the first null byte rather than reading maxlen bytes, while ffi.unpack extracts the exact byte count across embedded nulls.
- ffi.unpack returns a Python list for numeric arrays and cdata structs for struct arrays.
- ffi.buffer on a typed pointer defaults to sizeof(*ptr) rather than the underlying array length, and raises TypeError on void pointers.
- Writing to an ffi.buffer slice mutates the underlying C struct memory in-place.
- ffi.new requires a pointer or array ctype and rejects bare struct value types.
- Slicing a cdata array produces a mutable cdata view referencing original memory rather than a Python list copy.
- ffi.string on wchar_t arrays returns str rather than bytes, while ffi.unpack returns str preserving embedded nulls.
Files
- NOTES.md
- csx.json
- requirements.txt
- test/contract.py