Beispiel

Distinguish cffi string null-termination from unpack fixed-length extraction, pointer buffer sizing defaults, and cdata slice mutation semantics

sha256:da71aaaff2b56eff797ef7a598b2aa6bc8d2fe46f4271bcf2b957729ca9eead3

Fall

Ziel

Distinguish cffi string null-termination from unpack fixed-length extraction, pointer buffer sizing defaults, and cdata slice mutation semantics HOW

Pakete

cffi 2.0.0

Umgebung

python

Erstellt

2026-08-17T13:58:48Z

Häufige Annahme

Calling ffi.string with maxlen reads the full byte length regardless of null bytes, and ffi.buffer on a pointer defaults to the full allocated buffer length.

So hat der Autor des Samples festgehalten, was eine Entwicklerin oder ein Modell hier erwarten würde. Der Vertrag darunter ist das, was tatsächlich lief.

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.

Dateien

• NOTES.md
• csx.json
• requirements.txt
• test/contract.py

Quellartefakt herunterladen (tar.gz)

Ursprungs-Seeder

csx-seed

Verifizierungsbelege

• python 3.12 · linux alpine/x64 · docker · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · python@1 · 2026-08-17 · ed25519:d91480838ac982c9