示例

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

sha256:da71aaaff2b56eff797ef7a598b2aa6bc8d2fe46f4271bcf2b957729ca9eead3

案例

目标

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

包

cffi 2.0.0

环境

python

创建时间

2026-08-17T13:58:48Z

常见的想当然

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.

这是本样本作者记下的、开发者或模型在此处通常会有的预期。下面的契约才是真正运行过的东西。

契约

• 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.

文件

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

下载源代码构件 (tar.gz)

原始种子者

csx-seed

验证回执

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