rust-multipart

This package provides a Sans-IO parser for RFC 7578 multipart/form-data. It is heavily inspired by defnull/multipart.

Installation

pip install rust-multipart

Usage

from rust_multipart import MultipartParser, PartBegin, PartData, PartEnd

parser = MultipartParser(boundary=b"boundary")
events = parser.feed(b'--boundary\r\nContent-Disposition: form-data; name="user"\r\n\r\nPotato\r\n--boundary--\r\n')
parser.finish()

begin, data, end = events
assert isinstance(begin, PartBegin)
assert begin.headers == [(b"Content-Disposition", b'form-data; name="user"')]
assert isinstance(data, PartData)
assert data.data == b"Potato"
assert isinstance(end, PartEnd)

You can call feed() repeatedly with partial input. Each call returns the batch of events produced by that chunk: PartBegin carries the ordered raw byte headers, PartData carries a body chunk, and PartEnd closes the part. The parser never accumulates part bodies, so memory stays bounded regardless of upload size. Call finish() once the input ends: it raises ValueError if the closing boundary was never received.

Use parse_options_header() to parse header values like Content-Disposition:

from rust_multipart import parse_options_header

value, parameters = parse_options_header('form-data; name="user"')
assert value == "form-data"
assert parameters == {"name": "user"}

Development

uv sync --group dev
uv run maturin develop
scripts/check

scripts/check runs formatting, linting, type checking, Python coverage, native Rust coverage, and the high-level test suite. Both Python and Rust line coverage must remain at 100%.

Run the CodSpeed benchmarks locally with:

uv run pytest benchmarks --codspeed

License

This project is licensed under the MIT License.