test.py

import os
from flask import Flask, request
from io import BufferedReader
import magic

app = Flask(__name__)

@app.route("/<string:filename>", methods=['PUT'])
def upload(filename):
    head = request.stream.read(1024)
    mime = magic.from_buffer(head, mime=True)
    length = len(head)

    with open("uploads/{}".format(os.path.basename(filename)), 'wb') as f:
        f.write(head)

        while not request.stream.is_exhausted:
            buf = request.stream.read(1024)
            length += len(buf)
            f.write(buf)

    return "Wrote {} bytes to {}, type {}".format(length, filename, mime)

if __name__ == '__main__':
    app.run()