I have another question: what happens if there is a partial read?

For example, let's says I return a 1024-bytes buffer in get_buffer(), but recv_into() receives data in 512 chunks.  Is it:

1. getbuffer() is called, returns 1024 bytes buffer
2. recv_into() receives 512 bytes, writes them in buf[0:512]
3. recv_into() receives another 512 bytes, writes them in buf[512:1024]

or is it:

1. getbuffer() is called, returns 1024 bytes buffer
2. recv_into() receives 512 bytes, writes them in buf[0:512]
3. getbuffer() is called, returns another 1024 bytes buffer
4. recv_into() receives 512 bytes, writes them in newbuf[0:512]