Function recvfrom 

pub unsafe extern "C" fn recvfrom(
    __fd: c_int,
    __buf: *mut c_void,
    __n: usize,
    __flags: c_int,
    __addr: *mut sockaddr,
    __addr_len: *mut socklen_t,
) -> isize

Read N bytes into BUF through socket FD. If ADDR is not NULL, fill in *ADDR_LEN bytes of it with the address of the sender, and store the actual size of the address in *ADDR_LEN. Returns the number of bytes read or -1 for errors.

This function is a cancellation point and therefore not marked with __THROW.