import struct, os

LU_MAXDATA    = 4096
MAX_DATA      = LU_MAXDATA*2
PVERSION      = 0x02

MESSAGES      = ["OK", "MOUNT", "READ", "WRITE", "READDIR", "STAT", "UMOUNT",
                 "SETATTR", "MKDIR", "RMDIR", "CREATE", "UNLINK", "RENAME",
                 "OPEN", "RELEASE", "READLINK", "LINK", "SYMLINK"]
ERROR         = 0x100

HDR_LEN       = struct.calcsize("HHHH")
PID           = os.getpid()


for _name, _i in zip(MESSAGES, range(len(MESSAGES))):
    globals()[_name] = _i
del _name, _i

# ____________________________________________________________

def recvall(s, size):
    data = ''
    while len(data) < size:
        t = s.recv(size - len(data))
        if not t:
            raise EOFError
        data += t
    return data

def recvmsg(s):
    hdr = struct.unpack("HHHH", recvall(s, HDR_LEN))
    version, typ, datalen, pid = hdr
    if datalen:
        if datalen > MAX_DATA:
            raise ValueError, "message too long: %d bytes" % datalen
        data = recvall(s, datalen)
    else:
        data = ''
    return (typ, data)

def sendmsg(s, typ, data):
    msg = struct.pack("HHHH", PVERSION, typ, len(data), PID)
    s.sendall(msg)
    if data:
        s.sendall(data)