import sys
try:
    import thread
except:
    import dummy_thread as thread

from ctypes import *
import ctypes.util

__doc__ = """This module performs file control and I/O control on file
descriptors.  It is an interface to the fcntl() and ioctl() Unix
routines.  File descriptors can be obtained with the fileno() method of
a file or socket object."""

_libc = cdll.LoadLibrary(ctypes.util.find_library("c"))

# constants, look in fcntl.h and platform docs for the meaning
LOCK_SH = 1
LOCK_EX = 2
LOCK_NB = 4
LOCK_UN = 8
F_DUPFD = 0
F_GETFD = 1
F_SETFD = 2
F_GETFL = 3
F_SETFL = 4
F_UNLCK = 2
FD_CLOEXEC = 1

if "linux" in sys.platform:
    LOCK_MAND = 32
    LOCK_READ = 64
    LOCK_WRITE = 128
    LOCK_RW = 192
    F_GETSIG = 11
    F_SETSIG = 10
    F_GETLK64 = 12
    F_SETLK64 = 13
    F_SETLKW64 = 14
    # in CPython they are 12, 13 and 14
    # in plain C they are 5, 6 and 7. Look at bits/fcntl.h
    F_GETLK = F_GETLK64
    F_SETLK = F_SETLK64
    F_SETLKW = F_SETLKW64
    F_GETOWN = 9
    F_SETOWN = 8
    F_RDLCK = 0
    F_WRLCK = 1
    F_SETLEASE = 1024
    F_GETLEASE = 1025
    F_NOTIFY = 1026
    F_EXLCK = 4
    F_SHLCK = 8
    DN_ACCESS = 0x00000001
    DN_MODIFY = 0x00000002
    DN_CREATE = 0x00000004
    DN_DELETE = 0x00000008
    DN_RENAME = 0x00000010
    DN_ATTRIB = 0x00000020
    # Python turns it and long integer, we need the C's signed integer
    DN_MULTISHOT = c_int(0x80000000).value

    __SID = ord('S') << 8
    I_NREAD = __SID | 1
    I_PUSH = __SID | 2
    I_POP = __SID | 3
    I_LOOK = __SID | 4
    I_FLUSH = __SID | 5
    I_SRDOPT = __SID | 6
    I_GRDOPT = __SID | 7
    I_STR = __SID | 8
    I_SETSIG = __SID | 9
    I_GETSIG = __SID | 10
    I_FIND = __SID | 11
    I_LINK = __SID | 12
    I_UNLINK = __SID | 13
    I_PEEK = __SID | 15
    I_FDINSERT = __SID | 16
    I_SENDFD = __SID | 17
    I_RECVFD = __SID | 14
    I_SWROPT = __SID | 19
    I_LIST = __SID | 21
    I_PLINK = __SID | 22
    I_PUNLINK = __SID | 23
    I_FLUSHBAND = __SID | 28
    I_CKBAND = __SID | 29
    I_GETBAND = __SID | 30
    I_ATMARK = __SID | 31
    I_SETCLTIME = __SID | 32
    I_GETCLTIME = __SID | 33
    I_CANPUT = __SID | 34
    del __SID
else:
    F_GETLK = 7
    F_SETLK = 8
    F_SETLKW = 9
    F_GETOWN = 5
    F_SETOWN = 6
    F_RDLCK = 1
    F_WRLCK = 3

class _flock(Structure):
    _fields_ = [("l_type", c_short),
                ("l_whence", c_short),
                ("l_start", c_long),
                ("l_len", c_long),
                ("l_pid", c_int)]


def _conv_descriptor(f):
    if not (isinstance(f, (int, long)) or hasattr(f, "fileno")):
        raise TypeError, "argument must be an int, or have a fileno() method."

    try:
        return f.fileno()
    except AttributeError:
        return f

def _get_error_msg():
    errno = c_int.in_dll(_libc, "errno")
    _libc.strerror.restype = c_char_p
    msg = _libc.strerror(errno)
    return msg

def _call_func(f_name, fd, code, arg):
    func = getattr(_libc, f_name)

    lock = thread.allocate_lock()

    lock.acquire()
    rv = func(fd, code, arg)
    lock.release()

    if rv < 0:
        raise IOError, _get_error_msg()

    return rv


def _check_flock_op(op):
    l = _flock()

    if op == LOCK_UN:
        l.l_type = F_UNLCK
    elif op & LOCK_SH:
        l.l_type = F_RDLCK
    elif op & LOCK_EX:
        l.l_type = F_WRLCK
    else:
        raise ValueError, "unrecognized flock argument"

    return l

def _is_mutable(arg):
    try:
        arg[0] = arg[0]
    except TypeError:
        return False
    else:
        return True

def fcntl(fd, op, arg=0):
    """fcntl(fd, op, [arg])

    Perform the requested operation on file descriptor fd.  The operation
    is defined by op and is operating system dependent.  These constants are
    available from the fcntl module.  The argument arg is optional, and
    defaults to 0; it may be an int or a string. If arg is given as a string,
    the return value of fcntl is a string of that length, containing the
    resulting value put in the arg buffer by the operating system. The length
    of the arg string is not allowed to exceed 1024 bytes. If the arg given
    is an integer or if none is specified, the result value is an integer
    corresponding to the return value of the fcntl call in the C code."""

    fd = _conv_descriptor(fd)

    if not isinstance(op, (int, long)):
        raise TypeError, "an integer is required"

    if isinstance(arg, (int, long)):
        rv = _call_func("fcntl", fd, op, arg)
        return rv
    elif isinstance(arg, str):
        if len(arg) > 1024:
            raise ValueError, "fcntl string arg too long"

        _call_func("fcntl", fd, op, arg)
        return arg
    else:
        raise TypeError, "int or string required"

def flock(fd, op):
    """flock(fd, operation)

    Perform the lock operation op on file descriptor fd.  See the Unix
    manual flock(3) for details.  (On some systems, this function is
    emulated using fcntl().)"""

    fd = _conv_descriptor(fd)

    if not isinstance(op, (int, long)):
        raise TypeError, "an integer is required"

    if hasattr(_libc, "flock"):
        lock = thread.allocate_lock()
        lock.acquire()
        rv = _libc.flock(fd, op)
        lock.release()

        if rv < 0:
            raise IOError, _get_error_msg()
    else:
        l = _check_flock_op(op)
        l.l_whence = l.l_start = l.l_len = 0
        op = (F_SETLKW, F_SETLK)[op & LOCK_NB]
        _libc.fcntl.argtypes = [c_int, c_int, POINTER(_flock)]
        rv = _call_func("fcntl", fd, op, byref(l))

def lockf(fd, op, length=0, start=0, whence=0):
    """lockf (fd, operation, length=0, start=0, whence=0)

    This is essentially a wrapper around the fcntl() locking calls.  fd is the
    file descriptor of the file to lock or unlock, and operation is one of the
    following values:

    LOCK_UN - unlock
    LOCK_SH - acquire a shared lock
    LOCK_EX - acquire an exclusive lock

    When operation is LOCK_SH or LOCK_EX, it can also be bit-wise OR'd with
    LOCK_NB to avoid blocking on lock acquisition.  If LOCK_NB is used and the
    lock cannot be acquired, an IOError will be raised and the exception will
    have an errno attribute set to EACCES or EAGAIN (depending on the
    operating system -- for portability, check for either value).

    length is the number of bytes to lock, with the default meaning to lock to
    EOF.  start is the byte offset, relative to whence, to that the lock
    starts.  whence is as with fileobj.seek(), specifically:

    0 - relative to the start of the file (SEEK_SET)
    1 - relative to the current buffer position (SEEK_CUR)
    2 - relative to the end of the file (SEEK_END)"""

    fd = _conv_descriptor(fd)

    for v in [op, length, start, whence]:
        if not isinstance(v, (int, long)):
            raise TypeError, "an integer is required"

    l = _check_flock_op(op)
    l.l_start = l.l_len = 0

    if start:
        l.l_start = long(start)
    if len:
        l.l_len = long(length)
    l.l_whence = whence

    op = (F_SETLKW, F_SETLK)[op & LOCK_NB]
    _libc.fcntl.argtypes = [c_int, c_int, POINTER(_flock)]
    _call_func("fcntl", fd, op, byref(l))

def ioctl(fd, op, arg=0, mutate_flag=True):
    """ioctl(fd, opt[, arg[, mutate_flag]])

    Perform the requested operation on file descriptor fd.  The operation is
    defined by opt and is operating system dependent.  Typically these codes
    are retrieved from the fcntl or termios library modules.

    The argument arg is optional, and defaults to 0; it may be an int or a
    buffer containing character data (most likely a string or an array).

    If the argument is a mutable buffer (such as an array) and if the
    mutate_flag argument (which is only allowed in this case) is true then the
    buffer is (in effect) passed to the operating system and changes made by
    the OS will be reflected in the contents of the buffer after the call has
    returned.  The return value is the integer returned by the ioctl system
    call.

    If the argument is a mutable buffer and the mutable_flag argument is not
    passed or is false, the behavior is as if a string had been passed.  This
    behavior will change in future releases of Python.

    If the argument is an immutable buffer (most likely a string) then a copy
    of the buffer is passed to the operating system and the return value is a
    string of the same length containing whatever the operating system put in
    the buffer.  The length of the arg buffer in this case is not allowed to
    exceed 1024 bytes.

    If the arg given is an integer or if none is specified, the result value
    is an integer corresponding to the return value of the ioctl call in the
    C code."""

    fd = _conv_descriptor(fd)
    # Python turns number > sys.maxint into long, we need the signed C value
    op = c_int(op).value

    IOCTL_BUFSZ = 1024

    if "linux" in sys.platform:
        _libc.ioctl.argtypes = [c_int, c_int, c_char_p]
    else:
        _libc.ioctl.argtypes = [c_int, c_ulong, c_char_p]

    if not isinstance(op, (int, long)):
        raise TypeError, "an integer is required"

    if not isinstance(mutate_flag, int):
        raise TypeError, "a boolean is required"

    if isinstance(arg, (int, long)):
        rv = _call_func("ioctl", fd, op, arg)
        return int(rv)
    elif _is_mutable(arg):
        # AFAIK array.array is the only mutable buffer in Python
        try:
            buf = create_string_buffer(arg.tostring())
        except AttributeError:
            buf = create_string_buffer(str(arg))

        if not mutate_flag:
            if len(arg) > IOCTL_BUFSZ:
                raise ValueError, "ioctl string arg too long"

        rv = _call_func("ioctl", fd, op, buf)

        if mutate_flag:
            return rv
        else:
            return buf.value
    elif not _is_mutable(arg):
        if len(arg) > IOCTL_BUFSZ:
            raise ValueError, "ioctl string arg too long"

        buf = create_string_buffer(str(arg))

        rv = _call_func("ioctl", fd, op, buf)

        return buf.value
    else:
        raise TypeError, "an integer or a buffer required"


__all__ = ["fcntl", "flock", "lockf", "ioctl"]

if __name__ == "__main__":
    import struct
    import os
    import array
    import termios

    f = open("temp", "w")
    print "fcntl(f, F_SETFL, os.O_NDELAY):", fcntl(f, F_SETFL, os.O_NDELAY)

    lockdata = struct.pack('hhllhh', F_WRLCK, 0, 0, 0, 0, 0)
    print "lockdata:", repr(lockdata)
    print "fcntl(f, F_SETLKW, lockdata):", repr(fcntl(f, F_SETLKW, lockdata))
    os.unlink("temp")

    buf = array.array('h', [0])
    ret = ioctl(0, termios.TIOCGPGRP, buf, False)
    print "buf:", buf
    print "ioctl(0, termios.TIOCGPGRP, buf, False):", repr(ret)