#!/usr/bin/python2

# Copyright (c) 2003 Intel Corporation
# All rights reserved.
#
# Copyright (c) 2004-2006 The Trustees of Princeton University
# All rights reserved.
# expected /proc/partitions format

import os, sys, shutil
import popen2
import socket
import fcntl
import string
import exceptions

from Exceptions import *


def makedirs( path ):
    """
    from python docs for os.makedirs:
    Throws an error exception if the leaf directory
    already exists or cannot be created.

    That is real useful. Instead, we'll create the directory, then use a
    separate function to test for its existance.

    Return 1 if the directory exists and/or has been created, a BootManagerException
    otherwise. Does not test the writability of said directory.
    """
    try:
        os.makedirs( path )
    except OSError:
        pass
    try:
        os.listdir( path )
    except OSError:
        raise BootManagerException, "Unable to create directory tree: %s" % path
    
    return 1



def removedir( path ):
    """
    remove a directory tree, return 1 if successful, a BootManagerException
    if failure.
    """
    try:
        os.listdir( path )
    except OSError:
        return 1

    try:
        shutil.rmtree( path )
    except OSError, desc:
        raise BootManagerException, "Unable to remove directory tree: %s" % path
    
    return 1



def sysexec( cmd, log= None ):
    """
    execute a system command, output the results to the logger
    if log <> None

    return 1 if command completed (return code of non-zero),
    0 if failed. A BootManagerException is raised if the command
    was unable to execute or was interrupted by the user with Ctrl+C
    """
    prog= popen2.Popen4( cmd, 0 )
    if prog is None:
        raise BootManagerException, \
              "Unable to create instance of popen2.Popen3 " \
              "for command: %s" % cmd

    if log is not None:
        try:
            for line in prog.fromchild:
                log.write( line )
        except KeyboardInterrupt:
            raise BootManagerException, "Interrupted by user"

    returncode= prog.wait()
    if returncode != 0:
        raise BootManagerException, "Running %s failed (rc=%d)" % (cmd,returncode)

    prog= None
    return 1


def sysexec_noerr( cmd, log= None ):
    """
    same as sysexec, but capture boot manager exceptions
    """
    try:
        rc= 0
        rc= sysexec( cmd, log )
    except BootManagerException, e:
        pass

    return rc



def chdir( dir ):
    """
    change to a directory, return 1 if successful, a BootManagerException if failure
    """
    try:
        os.chdir( dir )
    except OSError:
        raise BootManagerException, "Unable to change to directory: %s" % dir

    return 1



def removefile( filepath ):
    """
    removes a file, return 1 if successful, 0 if failure
    """
    try:
        os.remove( filepath )
    except OSError:
        raise BootManagerException, "Unable to remove file: %s" % filepath

    return 1



# from: http://forums.devshed.com/archive/t-51149/
#              Ethernet-card-address-Through-Python-or-C

def hexy(n):
    return "%02x" % (ord(n))

def get_mac_from_interface(ifname):
    """
    given a device name, like eth0, return its mac_address.
    return None if the device doesn't exist.
    """
    
    SIOCGIFHWADDR = 0x8927 # magic number

    s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    ifname = string.strip(ifname)
    ifr = ifname + '\0'*(32-len(ifname))

    try:
        r= fcntl.ioctl(s.fileno(),SIOCGIFHWADDR,ifr)
        addr = map(hexy,r[18:24])
        ret = (':'.join(map(str, addr)))
    except IOError, e:
        ret = None
        
    return ret