allow passing of alternative units such as GB, MB to --segment-size in python-swiftclient

gistfile1.py

st_upload_help = '''
Uploads specified files and directories to the given container

Positional arguments:
  <container>           Name of container to upload to
  <file_or_directory>   Name of file or directory to upload. Specify multiple
                        times for multiple uploads

Optional arguments:
  --changed             Only upload files that have changed since the last
                        upload
  --segment-size <size> Upload files in segments no larger than <size> and
                        then create a "manifest" file that will download all
                        the segments as if it were the original file. Valid
                        args are N, NG, Ng, NM, Nm, NK, Nk, where N is some 
                        integer, and G or g represents GiB, M or m represents 
                        MiB, and K or k represents KiB. N without a modifier
                        represents a number of bytes. Can also be set via
                        the environment variable ST_SEGMENT_SIZE



def st_upload(parser, args, thread_manager):
#.
#.
#.
#.
    parser.add_option(
        '', '--use-slo', action='store_true', default=False,
        help='When used in conjunction with --segment-size will '
        'create a Static Large Object instead of the default '
        'Dynamic Large Object.')
    (options, args) = parse_args(parser, args)

############# BEGIN MOD ############################################
    
    # allowed size modifiers : multiplier
    # none : 1
    # G or g:  1073741824 (GiB)
    # M or m : 1048576    (MiB)
    # K or k : 1024       (KiB)
    
    def _parse_segment_size( size ):
        l2m = { 'g' : 1073741824, 'm' : 1048576, 'k' : 1024 }

        # if size is a number, return integer representation
        try:
            int( size )
            return size
        except:
            pass

        # if size is not a number, see if it matches the form 
        # 5G, 5g, 5 G, 5 g, 5M, 5m, 5 M, 5 m, 5k, 5K, 5 k, 5K
        # 0.5G, etc, as above
        # if not throw an error
        mo = re.match( r'^(\d+\.?\d*)(?:\s+)?([gmk])$', size.lower() )
        if ( mo ):
            digits = mo.group(1)
            multiplier = mo.group(2)

            if ( not digits and multiplier ):
                raise ClientException( "bad segment_size: '%s'" % ( size, ) )
        
            try:
                size = float( digits ) * l2m[ multiplier ]
            except ValueError:
                raise ClientException( "bad segment_size: '%s'" % ( size, ) )

            return int( size )
      
        else:
            raise ClientException( "bad segment_size: '%s'" % ( size, ) )


    # need to process segment_size
    # order of precedence: commandline setting, envvar setting, default
    if ( options.segment_size ):
        options.segment_size = _parse_segment_size( options.segment_size )
    elif ( environ.get( 'ST_SEGMENT_SIZE' ) ):
        options.segment_size = _parse_segment_size( environ[ 'ST_SEGMENT_SIZE' ] )
    else:
        options.segment_size = _parse_segment_size( '5G' )

#### END MOD ######################################################


    args = args[1:]
    if len(args) < 2:
        thread_manager.error(
            'Usage: %s upload %s\n%s', basename(argv[0]), st_upload_options,
            st_upload_help)
        return