PDF xreftable position

"""
........
%xref
%0 8
%0000000000 65535 f
%0000000010 00000 n
%0000000079 00000 n
%0000000179 00000 n
%0000000315 00000 n
%0000000394 00000 n
%0000000506 00000 n
%0000000602 00000 n
trailer
<<
  /Size 8
  /Root 1 0 R
>>
%startxref
%732
%%EOF
"""

#We want to get '732' value
def getXrefTable(hfile):
    hfile.seek(0, 2)
    size = hfile.tell()
    chunk=100 #1 iteration is enough in most cases i hope
    for i in range(1, int(size/chunk)+1):
        hfile.seek(-chunk*i, 2)
        dat = filter(bool, [l.strip() for l in hfile.readlines()])
        if len(dat) > 3: #to be sure that we've read last 3 lines
            if (dat[-1]=="%%EOF") & (dat[-3]=="startxref"):
                xrefpos=int(dat[-2])
                break
    return xrefpos