small util get reading upk info

upk reader

#
# utils for get information of upk file
# http://wiki.beyondunreal.com/Legacy:Package_File_Format


DWORD = 4
WORD = 2
GUID = 16


def endineFixWin(type,arr):
    """
    this method may not correct due to different os's byte order
    """
    if type == DWORD:
        arr[0],arr[1],arr[2],arr[3]=arr[3],arr[2],arr[1],arr[0]
    elif type==WORD:
        arr[0],arr[1]=arr[1],arr[0]
    return arr

UPKDef={
    "Signature": (0,DWORD),
    "PackageVersion":     (4,WORD),
    "LicenseMode":      (6,WORD),
    "PackageFlags":      (8,DWORD),
    "NameCount":      (12,DWORD),
    "NameOffset":      (16,DWORD),
    "ExportCount":      (20,DWORD),
    "ExportOffset":      (24,DWORD),
    "ImportCount":      (28,DWORD),
    "ImportOffset":      (32,DWORD),
    "GUID":         (36,GUID)
    }

class UPK:
    def __init__(self,f):
        self.file=f

    def readHeader(self,offset,count):
        self.file.seek(offset)
        return endineFixWin(count,bytearray(self.file.read(count)))
        
    def __getitem__(self,name):
        if name in UPKDef:
            prop=UPKDef[name]
            return self.readHeader(prop[0],prop[1])

    
    def isValid(self):
        return str(self["Signature"]).encode('hex') == '9e2a83c1'



if __name__ == "__main__":
    import sys,os
    if len(sys.argv) < 2:
        print "input file required"
    elif not os.path.exists(sys.argv[1]):
        print "invalid file path"
    else:
        file=open(sys.argv[1])
        upk=UPK(file)
        print "is valid upk? ",upk.isValid()
        for k in UPKDef.keys():
            print k,":",str(upk[k]).encode('hex')
        file.close()