#!/usr/bin/env python

import os
import sys
import zlib

from struct import pack, unpack
from time import ctime

def parse_npk(filename):
    f = open(filename, "r")
    data = f.read()
    f.close()

    # location different each time, not going to waste time on this, changed all the 70 and 74's below
    #header = data[:65]
    header = data[:74]

    #(58:62 @ 6.4)
    #(70:74 @ 6.38.3)

    #dsize = unpack("<I", header[58:62])[0]
    dsize = unpack("<I", header[70:74])[0]
    print "Dsize: %s" % (dsize)
    header += data[74:74+dsize+40]

    data = data[74+dsize+40:]
    res=[]
    while len(data)>6:
        type = unpack("<H", data[:2])[0]
        size = unpack("<I", data[2:6])[0]
        #print "type: %s, size: %s" % (type,size)
        contents = data[6:6+size]
        if type == 4:
            contents = zlib.decompress(contents)
        res.append({"type": type, "size": size, "contents": contents})
        data = data[6+size:]

    return header, res

def parse_data(data):
    res = []
    while len(data)>30:
        header = data[:30]
        dsize = unpack("<I", header[24:28])[0]
        fsize = unpack("<H", header[28:30])[0]
        if len(data) - 30 - fsize - dsize < 0:
            dsize = len(data) - 30 - fsize
        fstuff = data[30:30+fsize]
        dstuff = data[30+fsize:30+fsize+dsize]
        res.append({"header": header, "file": fstuff, "data": dstuff})
        data = data[30+fsize+dsize:]
    return res

if __name__ == "__main__":
    w = 1
    if len(sys.argv) > 1:
        for i in sys.argv[1:]:
            header, res = parse_npk(i)
            for j in res:
                if j["type"] == 4:
                    print "Kernel files in package:"
                    data = parse_data(j["contents"])
                    for k in data:
                        perm, type, z1, z2, tim = unpack("<BBHII", k["header"][:12])
                        pathname_len = len(k["file"])
                        pathname_len -= 1
                        pathname_check = k["file"][ :-pathname_len]
                        if pathname_check == "/":
                            k["file"] = k["file"][1: ]
                        if perm == 237:
                            perm = "ex"
                        if perm == 164:
                            perm = "nx"
                        if type == 65:
                            type = "dir"
                            if k["file"] == "boot":
                                if not os.path.exists(k["file"]):
                                    os.mkdir(k["file"])
                        if type == 129:
                            if k["file"][-6:] == "kernel":
                                type = "fil"
                                print "-> " + k["file"] + str(w)
                                try:
                                    f = open(k["file"] + str(w), "wb+")
                                    f.write(k['data'])
                                    f.close()
                                    w = w + 1
                                except:
                                    pass