ips.py

def split_as_size(arr,size):return arr[:size],arr[size:]

class IPS:
    MAGIC = b'\x50\x41\x54\x43\x48'
    END = b'\x45\x4f\x46'
    @classmethod
    def create_from_stream(cls,stream):
        return cls.create_from_bytes(stream.read())
    @classmethod
    def create_from_bytes(cls,byte_array):
        def extract_chunk(arr):
            offset,arr=split_as_size(arr,3)
            size,arr=split_as_size(arr,2)
            data,arr=split_as_size(arr,int.from_bytes(size))
            return Chunk(offset,int.from_bytes(data)),arr
        def pull_all_chunks(arr):
            while len(arr)>3:
                chunk,arr=extract_chunk(arr)
                yield chunk
        return cls(list(pull_all_chunks(byte_array)))
    def __init__(self,chunks):self.chunks = chunks
    def apply(self,arr):
        for chunk in self.chunks:
            arr[chunk.position:chunk.position+chunk.size]=chunk.data
        return arr

if __name__=="__main__":
    from sys import argv;argv=argv[1:]
    from os.path import isfile
    patches,target=[],None
    for filename in argv:
        if not isfile(filename):continue
        if filename[:filename.rfind(".")].lower()=='ips':
            patches.append(filename)
        else:target=filename
    if target and patches:
        base_data = open(target,'rb').read()#read in the data to modify.
        for patch in map(IPS.create_from_stream,map(lambda fn:open(fn,'rb'),patches)):
            base_data=patch.apply(base_data)
        with open('patched-{}-{}'.format("-".join(map(patch_name,patches)),target),'wb') as output:
            output.write(base_data)