GeckoLoader/dolreader.py

import struct 
from io import BytesIO, RawIOBase


def read_ubyte(f):
    return struct.unpack("B", f.read(1))[0]

def read_uint32(f):
    return struct.unpack(">I", f.read(4))[0]

def write_uint32(f, val):
    f.write(struct.pack(">I", val))

class DolFile(object):
    def __init__(self, f):
        self._rawdata = BytesIO(f.read())
        fileoffset = 0
        addressoffset = 0x48
        sizeoffset = 0x90 
        
        self._text = []
        self._data = []
        
        nomoretext = False 
        nomoredata = False
        
        self._current_end = None 
        
        # Read text and data section addresses and sizes 
        for i in range(18):
            f.seek(fileoffset+i*4)
            offset = read_uint32(f)
            f.seek(addressoffset+i*4)
            address = read_uint32(f)
            f.seek(sizeoffset+i*4)
            size = read_uint32(f)
            
            if i <= 6:
                if offset == 0:
                    nomoretext = True 
                elif not nomoretext:
                    self._text.append((offset, address, size))
                    # print("text{0}".format(i), hex(offset), hex(address), hex(size))
            else:
                #datanum = i - 7
                if offset == 0:
                    nomoredata = True 
                elif not nomoredata:
                    self._data.append((offset, address, size))
                    # print("data{0}".format(datanum), hex(offset), hex(address), hex(size))
        
        f.seek(0xD8)
        self._bssoffset = read_uint32(f)
        self._bsssize = read_uint32(f)
        self._init = read_uint32(f)
        
        self.bss = BytesIO(self._rawdata.getbuffer()[self._bssoffset:self._bssoffset+self._bsssize])
        
        self._curraddr = self._text[0][1]
        self.seek(self._curraddr)
        f.seek(0)
        
    # Internal function for 
    def _resolve_address(self, gc_addr):
        for offset, address, size in self._text:
            if address <= gc_addr < address+size:
                return offset, address, size 
        for offset, address, size in self._data:
            if address <= gc_addr < address+size:
                return offset, address, size 
        
        raise RuntimeError("Unmapped address: {0}".format(hex(gc_addr)))

    def seekSafeAddress(self, gc_addr, buffer=0):
        for offset, address, size in self._text:
            if address > (gc_addr + buffer) or address+size < gc_addr:
                continue
            gc_addr = address + size
        for offset, address, size in self._data:
            if address > (gc_addr + buffer) or address+size < gc_addr:
                continue
            gc_addr = address + size
        return gc_addr
    
    # Unsupported: Reading an entire dol file 
    # Assumption: A read should not go beyond the current section 
    def read(self, size):
        if self._curraddr + size > self._current_end:
            raise RuntimeError("Read goes over current section")
            
        self._curraddr += size  
        return self._rawdata.read(size)
        
    # Assumption: A write should not go beyond the current section 
    def write(self, data):
        if self._curraddr + len(data) > self._current_end:
            raise RuntimeError("Write goes over current section")
            
        self._rawdata.write(data)
        self._curraddr += len(data)
    
    def seek(self, where, whence=0):
        if whence == 0:
            offset, gc_start, gc_size = self._resolve_address(where)
            self._rawdata.seek(offset + (where-gc_start))
            
            self._curraddr = where
            self._current_end = gc_start + gc_size
        elif whence == 1:
            offset, gc_start, gc_size = self._resolve_address(self._curraddr + where)
            self._rawdata.seek(offset + ((self._curraddr + where)-gc_start))
            
            self._curraddr += where
            self._current_end = gc_start + gc_size
        else:
            raise RuntimeError("Unsupported whence type '{}'".format(whence))
        
    def tell(self):
        return self._curraddr
    
    def save(self, f):
        f.seek(0)
        f.write(self._rawdata.getbuffer())

    def getsize(self):
        oldpos = self._rawdata.tell()
        self._rawdata.seek(0, 2)
        size = self._rawdata.tell()
        self._rawdata.seek(oldpos)
        return size

    def getalignment(self, alignment):
        size = self.getsize()

        if size % alignment != 0:
            return alignment - (size % alignment)
        else:
            return 0

    def setInitPoint(self, address):
        oldpos = self._rawdata.tell()
        self._rawdata.seek(0xE0)
        self._rawdata.write(bytes.fromhex('{:08X}'.format(address)))
        self._rawdata.seek(oldpos)

    def align(self, alignment):
        oldpos = self._rawdata.tell()
        self._rawdata.seek(0, 2)
        self._rawdata.write(bytes.fromhex("00" * self.getalignment(alignment)))
        self._rawdata.seek(oldpos)

    def insertBranch(self, to, _from, lk=0):
        self.write(((to - _from) & 0x3FFFFFF | 0x48000000 | lk).to_bytes(4, byteorder='big', signed=False))

        

if __name__ == "__main__":
    # Example usage (reading some enemy info from the Pikmin 2 demo from US demo disc 17)
    
    def read_string(f):
        start = f.tell()
        length = 0
        while f.read(1) != b"\x00":
            length += 1
            if length > 100:
                break
        
        f.seek(start)
        return f.read(length)
    
    entries = []

    with open("main.dol", "rb") as f:
        dol = DolFile(f)

    start = 0x804ac478 # memory address to start of enemy info table.

    for i in range(100):
        dol.seek(start+0x34*i, 0)
        
        # string offset would normally be pointing to a location in RAM and thus
        # wouldn't be suitable as a file offset but because the seek function of DolFile 
        # takes into account the memory address at which the data sections of the dol file 
        # is loaded, we can use the string offset directly..
        stringoffset = read_uint32(dol) 
        identifier = read_ubyte(dol) 
        dol.seek(stringoffset, 0)
        name = read_string(dol)
         
        entries.append((identifier,i, name, hex(stringoffset)))
        
    entries.sort(key=lambda x: x[0])
    for val in entries:
        print(hex(val[0]), val)