import io import struct class Reader: def __init__(self, file, chunk_id: str, parent=None, indent=0): self.file = file self.size: int = 0 self.size_pos = None self.parent = parent self.header = chunk_id self.indent = " " * indent def __enter__(self): self.size_pos = self.file.tell() self.file.seek(4,1) #skip header, will add check later self.size = self.read_u32() padding_length = 4 - (self.size % 4) if self.size % 4 > 0 else 0 self.end_pos = self.size_pos + padding_length + self.size + 8 print(self.indent + "Begin " + self.header + ", Size: " + str(self.size) + ", Pos: " + str(self.size_pos)) return self def __exit__(self, exc_type, exc_value, traceback): if self.size > self.MAX_SIZE: raise OverflowError(f".msh file overflowed max size. size = {self.size} MAX_SIZE = {self.MAX_SIZE}") print(self.indent + "End " + self.header) self.file.seek(self.end_pos) def read_bytes(self,num_bytes): return self.file.read(num_bytes) def read_string(self): last_byte = self.read_bytes(1) result = b'' while last_byte[0] != 0x0: result += last_byte last_byte = self.read_bytes(1) return result.decode("utf-8") def read_i8(self, num=1): buf = self.read_bytes(num) result = struct.unpack(f"<{num}b", buf) return result[0] if num == 1 else result def read_u8(self, num=1): buf = self.read_bytes(num) result = struct.unpack(f"<{num}B", buf) return result[0] if num == 1 else result def read_i16(self, num=1): buf = self.read_bytes(num * 2) result = struct.unpack(f"<{num}h", buf) return result[0] if num == 1 else result def read_u16(self, num=1): buf = self.read_bytes(num * 2) result = struct.unpack(f"<{num}H", buf) return result[0] if num == 1 else result def read_i32(self, num=1): buf = self.read_bytes(num * 4) result = struct.unpack(f"<{num}i", buf) return result[0] if num == 1 else result def read_u32(self, num=1): buf = self.read_bytes(num * 4) result = struct.unpack(f"<{num}I", buf) return result[0] if num == 1 else result def read_f32(self, num=1): buf = self.read_bytes(num * 4) result = struct.unpack(f"<{num}f", buf) return result[0] if num == 1 else result def read_child(self, child_id: str): child = Reader(self.file, chunk_id=child_id, parent=self, indent=int(len(self.indent) / 2) + 1) return child def skip_bytes(self,num): self.file.seek(num,1) def peak_next_header(self): buf = self.read_bytes(4); self.file.seek(-4,1) return buf.decode("utf-8") def could_have_child(self): return self.end_pos - self.file.tell() >= 8 MAX_SIZE: int = 2147483647 - 8 ''' with open("/Users/will/Desktop/spacedoortest/spa1_prop_impdoor.msh", "rb") as tst_stream: with Reader(tst_stream, "HEDR") as hedr: print(hedr.peak_next_header()) '''