ctr_e3_dump_code.py

EXEFS_SECTIONS = [
    ".text",
    ".ro",
    ".rw"
]

def align_block(v: int) -> int:
    return v + 15 & ~(15)

def make_name(data: bytes) -> str:
    index = 0
    for b in data:
        if b == 0:
            break
        index += 1
    return data.decode()[:index]

def extract_code(app_path: str):
    input = open(app_path, "rb")

    input.seek(0x1A0, 0)
    exefs_offset = int.from_bytes(input.read(4), byteorder='little')
    input.seek(exefs_offset, 0)
    exefs_header = input.read(0x30)

    code_size = 0
    for i in range(len(EXEFS_SECTIONS)):
        index = i * 0x10
        name = make_name(exefs_header[index:index + 0x08])

        if name != EXEFS_SECTIONS[i]:
            raise Exception(f"Expected {EXEFS_SECTIONS[i]}, found {name}")

        index += 0x0C
        size = int.from_bytes(exefs_header[index:index + 0x04], byteorder='little')
        code_size += align_block(size)

    input.seek(0xC00, 0)
    with open("code.bin", "wb") as out:
        out.write(input.read(code_size))
    
    input.close()

extract_code("HID3.app")
print("Done")