Function normalize_writes

pwnlib/fmtstr.py:126–154

r""" This function converts user-specified writes to a dict ``{ address1: data1, address2: data2, ... }`` such that all values are raw bytes and consecutive writes are merged to a single key. Examples: >>> context.clear(endian="little", bits=32) >>> normalize_writes({0x

(writes)

}

def normalize_writes(writes):
    r"""
    This function converts user-specified writes to a dict ``{ address1: data1, address2: data2, ... }``
    such that all values are raw bytes and consecutive writes are merged to a single key.

    Examples:

        >>> context.clear(endian="little", bits=32)
        >>> normalize_writes({0x0: [p32(0xdeadbeef)], 0x4: p32(0xf00dface), 0x10: 0x41414141})
        [(0, b'\xef\xbe\xad\xde\xce\xfa\r\xf0'), (16, b'AAAA')]
    """
    # make all writes flat
    writes = { address: flat(data) for address, data in writes.items() }

    # merge adjacent writes (and detect overlaps)
    merged = []
    prev_end = -1
    for address, data in sorted(writes.items(), key=itemgetter(0)):
        if address < prev_end:
            raise ValueError("normalize_writes(): data at offset %d overlaps with previous data which ends at offset %d" % (address, prev_end))

        if address == prev_end and merged:
            merged[-1] = (merged[-1][0], merged[-1][1] + data)
        else:
            merged.append((address, data))

        prev_end = address + len(data)

    return merged

# optimization examples (with bytes_written=0)
#