How to Unserialize File From Scratch (without library) In C++

I was given a file with data stored in a custom format, for example, "data.asd", and tasked with extracting the information out of it. I was given a file specification of the ".asd" format.

All asd files begin at 0x0 which starts with the 5 bytes "Hello" and a 6th one for the \0 termination. Next 32 bits is a pointer to an entry list, which is an array of 127 entries. Each entry contains a 16 char null terminated string, a pointer to some data, and a size variable that tells the size of the data. The value 0xFFFFFFFF signifies the end of the list.

I've look into using the C++ boost serializing library, but get errors when I tried to open the file. I'm assuming boost can only read files it has wrote.

std::ifstream ifs("data.asd");
boost::archive::binary_iarchive in_arch(ifs);

I've since checked out serializing "manually" by opening in ifstream, copying the binary file into a vector, and then using memmove.

ifs.open(fileName, ios::in | ios::binary);

//copy all contents in binary into buffer
vector<char> buffer((
    istreambuf_iterator<char>(ifs)),
    (istreambuf_iterator<char>()));

memmove(s, &buffer.at(0), 6); // move char array 'hello' into string s

I should be able to figure out where the data, entry list, and strings end by checking for termination bits. That way I can get by using memmove and serialize the file by checking bits.

For my case, is there any better option? If i am stuck using memmove, how do I figure out what the pointers point to? Using memmove I was able to move the six bits into a string 's' and rebuild the variable, but I'm unsure how to handle the pointers.

You could memory map things and use Boost Endian.

Alternatively you could use Boost Spirit's Binary parsers: https://www.boost.org/doc/libs/1_51_0/libs/spirit/doc/html/spirit/qi/reference/binary.html

There's an example:

 std::uint32_t length;

 bool valid = qi::parse(first, last,
      "Hello" >> qi::little_word >> char_('\0'), length);