I have binary data in a byte sequence described by const unsigned char *p and size_t len. I want to be able to pass this data to a function that expects a std::istream *.
I think I should be able to do this without copying the data, unsafe casts or writing a new stream class. But so far I'm failing. Can anyone help?
Update
Thanks all for the comments. This would seem to be an unanswerable question because std::istream operates with char and conversion would at some point require at least an integer cast from unsigned char.
The pragmatic approach is to do this:
std::string s(reinterpret_cast<const char*>(p), len);
std::istringstream i(s);
and pass &i to the function expecting std::istream *.
Your answer is still copying.
Have you considered something like this?
const unsigned char *p;
size_t len;
std::istringstream str;
str.rdbuf()->pubsetbuf(
reinterpret_cast<char*>(const_cast<unsigned char*>(p)), len);