Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Create a new non-modifiable buffer from an existing buffer.

const_buffer buffer(
    const const_buffer & b,
    std::size_t max_size_in_bytes);

A const_buffer value equivalent to:

const_buffer(
   b.data(),
   min(b.size(), max_size_in_bytes));