Convert boost`s bufferstream to istream

Question

Is it possible to convert boost`s bufferstream to istream? I am trying to do conversion, however it is still unclear to me whether I am doing something wrong or it is just not possible to do that at all. I would appreciate any answers.

char *copy = static_cast <char*> (region.get_address());
for (int i = 0;i < length;i++) copy[i] = str[i];
bufferstream input_stream (copy, length);

And then I need to convert bufferstream into istream. Basically, I need to make bufferstream instances be passed as a parameter to a function which accepts istream &.

Answer 1

It's unclear what you want to achieve¹, here's my best guess:

Live² On Coliru

#include <boost/interprocess/mapped_region.hpp>
#include <boost/interprocess/shared_memory_object.hpp>
#include <boost/interprocess/streams/bufferstream.hpp>
#include <iostream>

namespace bip = boost::interprocess;

int main() {
    bip::shared_memory_object smo(bip::open_or_create, "MySharedMemory", bip::read_write);

    std::string str = "test data";
    smo.truncate(10ull << 10); // 10 KiB
    bip::mapped_region r(smo, bip::read_write);

    bip::bufferstream stream(reinterpret_cast<char*>(r.get_address()), r.get_size());

    if (stream << str)
        std::cout << "Written";
}

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¹ https://meta.stackexchange.com/questions/66377/what-is-the-xy-problem

² shared memory is not supported on Coliru