InfoBase.hxx

#pragma once
 
// C++
#include <cstring>
 
// cosmos
#include <cosmos/error/ApiError.hxx>
#include <cosmos/error/RuntimeError.hxx>
#include <cosmos/memory.hxx>
 
namespace cosmos {
 
constexpr size_t BUF_INIT_SIZE = 512;
constexpr size_t BUF_MAX_SIZE = 65535;
 
template <typename DB_STRUCT>
bool InfoBase<DB_STRUCT>::getInfo(std::function<int(DB_STRUCT**)> get_func, const char *errlabel) {
        DB_STRUCT *res;
        m_buf.resize(BUF_INIT_SIZE);
 
        while (true) {
                const auto err = get_func(&res);
                switch(Errno{err}) {
                        case Errno::NO_ERROR:
                                return res != nullptr;
                        case Errno::RANGE: m_buf.resize(m_buf.size() << 1); break;
                        default: cosmos_throw(ApiError(errlabel, Errno{err})); break;
                }
 
                if (m_buf.size() > BUF_MAX_SIZE) {
                        // don't get too crazy here
                        cosmos_throw(RuntimeError("buffer size limit reached"));
                }
        }
 
        return false;
}
 
template <typename DB_STRUCT>
void InfoBase<DB_STRUCT>::reset() {
        m_buf.clear();
        zero_object(m_info);
        m_valid = false;
}
 
} // end ns