fdstream.h

 
#ifndef LIB_FDSTREAM_H_
#define LIB_FDSTREAM_H_
 
#include <array>
#include <cstddef>
#include <cstdio>
#include <iostream>
#include <streambuf>
#include <variant>
 
namespace P4 {

class FdStream final : public std::iostream {
    class Buffer final : public std::streambuf {
        static constexpr std::size_t BUFFER_SIZE = 8192;
        std::variant<int, FILE *> source;
        std::array<char, BUFFER_SIZE> inputBuffer{};
        std::array<char, BUFFER_SIZE> outputBuffer{};
        int stdioReadError = 0;
        bool stdioOutputPending = false;
 
        std::size_t readStdio(FILE *file);
 
     protected:
        int_type underflow() override;
        int_type overflow(int_type c) override;
        int sync() override;
 
     public:
        explicit Buffer(int fd);
        explicit Buffer(FILE *file);
    } buffer;
 
 public:
    explicit FdStream(int fd);
    explicit FdStream(FILE *file);
    ~FdStream() override;
 
    FdStream(const FdStream &) = delete;
    FdStream &operator=(const FdStream &) = delete;
    FdStream(FdStream &&) = delete;
    FdStream &operator=(FdStream &&) = delete;
};
 
}  // namespace P4
 
#endif  // LIB_FDSTREAM_H_