FileRAII.h

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#include <string>
#include <cstdio>
#include <cerrno>

#include <vigra/error.hxx>

namespace vigra_ext
{
class FileRAII
{
public:
    FileRAII(const char *path, const char *mode)
    {
        file = std::fopen(path, mode);
        if (file == 0) {
            std::string msg("Unable to open file '");
            msg += path;
            msg += "'.";
            vigra_precondition(0, msg.c_str());
        }
    }

    ~FileRAII()
    {
        if (file) {
            errno = 0;
            if (std::fclose(file)) {
                // there are several possible errors, handle some of them
                std::string msg;
                switch(errno)
                {
                    case EBADF:
                        msg = "Bad file descriptor.";
                        break;
                    case EIO:
                        msg = "An I/O error occurred while closing the file.";
                        break;
                    default:
                        msg = "An error ocured while closing the file.";
                        break;
                }
                vigra_postcondition(0, msg.c_str());
            }
        }
    }

    FILE* get()
    {
        return file;
    }

private:
    FILE* file;

    // this class should never be copied or assigned
    FileRAII(const FileRAII &);
    FileRAII& operator=(const FileRAII &);
};

}