static char *mk_file_path(const char *dir, const char *file)
{
#ifndef OPENSSL_SYS_VMS
    const char *sep = "/";
#else
    const char *sep = "";
#endif
    size_t len = strlen(dir) + strlen(sep) + strlen(file) + 1;
    char *full_file = OPENSSL_zalloc(len);

    if (full_file != NULL) {
        OPENSSL_strlcpy(full_file, dir, len);
        OPENSSL_strlcat(full_file, sep, len);
        OPENSSL_strlcat(full_file, file, len);
    }

    return full_file;
}