Function CPLvsnprintf

port/cpl_string.cpp:1128–1318

vsnprintf() wrapper that is not sensitive to LC_NUMERIC settings. * * This function has the same contract as standard vsnprintf(), except that * formatting of floating-point numbers will use decimal point, whatever the * current locale is set. * * @param str output buffer * @param size size of the output buffer (including space for terminating nul) * @param fmt formatting string * @param

 * for Visual Studio < 2015.
 */
int CPLvsnprintf(char *str, size_t size, CPL_FORMAT_STRING(const char *fmt),
                 va_list args)
{
    if (size == 0)
        return vsnprintf(str, size, fmt, args);

    va_list wrk_args;

#ifdef va_copy
    va_copy(wrk_args, args);
#else
    wrk_args = args;
#endif

    const char *fmt_ori = fmt;
    size_t offset_out = 0;
    char ch = '\0';
    bool bFormatUnknown = false;

    for (; (ch = *fmt) != '\0'; ++fmt)
    {
        if (ch == '%')
        {
            if (strncmp(fmt, "%.*f", 4) == 0)
            {
                const int precision = va_arg(wrk_args, int);
                const double val = va_arg(wrk_args, double);
                const int local_ret =
                    snprintf(str + offset_out, size - offset_out, "%.*f",
                             precision, val);
                // MSVC vsnprintf() returns -1.
                if (local_ret < 0 || offset_out + local_ret >= size)
                    break;
                for (int j = 0; j < local_ret; ++j)
                {
                    if (str[offset_out + j] == ',')
                    {
                        str[offset_out + j] = '.';
                        break;
                    }
                }
                offset_out += local_ret;
                fmt += strlen("%.*f") - 1;
                continue;
            }

            const char *ptrend = CPLvsnprintf_get_end_of_formatting(fmt + 1);
            if (ptrend == nullptr || ptrend - fmt >= 20)
            {
                bFormatUnknown = true;
                break;
            }
            char end = *ptrend;
            char end_m1 = ptrend[-1];

            char localfmt[22] = {};
            memcpy(localfmt, fmt, ptrend - fmt + 1);
            localfmt[ptrend - fmt + 1] = '\0';