Function CPLProjectRelativeFilenameSafe

port/cpl_path.cpp:1035–1053

 */

std::string CPLProjectRelativeFilenameSafe(const char *pszProjectDir,
                                           const char *pszSecondaryFilename)

{
    if (pszProjectDir == nullptr || pszProjectDir[0] == 0 ||
        !CPLIsFilenameRelative(pszSecondaryFilename))
    {
        return pszSecondaryFilename;
    }

    std::string osRes(pszProjectDir);
    if (osRes.back() != '/' && osRes.back() != '\\')
    {
        osRes += VSIGetDirectorySeparator(pszProjectDir);
    }

    osRes += pszSecondaryFilename;
    return osRes;
}

/************************************************************************/
/*                     CPLProjectRelativeFilename()                     */