When parsing configuration files on systems with differing locales, the use of strtod can produce different results, or in the worst case - fail to parse expected values. Fix this by using strtod_l() instead. To avoid constructing and destructing a locale_t instance for every use of strtod_l(), create an RAII class that wraps the locale_t and use it to provide a global "C" locale. Bug: https://bugs.libcamera.org/show_bug.cgi?id=174 Bug: https://github.com/raspberrypi/libcamera/issues/29 Reported-by: https://github.com/kralo Reported-by: Hannes Winkler <hanneswinkler2000@web.de> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>