Do not offer upgrade if existing version cannot keep cfg on silent un…

…install

Old versions before 12.4.5 cannot keep config files when silenly uninstalling.
So do not offer upgrade there.

Fixes #234: Do not offer upgrade if existing version cannot keep cfg on silent uninstall

platforms/win32/winbareos.nsi

@@ -74,6 +74,7 @@ Var Upgrading
 !include "nsDialogs.nsh"
 !include "x64.nsh"
 !include "WinVer.nsh"
+!include "WordFunc.nsh"
 
 # call functions once to have them included
 ${StrCase}
@@ -550,7 +551,22 @@ Function .onInit
   ReadRegStr $2  ${PRODUCT_UNINST_ROOT_KEY} "${PRODUCT_UNINST_KEY}" "DisplayName"
   ReadRegStr $0  ${PRODUCT_UNINST_ROOT_KEY} "${PRODUCT_UNINST_KEY}" "DisplayVersion"
   ReadRegStr $R0 ${PRODUCT_UNINST_ROOT_KEY} "${PRODUCT_UNINST_KEY}" "UninstallString"
+
+  #
+  # If there is no version installed there is not much to upgrade so jump to done.
+  #
   StrCmp $R0 "" done
+
+  #
+  # As versions before 12.4.5 cannot keep the config files during silent install, we do not support upgrading here
+  #
+  ${VersionCompare} "12.4.5" "$0" $1
+  ${select} $1
+  ${case} 1
+      MessageBox MB_OK|MB_ICONSTOP "Upgrade from version $0 is not supported.$\r$\nPlease uninstall and then install again."
+      Abort
+  ${endselect}
+
   strcpy $Upgrading "yes"
   ${StrRep} $INSTDIR $R0 "uninst.exe" "" # find current INSTDIR by cutting uninst.exe out of uninstall string