Add fix from http://nsis.sourceforge.net/Environmental_Variables:_app…

…end,_prepend,_and_remove_entries for trapping long strings

Refs #330

git-svn-id: https://svn.nexusformat.org/code/trunk@1844 ff5d1e40-2be0-497f-93bd-dc18237bd3c7

cmake_modules/NSIS.template.in

@@ -1096,7 +1096,31 @@ Function ${UN}EnvVarUpdate
     DetailPrint "ERROR: PathString is blank"
     Goto EnvVarUpdate_Restore_Vars
   ${EndIf}
-
+
+  ;; From http://nsis.sourceforge.net/Environmental_Variables:_append,_prepend,_and_remove_entries
+  ;; khc - here check if length is going to be greater then max string length
+  ;;       and abort if so - also abort if original path empty - may mean
+  ;;       it was too long as well- write message to say set it by hand 
+   Push $6
+   Push $7
+   Push $8
+   StrLen $7 $4  
+   StrLen $6 $5
+   IntOp $8 $6 + $7
+   ${If} $5 == ""
+   ${OrIf} $8 >= ${NSIS_MAX_STRLEN}
+     SetErrors
+     DetailPrint "Current $1 length ($6) too long to modify in NSIS; set manually if needed"
+     Pop $8
+     Pop $7
+     Pop $6
+     Goto EnvVarUpdate_Restore_Vars
+   ${EndIf}
+   Pop $8
+   Pop $7
+   Pop $6
+ ;;khc 
+
   ; Make sure we've got some work to do
   ${If} $5 == ""
   ${AndIf} $2 == "R"