catching error when creating lua state due to missing libraries in factory and logging it right there, to allow printing error to chat the first time, too; different name the lib is saved to the tmp folder to reduce the chance of collisions; explicit message for windows users reminding them to install the vc2012 runtimes on library load errors

li/cil/oc/util/LuaStateFactory.scala

@@ -5,6 +5,7 @@ import com.naef.jnlua.{LuaState, NativeSupport}
 import java.io.File
 import java.io.FileOutputStream
 import java.nio.channels.Channels
+import java.util.logging.Level
 import li.cil.oc.server.component.Computer
 import li.cil.oc.util.ExtendedLuaState._
 import li.cil.oc.{OpenComputers, Settings}
@@ -27,6 +28,8 @@ object LuaStateFactory {
   /** Set to true in initialization code below if available. */
   private var haveNativeLibrary = false
 
+  private var isWindows = false
+
   private var _is64Bit = false
 
   def is64Bit = _is64Bit
@@ -76,6 +79,7 @@ object LuaStateFactory {
             break()
         }
     }
+    isWindows = extension == ".dll"
     val libPath = "/assets/" + Settings.resourceDomain + "/lib/"
 
     val tmpPath = {
@@ -92,7 +96,7 @@ object LuaStateFactory {
     }
 
     // Found file with proper extension. Create a temporary file.
-    val file = new File(tmpPath + library)
+    val file = new File(tmpPath + "OpenComputersMod-" + library)
     // Try to delete an old instance of the library, in case we have an update
     // and deleteOnExit fails (which it regularly does on Windows it seems).
     try {
@@ -145,6 +149,7 @@ object LuaStateFactory {
   def createState(): Option[LuaState] = {
     if (!haveNativeLibrary) return None
 
+    try {
       val state = new LuaState(Int.MaxValue)
       try {
         // Load all libraries.
@@ -278,12 +283,26 @@ object LuaStateFactory {
 
         state.setGlobal("unicode")
 
-      Some(state)
-    } catch {
-      case ex: Throwable =>
-        ex.printStackTrace()
-        state.close()
-        return None
+        return Some(state)
       }
+      catch {
+        case t: Throwable =>
+          OpenComputers.log.log(Level.WARNING, "Failed creating Lua state.", t)
+          state.close()
+      }
+    }
+    catch {
+      case _: UnsatisfiedLinkError =>
+        OpenComputers.log.severe("Failed loading the native libraries.")
+        if (isWindows) {
+          OpenComputers.log.severe(
+            "Please ensure you have the Visual C++ 2012 Runtime installed " +
+              "(when on 64 Bit, both the 32 bit and 64 bit version of the " +
+              "runtime).")
+        }
+      case t: Throwable =>
+        OpenComputers.log.log(Level.WARNING, "Failed creating Lua state.", t)
+    }
+    None
   }
 }