Migrated upgradeGetdown() out of Yohoho and into a Getdown utility class.

src/java/com/threerings/getdown/util/LaunchUtil.java

@@ -4,6 +4,11 @@
 package com.threerings.getdown.util;
 
 import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+
+import org.apache.commons.io.CopyUtils;
 
 import com.threerings.getdown.Log;
 
@@ -52,6 +57,65 @@ public class LaunchUtil
         return apbase + "java";
     }
 
+    /**
+     * Upgrades Getdown by moving an installation managed copy of the Getdown
+     * jar file over the non-managed copy (which would be used to run Getdown
+     * itself).
+     *
+     * <p> If the upgrade fails for a variety of reasons, warnings are logged
+     * but no other actions are taken. There's not much else one can do other
+     * than try again next time around.
+     */
+    public static void upgradeGetdown (File oldgd, File curgd, File newgd)
+    {
+        // we assume getdown's jar file size changes with every upgrade, this
+        // is not guaranteed, but in reality it will, and it allows us to avoid
+        // pointlessly upgrading getdown every time the client is updated which
+        // is unnecessarily flirting with danger
+        if (!newgd.exists() || newgd.length() == curgd.length()) {
+            return;
+        }
+
+        Log.info("Updating Getdown with " + newgd + "...");
+
+        // clear out any old getdown
+        if (oldgd.exists()) {
+            oldgd.delete();
+        }
+
+        // now try updating using renames
+        if (!curgd.exists() || curgd.renameTo(oldgd)) {
+            if (newgd.renameTo(curgd)) {
+                oldgd.delete(); // yay!
+                try {
+                    // copy the moved file back to getdown-dop-new.jar so that
+                    // we don't end up downloading another copy next time
+                    CopyUtils.copy(new FileInputStream(curgd),
+                                   new FileOutputStream(newgd));
+                } catch (IOException e) {
+                    Log.warning("Error copying updated Getdown back: " + e);
+                }
+                return;
+            }
+
+            Log.warning("Unable to renameTo(" + oldgd + ").");
+            // try to unfuck ourselves
+            if (!oldgd.renameTo(curgd)) {
+                Log.warning("Oh God, why dost thee scorn me so.");
+            }
+        }
+
+        // that didn't work, let's try copying it
+        Log.info("Attempting to upgrade by copying over " + curgd + "...");
+        try {
+            CopyUtils.copy(new FileInputStream(newgd),
+                           new FileOutputStream(curgd));
+        } catch (IOException ioe) {
+            Log.warning("Mayday! Brute force copy method also failed.");
+            Log.logStackTrace(ioe);
+        }
+    }
+
     /**
      * Returns true if, on this operating system, we have to stick around
      * and read the stderr from our children processes to prevent them