new file mode 100644
--- /dev/null
+++ b/tools/common.sh
@@ -0,0 +1,26 @@
+function verify_current_revision()
+{
+    /bin/rm -rf *
+    exportcmd="svn export `hg svn info 2> /dev/null | grep '^URL: ' | sed 's/URL: //'` -r`hg svn info | grep ^Revision | sed 's/.*: //;s/ .*//'` . --force"
+    `echo $exportcmd` > /dev/null
+    x=$?
+    if [[ "$x" != "0" ]] ; then
+        echo $exportcmd
+        echo 'export failed!'
+        return 255
+    fi
+    if [[ "`hg st | wc -l | python -c 'import sys; print sys.stdin.read().strip()'`" == "0" ]] ; then
+        return 0
+    else
+        if [[ $1 != "keep" ]] ; then
+            revert_all_files
+        fi
+        return 1
+    fi
+}
+
+function revert_all_files()
+{
+    hg revert --all
+    hg purge
+}