OID::newState to generate fresh "machine" bits

2 files changed, 14 insertions, 3 deletions

diff --git a/db/jsobj.cpp b/db/jsobj.cpp
index 95650aeb15f..efadfc16406 100644
--- a/db/jsobj.cpp
+++ b/db/jsobj.cpp
@@ -1423,10 +1423,14 @@ namespace mongo {
     }
 */
 
+    unsigned OID::_machine = (unsigned) security.getNonce();
+    void OID::newState(){
+        // using fresh Security object to avoid buffered devrandom
+        _machine = (unsigned) Security().getNonce();
+    }
+    
     void OID::init() {
-        static unsigned machine = (unsigned) security.getNonce();
         static unsigned inc = (unsigned) security.getNonce();
-
         unsigned t = (unsigned) time(0);
         char *T = (char *) &t;
         data[0] = T[3];
@@ -1434,7 +1438,8 @@ namespace mongo {
         data[2] = T[1];
         data[3] = T[0];
 
-        (unsigned&) data[4] = machine;
+        (unsigned&) data[4] = _machine;
+
         // TODO: use compiler intrinsic atomic increment instead of inc++
         int old_inc = inc++;
         T = (char *) &old_inc;
diff --git a/db/jsobj.h b/db/jsobj.h
index 2a3030f9ffa..c329613e01c 100644
--- a/db/jsobj.h
+++ b/db/jsobj.h
@@ -109,6 +109,8 @@ namespace mongo {
         is likely to be unique to the system.  You may also use other types for _id's.
         When _id field is missing from a BSON object, on an insert the database may insert one 
         automatically in certain circumstances.
+
+        Warning: You must call OID::newState() after a fork().
     */
     class OID {
         union {
@@ -118,7 +120,11 @@ namespace mongo {
             };
             unsigned char data[12];
         };
+        static unsigned _machine;
     public:
+        /** call this after a fork */
+        static void newState();
+
 		/** initialize to 'null' */
 		void clear() { a = 0; b = 0; }