1 files changed, 23 insertions, 0 deletions
diff --git a/src/mongo/db/keypattern.cpp b/src/mongo/db/keypattern.cpp
index 89eca1f16c6..c2a1f18cba2 100644
--- a/src/mongo/db/keypattern.cpp
+++ b/src/mongo/db/keypattern.cpp
@@ -14,6 +14,18 @@
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*
+*    As a special exception, the copyright holders give permission to link the
+*    code of portions of this program with the OpenSSL library under certain
+*    conditions as described in each individual source file and distribute
+*    linked combinations including the program with the OpenSSL library. You
+*    must comply with the GNU Affero General Public License in all respects for
+*    all of the code used other than as permitted herein. If you modify file(s)
+*    with this exception, you may extend this exception to your version of the
+*    file(s), but you are not obligated to do so. If you do not wish to do so,
+*    delete this exception statement from your version. If you delete this
+*    exception statement from all source files in the program, then also delete
+*    it in the license file.
 */
 
 #include "mongo/db/keypattern.h"
@@ -40,6 +52,17 @@ namespace mongo {
         }
     }
 
+    bool KeyPattern::isIdKeyPattern(const BSONObj& pattern) {
+        BSONObjIterator i(pattern);
+        BSONElement e = i.next();
+        // _id index must have form exactly {_id : 1} or {_id : -1}.
+        // Allows an index of form {_id : "hashed"} to exist but
+        // do not consider it to be the primary _id index
+        return (0 == strcmp(e.fieldName(), "_id"))
+               && (e.numberInt() == 1 || e.numberInt() == -1)
+               && i.next().eoo();
+    }
+
     BSONObj KeyPattern::extractSingleKey(const BSONObj& doc ) const {
         if ( _pattern.isEmpty() )
             return BSONObj();