Merge pull request mongodb#315 from daveh86/SERVER-7017

Fix for SERVER-7017

jstests/rename2.js

@@ -17,3 +17,28 @@ assert( a.renameCollection( "rename2b" ) , "the command" );
 
 assert.eq( 0 , a.count() , "C" )
 assert.eq( 3 , b.count() , "D" )
+
+// Test for SERVER-7017
+// We shouldn't rename a collection when one of its indexes will generate a namespace
+// that is greater than 120 chars. To do this we create a long index name and try
+// and rename the collection to one with a much longer name. We use the test database
+// by default and we add this here to ensure we are using it
+testDB = db.getSiblingDB("test")
+c = "rename2c";
+dbc = testDB.getCollection(c);
+d = "dest4567890123456789012345678901234567890123456789012345678901234567890"
+dbd = testDB.getCollection(d);
+dbc.ensureIndex({ "name" : 1,
+                  "date" : 1,
+                  "time" : 1,
+                  "renameCollection" : 1,
+                  "mongodb" : 1,
+                  "testing" : 1,
+                  "data" : 1});
+//Checking for the newly created index and the _id index in original collection
+assert.eq(2, testDB.system.indexes.find( { "ns" : "test." + c } ).count(), "Long Rename Init");
+//Should fail to rename collection as the index namespace is too long
+assert.commandFailed( dbc.renameCollection( dbd ) , "Long Rename Exec" );
+//Since we failed we should have the 2 indexes unmoved and no indexes under the new collection name
+assert.eq(2, testDB.system.indexes.find( { "ns" : "test." + c } ).count(), "Long Rename Result 1");
+assert.eq(0, testDB.system.indexes.find( { "ns" : "test." + d } ).count(), "Long Rename Result 2");

src/mongo/db/cloner.cpp

@@ -721,6 +721,9 @@ namespace mongo {
 
     class CmdRenameCollection : public Command {
     public:
+        // Absolute maximum Namespace is 128 incl NUL
+        // Namespace is 128 minus .$ and $extra so 120 before additions
+        static const int maxNamespaceLen = 120;
         CmdRenameCollection() : Command( "renameCollection" ) {}
         virtual bool adminOnly() const {
             return true;
@@ -746,6 +749,28 @@ namespace mongo {
                 return false;
             }
 
+            string sourceDB = nsToDatabase(source);
+            string targetDB = nsToDatabase(target);
+            string databaseName = sourceDB;
+            databaseName += ".system.indexes";
+
+            int longestIndexNameLength = 0;
+            vector<BSONObj> oldIndSpec = Helpers::findAll(databaseName, BSON("ns" << source));
+            for (size_t i = 0; i < oldIndSpec.size(); ++i) {
+                int thisLength = oldIndSpec[i].getField("name").valuesize();
+                if (thisLength > longestIndexNameLength) {
+                     longestIndexNameLength = thisLength;
+                }
+            }
+            unsigned int longestAllowed = maxNamespaceLen - longestIndexNameLength - 1;
+            if (target.size() > longestAllowed) {
+                StringBuilder sb;
+                sb << "collection name length of " << target.size()
+                << " exceeds maximum length of " << longestAllowed
+                << ", allowing for index names";
+                uasserted(16445, sb.str());
+            }
+
             bool capped = false;
             long long size = 0;
             {
@@ -773,11 +798,7 @@ namespace mongo {
             // if we are renaming in the same database, just
             // rename the namespace and we're done.
             {
-                char from[256];
-                nsToDatabase( source.c_str(), from );
-                char to[256];
-                nsToDatabase( target.c_str(), to );
-                if ( strcmp( from, to ) == 0 ) {
+                if ( sourceDB == targetDB ) {
                     renameNamespace( source.c_str(), target.c_str(), cmdObj["stayTemp"].trueValue() );
                     // make sure we drop counters etc
                     Top::global.collectionDropped( source );