SERVER-27030 Improve error for legacy find/getMore on view

2 files changed, 59 insertions, 13 deletions

diff --git a/jstests/views/views_legacy.js b/jstests/views/views_legacy.js
index bd31d5bb74e..af2e7d2a380 100644
--- a/jstests/views/views_legacy.js
+++ b/jstests/views/views_legacy.js
@@ -1,6 +1,6 @@
 /**
  * Tests that views properly reject queries in legacy read mode, and reject writes performed in
- * legacy write mode.
+ * legacy write mode. Also confirms that legacy killCursors execution is successful.
  *
  * TODO(SERVER-25641): If the views test suite is moved under core, we can get rid of this test
  * after ensuring that it is included in a legacy passthrough suite.
@@ -13,28 +13,55 @@
     let viewsDB = conn.getDB("views_legacy");
     assert.commandWorked(viewsDB.dropDatabase());
     assert.commandWorked(viewsDB.createView("view", "collection", []));
+    let coll = viewsDB.getCollection("collection");
 
-    // Helper function for performing getLastError.
-    function assertGetLastErrorFailed() {
-        let gle = viewsDB.runCommand({getLastError: 1});
-        assert.commandWorked(gle);
-        assert.eq(gle.code, ErrorCodes.CommandNotSupportedOnView, tojson(gle));
+    for (let i = 0; i < 10; ++i) {
+        assert.writeOK(coll.insert({a: i}));
     }
 
-    // A view should reject all write CRUD operations performed in legacy write mode.
+    conn.forceReadMode("legacy");
     conn.forceWriteMode("legacy");
 
+    //
+    // Legacy getMore is explicitly prohibited on views; you must use the getMore command.
+    //
+    let cmdRes =
+        viewsDB.runCommand({find: "view", filter: {a: {$gt: 0}}, sort: {a: 1}, batchSize: 0});
+    assert.commandWorked(cmdRes);
+    let cursor = new DBCommandCursor(viewsDB.getMongo(), cmdRes, 2);
+
+    let err = assert.throws(function() {
+        cursor.itcount();
+    }, [], "Legacy getMore expected to fail on a view cursor");
+    assert.eq(ErrorCodes.CommandNotSupportedOnView, err.code, tojson(err));
+
+    //
+    // Legacy killcursors is expected to work on views.
+    //
+    cmdRes = viewsDB.runCommand({find: "view", filter: {a: {$gt: 0}}, sort: {a: 1}, batchSize: 0});
+    assert.commandWorked(cmdRes);
+    cursor = new DBCommandCursor(viewsDB.getMongo(), cmdRes, 2);
+
+    // When DBCommandCursor is constructed under legacy readMode, cursor.close() will execute a
+    // legacy killcursors operation.
+    cursor.close();
+    assert.gleSuccess(viewsDB, "legacy killcursors expected to work on view cursor");
+
+    //
+    // A view should reject all write CRUD operations performed in legacy write mode.
+    //
     viewsDB.view.insert({x: 1});
-    assertGetLastErrorFailed();
+    assert.gleErrorCode(viewsDB, ErrorCodes.CommandNotSupportedOnView);
 
     viewsDB.view.remove({x: 1});
-    assertGetLastErrorFailed();
+    assert.gleErrorCode(viewsDB, ErrorCodes.CommandNotSupportedOnView);
 
     viewsDB.view.update({x: 1}, {x: 2});
-    assertGetLastErrorFailed();
+    assert.gleErrorCode(viewsDB, ErrorCodes.CommandNotSupportedOnView);
 
+    //
     // Legacy find is explicitly prohibited on views; you must use the find command.
-    conn.forceReadMode("legacy");
+    //
     let res = assert.throws(function() {
         viewsDB.view.find({x: 1}).toArray();
     });
diff --git a/src/mongo/db/query/find.cpp b/src/mongo/db/query/find.cpp
index 079ae46c61c..0f3b27907d9 100644
--- a/src/mongo/db/query/find.cpp
+++ b/src/mongo/db/query/find.cpp
@@ -267,7 +267,17 @@ Message getMore(OperationContext* txn,
         // the data within a collection.
         cursorManager = CursorManager::getGlobalCursorManager();
     } else {
-        ctx = stdx::make_unique<AutoGetCollectionForRead>(txn, nss);
+        ctx = stdx::make_unique<AutoGetCollectionOrViewForRead>(txn, nss);
+        auto viewCtx = static_cast<AutoGetCollectionOrViewForRead*>(ctx.get());
+        if (viewCtx->getView()) {
+            uasserted(
+                ErrorCodes::CommandNotSupportedOnView,
+                str::stream() << "Namespace " << nss.ns()
+                              << " is a view. OP_GET_MORE operations are not supported on views. "
+                              << "Only clients which support the getMore command can be used to "
+                                 "query views.");
+        }
+
         Collection* collection = ctx->getCollection();
         uassert(17356, "collection dropped between getMore calls", collection);
         cursorManager = collection->getCursorManager();
@@ -514,9 +524,18 @@ std::string runQuery(OperationContext* txn,
     LOG(2) << "Running query: " << redact(cq->toStringShort());
 
     // Parse, canonicalize, plan, transcribe, and get a plan executor.
-    AutoGetCollectionForRead ctx(txn, nss);
+    AutoGetCollectionOrViewForRead ctx(txn, nss);
     Collection* collection = ctx.getCollection();
 
+    if (ctx.getView()) {
+        uasserted(ErrorCodes::CommandNotSupportedOnView,
+                  str::stream()
+                      << "Namespace "
+                      << nss.ns()
+                      << " is a view. Legacy find operations are not supported on views. "
+                      << "Only clients which support the find command can be used to query views.");
+    }
+
     // We have a parsed query. Time to get the execution plan for it.
     std::unique_ptr<PlanExecutor> exec = uassertStatusOK(
         getExecutorFind(txn, collection, nss, std::move(cq), PlanExecutor::YIELD_AUTO));