Filter out index names for legacy list collections operations.

GODRIVER-1132

Change-Id: Ia55ea07f52436895a830ad511ea5ebf64b41dc08

Author: Divjot Arora

mongo/database_internal_test.go

@@ -9,6 +9,7 @@ package mongo
 import (
 	"context"
 	"errors"
+	"strings"
 	"testing"
 
 	"fmt"
@@ -381,3 +382,50 @@ func TestDatabase_ListCollections(t *testing.T) {
 		})
 	}
 }
+
+func TestDatabase_LegacyListCollections(t *testing.T) {
+	db := createTestDatabase(t, nil, nil)
+	version, err := getServerVersion(db)
+	noerr(t, err)
+	if compareVersions(t, version, "2.6") > 0 {
+		t.Skip("skipping for server versions > 2.6")
+	}
+
+	coll := db.Collection("bar", options.Collection().SetWriteConcern(writeconcern.New(writeconcern.WMajority())))
+	initCollection(t, coll)
+
+	t.Run("ignore indexes", func(t *testing.T) {
+		// legacy list collections should not return any collections containing a $
+		c, err := db.ListCollections(ctx, bson.D{})
+		noerr(t, err)
+		defer func() {
+			_ = c.Close(ctx)
+		}()
+
+		for c.Next(ctx) {
+			name := c.Current.Lookup("name").StringValue()
+			if strings.Contains(name, "$") {
+				t.Fatalf("index %s returned from ListCollections", name)
+			}
+		}
+	})
+	t.Run("filter name", func(t *testing.T) {
+		c, err := db.ListCollections(ctx, bson.D{{"name", "bar"}})
+		noerr(t, err)
+		defer func() {
+			_ = c.Close(ctx)
+		}()
+
+		var foundBar bool
+		for c.Next(ctx) {
+			name := c.Current.Lookup("name").StringValue()
+			if name == "bar" {
+				foundBar = true
+				break
+			}
+		}
+		if !foundBar {
+			t.Fatalf("collection bar not returned from ListCollections")
+		}
+	})
+}

x/mongo/driver/list_collections.go

@@ -115,19 +115,27 @@ func legacyListCollections(
 // modify the user-supplied filter to prefix the "name" field with the database name.
 // returns the original filter if the name field is not present or a copy with the modified name field if it is
 func transformFilter(filter bsonx.Doc, dbName string) (bsonx.Doc, error) {
+	regexFilter := bsonx.Doc{
+		{"name", bsonx.Regex("^[^$]*$", "")},
+	}
+
 	if filter == nil {
-		return filter, nil
+		return regexFilter, nil
 	}
 
-	if nameVal, err := filter.LookupErr("name"); err == nil {
-		name, ok := nameVal.StringValueOK()
+	converted := filter
+	if nameIdx := filter.IndexOf("name"); nameIdx != -1 {
+		name, ok := filter[nameIdx].Value.StringValueOK()
 		if !ok {
 			return nil, ErrFilterType
 		}
 
-		filterCopy := filter.Copy()
-		filterCopy.Set("name", bsonx.String(dbName+"."+name))
-		return filterCopy, nil
+		converted = filter.Copy()
+		converted[nameIdx].Value = bsonx.String(dbName + "." + name)
 	}
-	return filter, nil
+
+	filterArr := bsonx.Arr{bsonx.Document(regexFilter), bsonx.Document(converted)}
+	return bsonx.Doc{
+		{"$and", bsonx.Array(filterArr)},
+	}, nil
 }

x/mongo/driver/list_collections_test.go

@@ -12,6 +12,20 @@ import (
 	"testing"
 )
 
+func addRegexFitler(filter bsonx.Doc) bsonx.Doc {
+	regexFilter := bsonx.Doc{
+		{"name", bsonx.Regex("^[^$]*$", "")},
+	}
+	if filter == nil {
+		return regexFilter
+	}
+
+	arr := bsonx.Arr{bsonx.Document(regexFilter), bsonx.Document(filter)}
+	return bsonx.Doc{
+		{"$and", bsonx.Array(arr)},
+	}
+}
+
 func TestListCollections(t *testing.T) {
 	dbName := "db"
 	noNameFilter := bsonx.Doc{
@@ -34,10 +48,10 @@ func TestListCollections(t *testing.T) {
 			expectedFilter bsonx.Doc
 			err            error
 		}{
-			{"TestNilFilter", nil, nil, nil},
-			{"TestNoName", noNameFilter, noNameFilter, nil},
+			{"TestNilFilter", nil, addRegexFitler(nil), nil},
+			{"TestNoName", noNameFilter, addRegexFitler(noNameFilter), nil},
 			{"TestNonStringName", nonStringFilter, nil, ErrFilterType},
-			{"TestName", nameFilter, modifiedFilter, nil},
+			{"TestName", nameFilter, addRegexFitler(modifiedFilter), nil},
 		}
 
 		for _, tc := range testCases {