shell: refuse s3.bucket.create on an existing bucket (#11455)

* shell: refuse s3.bucket.create on an existing bucket

CreateEntry without o_excl replaces the bucket entry, dropping every
extended attribute: lifecycle configuration, owner, versioning and the
irreversible Object Lock flag. Send o_excl so a re-run fails with
'bucket already exists' instead of silently resetting the bucket.

* filer: fail exclusive creates when the lookup itself fails

CreateEntry discards FindEntry errors, so an o_excl create hitting a
transient store failure would take the insert path and upsert over the
entry it was meant to preserve. Propagate the lookup error when o_excl
is set; non-exclusive creates keep their existing semantics.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* shell: test s3.bucket.create requests an exclusive create

Exercises the command end to end through a fake filer gRPC server and
asserts the OExcl flag reaches the wire along with the already-exists
error path.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* shell: synchronize captured requests and assert the exact bucket error

The fake filer records CreateEntry requests on the gRPC server goroutine,
so reads need the same mutex; the test also now checks for the exact
"bucket my-bucket already exists" message rather than any error that
mentions existence.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

---------

Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

weed/shell/command_s3_bucket_create.go

@@ -2,6 +2,7 @@ package shell
 
 import (
 	"context"
+	"errors"
 	"flag"
 	"fmt"
 	"io"
@@ -112,11 +113,16 @@ func (c *commandS3BucketCreate) Do(args []string, commandEnv *CommandEnv, writer
 			entry.Extended[s3_constants.ExtObjectLockEnabledKey] = []byte(s3_constants.ObjectLockEnabled)
 		}
 
-		if _, err := client.CreateEntry(context.Background(), &filer_pb.CreateEntryRequest{
+		createErr := filer_pb.CreateEntry(context.Background(), client, &filer_pb.CreateEntryRequest{
 			Directory: filerBucketsPath,
 			Entry:     entry,
-		}); err != nil {
-			return err
+			OExcl:     true,
+		})
+		if errors.Is(createErr, filer_pb.ErrEntryAlreadyExists) {
+			return fmt.Errorf("bucket %s already exists", *bucketName)
+		}
+		if createErr != nil {
+			return createErr
 		}
 
 		fmt.Fprintln(writer, "created bucket", *bucketName)

weed/shell/command_s3_bucket_create_test.go

@@ -0,0 +1,97 @@
+package shell
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"net"
+	"os"
+	"path/filepath"
+	"sync"
+	"testing"
+
+	"github.com/seaweedfs/seaweedfs/weed/pb"
+	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+)
+
+type bucketCreateTestFilerServer struct {
+	filer_pb.UnimplementedSeaweedFilerServer
+
+	mu         sync.Mutex
+	createReqs []*filer_pb.CreateEntryRequest
+}
+
+func (s *bucketCreateTestFilerServer) GetFilerConfiguration(context.Context, *filer_pb.GetFilerConfigurationRequest) (*filer_pb.GetFilerConfigurationResponse, error) {
+	return &filer_pb.GetFilerConfigurationResponse{DirBuckets: "/buckets"}, nil
+}
+
+func (s *bucketCreateTestFilerServer) CreateEntry(_ context.Context, req *filer_pb.CreateEntryRequest) (*filer_pb.CreateEntryResponse, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.createReqs = append(s.createReqs, req)
+	return &filer_pb.CreateEntryResponse{
+		ErrorCode: filer_pb.FilerError_ENTRY_ALREADY_EXISTS,
+		Error:     "entry already exists",
+	}, nil
+}
+
+func (s *bucketCreateTestFilerServer) createRequests() []*filer_pb.CreateEntryRequest {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return append([]*filer_pb.CreateEntryRequest(nil), s.createReqs...)
+}
+
+func TestS3BucketCreateRequestsExclusiveCreate(t *testing.T) {
+	filerServer := &bucketCreateTestFilerServer{}
+	commandEnv, cleanup := newBucketCreateTestCommandEnv(t, filerServer)
+	defer cleanup()
+
+	var output bytes.Buffer
+	err := (&commandS3BucketCreate{}).Do([]string{"-name", "my-bucket"}, commandEnv, &output)
+	require.EqualError(t, err, "bucket my-bucket already exists")
+
+	reqs := filerServer.createRequests()
+	require.Len(t, reqs, 1)
+	req := reqs[0]
+	assert.True(t, req.OExcl, "bucket create must not replace an existing entry")
+	assert.Equal(t, "/buckets", req.Directory)
+	assert.Equal(t, "my-bucket", req.Entry.Name)
+}
+
+func newBucketCreateTestCommandEnv(t *testing.T, filerServer filer_pb.SeaweedFilerServer) (*CommandEnv, func()) {
+	t.Helper()
+
+	socketDir, err := os.MkdirTemp("", "swbucket-")
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = os.RemoveAll(socketDir) })
+
+	socketPath := filepath.Join(socketDir, "filer.sock")
+	listener, err := net.Listen("unix", socketPath)
+	require.NoError(t, err)
+
+	grpcServer := grpc.NewServer()
+	filer_pb.RegisterSeaweedFilerServer(grpcServer, filerServer)
+	go func() {
+		_ = grpcServer.Serve(listener)
+	}()
+
+	grpcPort := 48000 + os.Getpid()%1000
+	pb.RegisterLocalGrpcSocket("127.0.0.1", grpcPort, socketPath)
+
+	cleanup := func() {
+		grpcServer.Stop()
+		_ = listener.Close()
+	}
+
+	return &CommandEnv{
+		option: &ShellOptions{
+			FilerAddress:   pb.ServerAddress(fmt.Sprintf("127.0.0.1:8888.%d", grpcPort)),
+			GrpcDialOption: grpc.WithTransportCredentials(insecure.NewCredentials()),
+			Directory:      "/",
+		},
+	}, cleanup
+}