Add proper custom errors object creations (#7387)

In scenario 1

```
- bucket/object-prefix
- bucket/object-prefix/object
```

Server responds with `XMinioParentIsObject`

In scenario 2

```
- bucket/object-prefix/object
- bucket/object-prefix
```

Server responds with `XMinioObjectExistsAsDirectory`

Fixes #6566

cmd/api-errors.go

@@ -180,6 +180,7 @@ const (
 	// Minio extended errors.
 	ErrReadQuorum
 	ErrWriteQuorum
+	ErrParentIsObject
 	ErrStorageFull
 	ErrRequestBodyParse
 	ErrObjectExistsAsDirectory
@@ -858,6 +859,11 @@ var errorCodes = errorCodeMap{
 		Description:    "Storage backend has reached its minimum free disk threshold. Please delete a few objects to proceed.",
 		HTTPStatusCode: http.StatusInsufficientStorage,
 	},
+	ErrParentIsObject: {
+		Code:           "XMinioParentIsObject",
+		Description:    "Object-prefix is already an object, please choose a different object-prefix name.",
+		HTTPStatusCode: http.StatusBadRequest,
+	},
 	ErrRequestBodyParse: {
 		Code:           "XMinioRequestBodyParse",
 		Description:    "The request body failed to parse.",
@@ -1561,6 +1567,8 @@ func toAPIErrorCode(ctx context.Context, err error) (apiErr APIErrorCode) {
 		apiErr = ErrObjectExistsAsDirectory
 	case PrefixAccessDenied:
 		apiErr = ErrAccessDenied
+	case ParentIsObject:
+		apiErr = ErrParentIsObject
 	case BucketNameInvalid:
 		apiErr = ErrInvalidBucketName
 	case BucketNotFound:

cmd/disk-cache-fs.go

@@ -332,7 +332,7 @@ func (cfs *cacheFSObjects) PutObject(ctx context.Context, bucket string, object
 	if isObjectDir(object, data.Size()) {
 		// Check if an object is present as one of the parent dir.
 		if fs.parentDirIsObject(ctx, bucket, path.Dir(object)) {
-			return ObjectInfo{}, toObjectErr(errFileAccessDenied, bucket, object)
+			return ObjectInfo{}, toObjectErr(errFileParentIsFile, bucket, object)
 		}
 		if err = mkdirAll(pathJoin(fs.fsPath, bucket, object), 0777); err != nil {
 			return ObjectInfo{}, toObjectErr(err, bucket, object)
@@ -350,7 +350,7 @@ func (cfs *cacheFSObjects) PutObject(ctx context.Context, bucket string, object
 
 	// Check if an object is present as one of the parent dir.
 	if fs.parentDirIsObject(ctx, bucket, path.Dir(object)) {
-		return ObjectInfo{}, toObjectErr(errFileAccessDenied, bucket, object)
+		return ObjectInfo{}, toObjectErr(errFileParentIsFile, bucket, object)
 	}
 
 	// Validate input data size and it can never be less than zero.

cmd/fs-v1-multipart.go

@@ -487,7 +487,7 @@ func (fs *FSObjects) CompleteMultipartUpload(ctx context.Context, bucket string,
 
 	// Check if an object is present as one of the parent dir.
 	if fs.parentDirIsObject(ctx, bucket, pathutil.Dir(object)) {
-		return oi, toObjectErr(errFileAccessDenied, bucket, object)
+		return oi, toObjectErr(errFileParentIsFile, bucket, object)
 	}
 
 	if _, err := fs.statBucketDir(ctx, bucket); err != nil {

cmd/fs-v1.go

@@ -839,8 +839,7 @@ func (fs *FSObjects) putObject(ctx context.Context, bucket string, object string
 	if isObjectDir(object, data.Size()) {
 		// Check if an object is present as one of the parent dir.
 		if fs.parentDirIsObject(ctx, bucket, path.Dir(object)) {
-			logger.LogIf(ctx, errFileAccessDenied)
+			return ObjectInfo{}, toObjectErr(errFileParentIsFile, bucket, object)
-			return ObjectInfo{}, toObjectErr(errFileAccessDenied, bucket, object)
 		}
 		if err = mkdirAll(pathJoin(fs.fsPath, bucket, object), 0777); err != nil {
 			logger.LogIf(ctx, err)
@@ -859,8 +858,7 @@ func (fs *FSObjects) putObject(ctx context.Context, bucket string, object string
 
 	// Check if an object is present as one of the parent dir.
 	if fs.parentDirIsObject(ctx, bucket, path.Dir(object)) {
-		logger.LogIf(ctx, errFileAccessDenied)
+		return ObjectInfo{}, toObjectErr(errFileParentIsFile, bucket, object)
-		return ObjectInfo{}, toObjectErr(errFileAccessDenied, bucket, object)
 	}
 
 	// Validate input data size and it can never be less than zero.

cmd/fs-v1_test.go

@@ -230,8 +230,8 @@ func TestFSPutObject(t *testing.T) {
 	if err == nil {
 		t.Fatal("Unexpected should fail here, backend corruption occurred")
 	}
-	if nerr, ok := err.(PrefixAccessDenied); !ok {
+	if nerr, ok := err.(ParentIsObject); !ok {
-		t.Fatalf("Expected PrefixAccessDenied, got %#v", err)
+		t.Fatalf("Expected ParentIsObject, got %#v", err)
 	} else {
 		if nerr.Bucket != "bucket" {
 			t.Fatalf("Expected 'bucket', got %s", nerr.Bucket)
@@ -245,8 +245,8 @@ func TestFSPutObject(t *testing.T) {
 	if err == nil {
 		t.Fatal("Unexpected should fail here, backned corruption occurred")
 	}
-	if nerr, ok := err.(PrefixAccessDenied); !ok {
+	if nerr, ok := err.(ParentIsObject); !ok {
-		t.Fatalf("Expected PrefixAccessDenied, got %#v", err)
+		t.Fatalf("Expected ParentIsObject, got %#v", err)
 	} else {
 		if nerr.Bucket != "bucket" {
 			t.Fatalf("Expected 'bucket', got %s", nerr.Bucket)

cmd/object-api-errors.go

@@ -19,6 +19,7 @@ package cmd
 import (
 	"fmt"
 	"io"
+	"path"
 )
 
 // Converts underlying storage error. Convenience function written to
@@ -47,6 +48,13 @@ func toObjectErr(err error, params ...string) error {
 				Object: params[1],
 			}
 		}
+	case errFileParentIsFile:
+		if len(params) >= 2 {
+			err = ParentIsObject{
+				Bucket: params[0],
+				Object: params[1],
+			}
+		}
 	case errIsNotRegular:
 		if len(params) >= 2 {
 			err = ObjectExistsAsDirectory{
@@ -182,6 +190,13 @@ func (e PrefixAccessDenied) Error() string {
 	return "Prefix access is denied: " + e.Bucket + "/" + e.Object
 }
 
+// ParentIsObject object access is denied.
+type ParentIsObject GenericError
+
+func (e ParentIsObject) Error() string {
+	return "Parent is object " + e.Bucket + "/" + path.Dir(e.Object)
+}
+
 // BucketExists bucket exists.
 type BucketExists GenericError
 

cmd/os-reliable.go

@@ -142,6 +142,10 @@ func renameAll(srcFilePath, dstFilePath string) (err error) {
 			return fmt.Errorf("%s (%s)->(%s)", errCrossDeviceLink, srcFilePath, dstFilePath)
 		case os.IsNotExist(err):
 			return errFileNotFound
+		case os.IsExist(err):
+			// This is returned only when destination is a directory and we
+			// are attempting a rename from file to directory.
+			return errIsNotRegular
 		default:
 			return err
 		}

cmd/storage-errors.go

@@ -66,9 +66,12 @@ var errVolumeNotEmpty = errors.New("volume is not empty")
 // errVolumeAccessDenied - cannot access volume, insufficient permissions.
 var errVolumeAccessDenied = errors.New("volume access denied")
 
-// errVolumeAccessDenied - cannot access file, insufficient permissions.
+// errFileAccessDenied - cannot access file, insufficient permissions.
 var errFileAccessDenied = errors.New("file access denied")
 
+// errFileParentIsFile - cannot have overlapping objects, parent is already a file.
+var errFileParentIsFile = errors.New("parent is a file")
+
 // errBitrotHashAlgoInvalid - the algo for bit-rot hash
 // verification is empty or invalid.
 var errBitrotHashAlgoInvalid = errors.New("bit-rot hash algorithm is invalid")

cmd/xl-v1-multipart.go

@@ -624,7 +624,7 @@ func (xl xlObjects) CompleteMultipartUpload(ctx context.Context, bucket string,
 	// Check if an object is present as one of the parent dir.
 	// -- FIXME. (needs a new kind of lock).
 	if xl.parentDirIsObject(ctx, bucket, path.Dir(object)) {
-		return oi, toObjectErr(errFileAccessDenied, bucket, object)
+		return oi, toObjectErr(errFileParentIsFile, bucket, object)
 	}
 
 	// Calculate s3 compatible md5sum for complete multipart.

cmd/xl-v1-object.go

@@ -577,7 +577,7 @@ func (xl xlObjects) putObject(ctx context.Context, bucket string, object string,
 		// -- FIXME. (needs a new kind of lock).
 		// -- FIXME (this also causes performance issue when disks are down).
 		if xl.parentDirIsObject(ctx, bucket, path.Dir(object)) {
-			return ObjectInfo{}, toObjectErr(errFileAccessDenied, bucket, object)
+			return ObjectInfo{}, toObjectErr(errFileParentIsFile, bucket, object)
 		}
 
 		if err = xl.putObjectDir(ctx, minioMetaTmpBucket, tempObj, writeQuorum); err != nil {
@@ -608,7 +608,7 @@ func (xl xlObjects) putObject(ctx context.Context, bucket string, object string,
 	// -- FIXME. (needs a new kind of lock).
 	// -- FIXME (this also causes performance issue when disks are down).
 	if xl.parentDirIsObject(ctx, bucket, path.Dir(object)) {
-		return ObjectInfo{}, toObjectErr(errFileAccessDenied, bucket, object)
+		return ObjectInfo{}, toObjectErr(errFileParentIsFile, bucket, object)
 	}
 
 	// Limit the reader to its provided size if specified.