fs: Handle cases of PutObject for an existing prefix. (#1478)

object-common.go

@@ -138,14 +138,14 @@ func putObjectCommon(storage StorageAPI, bucket string, object string, size int6
 			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
 				return "", clErr
 			}
-			return "", toObjectErr(err)
+			return "", toObjectErr(err, bucket, object)
 		}
 	} else {
 		if _, err = io.Copy(multiWriter, data); err != nil {
 			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
 				return "", clErr
 			}
-			return "", err
+			return "", toObjectErr(err, bucket, object)
 		}
 	}
 
@@ -169,7 +169,10 @@ func putObjectCommon(storage StorageAPI, bucket string, object string, size int6
 	}
 	err = storage.RenameFile(minioMetaBucket, tempObj, bucket, object)
 	if err != nil {
-		return "", err
+		if derr := storage.DeleteFile(minioMetaBucket, tempObj); derr != nil {
+			return "", derr
+		}
+		return "", toObjectErr(err, bucket, object)
 	}
 
 	// Return md5sum, successfully wrote object.

object-errors.go

@@ -40,7 +40,7 @@ func toObjectErr(err error, params ...string) error {
 		return StorageInsufficientReadResources{}
 	case errWriteQuorum:
 		return StorageInsufficientWriteResources{}
-	case errIsNotRegular:
+	case errIsNotRegular, errFileAccessDenied:
 		if len(params) >= 2 {
 			return ObjectExistsAsPrefix{
 				Bucket: params[0],

posix.go

@@ -596,12 +596,13 @@ func (s fsStorage) CreateFile(volume, path string) (writeCloser io.WriteCloser,
 		}).Debugf("getVolumeDir failed with %s", err)
 		return nil, err
 	}
-	if err := checkDiskFree(s.diskPath, s.minFreeDisk); err != nil {
+	if err = checkDiskFree(s.diskPath, s.minFreeDisk); err != nil {
 		return nil, err
 	}
 	filePath := filepath.Join(volumeDir, path)
 	// Verify if the file already exists and is not of regular type.
-	if st, err := os.Stat(filePath); err == nil {
+	var st os.FileInfo
+	if st, err = os.Stat(filePath); err == nil {
 		if st.IsDir() {
 			log.WithFields(logrus.Fields{
 				"diskPath": s.diskPath,
@@ -610,7 +611,15 @@ func (s fsStorage) CreateFile(volume, path string) (writeCloser io.WriteCloser,
 			return nil, errIsNotRegular
 		}
 	}
-	return safe.CreateFileWithPrefix(filePath, "$tmpfile")
+	w, err := safe.CreateFileWithPrefix(filePath, "$tmpfile")
+	if err != nil {
+		// File path cannot be verified since one of the parents is a file.
+		if strings.Contains(err.Error(), "not a directory") {
+			return nil, errFileAccessDenied
+		}
+		return nil, err
+	}
+	return w, nil
 }
 
 // StatFile - get file info.
@@ -753,6 +762,10 @@ func (s fsStorage) RenameFile(srcVolume, srcPath, dstVolume, dstPath string) err
 		return err
 	}
 	if err = os.MkdirAll(path.Join(dstVolumeDir, path.Dir(dstPath)), 0755); err != nil {
+		// File path cannot be verified since one of the parents is a file.
+		if strings.Contains(err.Error(), "not a directory") {
+			return errFileAccessDenied
+		}
 		log.Errorf("os.MkdirAll failed with %s", err)
 		return err
 	}

signature-v4-postpolicyform.go

@@ -157,8 +157,8 @@ func checkPostPolicy(formValues map[string]string) APIErrorCode {
 		return ErrSignatureVersionNotSupported
 	}
 	/// Decoding policy
-	policyBytes, e := base64.StdEncoding.DecodeString(formValues["Policy"])
+	policyBytes, err := base64.StdEncoding.DecodeString(formValues["Policy"])
-	if e != nil {
+	if err != nil {
 		return ErrMalformedPOSTRequest
 	}
 	postPolicyForm, err := parsePostPolicyFormV4(string(policyBytes))