server: Add more elaborate startup messages. (#2731)

These messages based on our prep stage during XL
and prints more informative message regarding
drive information.

This change also does a much needed refactoring.

cmd/storage-rpc-client_test.go

@@ -0,0 +1,114 @@
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cmd
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"net/rpc"
+	"testing"
+)
+
+// Tests storage error transformation.
+func TestStorageErr(t *testing.T) {
+	unknownErr := errors.New("Unknown error")
+	testCases := []struct {
+		expectedErr error
+		err         error
+	}{
+		{
+			expectedErr: nil,
+			err:         nil,
+		},
+		{
+			expectedErr: io.EOF,
+			err:         fmt.Errorf("%s", io.EOF.Error()),
+		},
+		{
+			expectedErr: io.ErrUnexpectedEOF,
+			err:         fmt.Errorf("%s", io.ErrUnexpectedEOF.Error()),
+		},
+		{
+			expectedErr: errDiskNotFound,
+			err:         &net.OpError{},
+		},
+		{
+			expectedErr: errDiskNotFound,
+			err:         rpc.ErrShutdown,
+		},
+		{
+			expectedErr: errUnexpected,
+			err:         fmt.Errorf("%s", errUnexpected.Error()),
+		},
+		{
+			expectedErr: errDiskFull,
+			err:         fmt.Errorf("%s", errDiskFull.Error()),
+		},
+		{
+			expectedErr: errVolumeNotFound,
+			err:         fmt.Errorf("%s", errVolumeNotFound.Error()),
+		},
+		{
+			expectedErr: errVolumeExists,
+			err:         fmt.Errorf("%s", errVolumeExists.Error()),
+		},
+		{
+			expectedErr: errFileNotFound,
+			err:         fmt.Errorf("%s", errFileNotFound.Error()),
+		},
+		{
+			expectedErr: errFileAccessDenied,
+			err:         fmt.Errorf("%s", errFileAccessDenied.Error()),
+		},
+		{
+			expectedErr: errIsNotRegular,
+			err:         fmt.Errorf("%s", errIsNotRegular.Error()),
+		},
+		{
+			expectedErr: errVolumeNotEmpty,
+			err:         fmt.Errorf("%s", errVolumeNotEmpty.Error()),
+		},
+		{
+			expectedErr: errVolumeAccessDenied,
+			err:         fmt.Errorf("%s", errVolumeAccessDenied.Error()),
+		},
+		{
+			expectedErr: errCorruptedFormat,
+			err:         fmt.Errorf("%s", errCorruptedFormat.Error()),
+		},
+		{
+			expectedErr: errUnformattedDisk,
+			err:         fmt.Errorf("%s", errUnformattedDisk.Error()),
+		},
+		{
+			expectedErr: errFileNameTooLong,
+			err:         fmt.Errorf("%s", errFileNameTooLong.Error()),
+		},
+		{
+			expectedErr: unknownErr,
+			err:         unknownErr,
+		},
+	}
+	for i, testCase := range testCases {
+		resultErr := toStorageErr(testCase.err)
+		if testCase.expectedErr != resultErr {
+			t.Errorf("Test %d: Expected %s, got %s", i+1, testCase.expectedErr, resultErr)
+		}
+	}
+}