Make some doc changes to cat cmd

cmd-cat.go

@@ -25,6 +25,7 @@ import (
 	"sync"
 
 	"github.com/minio-io/cli"
+	"github.com/minio-io/mc/pkg/client"
 	"github.com/minio-io/mc/pkg/console"
 	"github.com/minio-io/minio/pkg/iodine"
 	"github.com/minio-io/minio/pkg/utils/crypto/md5"
@@ -92,16 +93,18 @@ func doCatCmd(manager clientManager, writer io.Writer, sourceURLConfigMap map[st
 			return "Unable to retrieve file: " + url, iodine.New(err, nil)
 		}
 		defer reader.Close()
+		var teeReader io.Reader
+		var actualMd5 []byte
+		if client.GetType(url) != client.Filesystem {
 			wg := &sync.WaitGroup{}
 			md5Reader, md5Writer := io.Pipe()
-		var actualMd5 []byte
 			wg.Add(1)
 			go func() {
 				actualMd5, _ = md5.Sum(md5Reader)
 				// drop error, we'll catch later on if it fails
 				wg.Done()
 			}()
-		teeReader := io.TeeReader(reader, md5Writer)
+			teeReader = io.TeeReader(reader, md5Writer)
 			_, err = io.CopyN(writer, teeReader, size)
 			md5Writer.Close()
 			wg.Wait()
@@ -110,7 +113,15 @@ func doCatCmd(manager clientManager, writer io.Writer, sourceURLConfigMap map[st
 			}
 			actualMd5String := hex.EncodeToString(actualMd5)
 			if expectedMd5 != actualMd5String {
-			return "Copying data from source was corrupted in transit: " + url, iodine.New(errors.New("Data copied from source was corrupted in transit"), nil)
+				return "Copying data from source was corrupted in transit: " + url,
+					iodine.New(errors.New("Data copied from source was corrupted in transit"), nil)
+			}
+			return "", nil
+		}
+		teeReader = reader
+		_, err = io.CopyN(writer, teeReader, size)
+		if err != nil {
+			return "Copying data from source failed: " + url, iodine.New(errors.New("Copy data from source failed"), nil)
 		}
 	}
 	return "", nil

cmd-options.go

@@ -28,7 +28,7 @@ import (
 var (
 	catCmd = cli.Command{
 		Name:   "cat",
-		Usage:  "Copy an object to standard out",
+		Usage:  "Concantenate an object to standard output",
 		Action: runCatCmd,
 		CustomHelpTemplate: `NAME:
    mc {{.Name}} - {{.Usage}}
@@ -44,11 +44,11 @@ OPTIONS:
    {{end}}{{ end }}
 
 EXAMPLES:
-   1. Copy an object from Amazon S3 object storage to standard out.
-      $ mc {{.Name}} https://s3.amazonaws.com/jukebox/klingon_opera_aktuh_maylotah.ogg
+   1. Concantenate an object from Amazon S3 object storage to mplayer standard input
+      $ mc {{.Name}} https://s3.amazonaws.com/jukebox/klingon_opera_aktuh_maylotah.ogg | mplayer -
 
-   2. Copy an object from the file system to standard out.
-      $ mc {{.Name}} klingon_opera_aktuh_maylotah.ogg
+   2. Concantenate a file from local filesystem to standard output.
+      $ mc {{.Name}} khitomer-accords.txt
 
 `,
 	}

cmd_test.go

@@ -484,7 +484,7 @@ func (s *CmdTestSuite) TestMbCmdOnFile(c *C) {
 	cl1.AssertExpectations(c)
 }
 
-func (s *CmdTestSuite) TestCatCmd(c *C) {
+func (s *CmdTestSuite) TestCatCmdObject(c *C) {
 	sourceURL, err := getURL("http://example.com/bucket1/object1", nil)
 	c.Assert(err, IsNil)
 
@@ -514,3 +514,32 @@ func (s *CmdTestSuite) TestCatCmd(c *C) {
 	manager.AssertExpectations(c)
 	cl1.AssertExpectations(c)
 }
+
+func (s *CmdTestSuite) TestCatCmdFile(c *C) {
+	sourceURL, err := getURL("object1", nil)
+	c.Assert(err, IsNil)
+
+	manager := &MockclientManager{}
+	cl1 := &clientMocks.Client{}
+
+	data1 := "hello1"
+	dataLen1 := int64(len(data1))
+
+	sourceURLConfigMap := make(map[string]*hostConfig)
+	sourceConfig := new(hostConfig)
+	sourceConfig.AccessKeyID = ""
+	sourceConfig.SecretAccessKey = ""
+	sourceURLConfigMap[sourceURL] = sourceConfig
+
+	var results bytes.Buffer
+	manager.On("getNewClient", sourceURL, sourceConfig, false).Return(cl1, nil).Once()
+	cl1.On("Get").Return(ioutil.NopCloser(bytes.NewBufferString(data1)), dataLen1, "", nil)
+	msg, err := doCatCmd(manager, &results, sourceURLConfigMap, false)
+	c.Assert(msg, Equals, "")
+	c.Assert(err, IsNil)
+
+	c.Assert(data1, Equals, results.String())
+
+	manager.AssertExpectations(c)
+	cl1.AssertExpectations(c)
+}