Refactoring input parsing for erasure-demo

cmd/erasure-demo/decode.go

@@ -5,7 +5,6 @@ import (
 	"log"
 	"os"
 	"strconv"
-	"strings"
 
 	"github.com/codegangsta/cli"
 	"github.com/minio-io/minio/pkgs/erasure"
@@ -18,39 +17,21 @@ func decode(c *cli.Context) {
 		return
 	}
 
-	// get input path
+	config, err := parseInput(c)
-	inputFilePath := c.Args().Get(0)
-
-	// get output path
-	outputFilePath := inputFilePath
-	if c.String("output") != "" {
-		outputFilePath = c.String("output")
-	}
-
-	protectionLevel := c.String("protection-level")
-	protectionLevelSplit := strings.Split(protectionLevel, ",")
-	if len(protectionLevelSplit) != 2 {
-		log.Fatal("Malformed input for protection-level")
-	}
-
-	k, err := strconv.Atoi(protectionLevelSplit[0])
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	m, err := strconv.Atoi(protectionLevelSplit[1])
 	if err != nil {
 		log.Fatal(err)
 	}
 
+	k := config.k
+	m := config.m
 	// get chunks
 	chunks := make([][]byte, k+m)
 	for i := 0; i < k+m; i++ {
-		chunks[i], _ = ioutil.ReadFile(inputFilePath + "." + strconv.Itoa(i))
+		chunks[i], _ = ioutil.ReadFile(config.input + "." + strconv.Itoa(i))
 	}
 
 	// get length
-	lengthBytes, err := ioutil.ReadFile(inputFilePath + ".length")
+	lengthBytes, err := ioutil.ReadFile(config.input + ".length")
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -70,8 +51,8 @@ func decode(c *cli.Context) {
 	}
 
 	// write decode data out
-	if _, err := os.Stat(outputFilePath); os.IsNotExist(err) {
+	if _, err := os.Stat(config.output); os.IsNotExist(err) {
-		ioutil.WriteFile(outputFilePath, decodedData, 0600)
+		ioutil.WriteFile(config.output, decodedData, 0600)
 	} else {
 		log.Fatal("Output file already exists")
 	}

cmd/erasure-demo/encode.go

@@ -5,7 +5,6 @@ import (
 	"log"
 	"os"
 	"strconv"
-	"strings"
 
 	"github.com/codegangsta/cli"
 	"github.com/minio-io/minio/pkgs/erasure"
@@ -18,33 +17,13 @@ func encode(c *cli.Context) {
 		return
 	}
 
-	// get input path
+	config, err := parseInput(c)
-	inputFilePath := c.Args().Get(0)
-
-	// get output path
-	outputFilePath := inputFilePath
-	if c.String("output") != "" {
-		outputFilePath = c.String("output")
-	}
-
-	protectionLevel := c.String("protection-level")
-	protectionLevelSplit := strings.Split(protectionLevel, ",")
-	if len(protectionLevelSplit) != 2 {
-		log.Fatal("Malformed input for protection-level")
-	}
-
-	k, err := strconv.Atoi(protectionLevelSplit[0])
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	m, err := strconv.Atoi(protectionLevelSplit[1])
 	if err != nil {
 		log.Fatal(err)
 	}
 
 	// get file
-	inputFile, err := os.Open(inputFilePath)
+	inputFile, err := os.Open(config.input)
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -56,13 +35,13 @@ func encode(c *cli.Context) {
 	}
 
 	// set up encoder
-	erasureParameters, _ := erasure.ParseEncoderParams(k, m, erasure.CAUCHY)
+	erasureParameters, _ := erasure.ParseEncoderParams(config.k, config.m, erasure.CAUCHY)
 	// encode data
 	encodedData, length := erasure.Encode(input, erasureParameters)
 
 	// write encoded data out
 	for key, data := range encodedData {
-		ioutil.WriteFile(outputFilePath+"."+strconv.Itoa(key), data, 0600)
+		ioutil.WriteFile(config.output+"."+strconv.Itoa(key), data, 0600)
 	}
-	ioutil.WriteFile(outputFilePath+".length", []byte(strconv.Itoa(length)), 0600)
+	ioutil.WriteFile(config.output+".length", []byte(strconv.Itoa(length)), 0600)
 }

cmd/erasure-demo/main.go

@@ -1,7 +1,10 @@
 package main
 
 import (
+	"errors"
 	"os"
+	"strconv"
+	"strings"
 
 	"github.com/codegangsta/cli"
 )
@@ -48,3 +51,47 @@ func main() {
 	}
 	app.Run(os.Args)
 }
+
+// config representing cli input
+type inputConfig struct {
+	input     string
+	output    string
+	k         int
+	m         int
+	blockSize int
+}
+
+// parses input and returns an inputConfig with parsed input
+func parseInput(c *cli.Context) (inputConfig, error) {
+	// get input path
+	inputFilePath := c.Args().Get(0)
+
+	// get output path
+	outputFilePath := inputFilePath
+	if c.String("output") != "" {
+		outputFilePath = c.String("output")
+	}
+
+	protectionLevel := c.String("protection-level")
+	protectionLevelSplit := strings.Split(protectionLevel, ",")
+	if len(protectionLevelSplit) != 2 {
+		return inputConfig{}, errors.New("Malformed input for protection-level")
+	}
+
+	k, err := strconv.Atoi(protectionLevelSplit[0])
+	if err != nil {
+		return inputConfig{}, err
+	}
+
+	m, err := strconv.Atoi(protectionLevelSplit[1])
+	if err != nil {
+		return inputConfig{}, err
+	}
+
+	return inputConfig{
+		input:  inputFilePath,
+		output: outputFilePath,
+		k:      k,
+		m:      m,
+	}, nil
+}