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md5sum.go
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md5sum.go
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// Copyright 2018 the u-root Authors. All rights reserved
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"crypto/md5"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"github.com/spf13/pflag"
)
func getInput() (input []byte, err error) {
return ioutil.ReadAll(os.Stdin)
}
func helpPrinter() {
fmt.Printf("Usage:\nmd5sum <File Name>\n")
pflag.PrintDefaults()
os.Exit(0)
}
func versionPrinter() {
fmt.Println("md5sum utility, URoot Version.")
os.Exit(0)
}
func calculateMd5Sum(fileName string, data []byte) string {
if len(data) > 0 {
return fmt.Sprintf("%x", md5.Sum(data))
}
fileDesc, err := os.Open(fileName)
if err != nil {
log.Fatal(err)
}
defer fileDesc.Close()
md5Generator := md5.New()
if _, err := io.Copy(md5Generator, fileDesc); err != nil {
log.Fatal(err)
}
md5Sum := fmt.Sprintf("%x", md5Generator.Sum(nil))
return md5Sum
}
func main() {
var (
help bool
version bool
input []byte
err error
)
cliArgs := ""
pflag.BoolVarP(&help, "help", "h", false, "Show this help and exit")
pflag.BoolVarP(&version, "version", "v", false, "Print Version")
pflag.Parse()
if help {
helpPrinter()
}
if version {
versionPrinter()
}
if len(os.Args) >= 2 {
cliArgs = os.Args[1]
}
if cliArgs == "" {
input, err = getInput()
if err != nil {
fmt.Println("Error getting input.")
os.Exit(-1)
}
}
fmt.Printf("%s ", calculateMd5Sum(cliArgs, input))
if cliArgs == "" {
fmt.Printf(" -\n")
} else {
fmt.Printf(" %s\n", cliArgs)
}
os.Exit(0)
}