One read multiple hash

multihash.go

package main

import (
	"crypto/md5"
	"crypto/sha1"
	"crypto/sha256"
	"crypto/sha512"
	"fmt"
	"hash"
	"hash/crc32"
	"hash/crc64"
	"io"
	"log"
	"math"
	"os"

	"github.com/codahale/blake2"
	"github.com/jzelinskie/whirlpool"
	"github.com/michielbuddingh/spamsum"
	"golang.org/x/crypto/md4"
	"golang.org/x/crypto/ripemd160"
	"golang.org/x/crypto/sha3"
)

const (
	spamSumLength = uint64(64)
	minBlockSize  = uint64(3)
)

var (
	h         = map[string]hash.Hash{}
	fileChunk = minBlockSize
)

func main() {

	// Open the file
	fp, err := os.Open(os.Args[1])
	if err != nil {
		log.Fatal(err)
	}
	// close fp on exit and check for its returned error
	defer func() {
		if err := fp.Close(); err != nil {
			panic(err)
		}
	}()

	// Calculate chunk count
	stat, _ := fp.Stat()
	size := stat.Size()

	// Determine best blocksize

	for fileChunk*spamSumLength < uint64(size) {
		fileChunk = fileChunk * 2
	}

	// Initialize hash map

	h["crc32"] = crc32.NewIEEE()
	h["crc64"] = crc64.New(crc64.MakeTable(crc64.ISO))
	h["md4"] = md4.New()
	h["md5"] = md5.New()
	h["sha1"] = sha1.New()
	h["whirlpool"] = whirlpool.New()
	h["blake2b"] = blake2.NewBlake2B()
	h["sha2-256"] = sha256.New()
	h["sha2-512"] = sha512.New()
	h["ripemd160"] = ripemd160.New()
	h["sha3-256"] = sha3.New256()
	h["sha3-384"] = sha3.New384()
	h["sha3-512"] = sha3.New512()
	h["ssdeep"] = spamsum.StartFixedBlocksize(uint32(fileChunk))

	// Count file chunks
	chunks := uint64(math.Ceil(float64(size) / float64(fileChunk)))

	// Read file
	for i := uint64(0); i < chunks; i++ {
		csize := int(math.Min(float64(fileChunk), float64(uint64(size)-uint64(i*fileChunk))))
		buf := make([]byte, csize)

		_, err := fp.Read(buf)
		if err != nil && err != io.EOF {
			panic(err)
		}

		// Hash block
		for _, hf := range h {
			hf.Write(buf)
		}
	}

	// Display hash
	fmt.Printf("CRC32      : %x\n", h["crc32"].Sum(nil))
	fmt.Printf("CRC64      : %x\n", h["crc64"].Sum(nil))
	fmt.Printf("MD4        : %x\n", h["md4"].Sum(nil))
	fmt.Printf("MD5        : %x\n", h["md5"].Sum(nil))
	fmt.Printf("RIPEMD-160 : %x\n", h["ripemd160"].Sum(nil))
	fmt.Printf("SHA-1      : %x\n", h["sha1"].Sum(nil))
	fmt.Printf("SHA2-256   : %x\n", h["sha2-256"].Sum(nil))
	fmt.Printf("SHA3-256   : %x\n", h["sha3-256"].Sum(nil))
	fmt.Printf("SHA3-384   : %x\n", h["sha3-384"].Sum(nil))
	fmt.Printf("SHA2-512   : %x\n", h["sha2-512"].Sum(nil))
	fmt.Printf("SHA3-512   : %x\n", h["sha3-512"].Sum(nil))
	fmt.Printf("WHIRLPOOL  : %x\n", h["whirlpool"].Sum(nil))
	fmt.Printf("BLAKE2B    : %x\n", h["blake2b"].Sum(nil))
	fmt.Printf("SSDEEP     : %s\n", h["ssdeep"].(*spamsum.SpamSumWriter).String())
}