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package utils
import (
"crypto/md5"
"crypto/sha1"
"crypto/sha256"
"crypto/sha512"
"fmt"
"hash"
"io"
"os"
)
// MD5ChecksumForFile computes just the MD5 hash and not all the others
func MD5ChecksumForFile(path string) (string, error) {
file, err := os.Open(path)
if err != nil {
return "", err
}
defer func() {
_ = file.Close()
}()
hash := md5.New()
_, err = io.Copy(hash, file)
if err != nil {
return "", err
}
return fmt.Sprintf("%x", hash.Sum(nil)), nil
}
// ChecksumInfo represents checksums for a single file
type ChecksumInfo struct {
Size int64
MD5 string
SHA1 string
SHA256 string
SHA512 string
}
// Complete checks if all the checksums are present
func (cksum *ChecksumInfo) Complete() bool {
return cksum.MD5 != "" && cksum.SHA1 != "" && cksum.SHA256 != "" && cksum.SHA512 != ""
}
// ChecksumsForReader generates size, MD5, SHA1 & SHA256 checksums for the given
// io.Reader
func ChecksumsForReader(rd io.Reader) (ChecksumInfo, error) {
w := NewChecksumWriter()
_, err := io.Copy(w, rd)
if err != nil {
return ChecksumInfo{}, err
}
return w.Sum(), nil
}
// ChecksumsForFile generates size, MD5, SHA1 & SHA256 checksums for the file at
// the given path
func ChecksumsForFile(path string) (ChecksumInfo, error) {
file, err := os.Open(path)
if err != nil {
return ChecksumInfo{}, err
}
defer func() {
_ = file.Close()
}()
return ChecksumsForReader(file)
}
// ChecksumWriter is a writer that does checksum calculation on the fly passing data
// to real writer
type ChecksumWriter struct {
sum ChecksumInfo
hashes []hash.Hash
}
// Interface check
var (
_ io.Writer = &ChecksumWriter{}
)
// NewChecksumWriter creates checksum calculator for given writer w
func NewChecksumWriter() *ChecksumWriter {
return &ChecksumWriter{
hashes: []hash.Hash{md5.New(), sha1.New(), sha256.New(), sha512.New()},
}
}
// Write implememnts pass-through writing with checksum calculation on the fly
func (c *ChecksumWriter) Write(p []byte) (n int, err error) {
c.sum.Size += int64(len(p))
for _, h := range c.hashes {
h.Write(p)
}
return len(p), nil
}
// Sum returns caculated ChecksumInfo
func (c *ChecksumWriter) Sum() ChecksumInfo {
c.sum.MD5 = fmt.Sprintf("%x", c.hashes[0].Sum(nil))
c.sum.SHA1 = fmt.Sprintf("%x", c.hashes[1].Sum(nil))
c.sum.SHA256 = fmt.Sprintf("%x", c.hashes[2].Sum(nil))
c.sum.SHA512 = fmt.Sprintf("%x", c.hashes[3].Sum(nil))
return c.sum
}
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