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hashReaderWriter.go
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/
hashReaderWriter.go
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package iotools
import (
"crypto"
"fmt"
"hash"
"io"
"net/http"
"strings"
"github.com/mandelsoft/goutils/errors"
)
type Hashes map[crypto.Hash]hash.Hash
func NewHashes(algorithms ...crypto.Hash) Hashes {
hashMap := make(Hashes, len(algorithms))
for _, algorithm := range algorithms {
hashMap[algorithm] = algorithm.New()
}
return hashMap
}
func (h Hashes) Write(c int, buf []byte) {
if c > 0 {
for _, hash := range h {
hash.Write(buf[:c])
}
}
}
func (h Hashes) AsHttpHeader() http.Header {
headers := make(http.Header, len(h))
for algorithm := range h {
headers.Set(headerName(algorithm), h.GetString(algorithm))
}
return headers
}
func (h Hashes) GetBytes(algorithm crypto.Hash) []byte {
hash := h[algorithm]
if hash != nil {
return hash.Sum(nil)
}
return nil
}
func (h Hashes) GetString(algorithm crypto.Hash) string {
return fmt.Sprintf("%x", h.GetBytes(algorithm))
}
func headerName(algorithm crypto.Hash) string {
a := strings.ReplaceAll(algorithm.String(), "-", "")
return "X-Checksum-" + a[:1] + strings.ToLower(a[1:])
}
////////////////////////////////////////////////////////////////////////////////
type HashReader struct {
reader io.Reader
hashMap Hashes
}
func NewHashReader(delegate io.Reader, algorithms ...crypto.Hash) *HashReader {
newInstance := HashReader{
reader: delegate,
hashMap: NewHashes(algorithms...),
}
return &newInstance
}
func (h *HashReader) Read(buf []byte) (int, error) {
c, err := h.reader.Read(buf)
if err == nil {
h.hashMap.Write(c, buf)
}
return c, err
}
func (h *HashReader) Hashes() Hashes {
return h.hashMap
}
func (h *HashReader) ReadAll() ([]byte, error) {
return io.ReadAll(h.reader)
}
// CalcHashes returns the total number of bytes read and an error if any besides EOF.
func (h *HashReader) CalcHashes() (int64, error) {
b := make([]byte, 0, 512)
cnt := int64(0)
for {
n, err := h.Read(b[0:cap(b)]) // read a chunk, always from the beginning
b = b[:n] // reset slice to the actual read bytes
cnt += int64(n)
if err != nil {
if errors.Is(err, io.EOF) {
err = nil
}
return cnt, err
}
}
}
////////////////////////////////////////////////////////////////////////////////
type HashWriter struct {
writer io.Writer
hashMap Hashes
}
func NewHashWriter(w io.Writer, algorithms ...crypto.Hash) *HashWriter {
newInstance := HashWriter{
writer: w,
hashMap: NewHashes(algorithms...),
}
return &newInstance
}
func (h *HashWriter) Write(buf []byte) (int, error) {
c, err := h.writer.Write(buf)
if err == nil {
h.hashMap.Write(c, buf)
}
return c, err
}
func (h *HashWriter) Hashes() Hashes {
return h.hashMap
}