Add HashingWriter and HashAppendWriter
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5801d9f42f
commit
5c724b92b8
3 changed files with 140 additions and 1 deletions
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@ -65,7 +65,7 @@ func TestHashingReader(t *testing.T) {
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assert(t, n == int64(size),
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assert(t, n == int64(size),
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"HashAppendReader: invalid number of bytes read: got %d, expected %d",
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"HashAppendReader: invalid number of bytes read: got %d, expected %d",
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n, size+len(expectedHash))
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n, size)
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resultingHash := rd.Sum(nil)
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resultingHash := rd.Sum(nil)
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assert(t, bytes.Equal(expectedHash[:], resultingHash),
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assert(t, bytes.Equal(expectedHash[:], resultingHash),
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63
backend/writer.go
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63
backend/writer.go
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@ -0,0 +1,63 @@
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package backend
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import (
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"errors"
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"hash"
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"io"
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)
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type HashAppendWriter struct {
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w io.Writer
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origWr io.Writer
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h hash.Hash
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sum []byte
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closed bool
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}
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func NewHashAppendWriter(w io.Writer, h hash.Hash) *HashAppendWriter {
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return &HashAppendWriter{
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h: h,
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w: io.MultiWriter(w, h),
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origWr: w,
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sum: make([]byte, 0, h.Size()),
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}
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}
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func (h *HashAppendWriter) Close() error {
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if !h.closed {
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h.closed = true
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_, err := h.origWr.Write(h.h.Sum(nil))
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return err
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}
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return nil
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}
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func (h *HashAppendWriter) Write(p []byte) (n int, err error) {
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if !h.closed {
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return h.w.Write(p)
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}
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return 0, errors.New("Write() called on closed HashAppendWriter")
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}
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type HashingWriter struct {
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w io.Writer
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h hash.Hash
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}
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func NewHashingWriter(w io.Writer, h hash.Hash) *HashingWriter {
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return &HashingWriter{
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h: h,
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w: io.MultiWriter(w, h),
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}
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}
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func (h *HashingWriter) Write(p []byte) (int, error) {
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return h.w.Write(p)
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}
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func (h *HashingWriter) Sum(d []byte) []byte {
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return h.h.Sum(d)
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}
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76
backend/writer_test.go
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76
backend/writer_test.go
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@ -0,0 +1,76 @@
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package backend_test
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import (
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"bytes"
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"crypto/rand"
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"crypto/sha256"
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"io"
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"io/ioutil"
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"testing"
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"github.com/restic/restic/backend"
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)
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func TestHashAppendWriter(t *testing.T) {
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tests := []int{5, 23, 2<<18 + 23, 1 << 20}
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for _, size := range tests {
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data := make([]byte, size)
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_, err := io.ReadFull(rand.Reader, data)
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if err != nil {
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t.Fatalf("ReadFull: %v", err)
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}
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expectedHash := sha256.Sum256(data)
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target := bytes.NewBuffer(nil)
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wr := backend.NewHashAppendWriter(target, sha256.New())
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_, err = wr.Write(data)
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ok(t, err)
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ok(t, wr.Close())
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assert(t, len(target.Bytes()) == size+len(expectedHash),
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"HashAppendWriter: invalid number of bytes written: got %d, expected %d",
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len(target.Bytes()), size+len(expectedHash))
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r := target.Bytes()
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resultingHash := r[len(r)-len(expectedHash):]
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assert(t, bytes.Equal(expectedHash[:], resultingHash),
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"HashAppendWriter: hashes do not match: expected %02x, got %02x",
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expectedHash, resultingHash)
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// write again, this must return an error
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_, err = wr.Write([]byte{23})
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assert(t, err != nil,
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"HashAppendWriter: Write() after Close() did not return an error")
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}
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}
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func TestHashingWriter(t *testing.T) {
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tests := []int{5, 23, 2<<18 + 23, 1 << 20}
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for _, size := range tests {
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data := make([]byte, size)
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_, err := io.ReadFull(rand.Reader, data)
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if err != nil {
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t.Fatalf("ReadFull: %v", err)
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}
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expectedHash := sha256.Sum256(data)
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wr := backend.NewHashingWriter(ioutil.Discard, sha256.New())
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n, err := io.Copy(wr, bytes.NewReader(data))
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ok(t, err)
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assert(t, n == int64(size),
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"HashAppendWriter: invalid number of bytes written: got %d, expected %d",
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n, size)
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resultingHash := wr.Sum(nil)
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assert(t, bytes.Equal(expectedHash[:], resultingHash),
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"HashAppendWriter: hashes do not match: expected %02x, got %02x",
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expectedHash, resultingHash)
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}
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}
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