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Add hashing package
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parent
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commit
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29
src/restic/hashing/reader.go
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29
src/restic/hashing/reader.go
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@ -0,0 +1,29 @@
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package hashing
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import (
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"hash"
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"io"
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)
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// Reader hashes all data read from the underlying reader.
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type Reader struct {
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r io.Reader
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h hash.Hash
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}
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// NewReader returns a new Reader that uses the hash h.
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func NewReader(r io.Reader, h hash.Hash) *Reader {
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return &Reader{
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h: h,
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r: io.TeeReader(r, h),
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}
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}
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func (h *Reader) Read(p []byte) (int, error) {
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return h.r.Read(p)
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}
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// Sum returns the hash of the data read so far.
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func (h *Reader) Sum(d []byte) []byte {
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return h.h.Sum(d)
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}
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73
src/restic/hashing/reader_test.go
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73
src/restic/hashing/reader_test.go
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package hashing
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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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)
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func TestReader(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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rd := NewReader(bytes.NewReader(data), sha256.New())
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n, err := io.Copy(ioutil.Discard, rd)
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if err != nil {
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t.Fatal(err)
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}
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if n != int64(size) {
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t.Errorf("Reader: invalid number of bytes written: got %d, expected %d",
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n, size)
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}
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resultingHash := rd.Sum(nil)
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if !bytes.Equal(expectedHash[:], resultingHash) {
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t.Errorf("Reader: 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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}
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func BenchmarkReader(b *testing.B) {
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buf := make([]byte, 1<<22)
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_, err := io.ReadFull(rand.Reader, buf)
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if err != nil {
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b.Fatal(err)
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}
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expectedHash := sha256.Sum256(buf)
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b.SetBytes(int64(len(buf)))
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b.ResetTimer()
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for i := 0; i < b.N; i++ {
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rd := NewReader(bytes.NewReader(buf), sha256.New())
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n, err := io.Copy(ioutil.Discard, rd)
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if err != nil {
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b.Fatal(err)
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}
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if n != int64(len(buf)) {
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b.Errorf("Reader: invalid number of bytes written: got %d, expected %d",
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n, len(buf))
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}
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resultingHash := rd.Sum(nil)
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if !bytes.Equal(expectedHash[:], resultingHash) {
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b.Errorf("Reader: 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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}
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31
src/restic/hashing/writer.go
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31
src/restic/hashing/writer.go
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package hashing
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import (
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"hash"
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"io"
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)
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// Writer transparently hashes all data while writing it to the underlying writer.
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type Writer struct {
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w io.Writer
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h hash.Hash
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}
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// NewWriter wraps the writer w and feeds all data written to the hash h.
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func NewWriter(w io.Writer, h hash.Hash) *Writer {
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return &Writer{
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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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// Write wraps the write method of the underlying writer and also hashes all data.
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func (h *Writer) Write(p []byte) (int, error) {
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n, err := h.w.Write(p)
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return n, err
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}
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// Sum returns the hash of all data written so far.
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func (h *Writer) Sum(d []byte) []byte {
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return h.h.Sum(d)
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}
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74
src/restic/hashing/writer_test.go
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74
src/restic/hashing/writer_test.go
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@ -0,0 +1,74 @@
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package hashing
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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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)
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func TestWriter(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 := NewWriter(ioutil.Discard, sha256.New())
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n, err := io.Copy(wr, bytes.NewReader(data))
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if err != nil {
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t.Fatal(err)
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}
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if n != int64(size) {
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t.Errorf("Writer: invalid number of bytes written: got %d, expected %d",
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n, size)
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}
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resultingHash := wr.Sum(nil)
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if !bytes.Equal(expectedHash[:], resultingHash) {
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t.Errorf("Writer: 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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}
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func BenchmarkWriter(b *testing.B) {
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buf := make([]byte, 1<<22)
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_, err := io.ReadFull(rand.Reader, buf)
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if err != nil {
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b.Fatal(err)
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}
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expectedHash := sha256.Sum256(buf)
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b.SetBytes(int64(len(buf)))
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b.ResetTimer()
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for i := 0; i < b.N; i++ {
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wr := NewWriter(ioutil.Discard, sha256.New())
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n, err := io.Copy(wr, bytes.NewReader(buf))
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if err != nil {
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b.Fatal(err)
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}
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if n != int64(len(buf)) {
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b.Errorf("Writer: invalid number of bytes written: got %d, expected %d",
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n, len(buf))
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}
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resultingHash := wr.Sum(nil)
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if !bytes.Equal(expectedHash[:], resultingHash) {
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b.Errorf("Writer: 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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}
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