From b510c70c1ef2bd41eee962dc04fbbe0880edebd6 Mon Sep 17 00:00:00 2001
From: Stefan Breunig <stefan-github@yrden.de>
Date: Sat, 12 Aug 2017 12:57:34 +0200
Subject: [PATCH] =?UTF-8?q?b2:=20calculate=20missing=20hashes=20on=20the?=
 =?UTF-8?q?=20fly=20instead=20of=20spooling=20=E2=80=93=20fixes=20#1288?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 b2/b2.go     | 41 +++++--------------------------------
 b2/upload.go | 57 +++++++++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 57 insertions(+), 41 deletions(-)

diff --git a/b2/b2.go b/b2/b2.go
index 0ee1cd233..bc93ac7ae 100644
--- a/b2/b2.go
+++ b/b2/b2.go
@@ -10,9 +10,7 @@ import (
 	"fmt"
 	"hash"
 	"io"
-	"io/ioutil"
 	"net/http"
-	"os"
 	"path"
 	"regexp"
 	"strconv"
@@ -1249,42 +1247,13 @@ func (o *Object) Update(in io.Reader, src fs.ObjectInfo, options ...fs.OpenOptio
 	}
 
 	modTime := src.ModTime()
+
 	calculatedSha1, _ := src.Hash(fs.HashSHA1)
-
-	// If source cannot provide the hash, copy to a temporary file
-	// and calculate the hash while doing so.
-	// Then we serve the temporary file.
 	if calculatedSha1 == "" {
-		// Open a temp file to copy the input
-		fd, err := ioutil.TempFile("", "rclone-b2-")
-		if err != nil {
-			return err
-		}
-		_ = os.Remove(fd.Name()) // Delete the file - may not work on Windows
-		defer func() {
-			_ = fd.Close()           // Ignore error may have been closed already
-			_ = os.Remove(fd.Name()) // Delete the file - may have been deleted already
-		}()
-
-		// Copy the input while calculating the sha1
-		hash := sha1.New()
-		teed := io.TeeReader(in, hash)
-		n, err := io.Copy(fd, teed)
-		if err != nil {
-			return err
-		}
-		if n != size {
-			return errors.Errorf("read %d bytes expecting %d", n, size)
-		}
-		calculatedSha1 = fmt.Sprintf("%x", hash.Sum(nil))
-
-		// Rewind the temporary file
-		_, err = fd.Seek(0, 0)
-		if err != nil {
-			return err
-		}
-		// Set input to temporary file
-		in = fd
+		calculatedSha1 = "hex_digits_at_end"
+		har := newHashAppendingReader(in, sha1.New())
+		size += int64(har.AdditionalLength())
+		in = har
 	}
 
 	// Get upload URL
diff --git a/b2/upload.go b/b2/upload.go
index 214b23e1c..a803991b3 100644
--- a/b2/upload.go
+++ b/b2/upload.go
@@ -7,8 +7,11 @@ package b2
 import (
 	"bytes"
 	"crypto/sha1"
+	"encoding/hex"
 	"fmt"
+	"hash"
 	"io"
+	"strings"
 	"sync"
 
 	"github.com/ncw/rclone/b2/api"
@@ -17,6 +20,49 @@ import (
 	"github.com/pkg/errors"
 )
 
+type hashAppendingReader struct {
+	h         hash.Hash
+	in        io.Reader
+	hexSum    string
+	hexReader io.Reader
+}
+
+// Read returns bytes all bytes from the original reader, then the hex sum
+// of what was read so far, then EOF.
+func (har *hashAppendingReader) Read(b []byte) (int, error) {
+	if har.hexReader == nil {
+		n, err := har.in.Read(b)
+		if err == io.EOF {
+			har.in = nil // allow GC
+			err = nil    // allow reading hexSum before EOF
+
+			har.hexSum = hex.EncodeToString(har.h.Sum(nil))
+			har.hexReader = strings.NewReader(har.hexSum)
+		}
+		return n, err
+	}
+	return har.hexReader.Read(b)
+}
+
+// AdditionalLength returns how many bytes the appended hex sum will take up.
+func (har *hashAppendingReader) AdditionalLength() int {
+	return hex.EncodedLen(har.h.Size())
+}
+
+// HexSum returns the hash sum as hex. It's only available after the original
+// reader has EOF'd. It's an empty string before that.
+func (har *hashAppendingReader) HexSum() string {
+	return har.hexSum
+}
+
+// newHashAppendingReader takes a Reader and a Hash and will append the hex sum
+// after the original reader reaches EOF. The increased size depends on the
+// given hash, which may be queried through AdditionalLength()
+func newHashAppendingReader(in io.Reader, h hash.Hash) *hashAppendingReader {
+	withHash := io.TeeReader(in, h)
+	return &hashAppendingReader{h: h, in: withHash}
+}
+
 // largeUpload is used to control the upload of large files which need chunking
 type largeUpload struct {
 	f        *Fs                             // parent Fs
@@ -128,9 +174,9 @@ func (up *largeUpload) clearUploadURL() {
 
 // Transfer a chunk
 func (up *largeUpload) transferChunk(part int64, body []byte) error {
-	calculatedSHA1 := fmt.Sprintf("%x", sha1.Sum(body))
-	up.sha1s[part-1] = calculatedSHA1
-	size := int64(len(body))
+	in := newHashAppendingReader(bytes.NewReader(body), sha1.New())
+	size := int64(len(body)) + int64(in.AdditionalLength())
+
 	err := up.f.pacer.Call(func() (bool, error) {
 		fs.Debugf(up.o, "Sending chunk %d length %d", part, len(body))
 
@@ -165,11 +211,11 @@ func (up *largeUpload) transferChunk(part int64, body []byte) error {
 		opts := rest.Opts{
 			Method:  "POST",
 			RootURL: upload.UploadURL,
-			Body:    fs.AccountPart(up.o, bytes.NewBuffer(body)),
+			Body:    fs.AccountPart(up.o, in),
 			ExtraHeaders: map[string]string{
 				"Authorization":    upload.AuthorizationToken,
 				"X-Bz-Part-Number": fmt.Sprintf("%d", part),
-				sha1Header:         calculatedSHA1,
+				sha1Header:         "hex_digits_at_end",
 			},
 			ContentLength: &size,
 		}
@@ -191,6 +237,7 @@ func (up *largeUpload) transferChunk(part int64, body []byte) error {
 	} else {
 		fs.Debugf(up.o, "Done sending chunk %d", part)
 	}
+	up.sha1s[part-1] = in.HexSum()
 	return err
 }