Merge pull request #100 from tonistiigi/differ

receive: add differ selection

diff_containerd.go

@@ -1,7 +1,9 @@
 package fsutil
 
 import (
+	"bytes"
 	"context"
+	"io"
 	"os"
 	"strings"
 
@@ -35,14 +37,16 @@ const (
 // computed during a directory changes calculation.
 type ChangeFunc func(ChangeKind, string, os.FileInfo, error) error
 
+const compareChunkSize = 32 * 1024
+
 type currentPath struct {
 	path string
 	stat *types.Stat
 	//	fullPath string
 }
 
 // doubleWalkDiff walks both directories to create a diff
-func doubleWalkDiff(ctx context.Context, changeFn ChangeFunc, a, b walkerFn, filter FilterFunc) (err error) {
+func doubleWalkDiff(ctx context.Context, changeFn ChangeFunc, a, b walkerFn, filter FilterFunc, differ DiffType) (err error) {
 	g, ctx := errgroup.WithContext(ctx)
 
 	var (
@@ -116,7 +120,7 @@ func doubleWalkDiff(ctx context.Context, changeFn ChangeFunc, a, b walkerFn, fil
 				}
 				f1 = nil
 			case ChangeKindModify:
-				same, err := sameFile(f1, f2copy)
+				same, err := sameFile(f1, f2copy, differ)
 				if err != nil {
 					return err
 				}
@@ -165,7 +169,10 @@ func pathChange(lower, upper *currentPath) (ChangeKind, string) {
 	}
 }
 
-func sameFile(f1, f2 *currentPath) (same bool, retErr error) {
+func sameFile(f1, f2 *currentPath, differ DiffType) (same bool, retErr error) {
+	if differ == DiffNone {
+		return false, nil
+	}
 	// If not a directory also check size, modtime, and content
 	if !f1.stat.IsDir() {
 		if f1.stat.Size_ != f2.stat.Size_ {
@@ -177,7 +184,43 @@ func sameFile(f1, f2 *currentPath) (same bool, retErr error) {
 		}
 	}
 
-	return compareStat(f1.stat, f2.stat)
+	same, err := compareStat(f1.stat, f2.stat)
+	if err != nil || !same || differ == DiffMetadata {
+		return same, err
+	}
+	return compareFileContent(f1.path, f2.path)
+}
+
+func compareFileContent(p1, p2 string) (bool, error) {
+	f1, err := os.Open(p1)
+	if err != nil {
+		return false, err
+	}
+	defer f1.Close()
+	f2, err := os.Open(p2)
+	if err != nil {
+		return false, err
+	}
+	defer f2.Close()
+
+	b1 := make([]byte, compareChunkSize)
+	b2 := make([]byte, compareChunkSize)
+	for {
+		n1, err1 := f1.Read(b1)
+		if err1 != nil && err1 != io.EOF {
+			return false, err1
+		}
+		n2, err2 := f2.Read(b2)
+		if err2 != nil && err2 != io.EOF {
+			return false, err2
+		}
+		if n1 != n2 || !bytes.Equal(b1[:n1], b2[:n2]) {
+			return false, nil
+		}
+		if err1 == io.EOF && err2 == io.EOF {
+			return true, nil
+		}
+	}
 }
 
 // compareStat returns whether the stats are equivalent,

receive.go

@@ -11,12 +11,21 @@ import (
 	"golang.org/x/sync/errgroup"
 )
 
+type DiffType int
+
+const (
+	DiffMetadata DiffType = iota
+	DiffNone
+	DiffContent
+)
+
 type ReceiveOpt struct {
 	NotifyHashed  ChangeFunc
 	ContentHasher ContentHasher
 	ProgressCb    func(int, bool)
 	Merge         bool
 	Filter        FilterFunc
+	Differ        DiffType
 }
 
 func Receive(ctx context.Context, conn Stream, dest string, opt ReceiveOpt) error {
@@ -33,6 +42,7 @@ func Receive(ctx context.Context, conn Stream, dest string, opt ReceiveOpt) erro
 		progressCb:    opt.ProgressCb,
 		merge:         opt.Merge,
 		filter:        opt.Filter,
+		differ:        opt.Differ,
 	}
 	return r.run(ctx)
 }
@@ -47,6 +57,7 @@ type receiver struct {
 	progressCb func(int, bool)
 	merge      bool
 	filter     FilterFunc
+	differ     DiffType
 
 	notifyHashed   ChangeFunc
 	contentHasher  ContentHasher
@@ -132,7 +143,7 @@ func (r *receiver) run(ctx context.Context) error {
 		if !r.merge {
 			destWalker = getWalkerFn(r.dest)
 		}
-		err := doubleWalkDiff(ctx, dw.HandleChange, destWalker, w.fill, r.filter)
+		err := doubleWalkDiff(ctx, dw.HandleChange, destWalker, w.fill, r.filter, r.differ)
 		if err != nil {
 			return err
 		}