differ: fix deadlock on commit error

tonistiigi · tonistiigi · commit 5b9bd993a870 · 2019-04-25T17:50:17.000-07:00
Signed-off-by: Tonis Tiigi &lt;tonistiigi@gmail.com&gt;
diff --git a/content/local/writer.go b/content/local/writer.go
@@ -74,15 +74,16 @@ func (w *writer) Write(p []byte) (n int, err error) {
 }
 
 func (w *writer) Commit(ctx context.Context, size int64, expected digest.Digest, opts ...content.Opt) error {
+	// Ensure even on error the writer is fully closed
+	defer unlock(w.ref)
+
 	var base content.Info
 	for _, opt := range opts {
 		if err := opt(&base); err != nil {
 			return err
 		}
 	}
 
-	// Ensure even on error the writer is fully closed
-	defer unlock(w.ref)
 	fp := w.fp
 	w.fp = nil
 
diff --git a/diff/walking/differ.go b/diff/walking/differ.go
@@ -106,14 +106,15 @@ func (s *walkingDiff) Compare(ctx context.Context, lower, upper []mount.Mount, o
 				}
 			}()
 			if !newReference {
-				if err := cw.Truncate(0); err != nil {
+				if err = cw.Truncate(0); err != nil {
 					return err
 				}
 			}
 
 			if isCompressed {
 				dgstr := digest.SHA256.Digester()
-				compressed, err := compression.CompressStream(cw, compression.Gzip)
+				var compressed io.WriteCloser
+				compressed, err = compression.CompressStream(cw, compression.Gzip)
 				if err != nil {
 					return errors.Wrap(err, "failed to get compressed stream")
 				}

Original file line number	Diff line number	Diff line change
`@@ -74,15 +74,16 @@ func (w *writer) Write(p []byte) (n int, err error) {`
`74`	`74`	`}`
`75`	`75`
`76`	`76`	`func (w *writer) Commit(ctx context.Context, size int64, expected digest.Digest, opts ...content.Opt) error {`
	`77`	`+ // Ensure even on error the writer is fully closed`
	`78`	`+ defer unlock(w.ref)`
	`79`	`+`
`77`	`80`	`var base content.Info`
`78`	`81`	`for _, opt := range opts {`
`79`	`82`	`if err := opt(&base); err != nil {`
`80`	`83`	`return err`
`81`	`84`	`}`
`82`	`85`	`}`
`83`	`86`
`84`		`- // Ensure even on error the writer is fully closed`
`85`		`- defer unlock(w.ref)`
`86`	`87`	`fp := w.fp`
`87`	`88`	`w.fp = nil`
`88`	`89`
Original file line number	Diff line number	Diff line change
`@@ -106,14 +106,15 @@ func (s *walkingDiff) Compare(ctx context.Context, lower, upper []mount.Mount, o`
`106`	`106`	`}`
`107`	`107`	`}()`
`108`	`108`	`if !newReference {`
`109`		`- if err := cw.Truncate(0); err != nil {`
	`109`	`+ if err = cw.Truncate(0); err != nil {`
`110`	`110`	`return err`
`111`	`111`	`}`
`112`	`112`	`}`
`113`	`113`
`114`	`114`	`if isCompressed {`
`115`	`115`	`dgstr := digest.SHA256.Digester()`
`116`		`- compressed, err := compression.CompressStream(cw, compression.Gzip)`
	`116`	`+ var compressed io.WriteCloser`
	`117`	`+ compressed, err = compression.CompressStream(cw, compression.Gzip)`
`117`	`118`	`if err != nil {`
`118`	`119`	`return errors.Wrap(err, "failed to get compressed stream")`
`119`	`120`	`}`