Merge pull request #100 from dims/fix-svg-reliability

Fix --svg pipe deadlock

Author: dims

cmd/diff.go

@@ -966,14 +966,21 @@ func captureDOTOutput(fn func() error) (string, error) {
 		return "", err
 	}
 	os.Stdout = w
+	defer func() {
+		os.Stdout = oldStdout
+	}()
+
+	var buf bytes.Buffer
+	readErrCh := make(chan error, 1)
+	go func() {
+		_, readErr := io.Copy(&buf, r)
+		_ = r.Close()
+		readErrCh <- readErr
+	}()
 
 	runErr := fn()
 	closeErr := w.Close()
-	os.Stdout = oldStdout
-
-	var buf bytes.Buffer
-	_, readErr := io.Copy(&buf, r)
-	_ = r.Close()
+	readErr := <-readErrCh
 
 	if runErr != nil {
 		return "", runErr

cmd/why_test.go

@@ -68,17 +68,21 @@ func captureStdout(t *testing.T, fn func()) string {
 		os.Stdout = old
 	}()
 
+	var buf bytes.Buffer
+	readDone := make(chan error, 1)
+	go func() {
+		_, readErr := io.Copy(&buf, r)
+		_ = r.Close()
+		readDone <- readErr
+	}()
+
 	fn()
 
 	if err := w.Close(); err != nil {
 		t.Fatalf("close writer: %v", err)
 	}
-	var buf bytes.Buffer
-	if _, err := io.Copy(&buf, r); err != nil {
+	if err := <-readDone; err != nil {
 		t.Fatalf("read capture: %v", err)
 	}
-	if err := r.Close(); err != nil {
-		t.Fatalf("close reader: %v", err)
-	}
 	return buf.String()
 }