Buffer partial writes and only emit complete lines in logLineWriter

silv-io · silv-io · commit de6a7dfa5d3a · 2026-03-10T18:06:48.000+01:00
diff --git a/internal/update/update.go b/internal/update/update.go
@@ -1,6 +1,7 @@
 package update
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"fmt"
@@ -123,7 +124,9 @@ func updateHomebrew(ctx context.Context, sink output.Sink) error {
 	w := newLogLineWriter(sink, "brew")
 	cmd.Stdout = w
 	cmd.Stderr = w
-	return cmd.Run()
+	err := cmd.Run()
+	w.Flush()
+	return err
 }
 
 func updateNPM(ctx context.Context, sink output.Sink, projectDir string) error {
@@ -137,27 +140,48 @@ func updateNPM(ctx context.Context, sink output.Sink, projectDir string) error {
 	w := newLogLineWriter(sink, "npm")
 	cmd.Stdout = w
 	cmd.Stderr = w
-	return cmd.Run()
+	err := cmd.Run()
+	w.Flush()
+	return err
 }
 
-// logLineWriter adapts an output.Sink into an io.Writer, emitting each line as a LogLineEvent.
+// logLineWriter adapts an output.Sink into an io.Writer, emitting each
+// complete line as a LogLineEvent. Partial writes are buffered until a
+// newline arrives.
 type logLineWriter struct {
 	sink   output.Sink
 	source string
+	buf    []byte
 }
 
 func newLogLineWriter(sink output.Sink, source string) *logLineWriter {
 	return &logLineWriter{sink: sink, source: source}
 }
 
 func (w *logLineWriter) Write(p []byte) (int, error) {
-	line := strings.TrimRight(string(p), "\n")
-	if line != "" {
-		output.EmitLogLine(w.sink, w.source, line)
+	w.buf = append(w.buf, p...)
+	for {
+		i := bytes.IndexByte(w.buf, '\n')
+		if i < 0 {
+			break
+		}
+		line := string(w.buf[:i])
+		w.buf = w.buf[i+1:]
+		if line != "" {
+			output.EmitLogLine(w.sink, w.source, line)
+		}
 	}
 	return len(p), nil
 }
 
+// Flush emits any remaining buffered content that didn't end with a newline.
+func (w *logLineWriter) Flush() {
+	if len(w.buf) > 0 {
+		output.EmitLogLine(w.sink, w.source, string(w.buf))
+		w.buf = nil
+	}
+}
+
 func updateBinary(ctx context.Context, tag string) error {
 	ver := normalizeVersion(tag)
 	assetName := buildAssetName(ver, goruntime.GOOS, goruntime.GOARCH)
