Writes and verify image

clitools/pkg/controller/osimage/write.go

@@ -0,0 +1,82 @@
+package osimage
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os"
+)
+
+func WriteStreamToTarget(ctx context.Context,
+	src io.Reader,
+	targetPath string,
+	expectedSize int64, bufferSize int,
+	progress ProgressFunc,
+) (int64, error) {
+	if targetPath == "" {
+		return 0, fmt.Errorf("target path is required")
+	}
+	if bufferSize <= 0 {
+		bufferSize = 4 * 1024 * 1024
+	}
+
+	f, err := os.OpenFile(targetPath, os.O_WRONLY, 0)
+	if err != nil {
+		return 0, fmt.Errorf("open target: %w", err)
+	}
+	defer f.Close()
+
+	written, err := copyWithProgressBuffer(ctx, f, src, expectedSize, "flash", progress, make([]byte, bufferSize))
+	if err != nil {
+		return written, err
+	}
+
+	if expectedSize > 0 && written != expectedSize {
+		return written, fmt.Errorf("written size mismatch: got %d want %d", written, expectedSize)
+	}
+
+	if err := f.Sync(); err != nil {
+		return written, fmt.Errorf("sync target: %w", err)
+	}
+
+	return written, nil
+}
+
+func copyWithProgressBuffer(ctx context.Context, dst io.Writer, src io.Reader, total int64, stage string, progress ProgressFunc, buf []byte) (int64, error) {
+	var written int64
+
+	for {
+		select {
+		case <-ctx.Done():
+			return written, ctx.Err()
+		default:
+		}
+
+		nr, er := src.Read(buf)
+		if nr > 0 {
+			nw, ew := dst.Write(buf[:nr])
+			if nw > 0 {
+				written += int64(nw)
+				if progress != nil {
+					progress(Progress{
+						Stage:         stage,
+						BytesComplete: written,
+						BytesTotal:    total,
+					})
+				}
+			}
+			if ew != nil {
+				return written, ew
+			}
+			if nw != nr {
+				return written, io.ErrShortWrite
+			}
+		}
+		if er != nil {
+			if er == io.EOF {
+				return written, nil
+			}
+			return written, fmt.Errorf("copy %s: %w", stage, er)
+		}
+	}
+}