84 lines
1.8 KiB
Go
84 lines
1.8 KiB
Go
package writer
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import (
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"context"
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"fmt"
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"io"
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"os"
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"path/filepath"
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"strings"
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)
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// ProgressFunc receives write progress updates.
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type ProgressFunc func(written int64, total int64)
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// WriteImage writes src into dest using a direct buffered copy so callers can
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// share the same codepath for files and block devices.
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func WriteImage(ctx context.Context, src, dest string) error {
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return WriteImageWithProgress(ctx, src, dest, nil)
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}
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// WriteImageWithProgress writes src into dest while invoking progress after each chunk.
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func WriteImageWithProgress(ctx context.Context, src, dest string, progress ProgressFunc) error {
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if dest == "" {
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return fmt.Errorf("destination required")
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}
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srcInfo, err := os.Stat(src)
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if err != nil {
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return fmt.Errorf("source missing: %w", err)
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}
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return copyFile(ctx, src, dest, srcInfo.Size(), progress)
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}
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func isDevicePath(path string) bool {
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return strings.HasPrefix(filepath.Clean(path), "/dev/")
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}
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func copyFile(ctx context.Context, src, dest string, total int64, progress ProgressFunc) error {
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if err := os.MkdirAll(filepath.Dir(dest), 0o755); err != nil {
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return err
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}
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in, err := os.Open(src)
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if err != nil {
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return err
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}
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defer in.Close()
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out, err := os.Create(dest)
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if err != nil {
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return err
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}
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defer out.Close()
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buf := make([]byte, 4*1024*1024)
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var written int64
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for {
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if err := ctx.Err(); err != nil {
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return err
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}
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nr, readErr := in.Read(buf)
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if nr > 0 {
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nw, writeErr := out.Write(buf[:nr])
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if writeErr != nil {
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return writeErr
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}
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if nw != nr {
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return io.ErrShortWrite
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}
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written += int64(nw)
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if progress != nil {
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progress(written, total)
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}
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}
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if readErr != nil {
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if readErr == io.EOF {
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break
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}
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return readErr
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}
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}
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if err := out.Sync(); err != nil {
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return err
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}
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return nil
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}
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