ipfs/kubo · warning

copying binary %q: %w

Error message

copying binary %q: %w

What it means

binary() copies the executable bytes into the profile archive with io.Copy(w, fi), closes the file, and wraps any copy error as "copying binary %q" with the path. Collection already succeeded in finding and opening the binary; the failure happened while streaming its bytes into the destination writer.

Source

Thrown at profile/profile.go:242

		err  error
	)
	if goos == "linux" {
		pid := os.Getpid()
		path = fmt.Sprintf("/proc/%d/exe", pid)
	} else {
		path, err = os.Executable()
		if err != nil {
			return fmt.Errorf("finding binary path: %w", err)
		}
	}
	fi, err := os.Open(path)
	if err != nil {
		return fmt.Errorf("opening binary %q: %w", path, err)
	}
	_, err = io.Copy(w, fi)
	_ = fi.Close()
	if err != nil {
		return fmt.Errorf("copying binary %q: %w", path, err)
	}
	return nil
}

func mutexProfile(ctx context.Context, opts Options, w io.Writer) error {
	prev := runtime.SetMutexProfileFraction(opts.MutexProfileFraction)
	defer runtime.SetMutexProfileFraction(prev)
	err := waitOrCancel(ctx, opts.ProfileDuration)
	if err != nil {
		return err
	}
	return pprof.Lookup("mutex").WriteTo(w, 2)
}

func blockProfile(ctx context.Context, opts Options, w io.Writer) error {
	runtime.SetBlockProfileRate(int(opts.BlockProfileRate.Nanoseconds()))
	defer runtime.SetBlockProfileRate(0)
	err := waitOrCancel(ctx, opts.ProfileDuration)

View on GitHub (pinned to 329838acdf)

Solutions

1. Read the wrapped path and inner error to find whether read or write side failed
2. Check disk space on the archive destination before embedding large binaries
3. Never mutate/delete the running binary while profiling (serialize upgrade and profile collection)
4. Consider excluding the binary collector for very large executables if archives are size-constrained

if st, err := os.Stat(binPath); err != nil || st.Size() > maxEmbedSize {
    return skipBinaryCollector
}

if err := WriteProfiles(ctx, p); err != nil {
    if strings.HasPrefix(err.Error(), "copying binary") {
        log.Printf("binary copy failed mid-stream (%v); retry without concurrent upgrade", errors.Unwrap(err))
    }
    return err
}

When it happens

Trigger: io.Copy(w, fi) fails: the destination writer w (the profile buffer feeding the archive) hit an underlying write error, the binary file shrank/vanished mid-read (upgrade race), read() returned EIO on a damaged filesystem, or large binaries hit a size limit on the output.

Common situations: Disk filling up while a multi-hundred-MB binary is being embedded; concurrent self-upgrade truncating the executable during read; reading from a flaky network/overlay filesystem inside containers.

Related errors

• opening binary %q: %w
• unexpected error while checking writeablility of repo root:
• flushing %s: %w
• copying binary to stash: %w
• syncing stash file: %w

AI-assisted analysis of ipfs/kubo@329838acdf (2026-09-03). Data as JSON: /api/errors/1e704113bb60c119. Report an issue: GitHub.