What causes "failed to copy: %w" in yorukot/superfile?

Inspect the wrapped error for the true cause (stat vs write failure).

failed to copy

Error message

failed to copy: %w

What it means

When the source and destination are on different partitions (or os.Rename failed), moveElement falls back to copying via copyElement and then deleting the source; this error wraps any copy failure. The root cause (permission, disk full, missing source) is in the wrapped error chain.

Solutions

Inspect the wrapped error for the true cause (stat vs write failure).
Check free space on the destination (df -h) — ENOSPC is common on cross-partition moves.
Verify the destination directory exists and is writable.
Confirm the source still exists and is readable before moving.

Example fix

// before
moveElement("/home/data", "/mnt/full-disk/data") // ENOSPC
// after
// free space or choose another destination
moveElement("/home/data", "/mnt/other/data")

Defensive patterns

Strategy: try-catch

Validate before calling

srcInfo, err := os.Stat(src)
if err != nil { return fmt.Errorf("source missing: %w", err) }
if st, err := os.Stat(filepath.Dir(dst)); err != nil || !st.IsDir() {
    return fmt.Errorf("destination parent must be an existing writable dir")
}
// optional: free-space check via syscall.Statfs on dst volume

Type guard

func isWritableDir(p string) bool {
    st, err := os.Stat(p)
    return err == nil && st.IsDir()
}

Try / catch

if err := moveElement(src, dst); err != nil {
    if strings.Contains(err.Error(), "failed to copy") {
        log.Errorf("cross-partition move failed: %v", err)
        // keep source intact; surface ENOSPC/EACCES to the user
        return err
    }
    return err
}

Prevention

Check destination free space before large cross-partition moves.
Ensure the destination directory exists and is writable beforehand.
Verify the source exists immediately before initiating the move.
For very large trees, consider copy-with-progress so failures are resumable.

When it happens

Trigger: moveElement(src, dst) where copyElement fails: os.Stat fails on src, directory creation or file copy fails on dst (ENOENT parent, EACCES, ENOSPC).

Common situations: Moving across drives to a full destination disk; destination directory not writable; source disappeared between the rename attempt and the copy; copying a directory containing unreadable entries.

Related errors

AI-assisted analysis of yorukot/superfile@b72f550bc6 (2026-09-01). Data as JSON: /api/errors/8414d215d040ab14. Report an issue: GitHub.

Appendix: source

Thrown at src/internal/file_operations.go:66

func moveElement(src, dst string) error {
	// Check if source and destination are on the same partition
	sameDev, err := isSamePartition(src, dst)
	if err != nil {
		return fmt.Errorf("failed to check partitions: %w", err)
	}

	// If on the same partition, attempt to rename (which will use the same inode)
	if sameDev {
		if err = os.Rename(src, dst); err == nil {
			return nil
		}
		// If rename fails, fall back to copy+delete
	}

	// If on different partitions or rename failed, fall back to copy+delete
	err = copyElement(src, dst)
	if err != nil {
		return fmt.Errorf("failed to copy: %w", err)
	}

	err = os.RemoveAll(src)
	if err != nil {
		return fmt.Errorf("failed to remove source after copy: %w", err)
	}

	return nil
}

// copyElement handles copying of both files and directories
func copyElement(src, dst string) error {
	srcInfo, err := os.Stat(src)
	if err != nil {
		return fmt.Errorf("failed to stat source: %w", err)
	}

	if srcInfo.IsDir() {

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