yorukot/superfile · error

error writing file : %w

Error message

error writing file : %w

What it means

WriteTomlData writes the marshaled TOML bytes with os.WriteFile using ConfigFilePerm; this error wraps any failure from that write. It means serialization succeeded but the filesystem write did not. Common causes are path and permission problems rather than data problems.

Source

Thrown at src/pkg/utils/file_utils.go:33

	"github.com/pelletier/go-toml/v2"

	"github.com/charmbracelet/x/ansi"
	"golang.org/x/text/encoding/unicode"
	"golang.org/x/text/transform"
)

// Utility functions related to file operations
// Note : This is not used anymore as we use os.WriteAt to
// fix toml files now, but we will still keep it for later use.
func WriteTomlData(filePath string, data interface{}) error {
	tomlData, err := toml.Marshal(data)
	if err != nil {
		// return a wrapped error
		return fmt.Errorf("error encoding data : %w", err)
	}
	err = os.WriteFile(filePath, tomlData, ConfigFilePerm)
	if err != nil {
		return fmt.Errorf("error writing file : %w", err)
	}
	return nil
}

// Helper function to load and validate TOML files with field checking
// errorPrefix is appended before every error message
func LoadTomlFile(filePath string, defaultData string, target interface{},
	fixFlag bool, ignoreMissingFields bool) error {
	// Initialize with default config
	_ = toml.Unmarshal([]byte(defaultData), target)

	data, err := os.ReadFile(filePath)
	if err != nil {
		return &TomlLoadError{
			userMessage:  "config file doesn't exist",
			wrappedError: err,
		}
	}

View on GitHub (pinned to b72f550bc6)

Solutions

1. Check the parent directory exists (run CreateDirectories first) and is writable.
2. Verify permissions: `ls -la <file>`; chown/chmod or fix ConfigFilePerm if too restrictive for the runtime user.
3. Confirm the path points to a file, not a directory.
4. Check disk space (`df -h`) and mount state (`mount | grep <dir>`) for read-only filesystems.
5. Handle the error at the call site and surface it to the user instead of silently dropping config saves.

Example fix

// before
err := utils.WriteTomlData(cfgPath, cfg)
// after
if err := utils.CreateDirectories(filepath.Dir(cfgPath)); err != nil { return err }
if err := utils.WriteTomlData(cfgPath, cfg); err != nil {
    return fmt.Errorf("saving config to %s: %w", cfgPath, err)
}

func canWrite(path string) error {
    dir := filepath.Dir(path)
    info, err := os.Stat(dir)
    if err != nil { return err }
    if !info.IsDir() { return fmt.Errorf("%s is not a directory", dir) }
    f, err := os.CreateTemp(dir, ".wtest*")
    if err != nil { return err }
    f.Close(); os.Remove(f.Name())
    return nil
}

if err := utils.WriteTomlData(path, cfg); err != nil {
    if strings.Contains(err.Error(), "error writing file") {
        return fmt.Errorf("cannot save config to %s (check dir/permissions/disk): %w", path, err)
    }
    return err
}

When it happens

Trigger: Calling WriteTomlData when the target path's directory doesn't exist, the process lacks write permission on the file/directory, the path is a directory, the disk is full, or the file is locked/readonly.

Common situations: Read-only config dirs after package installs; saving config before CreateDirectories ran; running under a different user than the config owner; container filesystems mounted read-only; full disks on CI machines.

Understand the failure class

Background: "failed to write file", "Could not save figure", "Error saving remote file" — file write failed: causes and fixes across languages and libraries — this error's family across 38 libraries.

Related errors

• failed to create file %s: %w
• failed to initialize json file %s: %w
• failed to remove source after copy: %w
• failed to create destination directory: %w
• failed to read source directory: %w

AI-assisted analysis of yorukot/superfile@b72f550bc6 (2026-09-01). Data as JSON: /api/errors/c9e8f3d0ab72c396. Report an issue: GitHub.