pomme/internal/util/fs.go

package util

import (
	"errors"
	"fmt"
	"os"
)

var errEmptyFile = errors.New("will not save empty file to FS")

func MakeLocal(filename, username string, buf []byte) error {
	if _, err := os.Stat(fmt.Sprintf("/tmp/tmpfile-%s-%s", filename, username)); !os.IsNotExist(err) {
		return fmt.Errorf("file %s already exists: %w", filename, err)
	}

	if len(buf) == 0 {
		return errEmptyFile
	}

	f, err := os.Create("/tmp/tmpfile-" + filename + "-" + username) //nolint: gosec
	// this is set to nolint because I am doing everything os.CreateTemp does but here since I don't like some of the limitations
	if err != nil {
		return fmt.Errorf("failed to write file locally: %w", err)
	}

	// close and remove the temporary file at the end of the program
	defer func() {
		if err = f.Close(); err != nil {
			return
		}
	}()

	err = os.WriteFile(f.Name(), buf, 0o600)

	if err != nil {
		return fmt.Errorf("failed to write file locally: %w", err)
	}

	return nil
}