constellation/internal/file/file.go

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/*
Package file provides functions that combine file handling, JSON marshaling
and file system abstraction.
*/
package file
import (
"bytes"
"encoding/json"
"errors"
"io"
"io/fs"
"os"
"path"
"github.com/spf13/afero"
"github.com/talos-systems/talos/pkg/machinery/config/encoder"
"gopkg.in/yaml.v3"
)
// Option is a bitmask of options for file operations.
type Option uint
// Has determines if a set of options contains the given options.
func (o Option) Has(op Option) bool {
return o&op == op
}
const (
// OptNone is a no-op.
OptNone Option = 1 << iota / 2
// OptOverwrite overwrites an existing file.
OptOverwrite
// OptMkdirAll creates the path to the file.
OptMkdirAll
)
// Handler handles file interaction.
type Handler struct {
fs *afero.Afero
}
// NewHandler returns a new file handler.
func NewHandler(fs afero.Fs) Handler {
afs := &afero.Afero{Fs: fs}
return Handler{fs: afs}
}
// Read reads the file given name and returns the bytes read.
func (h *Handler) Read(name string) ([]byte, error) {
file, err := h.fs.OpenFile(name, os.O_RDONLY, 0o600)
if err != nil {
return nil, err
}
defer file.Close()
return io.ReadAll(file)
}
// Write writes the data bytes into the file with the given name.
func (h *Handler) Write(name string, data []byte, options Option) error {
if options.Has(OptMkdirAll) {
if err := h.fs.MkdirAll(path.Dir(name), os.ModePerm); err != nil {
return err
}
}
flags := os.O_WRONLY | os.O_CREATE | os.O_EXCL
if options.Has(OptOverwrite) {
flags = os.O_WRONLY | os.O_CREATE | os.O_TRUNC
}
file, err := h.fs.OpenFile(name, flags, 0o600)
if err != nil {
return err
}
_, err = file.Write(data)
if errTmp := file.Close(); errTmp != nil && err == nil {
err = errTmp
}
return err
}
// ReadJSON reads a JSON file from name and unmarshals it into the content interface.
// The interface content must be a pointer to a JSON marchalable object.
func (h *Handler) ReadJSON(name string, content any) error {
data, err := h.Read(name)
if err != nil {
return err
}
return json.Unmarshal(data, content)
}
// WriteJSON marshals the content interface to JSON and writes it to the path with the given name.
func (h *Handler) WriteJSON(name string, content any, options Option) error {
jsonData, err := json.MarshalIndent(content, "", "\t")
if err != nil {
return err
}
return h.Write(name, jsonData, options)
}
// ReadYAML reads a YAML file from name and unmarshals it into the content interface.
// The interface content must be a pointer to a YAML marchalable object.
func (h *Handler) ReadYAML(name string, content any) error {
return h.readYAML(name, content, false)
}
// ReadYAMLStrict does the same as ReadYAML, but fails if YAML contains fields
// that are not specified in content.
func (h *Handler) ReadYAMLStrict(name string, content any) error {
return h.readYAML(name, content, true)
}
func (h *Handler) readYAML(name string, content any, strict bool) error {
data, err := h.Read(name)
if err != nil {
return err
}
decoder := yaml.NewDecoder(bytes.NewBuffer(data))
decoder.KnownFields(strict)
return decoder.Decode(content)
}
// WriteYAML marshals the content interface to YAML and writes it to the path with the given name.
func (h *Handler) WriteYAML(name string, content any, options Option) (err error) {
defer func() {
if r := recover(); r != nil {
err = errors.New("recovered from panic")
}
}()
data, err := encoder.NewEncoder(content).Encode()
if err != nil {
return err
}
return h.Write(name, data, options)
}
// Remove deletes the file with the given name.
func (h *Handler) Remove(name string) error {
return h.fs.Remove(name)
}
// Stat returns a FileInfo describing the named file, or an error, if any
// happens.
func (h *Handler) Stat(name string) (fs.FileInfo, error) {
return h.fs.Stat(name)
}