netbird/util/file.go

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package util
import (
"bytes"
"context"
"encoding/json"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"text/template"
log "github.com/sirupsen/logrus"
)
// WriteJsonWithRestrictedPermission writes JSON config object to a file. Enforces permission on the parent directory
func WriteJsonWithRestrictedPermission(file string, obj interface{}) error {
configDir, configFileName, err := prepareConfigFileDir(file)
if err != nil {
return err
}
err = EnforcePermission(file)
if err != nil {
return err
}
return writeJson(file, obj, configDir, configFileName)
}
// WriteJson writes JSON config object to a file creating parent directories if required
// The output JSON is pretty-formatted
func WriteJson(file string, obj interface{}) error {
configDir, configFileName, err := prepareConfigFileDir(file)
if err != nil {
return err
}
return writeJson(file, obj, configDir, configFileName)
}
// DirectWriteJson writes JSON config object to a file creating parent directories if required without creating a temporary file
func DirectWriteJson(ctx context.Context, file string, obj interface{}) error {
_, _, err := prepareConfigFileDir(file)
if err != nil {
return err
}
targetFile, err := openOrCreateFile(file)
if err != nil {
return err
}
defer func() {
err = targetFile.Close()
if err != nil {
log.Errorf("failed to close file %s: %v", file, err)
}
}()
// make it pretty
bs, err := json.MarshalIndent(obj, "", " ")
if err != nil {
return err
}
err = targetFile.Truncate(0)
if err != nil {
return err
}
_, err = targetFile.Write(bs)
if err != nil {
return err
}
return nil
}
func writeJson(file string, obj interface{}, configDir string, configFileName string) error {
// make it pretty
bs, err := json.MarshalIndent(obj, "", " ")
if err != nil {
return err
}
tempFile, err := os.CreateTemp(configDir, ".*"+configFileName)
if err != nil {
return err
}
tempFileName := tempFile.Name()
// closing file ops as windows doesn't allow to move it
err = tempFile.Close()
if err != nil {
return err
}
defer func() {
_, err = os.Stat(tempFileName)
if err == nil {
os.Remove(tempFileName)
}
}()
err = os.WriteFile(tempFileName, bs, 0600)
if err != nil {
return err
}
err = os.Rename(tempFileName, file)
if err != nil {
return err
}
return nil
}
func openOrCreateFile(file string) (*os.File, error) {
s, err := os.Stat(file)
if err == nil {
return os.OpenFile(file, os.O_WRONLY, s.Mode())
}
if !os.IsNotExist(err) {
return nil, err
}
targetFile, err := os.Create(file)
if err != nil {
return nil, err
}
//no:lint
err = targetFile.Chmod(0640)
if err != nil {
_ = targetFile.Close()
return nil, err
}
return targetFile, nil
}
// ReadJson reads JSON config file and maps to a provided interface
func ReadJson(file string, res interface{}) (interface{}, error) {
f, err := os.Open(file)
if err != nil {
return nil, err
}
defer f.Close()
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bs, err := io.ReadAll(f)
if err != nil {
return nil, err
}
err = json.Unmarshal(bs, &res)
if err != nil {
return nil, err
}
return res, nil
}
// ReadJsonWithEnvSub reads JSON config file and maps to a provided interface with environment variable substitution
func ReadJsonWithEnvSub(file string, res interface{}) (interface{}, error) {
envVars := getEnvMap()
f, err := os.Open(file)
if err != nil {
return nil, err
}
defer f.Close()
bs, err := io.ReadAll(f)
if err != nil {
return nil, err
}
t, err := template.New("").Parse(string(bs))
if err != nil {
return nil, fmt.Errorf("error parsing template: %v", err)
}
var output bytes.Buffer
// Execute the template, substituting environment variables
err = t.Execute(&output, envVars)
if err != nil {
return nil, fmt.Errorf("error executing template: %v", err)
}
err = json.Unmarshal(output.Bytes(), &res)
if err != nil {
return nil, fmt.Errorf("failed parsing Json file after template was executed, err: %v", err)
}
return res, nil
}
// getEnvMap Convert the output of os.Environ() to a map
func getEnvMap() map[string]string {
envMap := make(map[string]string)
for _, env := range os.Environ() {
parts := strings.SplitN(env, "=", 2)
if len(parts) == 2 {
envMap[parts[0]] = parts[1]
}
}
return envMap
}
// CopyFileContents copies contents of the given src file to the dst file
func CopyFileContents(src, dst string) (err error) {
in, err := os.Open(src)
if err != nil {
return
}
defer in.Close()
out, err := os.Create(dst)
if err != nil {
return
}
defer func() {
cErr := out.Close()
if err == nil {
err = cErr
}
}()
if _, err = io.Copy(out, in); err != nil {
return
}
err = out.Sync()
return
}
func prepareConfigFileDir(file string) (string, string, error) {
configDir, configFileName := filepath.Split(file)
if configDir == "" {
return filepath.Dir(file), configFileName, nil
}
err := os.MkdirAll(configDir, 0750)
if err != nil {
return "", "", err
}
return configDir, configFileName, err
}