k3s/pkg/util/file.go

89 lines
1.9 KiB
Go

package util
import (
"context"
"os"
"os/user"
"path/filepath"
"strconv"
"strings"
"time"
"github.com/sirupsen/logrus"
"k8s.io/apimachinery/pkg/util/wait"
)
func SetFileModeForPath(name string, mode os.FileMode) error {
return os.Chmod(name, mode)
}
func SetFileGroupForPath(name string, group string) error {
// Try to use as group id
gid, err := strconv.Atoi(group)
if err == nil {
return os.Chown(name, -1, gid)
}
// Otherwise, it must be a group name
g, err := user.LookupGroup(group)
if err != nil {
return err
}
gid, err = strconv.Atoi(g.Gid)
if err != nil {
return err
}
return os.Chown(name, -1, gid)
}
func SetFileModeForFile(file *os.File, mode os.FileMode) error {
return file.Chmod(mode)
}
// ReadFile waits for a file to exist, then returns its trimmed contents as a string
func ReadFile(ctx context.Context, path string) (string, error) {
if path == "" {
return "", nil
}
var trimmed string
return trimmed, wait.PollUntilContextTimeout(ctx, 2*time.Second, 4*time.Minute, true, func(ctx context.Context) (bool, error) {
b, err := os.ReadFile(path)
if err == nil {
trimmed = strings.TrimSpace(string(b))
return true, nil
} else if os.IsNotExist(err) {
logrus.Infof("Waiting for file %q to be created\n", path)
return false, nil
}
return false, err
})
}
// AtomicWrite firsts writes data to a temp file, then renames to the destination file.
// This ensures that the destination file is never partially written.
func AtomicWrite(fileName string, data []byte, perm os.FileMode) error {
f, err := os.CreateTemp(filepath.Dir(fileName), filepath.Base(fileName)+".tmp")
if err != nil {
return err
}
tmpName := f.Name()
defer os.Remove(tmpName)
if _, err := f.Write(data); err != nil {
f.Close()
return err
}
if err := f.Chmod(perm); err != nil {
return err
}
if err := f.Sync(); err != nil {
return err
}
if err := f.Close(); err != nil {
return err
}
return os.Rename(tmpName, fileName)
}