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//go:build !windows
package timezone
import (
"errors"
"fmt"
"io"
"io/fs"
"os"
"path/filepath"
"github.com/containers/storage/pkg/fileutils"
securejoin "github.com/cyphar/filepath-securejoin"
"github.com/sirupsen/logrus"
"golang.org/x/sys/unix"
)
// ConfigureContainerTimeZone configure the time zone for a container.
// It returns the path of the created /etc/localtime file if needed.
func ConfigureContainerTimeZone(timezone, containerRunDir, mountPoint, etcPath, containerID string) (localTimePath string, err error) {
var timezonePath string
switch timezone {
case "":
return "", nil
case "local":
timezonePath, err = filepath.EvalSymlinks("/etc/localtime")
if err != nil {
return "", fmt.Errorf("finding local timezone for container %s: %w", containerID, err)
}
default:
// Allow using TZDIR per:
// https://sourceware.org/git/?p=glibc.git;a=blob;f=time/tzfile.c;h=8a923d0cccc927a106dc3e3c641be310893bab4e;hb=HEAD#l149
zoneinfo := os.Getenv("TZDIR")
if zoneinfo == "" {
// default zoneinfo location
zoneinfo = "/usr/share/zoneinfo"
}
timezonePath = filepath.Join(zoneinfo, timezone)
}
etcFd, err := openDirectory(etcPath)
if err != nil {
return "", fmt.Errorf("open /etc in the container: %w", err)
}
defer unix.Close(etcFd)
// Make sure to remove any existing localtime file in the container to not create invalid links
err = unix.Unlinkat(etcFd, "localtime", 0)
if err != nil && !errors.Is(err, fs.ErrNotExist) {
return "", fmt.Errorf("removing /etc/localtime: %w", err)
}
hostPath, err := securejoin.SecureJoin(mountPoint, timezonePath)
if err != nil {
return "", fmt.Errorf("resolve zoneinfo path in the container: %w", err)
}
var localtimePath string
if err := fileutils.Exists(hostPath); err != nil {
// File does not exist, which means tzdata is not installed in the container.
// Create /etc/localtime as a copy from the host.
logrus.Debugf("Timezone %s does not exist in the container, create our own copy from the host", timezonePath)
localtimePath, err = copyTimezoneFile(containerRunDir, timezonePath)
if err != nil {
return "", fmt.Errorf("setting timezone for container %s: %w", containerID, err)
}
} else {
// File exists, let's create a symlink according to localtime(5)
logrus.Debugf("Create localtime symlink for %s", timezonePath)
err = unix.Symlinkat(".."+timezonePath, etcFd, "localtime")
if err != nil {
return "", fmt.Errorf("creating /etc/localtime symlink: %w", err)
}
}
return localtimePath, nil
}
// copyTimezoneFile copies the timezone file from the host to the container.
func copyTimezoneFile(containerRunDir, zonePath string) (string, error) {
localtimeCopy := filepath.Join(containerRunDir, "localtime")
file, err := os.Stat(zonePath)
if err != nil {
return "", err
}
if file.IsDir() {
return "", errors.New("invalid timezone: is a directory")
}
src, err := os.Open(zonePath)
if err != nil {
return "", err
}
defer src.Close()
dest, err := os.Create(localtimeCopy)
if err != nil {
return "", err
}
defer dest.Close()
_, err = io.Copy(dest, src)
if err != nil {
return "", err
}
return localtimeCopy, err
}
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