62 lines
1.3 KiB
Go
62 lines
1.3 KiB
Go
package chroot
|
|
|
|
import (
|
|
"errors"
|
|
"fmt"
|
|
"os"
|
|
"path/filepath"
|
|
"strings"
|
|
)
|
|
|
|
// AvailableDevice finds an available device and returns it. Note that
|
|
// you should externally hold a flock or something in order to guarantee
|
|
// that this device is available across processes.
|
|
func AvailableDevice() (string, error) {
|
|
prefix, err := devicePrefix()
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
|
|
letters := "fghijklmnop"
|
|
for _, letter := range letters {
|
|
for i := 1; i < 16; i++ {
|
|
device := fmt.Sprintf("/dev/%s%c%d", prefix, letter, i)
|
|
if _, err := os.Stat(device); err != nil {
|
|
return device, nil
|
|
}
|
|
}
|
|
}
|
|
|
|
return "", errors.New("available device could not be found")
|
|
}
|
|
|
|
// devicePrefix returns the prefix ("sd" or "xvd" or so on) of the devices
|
|
// on the system.
|
|
func devicePrefix() (string, error) {
|
|
available := []string{"sd", "xvd"}
|
|
|
|
f, err := os.Open("/sys/block")
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
defer f.Close()
|
|
|
|
dirs, err := f.Readdirnames(-1)
|
|
if dirs != nil && len(dirs) > 0 {
|
|
for _, dir := range dirs {
|
|
dirBase := filepath.Base(dir)
|
|
for _, prefix := range available {
|
|
if strings.HasPrefix(dirBase, prefix) {
|
|
return prefix, nil
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
|
|
return "", errors.New("device prefix could not be detected")
|
|
}
|