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device.go
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device.go
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// Copyright 2017-2018 the u-root Authors. All rights reserved
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package diskboot
import (
"fmt"
"io/ioutil"
"path/filepath"
"strings"
"github.com/u-root/u-root/pkg/mount"
"golang.org/x/sys/unix"
)
// Device contains the path to a block filesystem along with its type
type Device struct {
DevPath string
MountPath string
Fstype string
Configs []*Config
}
// fstypes returns all block file system supported by the linuxboot kernel
func fstypes() (fstypes []string, err error) {
var bytes []byte
if bytes, err = ioutil.ReadFile("/proc/filesystems"); err != nil {
return nil, fmt.Errorf("Failed to read /proc/filesystems: %v", err)
}
for _, line := range strings.Split(string(bytes), "\n") {
if fields := strings.Fields(line); len(fields) == 1 {
fstypes = append(fstypes, fields[0])
}
}
return fstypes, nil
}
// FindDevices searches for devices with bootable configs
func FindDevices(devicesGlob string) (devices []*Device) {
fstypes, err := fstypes()
if err != nil {
return nil
}
sysList, err := filepath.Glob(devicesGlob)
if err != nil {
return nil
}
// The Linux /sys file system is a bit, er, awkward. You can't find
// the device special in there; just everything else.
for _, sys := range sysList {
blk := filepath.Join("/dev", filepath.Base(sys))
dev, _ := mountDevice(blk, fstypes)
if dev != nil && len(dev.Configs) > 0 {
devices = append(devices, dev)
}
}
return devices
}
// FindDevice attempts to construct a boot device at the given path
func FindDevice(devPath string) (*Device, error) {
fstypes, err := fstypes()
if err != nil {
return nil, nil
}
return mountDevice(devPath, fstypes)
}
func mountDevice(devPath string, fstypes []string) (*Device, error) {
mountPath, err := ioutil.TempDir("/tmp", "boot-")
if err != nil {
return nil, fmt.Errorf("Failed to create tmp mount directory: %v", err)
}
for _, fstype := range fstypes {
if err := mount.Mount(devPath, mountPath, fstype, "", unix.MS_RDONLY); err != nil {
continue
}
configs := FindConfigs(mountPath)
if len(configs) == 0 {
continue
}
return &Device{devPath, mountPath, fstype, configs}, nil
}
return nil, fmt.Errorf("Failed to find a valid boot device with configs")
}