| // +build linux |
| |
| /* |
| Copyright 2018 The Kubernetes Authors. |
| |
| Licensed under the Apache License, Version 2.0 (the "License"); |
| you may not use this file except in compliance with the License. |
| You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, software |
| distributed under the License is distributed on an "AS IS" BASIS, |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| See the License for the specific language governing permissions and |
| limitations under the License. |
| */ |
| |
| package volumepathhandler |
| |
| import ( |
| "errors" |
| "fmt" |
| "os" |
| "os/exec" |
| "strings" |
| |
| "k8s.io/klog" |
| ) |
| |
| // AttachFileDevice takes a path to a regular file and makes it available as an |
| // attached block device. |
| func (v VolumePathHandler) AttachFileDevice(path string) (string, error) { |
| blockDevicePath, err := v.GetLoopDevice(path) |
| if err != nil && err.Error() != ErrDeviceNotFound { |
| return "", err |
| } |
| |
| // If no existing loop device for the path, create one |
| if blockDevicePath == "" { |
| klog.V(4).Infof("Creating device for path: %s", path) |
| blockDevicePath, err = makeLoopDevice(path) |
| if err != nil { |
| return "", err |
| } |
| } |
| return blockDevicePath, nil |
| } |
| |
| // GetLoopDevice returns the full path to the loop device associated with the given path. |
| func (v VolumePathHandler) GetLoopDevice(path string) (string, error) { |
| _, err := os.Stat(path) |
| if os.IsNotExist(err) { |
| return "", errors.New(ErrDeviceNotFound) |
| } |
| if err != nil { |
| return "", fmt.Errorf("not attachable: %v", err) |
| } |
| |
| args := []string{"-j", path} |
| cmd := exec.Command(losetupPath, args...) |
| out, err := cmd.CombinedOutput() |
| if err != nil { |
| klog.V(2).Infof("Failed device discover command for path %s: %v %s", path, err, out) |
| return "", err |
| } |
| return parseLosetupOutputForDevice(out) |
| } |
| |
| func makeLoopDevice(path string) (string, error) { |
| args := []string{"-f", "--show", path} |
| cmd := exec.Command(losetupPath, args...) |
| out, err := cmd.CombinedOutput() |
| if err != nil { |
| klog.V(2).Infof("Failed device create command for path: %s %v %s ", path, err, out) |
| return "", err |
| } |
| return parseLosetupOutputForDevice(out) |
| } |
| |
| // RemoveLoopDevice removes specified loopback device |
| func (v VolumePathHandler) RemoveLoopDevice(device string) error { |
| args := []string{"-d", device} |
| cmd := exec.Command(losetupPath, args...) |
| out, err := cmd.CombinedOutput() |
| if err != nil { |
| if _, err := os.Stat(device); os.IsNotExist(err) { |
| return nil |
| } |
| klog.V(2).Infof("Failed to remove loopback device: %s: %v %s", device, err, out) |
| return err |
| } |
| return nil |
| } |
| |
| func parseLosetupOutputForDevice(output []byte) (string, error) { |
| if len(output) == 0 { |
| return "", errors.New(ErrDeviceNotFound) |
| } |
| |
| // losetup returns device in the format: |
| // /dev/loop1: [0073]:148662 (/dev/sda) |
| device := strings.TrimSpace(strings.SplitN(string(output), ":", 2)[0]) |
| if len(device) == 0 { |
| return "", errors.New(ErrDeviceNotFound) |
| } |
| return device, nil |
| } |