106 lines
2.8 KiB
Go
106 lines
2.8 KiB
Go
// +build linux
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/*
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Copyright 2017 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package util
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import (
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"errors"
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"fmt"
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"os"
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"os/exec"
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"strings"
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"github.com/golang/glog"
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)
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// AttachFileDevice takes a path to a regular file and makes it available as an
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// attached block device.
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func (v VolumePathHandler) AttachFileDevice(path string) (string, error) {
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blockDevicePath, err := v.GetLoopDevice(path)
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if err != nil && err.Error() != ErrDeviceNotFound {
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return "", err
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}
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// If no existing loop device for the path, create one
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if blockDevicePath == "" {
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glog.V(4).Infof("Creating device for path: %s", path)
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blockDevicePath, err = makeLoopDevice(path)
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if err != nil {
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return "", err
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}
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}
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return blockDevicePath, nil
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}
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// GetLoopDevice returns the full path to the loop device associated with the given path.
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func (v VolumePathHandler) GetLoopDevice(path string) (string, error) {
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_, err := os.Stat(path)
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if os.IsNotExist(err) {
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return "", errors.New(ErrNotAvailable)
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}
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if err != nil {
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return "", fmt.Errorf("not attachable: %v", err)
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}
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args := []string{"-j", path}
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cmd := exec.Command(losetupPath, args...)
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out, err := cmd.CombinedOutput()
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if err != nil {
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glog.V(2).Infof("Failed device discover command for path %s: %v", path, err)
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return "", err
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}
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return parseLosetupOutputForDevice(out)
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}
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func makeLoopDevice(path string) (string, error) {
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args := []string{"-f", "--show", path}
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cmd := exec.Command(losetupPath, args...)
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out, err := cmd.CombinedOutput()
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if err != nil {
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glog.V(2).Infof("Failed device create command for path %s: %v", path, err)
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return "", err
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}
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return parseLosetupOutputForDevice(out)
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}
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// RemoveLoopDevice removes specified loopback device
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func (v VolumePathHandler) RemoveLoopDevice(device string) error {
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args := []string{"-d", device}
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cmd := exec.Command(losetupPath, args...)
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out, err := cmd.CombinedOutput()
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if err != nil {
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if !strings.Contains(string(out), "No such device or address") {
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return err
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}
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}
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return nil
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}
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func parseLosetupOutputForDevice(output []byte) (string, error) {
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if len(output) == 0 {
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return "", errors.New(ErrDeviceNotFound)
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}
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// losetup returns device in the format:
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// /dev/loop1: [0073]:148662 (/dev/sda)
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device := strings.TrimSpace(strings.SplitN(string(output), ":", 2)[0])
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if len(device) == 0 {
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return "", errors.New(ErrDeviceNotFound)
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}
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return device, nil
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}
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