mirror of
https://github.com/coreos/ignition.git
synced 2026-02-07 03:47:55 +01:00
79 lines
2.1 KiB
Go
79 lines
2.1 KiB
Go
// Copyright 2016 CoreOS, Inc.
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package util
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import (
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"fmt"
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"os"
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"path/filepath"
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"time"
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)
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const (
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deviceAliasDir = "/run/ignition/dev_aliases"
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retrySymlinkDelay = 10 * time.Millisecond
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retrySymlinkTimeout = 30 * time.Second
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retrySymlinkCount = int(retrySymlinkTimeout / retrySymlinkDelay)
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)
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// DeviceAlias returns the aliased form of the supplied path.
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// Note device paths in ignition are always absolute.
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func DeviceAlias(path string) string {
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return filepath.Join(deviceAliasDir, filepath.Clean(path))
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}
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// evalSymlinks wraps filepath.EvalSymlinks, retrying if it fails
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func evalSymlinks(path string) (res string, err error) {
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for i := 0; i < retrySymlinkCount; i++ {
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res, err = filepath.EvalSymlinks(path)
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if err == nil {
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return res, nil
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} else if os.IsNotExist(err) {
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time.Sleep(retrySymlinkDelay)
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} else {
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return "", err
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}
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}
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return "", fmt.Errorf("failed to evaluate symlink after %v: %v", retrySymlinkTimeout, err)
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}
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// CreateDeviceAlias creates a device alias for the supplied path.
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// On success the canonicalized path used as the alias target is returned.
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func CreateDeviceAlias(path string) (string, error) {
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target, err := evalSymlinks(path)
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if err != nil {
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return "", err
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}
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alias := DeviceAlias(path)
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if err := os.Remove(alias); err != nil {
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if !os.IsNotExist(err) {
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return "", err
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}
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if err = os.MkdirAll(filepath.Dir(alias), 0750); err != nil {
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return "", err
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}
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}
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if err = os.Symlink(target, alias); err != nil {
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return "", err
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}
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return target, nil
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}
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