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/*
* path.go - Utility functions for dealing with filesystem paths
*
* Copyright 2017 Google Inc.
* Author: Joe Richey (joerichey@google.com)
*
* 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 filesystem
import (
"fmt"
"log"
"os"
"path/filepath"
"golang.org/x/sys/unix"
"github.com/pkg/errors"
)
// OpenFileOverridingUmask calls os.OpenFile but with the umask overridden so
// that no permission bits are masked out if the file is created.
func OpenFileOverridingUmask(name string, flag int, perm os.FileMode) (*os.File, error) {
oldMask := unix.Umask(0)
defer unix.Umask(oldMask)
return os.OpenFile(name, flag, perm)
}
// We only check the unix permissions and the sticky bit
const permMask = os.ModeSticky | os.ModePerm
// canonicalizePath turns path into an absolute path without symlinks.
func canonicalizePath(path string) (string, error) {
path, err := filepath.Abs(path)
if err != nil {
return "", err
}
path, err = filepath.EvalSymlinks(path)
// Get a better error if we have an invalid path
if pathErr, ok := err.(*os.PathError); ok {
err = errors.Wrap(pathErr.Err, pathErr.Path)
}
return path, err
}
// loggedStat runs os.Stat, but it logs the error if stat returns any error
// other than nil or IsNotExist.
func loggedStat(name string) (os.FileInfo, error) {
info, err := os.Stat(name)
if err != nil && !os.IsNotExist(err) {
log.Print(err)
}
return info, err
}
// isDir returns true if the path exists and is that of a directory.
func isDir(path string) bool {
info, err := loggedStat(path)
return err == nil && info.IsDir()
}
// isDirCheckPerm returns true if the path exists and is a directory. If the
// specified permissions and sticky bit of mode do not match the path, an error
// is logged.
func isDirCheckPerm(path string, mode os.FileMode) bool {
info, err := loggedStat(path)
// Check if directory
if err != nil || !info.IsDir() {
return false
}
// Check for bad permissions
if info.Mode()&permMask != mode&permMask {
log.Printf("directory %s has incorrect permissions", path)
}
return true
}
// isRegularFile returns true if the path exists and is that of a regular file.
func isRegularFile(path string) bool {
info, err := loggedStat(path)
return err == nil && info.Mode().IsRegular()
}
// DeviceNumber represents a combined major:minor device number.
type DeviceNumber uint64
func (num DeviceNumber) String() string {
return fmt.Sprintf("%d:%d", unix.Major(uint64(num)), unix.Minor(uint64(num)))
}
func newDeviceNumberFromString(str string) (DeviceNumber, error) {
var major, minor uint32
if count, _ := fmt.Sscanf(str, "%d:%d", &major, &minor); count != 2 {
return 0, errors.Errorf("invalid device number string %q", str)
}
return DeviceNumber(unix.Mkdev(major, minor)), nil
}
// getDeviceNumber returns the device number of the device node at the given
// path. If there is a symlink at the path, it is dereferenced.
func getDeviceNumber(path string) (DeviceNumber, error) {
var stat unix.Stat_t
if err := unix.Stat(path, &stat); err != nil {
return 0, err
}
return DeviceNumber(stat.Rdev), nil
}
// getNumberOfContainingDevice returns the device number of the filesystem which
// contains the given file. If the file is a symlink, it is not dereferenced.
func getNumberOfContainingDevice(path string) (DeviceNumber, error) {
var stat unix.Stat_t
if err := unix.Lstat(path, &stat); err != nil {
return 0, err
}
return DeviceNumber(stat.Dev), nil
}
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