go-mtree/updatefuncs.go

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package mtree
import (
"fmt"
"os"
"strconv"
"strings"
"time"
"github.com/sirupsen/logrus"
"github.com/vbatts/go-mtree/pkg/govis"
)
// UpdateKeywordFunc is the signature for a function that will restore a file's
// attributes. Where path is relative path to the file, and value to be
// restored to.
type UpdateKeywordFunc func(path string, kv KeyVal) (os.FileInfo, error)
// UpdateKeywordFuncs is the registered list of functions to update file attributes.
// Keyed by the keyword as it would show up in the manifest
var UpdateKeywordFuncs = map[Keyword]UpdateKeywordFunc{
"mode": modeUpdateKeywordFunc,
"time": timeUpdateKeywordFunc,
"tar_time": tartimeUpdateKeywordFunc,
"uid": uidUpdateKeywordFunc,
"gid": gidUpdateKeywordFunc,
"xattr": xattrUpdateKeywordFunc,
"link": linkUpdateKeywordFunc,
}
func uidUpdateKeywordFunc(path string, kv KeyVal) (os.FileInfo, error) {
uid, err := strconv.Atoi(kv.Value())
if err != nil {
return nil, err
}
stat, err := os.Lstat(path)
if err != nil {
return nil, err
}
if statIsUID(stat, uid) {
return stat, nil
}
if err := os.Lchown(path, uid, -1); err != nil {
return nil, err
}
return os.Lstat(path)
}
func gidUpdateKeywordFunc(path string, kv KeyVal) (os.FileInfo, error) {
gid, err := strconv.Atoi(kv.Value())
if err != nil {
return nil, err
}
stat, err := os.Lstat(path)
if err != nil {
return nil, err
}
if statIsGID(stat, gid) {
return stat, nil
}
if err := os.Lchown(path, -1, gid); err != nil {
return nil, err
}
return os.Lstat(path)
}
func modeUpdateKeywordFunc(path string, kv KeyVal) (os.FileInfo, error) {
info, err := os.Lstat(path)
if err != nil {
return nil, err
}
// don't set mode on symlinks, as it passes through to the backing file
if info.Mode()&os.ModeSymlink != 0 {
return info, nil
}
vmode, err := strconv.ParseInt(kv.Value(), 8, 32)
if err != nil {
return nil, err
}
stat, err := os.Lstat(path)
if err != nil {
return nil, err
}
if stat.Mode() == os.FileMode(vmode) {
return stat, nil
}
logrus.Debugf("path: %q, kv.Value(): %q, vmode: %o", path, kv.Value(), vmode)
if err := os.Chmod(path, os.FileMode(vmode)); err != nil {
return nil, err
}
return os.Lstat(path)
}
// since tar_time will only be second level precision, then when restoring the
// filepath from a tar_time, then compare the seconds first and only Chtimes if
// the seconds value is different.
func tartimeUpdateKeywordFunc(path string, kv KeyVal) (os.FileInfo, error) {
info, err := os.Lstat(path)
if err != nil {
return nil, err
}
v := strings.SplitN(kv.Value(), ".", 2)
if len(v) != 2 {
return nil, fmt.Errorf("expected a number like 1469104727.000000000")
}
sec, err := strconv.ParseInt(v[0], 10, 64)
if err != nil {
return nil, fmt.Errorf("expected seconds, but got %q", v[0])
}
// if the seconds are the same, don't do anything, because the file might
// have nanosecond value, and if using tar_time it would zero it out.
if info.ModTime().Unix() == sec {
return info, nil
}
vtime := time.Unix(sec, 0)
// if times are same then don't modify anything
// comparing Unix, since it does not include Nano seconds
if info.ModTime().Unix() == vtime.Unix() {
return info, nil
}
// symlinks are strange and most of the time passes through to the backing file
if info.Mode()&os.ModeSymlink != 0 {
if err := lchtimes(path, vtime, vtime); err != nil {
return nil, err
}
} else if err := os.Chtimes(path, vtime, vtime); err != nil {
return nil, err
}
return os.Lstat(path)
}
// this is nano second precision
func timeUpdateKeywordFunc(path string, kv KeyVal) (os.FileInfo, error) {
info, err := os.Lstat(path)
if err != nil {
return nil, err
}
v := strings.SplitN(kv.Value(), ".", 2)
if len(v) != 2 {
return nil, fmt.Errorf("expected a number like 1469104727.871937272")
}
nsec, err := strconv.ParseInt(v[0]+v[1], 10, 64)
if err != nil {
return nil, fmt.Errorf("expected nano seconds, but got %q", v[0]+v[1])
}
logrus.Debugf("arg: %q; nsec: %d", v[0]+v[1], nsec)
vtime := time.Unix(0, nsec)
// if times are same then don't modify anything
if info.ModTime().Equal(vtime) {
return info, nil
}
// symlinks are strange and most of the time passes through to the backing file
if info.Mode()&os.ModeSymlink != 0 {
if err := lchtimes(path, vtime, vtime); err != nil {
return nil, err
}
} else if err := os.Chtimes(path, vtime, vtime); err != nil {
return nil, err
}
return os.Lstat(path)
}
func linkUpdateKeywordFunc(path string, kv KeyVal) (os.FileInfo, error) {
linkname, err := govis.Unvis(kv.Value(), DefaultVisFlags)
if err != nil {
return nil, err
}
got, err := os.Readlink(path)
if err != nil {
return nil, err
}
if got == linkname {
return os.Lstat(path)
}
logrus.Debugf("linkUpdateKeywordFunc: removing %q to link to %q", path, linkname)
if err := os.Remove(path); err != nil {
return nil, err
}
if err := os.Symlink(linkname, path); err != nil {
return nil, err
}
return os.Lstat(path)
}