func setStat(user string, e trees.File, parent trees.Dir, nstat qp.Stat) error {
ostat, err := e.Stat()
if err != nil {
return err
}
length := false
name := false
mode := false
owner := false
if nstat.Type != ^uint16(0) && nstat.Type != ostat.Type {
return errors.New("it is illegal to modify type")
}
if nstat.Dev != ^uint32(0) && nstat.Dev != ostat.Dev {
return errors.New("it is illegal to modify dev")
}
if nstat.MUID != "" && nstat.MUID != ostat.MUID {
return errors.New("it is illegal to modify muid")
}
if nstat.Atime != ^uint32(0) && nstat.Atime != ostat.Atime {
return errors.New("it is illegal to modify atime")
}
if parent == nil && nstat.Name != "" && nstat.Name != ostat.Name {
return errors.New("it is illegal to rename root")
}
if nstat.Length != ^uint64(0) && nstat.Length != ostat.Length {
if ostat.Mode&qp.DMDIR != 0 {
return errors.New("cannot set length of directory")
}
if nstat.Length > ostat.Length {
return errors.New("cannot extend length")
}
length = true
}
if nstat.Name != "" && nstat.Name != ostat.Name {
name = true
}
if (nstat.UID != "" && nstat.UID != ostat.UID) || (nstat.GID != "" && nstat.GID != ostat.GID) {
owner = true
}
if nstat.Mode != ^qp.FileMode(0) && nstat.Mode != ostat.Mode {
mode = true
}
if nstat.Mtime != ^uint32(0) && nstat.Mtime != ostat.Mtime {
// We ignore mtime changes ATM. Only owner can change mtime.
}
if mode {
if err := e.SetMode(user, ostat.Mode&qp.DMDIR | nstat.Mode & ^qp.DMDIR); err != nil {
return err
}
}
if owner {
if err := e.SetOwner(user, nstat.UID, nstat.GID); err != nil {
e.SetMode(user, ostat.Mode)
return err
}
}
if name {
if err := parent.Rename(user, ostat.Name, nstat.Name); err != nil {
e.SetMode(user, ostat.Mode)
e.SetOwner(user, ostat.UID, ostat.GID)
return err
}
}
if length {
if err := e.SetLength(user, nstat.Length); err != nil {
e.SetMode(user, ostat.Mode)
e.SetOwner(user, ostat.UID, ostat.GID)
parent.Rename(user, nstat.Name, ostat.Name)
return err
}
}
return nil
}
