89 lines
2.0 KiB
Go
89 lines
2.0 KiB
Go
/*
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Copyright 2018 Google LLC
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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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"archive/tar"
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"github.com/sirupsen/logrus"
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"io"
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"os"
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"syscall"
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)
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var hardlinks = make(map[uint64]string)
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// AddToTar adds the file i to tar w at path p
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func AddToTar(p string, i os.FileInfo, w *tar.Writer) error {
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linkDst := ""
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if i.Mode()&os.ModeSymlink != 0 {
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var err error
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linkDst, err = os.Readlink(p)
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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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hdr, err := tar.FileInfoHeader(i, linkDst)
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if err != nil {
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return err
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}
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hdr.Name = p
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hardlink, linkDst := checkHardlink(p, i)
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if hardlink {
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hdr.Linkname = linkDst
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hdr.Typeflag = tar.TypeLink
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hdr.Size = 0
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}
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if err := w.WriteHeader(hdr); err != nil {
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return err
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}
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if !(i.Mode().IsRegular()) || hardlink {
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return nil
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}
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r, err := os.Open(p)
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if err != nil {
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return err
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}
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defer r.Close()
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if _, err := io.Copy(w, r); err != nil {
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return err
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}
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return nil
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}
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// Returns true if path is hardlink, and the link destination
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func checkHardlink(p string, i os.FileInfo) (bool, string) {
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hardlink := false
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linkDst := ""
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if sys := i.Sys(); sys != nil {
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if stat, ok := sys.(*syscall.Stat_t); ok {
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nlinks := stat.Nlink
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if nlinks > 1 {
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inode := stat.Ino
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if original, exists := hardlinks[inode]; exists && original != p {
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hardlink = true
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logrus.Debugf("%s inode exists in hardlinks map, linking to %s", p, original)
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linkDst = original
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} else {
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hardlinks[inode] = p
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}
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}
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}
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}
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return hardlink, linkDst
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}
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