ref: ed1ca142afcdc364ff7c9ec34f0405250c2c28c2
dir: /untar.go/
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// this was copied from golang.org/x/build/internal/untar
package main
import (
"archive/tar"
"compress/gzip"
"fmt"
"io"
"log"
"os"
"path"
"path/filepath"
"strings"
"time"
)
// TODO(bradfitz): this was copied from x/build/cmd/buildlet/buildlet.go
// but there were some buildlet-specific bits in there, so the code is
// forked for now. Unfork and add some opts arguments here, so the
// buildlet can use this code somehow.
// Untar reads the gzip-compressed tar file from r and writes it into dir.
func Untar(r io.Reader, dir string) error {
return untar(r, dir)
}
func untar(r io.Reader, dir string) (err error) {
t0 := time.Now()
nFiles := 0
madeDir := map[string]bool{}
defer func() {
td := time.Since(t0)
if err == nil {
log.Printf("extracted tarball into %s: %d files, %d dirs (%v)", dir, nFiles, len(madeDir), td)
} else {
log.Printf("error extracting tarball into %s after %d files, %d dirs, %v: %v", dir, nFiles, len(madeDir), td, err)
}
}()
zr, err := gzip.NewReader(r)
if err != nil {
return fmt.Errorf("requires gzip-compressed body: %v", err)
}
tr := tar.NewReader(zr)
loggedChtimesError := false
for {
f, err := tr.Next()
if err == io.EOF {
break
}
if err != nil {
log.Printf("tar reading error: %v", err)
return fmt.Errorf("tar error: %v", err)
}
if !validRelPath(f.Name) {
return fmt.Errorf("tar contained invalid name error %q", f.Name)
}
rel := filepath.FromSlash(f.Name)
abs := filepath.Join(dir, rel)
fi := f.FileInfo()
mode := fi.Mode()
switch {
case mode.IsRegular():
// Make the directory. This is redundant because it should
// already be made by a directory entry in the tar
// beforehand. Thus, don't check for errors; the next
// write will fail with the same error.
dir := filepath.Dir(abs)
if !madeDir[dir] {
if err := os.MkdirAll(filepath.Dir(abs), 0755); err != nil {
return err
}
madeDir[dir] = true
}
wf, err := os.OpenFile(abs, os.O_RDWR|os.O_CREATE|os.O_TRUNC, mode.Perm())
if err != nil {
return err
}
n, err := io.Copy(wf, tr)
if closeErr := wf.Close(); closeErr != nil && err == nil {
err = closeErr
}
if err != nil {
return fmt.Errorf("error writing to %s: %v", abs, err)
}
if n != f.Size {
return fmt.Errorf("only wrote %d bytes to %s; expected %d", n, abs, f.Size)
}
modTime := f.ModTime
if modTime.After(t0) {
// Clamp modtimes at system time. See
// golang.org/issue/19062 when clock on
// buildlet was behind the gitmirror server
// doing the git-archive.
modTime = t0
}
if !modTime.IsZero() {
if err := os.Chtimes(abs, modTime, modTime); err != nil && !loggedChtimesError {
// benign error. Gerrit doesn't even set the
// modtime in these, and we don't end up relying
// on it anywhere (the gomote push command relies
// on digests only), so this is a little pointless
// for now.
log.Printf("error changing modtime: %v (further Chtimes errors suppressed)", err)
loggedChtimesError = true // once is enough
}
}
nFiles++
case mode.IsDir():
if err := os.MkdirAll(abs, 0755); err != nil {
return err
}
madeDir[abs] = true
default:
return fmt.Errorf("tar file entry %s contained unsupported file type %v", f.Name, mode)
}
}
return nil
}
func validRelativeDir(dir string) bool {
if strings.Contains(dir, `\`) || path.IsAbs(dir) {
return false
}
dir = path.Clean(dir)
if strings.HasPrefix(dir, "../") || strings.HasSuffix(dir, "/..") || dir == ".." {
return false
}
return true
}
func validRelPath(p string) bool {
if p == "" || strings.Contains(p, `\`) || strings.HasPrefix(p, "/") || strings.Contains(p, "../") {
return false
}
return true
}