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/*
* Copyright (c) SAS Institute, Inc.
*
* 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 cpio
import (
"fmt"
"io"
"os"
"path"
"path/filepath"
"strings"
"github.com/sassoftware/go-rpmutils/fileutil"
)
// Standard set of permission bit masks.
const (
S_ISUID = 04000 // Set uid
S_ISGID = 02000 // Set gid
S_ISVTX = 01000 // Save text (sticky bit)
S_ISDIR = 040000 // Directory
S_ISFIFO = 010000 // FIFO
S_ISREG = 0100000 // Regular file
S_ISLNK = 0120000 // Symbolic link
S_ISBLK = 060000 // Block special file
S_ISCHR = 020000 // Character special file
S_ISSOCK = 0140000 // Socket
)
// Extract the contents of a cpio stream from r to the destination directory dest
func Extract(rs io.Reader, dest string) error {
dest = filepath.Clean(filepath.FromSlash(dest))
linkMap := make(map[int][]string)
stream := NewCpioStream(rs)
for {
entry, err := stream.ReadNextEntry()
if err != nil {
return err
}
if entry.Header.filename == TRAILER {
break
}
// sanitize path
target := path.Clean(entry.Header.filename)
for strings.HasPrefix(target, "../") {
target = target[3:]
}
target = filepath.Join(dest, filepath.FromSlash(target))
if !strings.HasPrefix(target, dest+string(filepath.Separator)) && dest != target {
// this shouldn't happen due to the sanitization above but always check
return fmt.Errorf("invalid cpio path %q", entry.Header.filename)
}
// Create the parent directory if it doesn't exist.
parent := filepath.Dir(target)
if err := os.MkdirAll(parent, 0755); err != nil {
return err
}
// FIXME: Need a makedev implementation in go.
switch entry.Header.Mode() &^ 07777 {
case S_ISCHR:
// FIXME: skipping due to lack of makedev.
continue
case S_ISBLK:
// FIXME: skipping due to lack of makedev.
continue
case S_ISDIR:
m := os.FileMode(entry.Header.Mode()).Perm()
if err := os.Mkdir(target, m); err != nil && !os.IsExist(err) {
return err
}
case S_ISFIFO:
if err := fileutil.Mkfifo(target, uint32(entry.Header.Mode())); err != nil {
return err
}
case S_ISLNK:
buf := make([]byte, entry.Header.filesize)
if _, err := entry.payload.Read(buf); err != nil {
return err
}
if err := os.Symlink(string(buf), target); err != nil {
return err
}
case S_ISREG:
// save hardlinks until after the taget is written
if entry.Header.nlink > 1 && entry.Header.filesize == 0 {
l, ok := linkMap[entry.Header.ino]
if !ok {
l = make([]string, 0)
}
l = append(l, target)
linkMap[entry.Header.ino] = l
continue
}
// FIXME: Set permissions on files when creating.
f, err := os.Create(target)
if err != nil {
return err
}
written, err := io.Copy(f, entry.payload)
if err != nil {
return err
}
if written != int64(entry.Header.filesize) {
return fmt.Errorf("short write")
}
if err := f.Close(); err != nil {
return err
}
// Create hardlinks after the file content is written.
if entry.Header.nlink > 1 && entry.Header.filesize > 0 {
l, ok := linkMap[entry.Header.ino]
if !ok {
return fmt.Errorf("hardlinks missing")
}
for _, t := range l {
if err := os.Link(target, t); err != nil {
return err
}
}
}
default:
return fmt.Errorf("unknown file mode 0%o for %s",
entry.Header.mode, entry.Header.filename)
}
}
return nil
}
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