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snapdir.go
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snapdir.go
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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2014-2015 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package snapdir
import (
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"github.com/snapcore/snapd/osutil"
"github.com/snapcore/snapd/snap"
"github.com/snapcore/snapd/snap/internal"
)
func IsSnapDir(path string) bool {
if osutil.IsDirectory(path) {
if osutil.FileExists(filepath.Join(path, "meta", "snap.yaml")) {
return true
}
}
return false
}
// SnapDir is the snapdir based snap.
type SnapDir struct {
path string
}
// Path returns the path of the backing container.
func (s *SnapDir) Path() string {
return s.path
}
// New returns a new snap directory container.
func New(path string) *SnapDir {
return &SnapDir{path: path}
}
func (s *SnapDir) Size() (size int64, err error) {
totalSize := int64(0)
f := func(_ string, info os.FileInfo, err error) error {
totalSize += info.Size()
return err
}
filepath.Walk(s.path, f)
return totalSize, nil
}
func (s *SnapDir) Install(targetPath, mountDir string, opts *snap.InstallOptions) (bool, error) {
// TODO:UC20: support MustNotCrossDevices somehow here
return false, os.Symlink(s.path, targetPath)
}
func (s *SnapDir) RandomAccessFile(file string) (interface {
io.ReaderAt
io.Closer
Size() int64
}, error) {
f, err := os.Open(filepath.Join(s.path, file))
if err != nil {
return nil, err
}
return internal.NewSizedFile(f)
}
func (s *SnapDir) ReadFile(file string) (content []byte, err error) {
return ioutil.ReadFile(filepath.Join(s.path, file))
}
func littleWalk(dirPath string, dirHandle *os.File, dirstack *[]string, walkFn filepath.WalkFunc) error {
const numSt = 100
sts, err := dirHandle.Readdir(numSt)
if err != nil {
return err
}
for _, st := range sts {
path := filepath.Join(dirPath, st.Name())
if err := walkFn(path, st, nil); err != nil {
if st.IsDir() && err == filepath.SkipDir {
// caller wants to skip this directory
continue
}
return err
} else if st.IsDir() {
*dirstack = append(*dirstack, path)
}
}
return nil
}
// Walk (part of snap.Container) is like filepath.Walk, without the ordering guarantee.
func (s *SnapDir) Walk(relative string, walkFn filepath.WalkFunc) error {
relative = filepath.Clean(relative)
if relative == "" || relative == "/" {
relative = "."
} else if relative[0] == '/' {
// I said relative, darn it :-)
relative = relative[1:]
}
root := filepath.Join(s.path, relative)
// we could just filepath.Walk(root, walkFn), but that doesn't scale
// well to insanely big directories as it reads the whole directory,
// in order to sort it. This Walk doesn't do that.
//
// Also the directory is always relative to the top of the container
// for us, which would make it a little more messy to get right.
f, err := os.Open(root)
if err != nil {
return walkFn(relative, nil, err)
}
defer func() {
if f != nil {
f.Close()
}
}()
st, err := f.Stat()
if err != nil {
return walkFn(relative, nil, err)
}
err = walkFn(relative, st, nil)
if err != nil {
return err
}
if !st.IsDir() {
return nil
}
var dirstack []string
for {
if err := littleWalk(relative, f, &dirstack, walkFn); err != nil {
if err != io.EOF {
err = walkFn(relative, nil, err)
if err != nil {
return err
}
}
if len(dirstack) == 0 {
// finished
break
}
f.Close()
f = nil
for f == nil && len(dirstack) > 0 {
relative = dirstack[0]
f, err = os.Open(filepath.Join(s.path, relative))
if err != nil {
err = walkFn(relative, nil, err)
if err != nil {
return err
}
}
dirstack = dirstack[1:]
}
if f == nil {
break
}
continue
}
}
return nil
}
func (s *SnapDir) ListDir(path string) ([]string, error) {
fileInfos, err := ioutil.ReadDir(filepath.Join(s.path, path))
if err != nil {
return nil, err
}
var fileNames []string
for _, fileInfo := range fileInfos {
fileNames = append(fileNames, fileInfo.Name())
}
return fileNames, nil
}
func (s *SnapDir) Unpack(src, dstDir string) error {
return fmt.Errorf("unpack is not supported with snaps of type snapdir")
}