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Add zipfs, an archive/zip-based read-only filesystem
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hillu committed Nov 15, 2017
1 parent 8d919cb commit 3cdbe1e
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157 changes: 157 additions & 0 deletions zipfs/file.go
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package zipfs

import (
"archive/zip"
"io"
"os"
"path/filepath"
"syscall"

"github.com/spf13/afero"
)

type File struct {
fs *Fs
zipfile *zip.File
reader io.ReadCloser
offset int64
isdir, closed bool
buf []byte
}

func (f *File) fillBuffer(offset int64) (err error) {
if f.reader == nil {
if f.reader, err = f.zipfile.Open(); err != nil {
return
}
}
if offset > int64(f.zipfile.UncompressedSize64) {
offset = int64(f.zipfile.UncompressedSize64)
err = io.EOF
}
if len(f.buf) >= int(offset) {
return
}
buf := make([]byte, int(offset)-len(f.buf))
n, _ := io.ReadFull(f.reader, buf)
if n > 0 {
f.buf = append(f.buf, buf[:n]...)
}
return
}

func (f *File) Close() (err error) {
f.zipfile = nil
f.closed = true
f.buf = nil
if f.reader != nil {
err = f.reader.Close()
f.reader = nil
}
return
}

func (f *File) Read(p []byte) (n int, err error) {
if f.isdir {
return 0, syscall.EISDIR
}
if f.closed {
return 0, afero.ErrFileClosed
}
err = f.fillBuffer(f.offset + int64(len(p)))
n = copy(p, f.buf[f.offset:])
f.offset += int64(len(p))
return
}

func (f *File) ReadAt(p []byte, off int64) (n int, err error) {
if f.isdir {
return 0, syscall.EISDIR
}
if f.closed {
return 0, afero.ErrFileClosed
}
err = f.fillBuffer(off + int64(len(p)))
n = copy(p, f.buf[int(off):])
return
}

func (f *File) Seek(offset int64, whence int) (int64, error) {
if f.isdir {
return 0, syscall.EISDIR
}
if f.closed {
return 0, afero.ErrFileClosed
}
switch whence {
case os.SEEK_SET:
case os.SEEK_CUR:
offset += f.offset
case os.SEEK_END:
offset += int64(f.zipfile.UncompressedSize64)
default:
return 0, syscall.EINVAL
}
if offset < 0 || offset > int64(f.zipfile.UncompressedSize64) {
return 0, afero.ErrOutOfRange
}
f.offset = offset
return offset, nil
}

func (f *File) Write(p []byte) (n int, err error) { return 0, syscall.EPERM }

func (f *File) WriteAt(p []byte, off int64) (n int, err error) { return 0, syscall.EPERM }

func (f *File) Name() string { return f.zipfile.Name }

func (f *File) getDirEntries() (map[string]*zip.File, error) {
if !f.isdir {
return nil, syscall.ENOTDIR
}
name := "/"
if f.zipfile != nil {
name = filepath.Join(splitpath(f.zipfile.Name))
}
entries, ok := f.fs.files[name]
if !ok {
return nil, &os.PathError{Op: "readdir", Path: name, Err: syscall.ENOENT}
}
return entries, nil
}

func (f *File) Readdir(count int) (fi []os.FileInfo, err error) {
zipfiles, err := f.getDirEntries()
if err != nil {
return nil, err
}
for _, zipfile := range zipfiles {
fi = append(fi, zipfile.FileInfo())
if count >= 0 && len(fi) >= count {
break
}
}
return
}

func (f *File) Readdirnames(count int) (names []string, err error) {
zipfiles, err := f.getDirEntries()
if err != nil {
return nil, err
}
for filename, _ := range zipfiles {
names = append(names, filename)
if count >= 0 && len(names) >= count {
break
}
}
return
}

func (f *File) Stat() (os.FileInfo, error) { return f.zipfile.FileInfo(), nil }

func (f *File) Sync() error { return nil }

func (f *File) Truncate(size int64) error { return syscall.EPERM }

func (f *File) WriteString(s string) (ret int, err error) { return 0, syscall.EPERM }
111 changes: 111 additions & 0 deletions zipfs/fs.go
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@@ -0,0 +1,111 @@
package zipfs

import (
"archive/zip"
"os"
"path/filepath"
"syscall"
"time"

"github.com/spf13/afero"
)

type Fs struct {
r *zip.Reader
files map[string]map[string]*zip.File
}

func splitpath(name string) (dir, file string) {
name = filepath.ToSlash(name)
if len(name) == 0 || name[0] != '/' {
name = "/" + name
}
name = filepath.Clean(name)
dir, file = filepath.Split(name)
dir = filepath.Clean(dir)
return
}

func New(r *zip.Reader) afero.Fs {
fs := &Fs{r: r, files: make(map[string]map[string]*zip.File)}
for _, file := range r.File {
d, f := splitpath(file.Name)
if _, ok := fs.files[d]; !ok {
fs.files[d] = make(map[string]*zip.File)
}
if _, ok := fs.files[d][f]; !ok {
fs.files[d][f] = file
}
if file.FileInfo().IsDir() {
dirname := filepath.Join(d, f)
if _, ok := fs.files[dirname]; !ok {
fs.files[dirname] = make(map[string]*zip.File)
}
}
}
return fs
}

func (fs *Fs) Create(name string) (afero.File, error) { return nil, syscall.EPERM }

func (fs *Fs) Mkdir(name string, perm os.FileMode) error { return syscall.EPERM }

func (fs *Fs) MkdirAll(path string, perm os.FileMode) error { return syscall.EPERM }

func (fs *Fs) Open(name string) (afero.File, error) {
d, f := splitpath(name)
if f == "" {
return &File{fs: fs, isdir: true}, nil
}
if _, ok := fs.files[d]; !ok {
return nil, &os.PathError{Op: "stat", Path: name, Err: syscall.ENOENT}
}
file, ok := fs.files[d][f]
if !ok {
return nil, &os.PathError{Op: "stat", Path: name, Err: syscall.ENOENT}
}
return &File{fs: fs, zipfile: file, isdir: file.FileInfo().IsDir()}, nil
}

func (fs *Fs) OpenFile(name string, flag int, perm os.FileMode) (afero.File, error) {
if flag != os.O_RDONLY {
return nil, syscall.EPERM
}
return fs.Open(name)
}

func (fs *Fs) Remove(name string) error { return syscall.EPERM }

func (fs *Fs) RemoveAll(path string) error { return syscall.EPERM }

func (fs *Fs) Rename(oldname, newname string) error { return syscall.EPERM }

type pseudoRoot struct{}

func (p *pseudoRoot) Name() string { return "/" }
func (p *pseudoRoot) Size() int64 { return 0 }
func (p *pseudoRoot) Mode() os.FileMode { return os.ModeDir | os.ModePerm }
func (p *pseudoRoot) ModTime() time.Time { return time.Now() }
func (p *pseudoRoot) IsDir() bool { return true }
func (p *pseudoRoot) Sys() interface{} { return nil }

func (fs *Fs) Stat(name string) (os.FileInfo, error) {
d, f := splitpath(name)
if f == "" {
return &pseudoRoot{}, nil
}
if _, ok := fs.files[d]; !ok {
return nil, &os.PathError{Op: "stat", Path: name, Err: syscall.ENOENT}
}
file, ok := fs.files[d][f]
if !ok {
return nil, &os.PathError{Op: "stat", Path: name, Err: syscall.ENOENT}
}
return file.FileInfo(), nil
}

func (fs *Fs) Name() string { return "zipfs" }

func (fs *Fs) Chmod(name string, mode os.FileMode) error { return syscall.EPERM }

func (fs *Fs) Chtimes(name string, atime time.Time, mtime time.Time) error { return syscall.EPERM }
Binary file added zipfs/testdata/t.zip
Binary file not shown.
88 changes: 88 additions & 0 deletions zipfs/zipfs_test.go
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@@ -0,0 +1,88 @@
package zipfs

import (
"github.com/spf13/afero"

"archive/zip"
"path/filepath"
"reflect"
"testing"
)

func TestZipFS(t *testing.T) {
zrc, err := zip.OpenReader("testdata/t.zip")
if err != nil {
t.Fatal(err)
}
zfs := New(&zrc.Reader)
a := &afero.Afero{Fs: zfs}

buf, err := a.ReadFile("testFile")
if err != nil {
t.Error(err)
}
if len(buf) != 8192 {
t.Errorf("short read: %d != 8192", len(buf))
}

buf = make([]byte, 8)
f, err := a.Open("testFile")
if err != nil {
t.Error(err)
}
if n, err := f.ReadAt(buf, 4092); err != nil {
t.Error(err)
} else if n != 8 {
t.Errorf("expected to read 8 bytes, got %d", n)
} else if string(buf) != "aaaabbbb" {
t.Errorf("expected to get <aaaabbbb>, got <%s>", string(buf))
}

buf = make([]byte, 8192)
if n, err := f.Read(buf); err != nil {
t.Error(err)
} else if n != 8192 {
t.Errorf("expected to read 8192 bytes, got %d", n)
} else if buf[4095] != 'a' || buf[4096] != 'b' {
t.Error("got wrong contents")
}

for _, s := range []struct {
path string
dir bool
}{
{"testDir1", true},
{"testDir1/testFile", false},
{"testFile", false},
{"sub", true},
{"sub/testDir2", true},
{"sub/testDir2/testFile", false},
} {
if dir, _ := a.IsDir(s.path); dir == s.dir {
t.Logf("%s: directory check ok", s.path)
} else {
t.Errorf("%s: directory check NOT ok: %t, expected %t", s.path, dir, s.dir)
}
}

for _, s := range []struct {
glob string
entries []string
}{
{filepath.FromSlash("/*"), []string{filepath.FromSlash("/sub"), filepath.FromSlash("/testDir1"), filepath.FromSlash("/testFile")}},
{filepath.FromSlash("*"), []string{filepath.FromSlash("sub"), filepath.FromSlash("testDir1"), filepath.FromSlash("testFile")}},
{filepath.FromSlash("sub/*"), []string{filepath.FromSlash("sub/testDir2")}},
{filepath.FromSlash("sub/testDir2/*"), []string{filepath.FromSlash("sub/testDir2/testFile")}},
{filepath.FromSlash("testDir1/*"), []string{filepath.FromSlash("testDir1/testFile")}},
} {
entries, err := afero.Glob(zfs, s.glob)
if err != nil {
t.Error(err)
}
if reflect.DeepEqual(entries, s.entries) {
t.Logf("glob: %s: glob ok", s.glob)
} else {
t.Errorf("glob: %s: got %#v, expected %#v", s.glob, entries, s.entries)
}
}
}

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