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Merge pull request #195 from stealthrocket/tarfs-noname
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tarfs: do not store file names
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@achille-roussel
achille-roussel authored Aug 7, 2023
2 parents 99d88bc + a8329c0 commit 7fb6f96
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Showing 5 changed files with 31 additions and 38 deletions.
37 changes: 18 additions & 19 deletions internal/sandbox/tarfs/dir.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,6 @@ import (
)

type dir struct {
name string
ents []dirEntry
info sandbox.FileInfo
}
Expand All @@ -23,8 +22,8 @@ type dirEntry struct {
file fileEntry
}

func (d *dir) open(fsys *FileSystem) (sandbox.File, error) {
open := &openDir{fsys: fsys}
func (d *dir) open(fsys *FileSystem, name string) (sandbox.File, error) {
open := &openDir{fsys: fsys, name: name}
open.dir.Store(d)
return open, nil
}
Expand All @@ -37,15 +36,12 @@ func (d *dir) mode() fs.FileMode {
return d.info.Mode
}

func (d *dir) memsize() (size uintptr) {
size += unsafe.Sizeof(dir{})
size += uintptr(len(d.name))

func (d *dir) memsize() uintptr {
size := unsafe.Sizeof(dir{})
for _, ent := range d.ents {
size += unsafe.Sizeof(ent)
size += uintptr(len(ent.name))
}

return size
}

Expand All @@ -59,19 +55,22 @@ func (d *dir) find(name string) fileEntry {
return d.ents[i].file
}

func resolve[R any](fsys *FileSystem, cwd *dir, name string, flags int, do func(fileEntry) (R, error)) (R, error) {
func resolve[R any](fsys *FileSystem, cwd *dir, cwdName, name string, flags int, do func(fileEntry, []string) (R, error)) (R, error) {
var zero R
pathElems := make([]string, 1, 8)
pathElems[0] = cwdName

for loop := 0; loop < sandbox.MaxFollowSymlink; loop++ {
if name == "" {
return do(cwd)
return do(cwd, pathElems)
}

var elem string
elem, name = fspath.Walk(name)

if elem == "/" {
cwd = &fsys.root
pathElems = append(pathElems[:0], "/")
continue
}

Expand All @@ -80,6 +79,8 @@ func resolve[R any](fsys *FileSystem, cwd *dir, name string, flags int, do func(
return zero, sandbox.ENOENT
}

pathElems = append(pathElems, elem)

if name != "" {
switch c := f.(type) {
case *symlink:
Expand All @@ -105,7 +106,7 @@ func resolve[R any](fsys *FileSystem, cwd *dir, name string, flags int, do func(
}
}

return do(f)
return do(f, pathElems)
}

return zero, sandbox.ELOOP
Expand All @@ -114,17 +115,15 @@ func resolve[R any](fsys *FileSystem, cwd *dir, name string, flags int, do func(
type openDir struct {
readOnlyFile
fsys *FileSystem
name string
dir atomic.Pointer[dir]
mu sync.Mutex
index int
offset uint64
}

func (d *openDir) Name() string {
if dir := d.dir.Load(); dir != nil {
return dir.name
}
return ""
return d.name
}

func (d *openDir) Close() error {
Expand All @@ -151,11 +150,11 @@ func (d *openDir) Open(name string, flags int, mode fs.FileMode) (sandbox.File,
flags |= sandbox.O_DIRECTORY
}

return resolve(d.fsys, dir, name, flags, func(f fileEntry) (sandbox.File, error) {
return resolve(d.fsys, dir, d.name, name, flags, func(f fileEntry, pathElems []string) (sandbox.File, error) {
if _, ok := f.(*symlink); ok {
return nil, sandbox.ELOOP
}
return f.open(d.fsys)
return f.open(d.fsys, path.Join(pathElems...))
})
}

Expand All @@ -168,7 +167,7 @@ func (d *openDir) Stat(name string, flags int) (sandbox.FileInfo, error) {
if (flags & sandbox.AT_SYMLINK_NOFOLLOW) != 0 {
openFlags |= sandbox.O_NOFOLLOW
}
return resolve(d.fsys, dir, name, openFlags, func(f fileEntry) (sandbox.FileInfo, error) {
return resolve(d.fsys, dir, d.name, name, openFlags, func(f fileEntry, _ []string) (sandbox.FileInfo, error) {
return f.stat(), nil
})
}
Expand All @@ -178,7 +177,7 @@ func (d *openDir) Readlink(name string, buf []byte) (int, error) {
if dir == nil {
return 0, sandbox.EBADF
}
return resolve(d.fsys, dir, name, sandbox.O_NOFOLLOW, func(f fileEntry) (int, error) {
return resolve(d.fsys, dir, d.name, name, sandbox.O_NOFOLLOW, func(f fileEntry, _ []string) (int, error) {
if s, ok := f.(*symlink); ok {
return copy(buf, s.link), nil
} else {
Expand Down
13 changes: 5 additions & 8 deletions internal/sandbox/tarfs/file.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,13 +11,12 @@ import (
)

type file struct {
name string
info sandbox.FileInfo
offset int64
}

func (f *file) open(fsys *FileSystem) (sandbox.File, error) {
open := new(openFile)
func (f *file) open(fsys *FileSystem, name string) (sandbox.File, error) {
open := &openFile{name: name}
open.file.Store(f)
open.data = *io.NewSectionReader(fsys.data, f.offset, f.info.Size)
return open, nil
Expand All @@ -32,21 +31,19 @@ func (f *file) mode() fs.FileMode {
}

func (f *file) memsize() uintptr {
return unsafe.Sizeof(file{}) + uintptr(len(f.name))
return unsafe.Sizeof(file{})
}

type openFile struct {
leafFile
name string
file atomic.Pointer[file]
seek sync.Mutex
data io.SectionReader
}

func (f *openFile) Name() string {
if file := f.file.Load(); file != nil {
return file.name
}
return ""
return f.name
}

func (f *openFile) Close() error {
Expand Down
2 changes: 1 addition & 1 deletion internal/sandbox/tarfs/placeholder.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@ type placeholder struct {
info sandbox.FileInfo
}

func (p *placeholder) open(fsys *FileSystem) (sandbox.File, error) {
func (p *placeholder) open(fsys *FileSystem, name string) (sandbox.File, error) {
return nil, syscall.EPERM
}

Expand Down
5 changes: 2 additions & 3 deletions internal/sandbox/tarfs/symlink.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -8,12 +8,11 @@ import (
)

type symlink struct {
name string
link string
info sandbox.FileInfo
}

func (s *symlink) open(fsys *FileSystem) (sandbox.File, error) {
func (s *symlink) open(fsys *FileSystem, name string) (sandbox.File, error) {
return nil, sandbox.ELOOP
}

Expand All @@ -26,5 +25,5 @@ func (s *symlink) mode() fs.FileMode {
}

func (s *symlink) memsize() uintptr {
return unsafe.Sizeof(symlink{}) + uintptr(len(s.name)) + uintptr(len(s.link))
return unsafe.Sizeof(symlink{}) + uintptr(len(s.link))
}
12 changes: 5 additions & 7 deletions internal/sandbox/tarfs/tarfs.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,7 @@ type FileSystem struct {

// Open satisfies sandbox.FileSystem.
func (fsys *FileSystem) Open(name string, flags int, mode fs.FileMode) (sandbox.File, error) {
f, err := fsys.root.open(fsys)
f, err := fsys.root.open(fsys, "/")
if err != nil {
return nil, err
}
Expand Down Expand Up @@ -64,7 +64,6 @@ func Open(data io.ReaderAt, size int64) (*FileSystem, error) {
data: data,
size: size,
root: dir{
name: "/",
info: makeDirInfo(modTime),
},
}
Expand Down Expand Up @@ -93,11 +92,11 @@ func Open(data io.ReaderAt, size int64) (*FileSystem, error) {
switch header.Typeflag {
case tar.TypeReg:
offset, _ := section.Seek(0, io.SeekCurrent)
entry = &file{name: name, info: info, offset: offset}
entry = &file{info: info, offset: offset}
case tar.TypeDir:
entry = &dir{name: name, info: info}
entry = &dir{info: info}
case tar.TypeSymlink:
entry = &symlink{name: name, info: info, link: header.Linkname}
entry = &symlink{info: info, link: header.Linkname}
case tar.TypeLink:
if _, exists := links[name]; exists {
return nil, fmt.Errorf("%s: duplicate link entry in tar archive", name)
Expand Down Expand Up @@ -172,7 +171,7 @@ func OpenFile(f *os.File) (*FileSystem, error) {
}

type fileEntry interface {
open(fsys *FileSystem) (sandbox.File, error)
open(fsys *FileSystem, name string) (sandbox.File, error)

stat() sandbox.FileInfo

Expand Down Expand Up @@ -223,7 +222,6 @@ func makePath(files map[string]fileEntry, name string, modTime time.Time, file f
return err
}
d = &dir{
name: name,
info: makeDirInfo(modTime),
}
files[dirname] = d
Expand Down

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