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port unionFs from filters to filesystems

This commit is contained in:
Steve Francia 2016-01-11 16:07:40 -05:00
parent 84018f2b47
commit c6185187f1
4 changed files with 67 additions and 109 deletions
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102
union.go
View File

@ -7,63 +7,6 @@ import (
"syscall"
)
type UnionFs func(Fs) FilterFs
// Create a new UnionFs:
//
// ufs := NewUnionFs(baseFs, layerFs, NewCoWUnionFs())
// cfs := NewUnionFs(baseFs, layerFs, NewCacheUnionFs(cacheTime))
func NewUnionFs(base Fs, overlay Fs, impl UnionFs) Fs {
ufs := impl(overlay)
ufs.SetSource(base)
return ufs
}
func copyToLayer(base Fs, layer Fs, name string) error {
bfh, err := base.Open(name)
if err != nil {
return err
}
defer bfh.Close()
exists, err := Exists(layer, filepath.Dir(name))
if err != nil {
return err
}
if !exists {
err = layer.MkdirAll(filepath.Dir(name), 0777) // FIXME?
if err != nil {
return err
}
}
lfh, err := layer.Create(name)
if err != nil {
return err
}
n, err := io.Copy(lfh, bfh)
if err != nil {
layer.Remove(name)
lfh.Close()
return err
}
bfi, err := bfh.Stat()
if err != nil || bfi.Size() != n {
layer.Remove(name)
lfh.Close()
return syscall.EIO
}
err = lfh.Close()
if err != nil {
layer.Remove(name)
lfh.Close()
return err
}
return layer.Chtimes(name, bfi.ModTime(), bfi.ModTime())
}
// The UnionFile implements the afero.File interface and will be returned
// when reading a directory present at least in the overlay or opening a file
// for writing.
@ -278,3 +221,48 @@ func (f *UnionFile) WriteString(s string) (n int, err error) {
}
return 0, BADFD
}
func copyToLayer(base Fs, layer Fs, name string) error {
bfh, err := base.Open(name)
if err != nil {
return err
}
defer bfh.Close()
exists, err := Exists(layer, filepath.Dir(name))
if err != nil {
return err
}
if !exists {
err = layer.MkdirAll(filepath.Dir(name), 0777) // FIXME?
if err != nil {
return err
}
}
lfh, err := layer.Create(name)
if err != nil {
return err
}
n, err := io.Copy(lfh, bfh)
if err != nil {
layer.Remove(name)
lfh.Close()
return err
}
bfi, err := bfh.Stat()
if err != nil || bfi.Size() != n {
layer.Remove(name)
lfh.Close()
return syscall.EIO
}
err = lfh.Close()
if err != nil {
layer.Remove(name)
lfh.Close()
return err
}
return layer.Chtimes(name, bfi.ModTime(), bfi.ModTime())
}

15
union_cache.go
View File

@ -25,21 +25,6 @@ type CacheUnionFs struct {
cacheTime time.Duration
}
func NewCacheUnionFs(t time.Duration) UnionFs {
return func(layer Fs) FilterFs {
return &CacheUnionFs{cacheTime: t, layer: layer}
}
}
func (u *CacheUnionFs) AddFilter(fs FilterFs) {
fs.SetSource(u.base)
u.base = fs
}
func (u *CacheUnionFs) SetSource(fs Fs) {
u.base = fs
}
type cacheState int
const (

50
union_cow.go
View File

@ -6,7 +6,7 @@ import (
"time"
)
// The CoWUnionFs is a union filesystem: a read only base file system with
// The CopyOnWriteUnionFs is a union filesystem: a read only base file system with
// a possibly writeable layer on top. Changes to the file system will only
// be made in the overlay: Changing an existing file in the base layer which
// is not present in the overlay will copy the file to the overlay ("changing"
@ -17,28 +17,12 @@ import (
// can handle this).
//
// Reading directories is currently only supported via Open(), not OpenFile().
type CoWUnionFs struct {
type CopyOnWriteUnionFs struct {
base Fs
layer Fs
}
func NewCoWUnionFs() UnionFs {
// returns a function to have it the same as other implemtations
return func(layer Fs) FilterFs {
return &CoWUnionFs{layer: layer}
}
}
func (u *CoWUnionFs) AddFilter(fs FilterFs) {
fs.SetSource(u.base)
u.base = fs
}
func (u *CoWUnionFs) SetSource(fs Fs) {
u.base = fs
}
func (u *CoWUnionFs) isBaseFile(name string) (bool, error) {
func (u *CopyOnWriteUnionFs) isBaseFile(name string) (bool, error) {
if _, err := u.layer.Stat(name); err == nil {
return false, nil
}
@ -46,11 +30,11 @@ func (u *CoWUnionFs) isBaseFile(name string) (bool, error) {
return true, err
}
func (u *CoWUnionFs) copyToLayer(name string) error {
func (u *CopyOnWriteUnionFs) copyToLayer(name string) error {
return copyToLayer(u.base, u.layer, name)
}
func (u *CoWUnionFs) Chtimes(name string, atime, mtime time.Time) error {
func (u *CopyOnWriteUnionFs) Chtimes(name string, atime, mtime time.Time) error {
b, err := u.isBaseFile(name)
if err != nil {
return err
@ -63,7 +47,7 @@ func (u *CoWUnionFs) Chtimes(name string, atime, mtime time.Time) error {
return u.layer.Chtimes(name, atime, mtime)
}
func (u *CoWUnionFs) Chmod(name string, mode os.FileMode) error {
func (u *CopyOnWriteUnionFs) Chmod(name string, mode os.FileMode) error {
b, err := u.isBaseFile(name)
if err != nil {
return err
@ -76,7 +60,7 @@ func (u *CoWUnionFs) Chmod(name string, mode os.FileMode) error {
return u.layer.Chmod(name, mode)
}
func (u *CoWUnionFs) Stat(name string) (os.FileInfo, error) {
func (u *CopyOnWriteUnionFs) Stat(name string) (os.FileInfo, error) {
fi, err := u.layer.Stat(name)
switch err {
case nil:
@ -89,7 +73,7 @@ func (u *CoWUnionFs) Stat(name string) (os.FileInfo, error) {
}
// Renaming files present only in the base layer is not permitted
func (u *CoWUnionFs) Rename(oldname, newname string) error {
func (u *CopyOnWriteUnionFs) Rename(oldname, newname string) error {
b, err := u.isBaseFile(oldname)
if err != nil {
return err
@ -103,7 +87,7 @@ func (u *CoWUnionFs) Rename(oldname, newname string) error {
// Removing files present only in the base layer is not permitted. If
// a file is present in the base layer and the overlay, only the overlay
// will be removed.
func (u *CoWUnionFs) Remove(name string) error {
func (u *CopyOnWriteUnionFs) Remove(name string) error {
err := u.layer.Remove(name)
switch err {
case syscall.ENOENT:
@ -117,7 +101,7 @@ func (u *CoWUnionFs) Remove(name string) error {
}
}
func (u *CoWUnionFs) RemoveAll(name string) error {
func (u *CopyOnWriteUnionFs) RemoveAll(name string) error {
err := u.layer.RemoveAll(name)
switch err {
case syscall.ENOENT:
@ -131,7 +115,7 @@ func (u *CoWUnionFs) RemoveAll(name string) error {
}
}
func (u *CoWUnionFs) OpenFile(name string, flag int, perm os.FileMode) (File, error) {
func (u *CopyOnWriteUnionFs) OpenFile(name string, flag int, perm os.FileMode) (File, error) {
b, err := u.isBaseFile(name)
if err != nil {
return nil, err
@ -151,7 +135,7 @@ func (u *CoWUnionFs) OpenFile(name string, flag int, perm os.FileMode) (File, er
return u.layer.OpenFile(name, flag, perm)
}
func (u *CoWUnionFs) Open(name string) (File, error) {
func (u *CopyOnWriteUnionFs) Open(name string) (File, error) {
b, err := u.isBaseFile(name)
if err != nil {
return nil, err
@ -176,7 +160,7 @@ func (u *CoWUnionFs) Open(name string) (File, error) {
return &UnionFile{base: bfile, layer: lfile}, nil
}
func (u *CoWUnionFs) Mkdir(name string, perm os.FileMode) error {
func (u *CopyOnWriteUnionFs) Mkdir(name string, perm os.FileMode) error {
dir, err := IsDir(u.base, name)
if err != nil {
return u.layer.MkdirAll(name, perm)
@ -187,11 +171,11 @@ func (u *CoWUnionFs) Mkdir(name string, perm os.FileMode) error {
return u.layer.MkdirAll(name, perm)
}
func (u *CoWUnionFs) Name() string {
return "CoWUnionFs"
func (u *CopyOnWriteUnionFs) Name() string {
return "CopyOnWriteUnionFs"
}
func (u *CoWUnionFs) MkdirAll(name string, perm os.FileMode) error {
func (u *CopyOnWriteUnionFs) MkdirAll(name string, perm os.FileMode) error {
dir, err := IsDir(u.base, name)
if err != nil {
return u.layer.MkdirAll(name, perm)
@ -202,7 +186,7 @@ func (u *CoWUnionFs) MkdirAll(name string, perm os.FileMode) error {
return u.layer.MkdirAll(name, perm)
}
func (u *CoWUnionFs) Create(name string) (File, error) {
func (u *CopyOnWriteUnionFs) Create(name string) (File, error) {
b, err := u.isBaseFile(name)
if err == nil && b {
if err = u.copyToLayer(name); err != nil {

9
union_test.go
View File

@ -11,7 +11,7 @@ func TestUnionCreateExisting(t *testing.T) {
base := &MemMapFs{}
roBase := &ReadOnlyFs{source: base}
ufs := NewUnionFs(roBase, &MemMapFs{}, NewCoWUnionFs())
ufs := &CopyOnWriteUnionFs{base: roBase, layer: &MemMapFs{}}
base.MkdirAll("/home/test", 0777)
fh, _ := base.Create("/home/test/file.txt")
@ -61,7 +61,7 @@ func TestUnionMergeReaddir(t *testing.T) {
base := &MemMapFs{}
roBase := &ReadOnlyFs{source: base}
ufs := NewUnionFs(roBase, &MemMapFs{}, NewCoWUnionFs())
ufs := &CopyOnWriteUnionFs{base: roBase, layer: &MemMapFs{}}
base.MkdirAll("/home/test", 0777)
fh, _ := base.Create("/home/test/file.txt")
@ -85,7 +85,8 @@ func TestUnionMergeReaddir(t *testing.T) {
func TestUnionCacheWrite(t *testing.T) {
base := &MemMapFs{}
layer := &MemMapFs{}
ufs := NewUnionFs(base, layer, NewCacheUnionFs(0))
ufs := &CacheUnionFs{base: base, layer: layer, cacheTime: 0}
base.Mkdir("/data", 0777)
@ -114,7 +115,7 @@ func TestUnionCacheWrite(t *testing.T) {
func TestUnionCacheExpire(t *testing.T) {
base := &MemMapFs{}
layer := &MemMapFs{}
ufs := NewUnionFs(base, layer, NewCacheUnionFs(1*time.Second))
ufs := &CacheUnionFs{base: base, layer: layer, cacheTime: 1 * time.Second}
base.Mkdir("/data", 0777)