/
storage.go
237 lines (186 loc) · 3.96 KB
/
storage.go
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package memfs
import (
"errors"
"fmt"
"io"
"os"
"path/filepath"
"sync"
)
type storage struct {
files map[string]*file
children map[string]map[string]*file
}
func newStorage() *storage {
return &storage{
files: make(map[string]*file, 0),
children: make(map[string]map[string]*file, 0),
}
}
func (s *storage) Has(path string) bool {
path = clean(path)
_, ok := s.files[path]
return ok
}
func (s *storage) New(path string, mode os.FileMode, flag int) (*file, error) {
path = clean(path)
if s.Has(path) {
if !s.MustGet(path).mode.IsDir() {
return nil, fmt.Errorf("file already exists %q", path)
}
return nil, nil
}
name := filepath.Base(path)
f := &file{
name: name,
content: &content{name: name},
mode: mode,
flag: flag,
}
s.files[path] = f
s.createParent(path, mode, f)
return f, nil
}
func (s *storage) createParent(path string, mode os.FileMode, f *file) error {
base := filepath.Dir(path)
base = clean(base)
if f.Name() == string(separator) {
return nil
}
if _, err := s.New(base, mode.Perm()|os.ModeDir, 0); err != nil {
return err
}
if _, ok := s.children[base]; !ok {
s.children[base] = make(map[string]*file, 0)
}
s.children[base][f.Name()] = f
return nil
}
func (s *storage) Children(path string) []*file {
path = clean(path)
l := make([]*file, 0)
for _, f := range s.children[path] {
l = append(l, f)
}
return l
}
func (s *storage) MustGet(path string) *file {
f, ok := s.Get(path)
if !ok {
panic(fmt.Errorf("couldn't find %q", path))
}
return f
}
func (s *storage) Get(path string) (*file, bool) {
path = clean(path)
if !s.Has(path) {
return nil, false
}
file, ok := s.files[path]
return file, ok
}
func (s *storage) Rename(from, to string) error {
from = clean(from)
to = clean(to)
if !s.Has(from) {
return os.ErrNotExist
}
move := [][2]string{{from, to}}
for pathFrom := range s.files {
if pathFrom == from || !filepath.HasPrefix(pathFrom, from) {
continue
}
rel, _ := filepath.Rel(from, pathFrom)
pathTo := filepath.Join(to, rel)
move = append(move, [2]string{pathFrom, pathTo})
}
for _, ops := range move {
from := ops[0]
to := ops[1]
if err := s.move(from, to); err != nil {
return err
}
}
return nil
}
func (s *storage) move(from, to string) error {
s.files[to] = s.files[from]
s.files[to].name = filepath.Base(to)
s.children[to] = s.children[from]
defer func() {
delete(s.children, from)
delete(s.files, from)
delete(s.children[filepath.Dir(from)], filepath.Base(from))
}()
return s.createParent(to, 0644, s.files[to])
}
func (s *storage) Remove(path string) error {
path = clean(path)
f, has := s.Get(path)
if !has {
return os.ErrNotExist
}
if f.mode.IsDir() && len(s.children[path]) != 0 {
return fmt.Errorf("dir: %s contains files", path)
}
base, file := filepath.Split(path)
base = filepath.Clean(base)
delete(s.children[base], file)
delete(s.files, path)
return nil
}
func clean(path string) string {
return filepath.Clean(filepath.FromSlash(path))
}
type content struct {
name string
bytes []byte
m sync.RWMutex
}
func (c *content) WriteAt(p []byte, off int64) (int, error) {
if off < 0 {
return 0, &os.PathError{
Op: "writeat",
Path: c.name,
Err: errors.New("negative offset"),
}
}
c.m.Lock()
prev := len(c.bytes)
diff := int(off) - prev
if diff > 0 {
c.bytes = append(c.bytes, make([]byte, diff)...)
}
c.bytes = append(c.bytes[:off], p...)
if len(c.bytes) < prev {
c.bytes = c.bytes[:prev]
}
c.m.Unlock()
return len(p), nil
}
func (c *content) ReadAt(b []byte, off int64) (n int, err error) {
if off < 0 {
return 0, &os.PathError{
Op: "readat",
Path: c.name,
Err: errors.New("negative offset"),
}
}
c.m.RLock()
size := int64(len(c.bytes))
if off >= size {
c.m.RUnlock()
return 0, io.EOF
}
l := int64(len(b))
if off+l > size {
l = size - off
}
btr := c.bytes[off : off+l]
c.m.RUnlock()
if len(btr) < len(b) {
err = io.EOF
}
n = copy(b, btr)
return
}