pkg/cas/dir-store.go

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package cas
import (
"io"
"io/ioutil"
"os"
"path/filepath"
"sync"
)
// NewDirStore create a new store backed by the given directory.
func NewDir(path string) *DirStore {
return &DirStore{
path: path,
}
}
// DirStore is a Store backed by a directory.
type DirStore struct {
path string
mutex sync.Mutex
}
var _ Store = &DirStore{}
// GetOrCreate is part of the Store interface.
func (s *DirStore) GetOrCreate(tag, item string, create func(io.Writer) error) (content Content, meta Meta, err error) {
fullPath := filepath.Join(s.path, tag, item)
f, err := os.Open(fullPath)
if err != nil {
s.mutex.Lock()
defer s.mutex.Unlock()
f, err = os.Open(fullPath)
}
if err != nil {
if !os.IsNotExist(err) {
return
}
err = os.MkdirAll(filepath.Dir(fullPath), 0700)
if err != nil {
return
}
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partFile := fullPath + ".part"
os.Remove(partFile)
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var out *os.File
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out, err = os.OpenFile(partFile, os.O_CREATE|os.O_TRUNC|os.O_WRONLY|os.O_EXCL, 0600)
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if err != nil {
return
}
err = create(out)
out.Close()
if err != nil {
os.Remove(fullPath + ".part")
return
}
if err = os.Rename(fullPath+".part", fullPath); err != nil {
return
}
f, err = os.Open(fullPath)
if err != nil {
return
}
}
stat, err := os.Stat(fullPath)
if err != nil {
return
}
return f, stat, nil
}
// Tags is part of the Store interface.
func (s *DirStore) Tags() (tags []string, err error) {
entries, err := ioutil.ReadDir(s.path)
if err != nil {
if os.IsNotExist(err) {
return []string{}, nil
}
return
}
tags = make([]string, 0, len(entries))
for _, entry := range entries {
if !entry.IsDir() {
continue
}
name := entry.Name()
if name[0] == '.' {
continue
}
tags = append(tags, name)
}
return
}
// Remove is part of the Store interface.
func (s *DirStore) Remove(tag string) error {
return os.RemoveAll(filepath.Join(s.path, tag))
}