107 lines
2.2 KiB
Go
107 lines
2.2 KiB
Go
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package fstree
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import (
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"crypto/sha256"
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"encoding/hex"
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"errors"
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"io/ioutil"
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"os"
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"path"
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objectSDK "github.com/nspcc-dev/neofs-api-go/pkg/object"
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)
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// FSTree represents object storage as filesystem tree.
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type FSTree struct {
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Info
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Depth int
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DirNameLen int
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}
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// Info groups the information about file storage.
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type Info struct {
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// Permission bits of the root directory.
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Permissions os.FileMode
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// Full path to the root directory.
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RootPath string
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}
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const (
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// DirNameLen is how many bytes is used to group keys into directories.
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DirNameLen = 1 // in bytes
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// MaxDepth is maximum depth of nested directories.
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MaxDepth = (sha256.Size - 1) / DirNameLen
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)
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// ErrFileNotFound is returned when file is missing.
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var ErrFileNotFound = errors.New("file not found")
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func stringifyAddress(addr *objectSDK.Address) string {
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h := sha256.Sum256([]byte(addr.String()))
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return hex.EncodeToString(h[:])
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}
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func (t *FSTree) treePath(addr *objectSDK.Address) string {
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sAddr := stringifyAddress(addr)
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dirs := make([]string, 0, t.Depth+1+1) // 1 for root, 1 for file
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dirs = append(dirs, t.RootPath)
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for i := 0; i < t.Depth; i++ {
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dirs = append(dirs, sAddr[:t.DirNameLen])
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sAddr = sAddr[t.DirNameLen:]
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}
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dirs = append(dirs, sAddr)
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return path.Join(dirs...)
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}
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// Delete removes object with the specified address from storage.
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func (t *FSTree) Delete(addr *objectSDK.Address) error {
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p, err := t.Exists(addr)
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if err != nil {
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return err
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}
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return os.Remove(p)
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}
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// Exists returns path to file with object contents if it exists in storage
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// and an error otherwise.
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func (t *FSTree) Exists(addr *objectSDK.Address) (string, error) {
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p := t.treePath(addr)
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_, err := os.Stat(p)
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if os.IsNotExist(err) {
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err = ErrFileNotFound
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}
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return p, err
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}
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// Put puts object in storage.
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func (t *FSTree) Put(addr *objectSDK.Address, data []byte) error {
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p := t.treePath(addr)
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if err := os.MkdirAll(path.Dir(p), t.Permissions); err != nil {
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return err
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}
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return ioutil.WriteFile(p, data, t.Permissions)
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}
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// Get returns object from storage by address.
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func (t *FSTree) Get(addr *objectSDK.Address) ([]byte, error) {
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p := t.treePath(addr)
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if _, err := os.Stat(p); os.IsNotExist(err) {
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return nil, ErrFileNotFound
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}
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return ioutil.ReadFile(p)
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}
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