360 lines
10 KiB
Go
360 lines
10 KiB
Go
package files
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import (
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"bytes"
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"context"
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"crypto/rand"
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"crypto/sha256"
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"encoding/hex"
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"fmt"
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"io"
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"os"
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"path/filepath"
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"strings"
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"sync"
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"time"
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"telesrv/internal/domain"
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)
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// BlobBackend 是 blob 字节内容的存储后端。第一阶段只有本地磁盘实现。
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// 内容寻址：Put 返回的 objectKey 是内容 sha256，相同内容自动去重。
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type BlobBackend interface {
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Name() string
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Put(ctx context.Context, data []byte) (objectKey string, err error)
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PutReader(ctx context.Context, r io.Reader) (objectKey string, size int64, sha256 []byte, err error)
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Get(ctx context.Context, objectKey string) ([]byte, error)
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// GetRange 只读 [offset, offset+limit) 段并返回该段字节与文件总大小（limit<=0 读到末尾），
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// 避免大文件每个 chunk 都整文件读入内存（getFile 按 chunk 多次请求 ⇒ 否则 O(N²) 放大）。
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GetRange(ctx context.Context, objectKey string, offset, limit int64) (data []byte, total int64, err error)
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}
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// UploadPartBackend 保存 upload.saveFilePart/saveBigFilePart 的临时分片字节。
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// 与正式 blob 不同，上传分片 key 唯一且可删除，成功组装/覆盖重传/GC 后必须清理。
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type UploadPartBackend interface {
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PutUploadPart(ctx context.Context, ownerUserID, fileID int64, part int, data []byte) (uploadPartObject, error)
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GetUploadPart(ctx context.Context, objectKey string) ([]byte, error)
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OpenUploadPart(ctx context.Context, objectKey string) (io.ReadCloser, error)
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DeleteUploadPart(ctx context.Context, objectKey string) error
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DeleteExpiredUploadParts(ctx context.Context, before time.Time, limit int) (int64, error)
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}
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type uploadPartObject struct {
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Backend domain.MediaBackend
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ObjectKey string
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Size int64
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SHA256 []byte
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}
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// LocalFS 把 blob 字节存到本地磁盘根目录下，路径按内容 hash 两级 fanout。
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type LocalFS struct {
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root string
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mu sync.Mutex
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openBlobFiles map[string]*sharedBlobFile
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}
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type sharedBlobFile struct {
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key string
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file *os.File
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refs int
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}
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// NewLocalFS 创建本地磁盘 blob backend，确保根目录存在。
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func NewLocalFS(root string) (*LocalFS, error) {
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if root == "" {
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return nil, fmt.Errorf("blob root dir is empty")
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}
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if err := os.MkdirAll(root, 0o755); err != nil {
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return nil, fmt.Errorf("create blob root %q: %w", root, err)
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}
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return &LocalFS{root: root, openBlobFiles: make(map[string]*sharedBlobFile)}, nil
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}
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// Name 返回后端标识，与 file_blobs.backend 一致。
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func (l *LocalFS) Name() string { return "localfs" }
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func (l *LocalFS) pathFor(objectKey string) string {
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if len(objectKey) < 4 {
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return filepath.Join(l.root, "_", objectKey)
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}
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return filepath.Join(l.root, objectKey[:2], objectKey[2:4], objectKey)
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}
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// Put 写入内容并返回 sha256 hex 作为 objectKey；同内容已存在则跳过写入（去重）。
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func (l *LocalFS) Put(ctx context.Context, data []byte) (string, error) {
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key, _, _, err := l.PutReader(ctx, bytes.NewReader(data))
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return key, err
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}
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// PutReader 流式写入内容，边复制边计算 sha256，避免上层为大视频先拼出完整 []byte。
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func (l *LocalFS) PutReader(ctx context.Context, r io.Reader) (string, int64, []byte, error) {
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tmpDir := filepath.Join(l.root, "_tmp")
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if err := os.MkdirAll(tmpDir, 0o755); err != nil {
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return "", 0, nil, fmt.Errorf("create blob tmp dir: %w", err)
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}
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tmp, err := os.CreateTemp(tmpDir, "blob-*.tmp")
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if err != nil {
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return "", 0, nil, fmt.Errorf("create blob tmp file: %w", err)
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}
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tmpPath := tmp.Name()
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committed := false
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defer func() {
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if !committed {
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_ = os.Remove(tmpPath)
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}
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}()
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h := sha256.New()
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size, err := copyWithContext(ctx, io.MultiWriter(tmp, h), r)
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closeErr := tmp.Close()
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if err != nil {
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return "", 0, nil, fmt.Errorf("write blob stream: %w", err)
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}
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if closeErr != nil {
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return "", 0, nil, fmt.Errorf("close blob stream: %w", closeErr)
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}
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sum := h.Sum(nil)
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key := hex.EncodeToString(sum)
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path := l.pathFor(key)
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if _, err := os.Stat(path); err == nil {
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committed = true
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_ = os.Remove(tmpPath)
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return key, size, append([]byte(nil), sum...), nil
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} else if err != nil && !os.IsNotExist(err) {
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return "", 0, nil, fmt.Errorf("stat blob: %w", err)
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}
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if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
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return "", 0, nil, fmt.Errorf("create blob dir: %w", err)
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}
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if err := os.Rename(tmpPath, path); err != nil {
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if _, statErr := os.Stat(path); statErr == nil {
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committed = true
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_ = os.Remove(tmpPath)
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return key, size, append([]byte(nil), sum...), nil
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}
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return "", 0, nil, fmt.Errorf("commit blob: %w", err)
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}
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committed = true
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return key, size, append([]byte(nil), sum...), nil
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}
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func copyWithContext(ctx context.Context, dst io.Writer, src io.Reader) (int64, error) {
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buf := make([]byte, 256<<10)
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var written int64
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for {
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select {
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case <-ctx.Done():
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return written, ctx.Err()
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default:
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}
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n, readErr := src.Read(buf)
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if n > 0 {
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w, writeErr := dst.Write(buf[:n])
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written += int64(w)
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if writeErr != nil {
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return written, writeErr
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}
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if w != n {
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return written, io.ErrShortWrite
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}
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}
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if readErr == io.EOF {
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return written, nil
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}
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if readErr != nil {
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return written, readErr
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}
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}
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}
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// Get 读取 objectKey 对应的全部字节。
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func (l *LocalFS) Get(_ context.Context, objectKey string) ([]byte, error) {
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return os.ReadFile(l.pathFor(objectKey))
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}
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// GetRange 用 ReadAt 只读 [offset, offset+limit) 段，total 取自文件大小；
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// n 受 total 约束，故即便客户端传超大 limit 也只分配文件实际大小，不会按客户端巨值分配。
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func (l *LocalFS) GetRange(_ context.Context, objectKey string, offset, limit int64) ([]byte, int64, error) {
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blobFile, err := l.openBlobFile(objectKey)
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if err != nil {
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return nil, 0, err
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}
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defer l.releaseBlobFile(blobFile)
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f := blobFile.file
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info, err := f.Stat()
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if err != nil {
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return nil, 0, err
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}
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total := info.Size()
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if offset < 0 {
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offset = 0
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}
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if offset >= total {
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return []byte{}, total, nil
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}
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n := total - offset
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if limit > 0 && limit < n {
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n = limit
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}
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buf := make([]byte, n)
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read, err := f.ReadAt(buf, offset)
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if err != nil && err != io.EOF {
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return nil, 0, err
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}
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return buf[:read], total, nil
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}
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func (l *LocalFS) openBlobFile(objectKey string) (*sharedBlobFile, error) {
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l.mu.Lock()
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defer l.mu.Unlock()
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if f, ok := l.openBlobFiles[objectKey]; ok {
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f.refs++
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return f, nil
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}
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f, err := os.Open(l.pathFor(objectKey))
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if err != nil {
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return nil, err
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}
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blobFile := &sharedBlobFile{
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key: objectKey,
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file: f,
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refs: 1,
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}
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l.openBlobFiles[objectKey] = blobFile
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return blobFile, nil
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}
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func (l *LocalFS) releaseBlobFile(blobFile *sharedBlobFile) {
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if blobFile == nil {
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return
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}
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l.mu.Lock()
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defer l.mu.Unlock()
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if blobFile.refs > 0 {
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blobFile.refs--
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}
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if blobFile.refs != 0 {
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return
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}
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if current := l.openBlobFiles[blobFile.key]; current == blobFile {
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delete(l.openBlobFiles, blobFile.key)
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}
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_ = blobFile.file.Close()
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}
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func (l *LocalFS) PutUploadPart(_ context.Context, ownerUserID, fileID int64, part int, data []byte) (uploadPartObject, error) {
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sum := sha256.Sum256(data)
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var nonce [16]byte
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if _, err := rand.Read(nonce[:]); err != nil {
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return uploadPartObject{}, fmt.Errorf("generate upload part key: %w", err)
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}
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key := filepath.ToSlash(filepath.Join(
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"upload_parts",
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fmt.Sprintf("%d", ownerUserID),
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fmt.Sprintf("%d", fileID),
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fmt.Sprintf("%06d-%s.part", part, hex.EncodeToString(nonce[:])),
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))
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path, err := l.uploadPartPath(key)
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if err != nil {
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return uploadPartObject{}, err
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}
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if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
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return uploadPartObject{}, fmt.Errorf("create upload part dir: %w", err)
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}
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tmp := path + ".tmp"
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if err := os.WriteFile(tmp, data, 0o644); err != nil {
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return uploadPartObject{}, fmt.Errorf("write upload part: %w", err)
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}
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if err := os.Rename(tmp, path); err != nil {
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_ = os.Remove(tmp)
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return uploadPartObject{}, fmt.Errorf("commit upload part: %w", err)
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}
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return uploadPartObject{
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Backend: domain.MediaBackend(l.Name()),
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ObjectKey: key,
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Size: int64(len(data)),
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SHA256: append([]byte(nil), sum[:]...),
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}, nil
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}
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func (l *LocalFS) GetUploadPart(_ context.Context, objectKey string) ([]byte, error) {
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path, err := l.uploadPartPath(objectKey)
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if err != nil {
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return nil, err
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}
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return os.ReadFile(path)
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}
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func (l *LocalFS) OpenUploadPart(_ context.Context, objectKey string) (io.ReadCloser, error) {
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path, err := l.uploadPartPath(objectKey)
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if err != nil {
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return nil, err
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}
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return os.Open(path)
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}
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func (l *LocalFS) DeleteUploadPart(_ context.Context, objectKey string) error {
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path, err := l.uploadPartPath(objectKey)
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if err != nil {
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return err
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}
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if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
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return fmt.Errorf("delete upload part: %w", err)
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}
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return nil
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}
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func (l *LocalFS) DeleteExpiredUploadParts(ctx context.Context, before time.Time, limit int) (int64, error) {
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if limit <= 0 {
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return 0, nil
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}
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root := filepath.Join(l.root, "upload_parts")
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if _, err := os.Stat(root); os.IsNotExist(err) {
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return 0, nil
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} else if err != nil {
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return 0, fmt.Errorf("stat upload parts root: %w", err)
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}
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var deleted int64
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err := filepath.WalkDir(root, func(path string, d os.DirEntry, err error) error {
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if err != nil {
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return err
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}
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if deleted >= int64(limit) {
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return filepath.SkipAll
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}
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select {
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case <-ctx.Done():
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return ctx.Err()
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default:
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}
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if d.IsDir() {
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return nil
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}
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info, err := d.Info()
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if err != nil {
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return err
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}
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if !info.ModTime().Before(before) {
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return nil
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}
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if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
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return err
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}
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deleted++
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return nil
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})
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if err != nil {
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return deleted, fmt.Errorf("delete expired upload part objects: %w", err)
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}
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return deleted, nil
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}
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func (l *LocalFS) uploadPartPath(objectKey string) (string, error) {
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clean := filepath.Clean(filepath.FromSlash(objectKey))
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prefix := "upload_parts" + string(os.PathSeparator)
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if clean == "." || clean == ".." || filepath.IsAbs(clean) || strings.HasPrefix(clean, ".."+string(os.PathSeparator)) || !strings.HasPrefix(clean, prefix) {
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return "", fmt.Errorf("invalid upload part object key %q", objectKey)
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}
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return filepath.Join(l.root, clean), nil
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}
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