feat(attach): 附件可配置限额、流式落盘与分阶段上传

管理端可配类型/体积；上传改流式避免整文件进内存；发帖先选再传并拦截未上传提交；提高 Next proxy 体积上限。 Co-authored-by: Cursor <cursoragent@cursor.com>
2026-09-17 07:33:16 +08:00
parent 6cc434f103
commit 61bf9fb48c
24 changed files with 2513 additions and 307 deletions
--- a/backend/service/post_file.go
+++ b/backend/service/post_file.go
@@ -4,37 +4,48 @@ import (
 	"crypto/rand"
 	"encoding/hex"
 	"errors"
-	"mime"
+	"fmt"
+	"io"
 	"os"
 	"path/filepath"
-	"strings"
 	"unicode/utf8"

 	"github.com/freefire/jiang13-bbs/model"
 	"gorm.io/gorm"
 )

+// 兼容旧引用：默认体积/个数（实际限额读 SettingService）
 const (
-	FileMaxBytes       = 20 << 20 // 20 MiB
+	FileMaxBytes       = 20 << 20 // 默认 20 MiB（缺省配置）
 	MaxPostAttachments = 10
 )

 var (
-	ErrAttachmentNotFound = errors.New("附件不存在")
+	ErrAttachmentNotFound  = errors.New("附件不存在")
 	ErrAttachmentForbidden = errors.New("无权操作此附件")
-	ErrTooManyAttachments = errors.New("附件数量超过上限")
+	ErrTooManyAttachments  = errors.New("附件数量超过上限")
+	ErrAttachmentExtDenied = errors.New("不支持该附件格式")
+	ErrAttachmentTooLarge  = errors.New("附件过大")
+	ErrAttachmentEmpty     = errors.New("文件为空")
 )

 // PostFileService 帖子文件附件（私有目录 + API 下载）
 type PostFileService struct {
-	db  *gorm.DB
-	dir string // data/private/files
+	db      *gorm.DB
+	dir     string // data/private/files
+	setting *SettingService
 }

 func NewPostFileService(db *gorm.DB, privateDir string) *PostFileService {
 	return &PostFileService{db: db, dir: filepath.Join(privateDir, "files")}
 }

+// WithSetting 注入站点设置（附件限额/扩展名）
+func (s *PostFileService) WithSetting(setting *SettingService) *PostFileService {
+	s.setting = setting
+	return s
+}
+
 func (s *PostFileService) EnsureDir() error {
 	return os.MkdirAll(s.dir, 0o755)
 }
@@ -43,13 +54,40 @@ func absPath(dir, stored string) string {
 	return filepath.Join(dir, stored)
 }

-// SaveDraftFile 上传附件（先挂 post_id=0，发帖时绑定）
-func (s *PostFileService) SaveDraftFile(userID uint, originalName string, data []byte, pricePoints int) (*model.PostAttachment, error) {
-	if len(data) == 0 {
-		return nil, errors.New("文件为空")
+func (s *PostFileService) maxBytes() int64 {
+	if s.setting == nil {
+		return FileMaxBytes
 	}
-	if len(data) > FileMaxBytes {
-		return nil, errors.New("附件不能超过 20MB")
+	n, err := s.setting.AttachmentMaxBytes()
+	if err != nil || n < 1 {
+		return FileMaxBytes
+	}
+	return n
+}
+
+func (s *PostFileService) maxCount() int {
+	if s.setting == nil {
+		return MaxPostAttachments
+	}
+	n, err := s.setting.AttachmentMaxCount()
+	if err != nil || n < 1 {
+		return MaxPostAttachments
+	}
+	return n
+}
+
+func (s *PostFileService) tooLargeErr() error {
+	mb := int(s.maxBytes() >> 20)
+	if mb < 1 {
+		mb = 1
+	}
+	return fmt.Errorf("%w：不能超过 %dMB", ErrAttachmentTooLarge, mb)
+}
+
+// SaveDraftFile 流式落盘附件（先挂 post_id=0，发帖时绑定）。整文件不进内存。
+func (s *PostFileService) SaveDraftFile(userID uint, originalName string, src io.Reader, pricePoints int) (*model.PostAttachment, error) {
+	if src == nil {
+		return nil, ErrAttachmentEmpty
 	}
 	if pricePoints < 0 {
 		pricePoints = 0
@@ -62,32 +100,63 @@ func (s *PostFileService) SaveDraftFile(userID uint, originalName string, data [
 		name = "file"
 	}

+	ext := ExtOfFilename(name)
+	if utf8.RuneCountInString(ext) > 16 {
+		ext = ""
+	}
+	if s.setting != nil {
+		ok, err := s.setting.AttachmentExtAllowed(ext)
+		if err != nil {
+			return nil, err
+		}
+		if !ok {
+			return nil, ErrAttachmentExtDenied
+		}
+	}
+
+	maxC := s.maxCount()
 	var orphan int64
 	if err := s.db.Model(&model.PostAttachment{}).
 		Where("user_id = ? AND post_id = 0", userID).Count(&orphan).Error; err != nil {
 		return nil, err
 	}
-	if orphan >= MaxPostAttachments {
+	if orphan >= int64(maxC) {
 		return nil, ErrTooManyAttachments
 	}

-	ext := filepath.Ext(name)
-	if utf8.RuneCountInString(ext) > 16 {
-		ext = ""
-	}
+	maxB := s.maxBytes()
 	raw := make([]byte, 16)
 	if _, err := rand.Read(raw); err != nil {
 		return nil, err
 	}
 	stored := hex.EncodeToString(raw) + ext
 	full := absPath(s.dir, stored)
-	if err := os.WriteFile(full, data, 0o600); err != nil {
+	tmp := full + ".partial"
+
+	f, err := os.OpenFile(tmp, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o600)
+	if err != nil {
 		return nil, err
 	}
+	// LimitReader 多读 1 字节以区分「刚好上限」与「超限」
+	written, copyErr := io.Copy(f, io.LimitReader(src, maxB+1))
+	_ = f.Close()
+	if copyErr != nil {
+		_ = os.Remove(tmp)
+		return nil, copyErr
+	}
+	if written == 0 {
+		_ = os.Remove(tmp)
+		return nil, ErrAttachmentEmpty
+	}
+	if written > maxB {
+		_ = os.Remove(tmp)
+		return nil, s.tooLargeErr()
+	}

-	mimeType := mime.TypeByExtension(ext)
-	if mimeType == "" {
-		mimeType = "application/octet-stream"
+	mimeType := ResolveAttachmentMIMEFile(ext, tmp)
+	if err := os.Rename(tmp, full); err != nil {
+		_ = os.Remove(tmp)
+		return nil, err
 	}

 	att := &model.PostAttachment{
@@ -96,7 +165,7 @@ func (s *PostFileService) SaveDraftFile(userID uint, originalName string, data [
 		Name:        name,
 		StoredName:  stored,
 		MIME:        mimeType,
-		Size:        len(data),
+		Size:        int(written),
 		PricePoints: pricePoints,
 	}
 	if err := s.db.Create(att).Error; err != nil {
@@ -106,30 +175,13 @@ func (s *PostFileService) SaveDraftFile(userID uint, originalName string, data [
 	return att, nil
 }

-func sanitizeFilename(name string) string {
-	name = filepath.Base(strings.ReplaceAll(name, "\\", "/"))
-	name = strings.TrimSpace(name)
-	name = strings.Map(func(r rune) rune {
-		switch r {
-		case '/', '\\', '\x00', ':', '*', '?', '"', '<', '>', '|':
-			return '_'
-		default:
-			return r
-		}
-	}, name)
-	if utf8.RuneCountInString(name) > 200 {
-		runes := []rune(name)
-		name = string(runes[:200])
-	}
-	return name
-}
-
 // BindToPost 将草稿附件绑定到帖子（仅本人、未绑定）
 func (s *PostFileService) BindToPost(userID, postID uint, ids []uint) error {
 	if len(ids) == 0 {
 		return nil
 	}
-	if len(ids) > MaxPostAttachments {
+	maxC := s.maxCount()
+	if len(ids) > maxC {
 		return ErrTooManyAttachments
 	}
 	return s.db.Transaction(func(tx *gorm.DB) error {
@@ -148,7 +200,8 @@ func (s *PostFileService) BindToPost(userID, postID uint, ids []uint) error {

 // ReplacePostAttachments 编辑时重绑附件列表（ids 为最终列表；可含已绑定本帖的）
 func (s *PostFileService) ReplacePostAttachments(userID, postID uint, ids []uint) error {
-	if len(ids) > MaxPostAttachments {
+	maxC := s.maxCount()
+	if len(ids) > maxC {
 		return ErrTooManyAttachments
 	}
 	return s.db.Transaction(func(tx *gorm.DB) error {
@@ -164,7 +217,6 @@ func (s *PostFileService) ReplacePostAttachments(userID, postID uint, ids []uint
 				return errors.New("部分附件无效或无权使用")
 			}
 		}
-		// 解绑本帖旧附件（软删物理文件可选：P1 仅解绑）
 		if err := tx.Model(&model.PostAttachment{}).
 			Where("post_id = ? AND user_id = ?", postID, userID).
 			Update("post_id", 0).Error; err != nil {
@@ -220,7 +272,7 @@ func (s *PostFileService) DeleteOwn(userID, attID uint) error {
 	return nil
 }

-// OpenForDownload 鉴权后打开文件；需先确认帖子可见与积分
+// Get 按 ID 取附件
 func (s *PostFileService) Get(attID uint) (*model.PostAttachment, error) {
 	var att model.PostAttachment
 	if err := s.db.First(&att, attID).Error; err != nil {
@@ -268,7 +320,6 @@ func (s *PostFileService) EnsureAttachmentUnlocked(userID uint, att *model.PostA
 		if _, err := DebitTx(tx, userID, att.PricePoints, model.PointReasonDownloadFile, "attachment", att.ID, "下载附件："+att.Name); err != nil {
 			return err
 		}
-		// 积分转给作者
 		if att.UserID > 0 && att.UserID != userID {
 			if _, err := CreditTx(tx, att.UserID, att.PricePoints, model.PointReasonDownloadFile, "attachment_earn", att.ID, "附件收益："+att.Name); err != nil {
 				return err