feat(fs): support skipping existing files in copy tasks

internal/conf/const.go

@@ -170,5 +170,6 @@ const (
 
 // ContextKey is the type of context keys.
 const (
-	NoTaskKey = "no_task"
+	NoTaskKey       = "no_task"
+	SkipExistingKey = "skip_existing"
 )

internal/fs/copy.go

@@ -28,6 +28,7 @@ type CopyTask struct {
 	dstStorage   driver.Driver `json:"-"`
 	SrcStorageMp string        `json:"src_storage_mp"`
 	DstStorageMp string        `json:"dst_storage_mp"`
+	SkipExisting bool          `json:"skip_existing"`
 }
 
 func (t *CopyTask) GetName() string {
@@ -69,8 +70,18 @@ func _copy(ctx context.Context, srcObjPath, dstDirPath string, lazyCache ...bool
 	if err != nil {
 		return nil, errors.WithMessage(err, "failed get dst storage")
 	}
+	skipExisting := ctx.Value(conf.SkipExistingKey) != nil
 	// copy if in the same storage, just call driver.Copy
 	if srcStorage.GetStorage() == dstStorage.GetStorage() {
+		if skipExisting {
+			if srcObj, err := op.Get(ctx, srcStorage, srcObjActualPath); err == nil && !srcObj.IsDir() {
+				dstFilePath := stdpath.Join(dstDirActualPath, srcObj.GetName())
+				if dstFile, err := op.Get(ctx, dstStorage, dstFilePath); err == nil &&
+					!dstFile.IsDir() && dstFile.GetSize() == srcObj.GetSize() {
+					return nil, nil
+				}
+			}
+		}
 		err = op.Copy(ctx, srcStorage, srcObjActualPath, dstDirActualPath, lazyCache...)
 		if !errors.Is(err, errs.NotImplement) && !errors.Is(err, errs.NotSupport) {
 			return nil, err
@@ -113,6 +124,7 @@ func _copy(ctx context.Context, srcObjPath, dstDirPath string, lazyCache ...bool
 		DstDirPath:   dstDirActualPath,
 		SrcStorageMp: srcStorage.GetStorage().MountPath,
 		DstStorageMp: dstStorage.GetStorage().MountPath,
+		SkipExisting: skipExisting,
 	}
 	CopyTaskManager.Add(t)
 	return t, nil
@@ -146,6 +158,7 @@ func copyBetween2Storages(t *CopyTask, srcStorage, dstStorage driver.Driver, src
 				DstDirPath:   dstObjPath,
 				SrcStorageMp: srcStorage.GetStorage().MountPath,
 				DstStorageMp: dstStorage.GetStorage().MountPath,
+				SkipExisting: t.SkipExisting,
 			})
 		}
 		t.Status = "src object is dir, added all copy tasks of objs"
@@ -160,6 +173,16 @@ func copyFileBetween2Storages(tsk *CopyTask, srcStorage, dstStorage driver.Drive
 		return errors.WithMessagef(err, "failed get src [%s] file", srcFilePath)
 	}
 	tsk.SetTotalBytes(srcFile.GetSize())
+	if tsk.SkipExisting {
+		dstFilePath := stdpath.Join(dstDirPath, srcFile.GetName())
+		// a failed probe falls through to a normal copy, worst case is a redundant transfer
+		if dstFile, err := op.Get(tsk.Ctx(), dstStorage, dstFilePath); err == nil &&
+			!dstFile.IsDir() && dstFile.GetSize() == srcFile.GetSize() {
+			tsk.Status = "skipped: destination file already exists"
+			tsk.SetProgress(100)
+			return nil
+		}
+	}
 	link, _, err := op.Link(tsk.Ctx(), srcStorage, srcFilePath, model.LinkArgs{
 		Header: http.Header{},
 	})

server/handles/fsmanage.go

@@ -1,12 +1,14 @@
 package handles
 
 import (
+	"context"
 	"fmt"
 	"io"
 	stdpath "path"
 
 	"github.com/alist-org/alist/v3/internal/task"
 
+	"github.com/alist-org/alist/v3/internal/conf"
 	"github.com/alist-org/alist/v3/internal/errs"
 	"github.com/alist-org/alist/v3/internal/fs"
 	"github.com/alist-org/alist/v3/internal/model"
@@ -66,6 +68,9 @@ type MoveCopyReq struct {
 	DstDir    string   `json:"dst_dir"`
 	Names     []string `json:"names"`
 	Overwrite bool     `json:"overwrite"`
+	// SkipExisting only takes effect on copy: existing destination files
+	// with the same size are skipped instead of failing the request
+	SkipExisting bool `json:"skip_existing"`
 }
 
 func FsMove(c *gin.Context) {
@@ -169,7 +174,7 @@ func FsCopy(c *gin.Context) {
 		common.ErrorResp(c, errs.PermissionDenied, 403)
 		return
 	}
-	if !req.Overwrite {
+	if !req.Overwrite && !req.SkipExisting {
 		for _, name := range req.Names {
 			dstPath, err := utils.JoinUnderBase(dstDir, name)
 			if err != nil {
@@ -182,6 +187,10 @@ func FsCopy(c *gin.Context) {
 			}
 		}
 	}
+	var ctx context.Context = c
+	if req.SkipExisting {
+		ctx = context.WithValue(ctx, conf.SkipExistingKey, struct{}{})
+	}
 	var addedTasks []task.TaskExtensionInfo
 	for i, name := range req.Names {
 		srcPath, err := utils.JoinUnderBase(srcDir, name)
@@ -194,7 +203,7 @@ func FsCopy(c *gin.Context) {
 			common.ErrorResp(c, err, 400)
 			return
 		}
-		t, err := fs.Copy(c, srcPath, dstDir, len(req.Names) > i+1)
+		t, err := fs.Copy(ctx, srcPath, dstDir, len(req.Names) > i+1)
 		if t != nil {
 			addedTasks = append(addedTasks, t)
 		}