feat: ftp server support (#7634 close #1898)

* feat: ftp server support

* fix(ftp): incorrect mode for dirs in LIST returns

server/ftp/fsmanage.go

@@ -0,0 +1,75 @@
+package ftp
+
+import (
+	"context"
+	"github.com/alist-org/alist/v3/internal/errs"
+	"github.com/alist-org/alist/v3/internal/fs"
+	"github.com/alist-org/alist/v3/internal/model"
+	"github.com/alist-org/alist/v3/internal/op"
+	"github.com/alist-org/alist/v3/server/common"
+	"github.com/pkg/errors"
+	stdpath "path"
+)
+
+func Mkdir(ctx context.Context, path string) error {
+	user := ctx.Value("user").(*model.User)
+	reqPath, err := user.JoinPath(path)
+	if err != nil {
+		return err
+	}
+	if !user.CanWrite() || !user.CanFTPManage() {
+		meta, err := op.GetNearestMeta(stdpath.Dir(reqPath))
+		if err != nil {
+			if !errors.Is(errors.Cause(err), errs.MetaNotFound) {
+				return err
+			}
+		}
+		if !common.CanWrite(meta, reqPath) {
+			return errs.PermissionDenied
+		}
+	}
+	return fs.MakeDir(ctx, reqPath)
+}
+
+func Remove(ctx context.Context, path string) error {
+	user := ctx.Value("user").(*model.User)
+	if !user.CanRemove() || !user.CanFTPManage() {
+		return errs.PermissionDenied
+	}
+	reqPath, err := user.JoinPath(path)
+	if err != nil {
+		return err
+	}
+	return fs.Remove(ctx, reqPath)
+}
+
+func Rename(ctx context.Context, oldPath, newPath string) error {
+	user := ctx.Value("user").(*model.User)
+	srcPath, err := user.JoinPath(oldPath)
+	if err != nil {
+		return err
+	}
+	dstPath, err := user.JoinPath(newPath)
+	if err != nil {
+		return err
+	}
+	srcDir, srcBase := stdpath.Split(srcPath)
+	dstDir, dstBase := stdpath.Split(dstPath)
+	if srcDir == dstDir {
+		if !user.CanRename() || !user.CanFTPManage() {
+			return errs.PermissionDenied
+		}
+		return fs.Rename(ctx, srcPath, dstBase)
+	} else {
+		if !user.CanFTPManage() || !user.CanMove() || (srcBase != dstBase && !user.CanRename()) {
+			return errs.PermissionDenied
+		}
+		if err := fs.Move(ctx, srcPath, dstDir); err != nil {
+			return err
+		}
+		if srcBase != dstBase {
+			return fs.Rename(ctx, stdpath.Join(dstDir, srcBase), dstBase)
+		}
+		return nil
+	}
+}