refactor: implement safe_relative_path utility for secure file handling

app/api/routers/cell_data.py

@@ -12,6 +12,7 @@ from app.api.routers.task_runtime import set_task_stage
 from app.config import AppConfig, CACHE_DIR
 from app.processor import ProcessLogger
 from app.services.cell_data import CellDataProcessor, refresh_cell_data
+from app.utils.files import safe_relative_path
 
 router = APIRouter(tags=["cell-data"])
 
@@ -72,7 +73,7 @@ async def upload_and_start_cell_data_processing(files: list[UploadFile] = File(.
     for file in files:
         if not file.filename:
             continue
-        target = upload_dir / file.filename.replace("\\", "/")
+        target = upload_dir / safe_relative_path(file.filename)
         target.parent.mkdir(parents=True, exist_ok=True)
         target.write_bytes(await file.read())
         saved_count += 1

app/api/routers/upload.py

@@ -5,6 +5,7 @@ from fastapi import APIRouter, File, HTTPException, UploadFile
 
 from app import state
 from app.config import CACHE_DIR
+from app.utils.files import safe_relative_path
 
 
 router = APIRouter(tags=["upload"])
@@ -70,12 +71,14 @@ async def upload_files(
             if not file.filename:
                 continue
 
-            file_path = work_dir / file.filename
+            relative_path = safe_relative_path(file.filename)
+            file_path = work_dir / relative_path
             file_path.parent.mkdir(parents=True, exist_ok=True)
             file_path.write_bytes(await file.read())
 
-            saved_files.append(file.filename)
+            saved_name = str(relative_path).replace("\\", "/")
-            session["files"].append(file.filename)
+            saved_files.append(saved_name)
+            session["files"].append(saved_name)
 
         record = state.history_manager.get(session_id)
         if record:
@@ -107,4 +110,3 @@ async def complete_upload_session(session_id: str):
     state.history_manager.update(session_id, file_count=len(session["files"]))
 
     return {"success": True, "session_id": session_id, "total_files": len(session["files"])}
-

app/utils/files.py

@@ -1,6 +1,17 @@
 from pathlib import Path
 
 
+def safe_relative_path(value: str, fallback: str = "upload.bin") -> Path:
+    parts = [
+        part
+        for part in str(value or "").replace("\\", "/").split("/")
+        if part and part not in {".", ".."}
+    ]
+    if not parts:
+        parts = [fallback]
+    return Path(*parts)
+
+
 def remove_file_safely(path: Path) -> None:
     try:
         path.unlink()