fix：修正写入失败判断。

.vscode/settings.json

@@ -20,7 +20,7 @@
         ],
         "visualizerFile": "${workspaceRoot}/.vscode/qt5.natvis",
         "args": [
-            "-h"
+            "-n", "1"
         ]
     },
     "cmake.environment": {

client/client.cpp

@@ -476,11 +476,10 @@ void CClient::handle_frame(CFrameBuffer* buf)
             th_down_active_ = std::thread([&]() { judget_down_active(); });
         }
         down_->file_.write(buf->data_, buf->len_);
-        auto ws = down_->file_.gcount();
-        if (static_cast<int>(ws) != buf->len_) {
+        if (down_->file_.fail()) {
             logger_->warn("no matched write and data.");
         }
-        cur_down_size_ += ws;
+        cur_down_size_ += buf->len_;
         break;
     }
     case TYPE_OPEN_FILE: {