HTTPDownloader: Move to util project

src/util/http_downloader_curl.h

@@ -0,0 +1,41 @@
+// SPDX-FileCopyrightText: 2019-2023 Connor McLaughlin <stenzek@gmail.com>
+// SPDX-License-Identifier: (GPL-3.0 OR CC-BY-NC-ND-4.0)
+
+#pragma once
+#include "http_downloader.h"
+
+#include "common/thirdparty/thread_pool.h"
+
+#include <atomic>
+#include <curl/curl.h>
+#include <memory>
+#include <mutex>
+
+class HTTPDownloaderCurl final : public HTTPDownloader
+{
+public:
+  HTTPDownloaderCurl();
+  ~HTTPDownloaderCurl() override;
+
+  bool Initialize(const char* user_agent);
+
+protected:
+  Request* InternalCreateRequest() override;
+  void InternalPollRequests() override;
+  bool StartRequest(HTTPDownloader::Request* request) override;
+  void CloseRequest(HTTPDownloader::Request* request) override;
+
+private:
+  struct Request : HTTPDownloader::Request
+  {
+    CURL* handle = nullptr;
+    std::atomic_bool closed{false};
+  };
+
+  static size_t WriteCallback(char* ptr, size_t size, size_t nmemb, void* userdata);
+  void ProcessRequest(Request* req);
+
+  std::string m_user_agent;
+  std::unique_ptr<cb::ThreadPool> m_thread_pool;
+  std::mutex m_cancel_mutex;
+};