lib/curl/Easy: add getter functions

src/lib/curl/Easy.hxx

@@ -30,6 +30,8 @@
 #ifndef CURL_EASY_HXX
 #define CURL_EASY_HXX
 
+#include "util/Compiler.h"
+
 #include <curl/curl.h>
 
 #include <utility>
@@ -160,6 +162,22 @@ public:
 		SetOption(CURLOPT_HTTPPOST, post);
 	}
 
+	template<typename T>
+	bool GetInfo(CURLINFO info, T value_r) const noexcept {
+		return ::curl_easy_getinfo(handle, info, value_r) == CURLE_OK;
+	}
+
+	/**
+	 * Returns the response body's size, or -1 if that is unknown.
+	 */
+	gcc_pure
+	int64_t GetContentLength() const noexcept {
+		double value;
+		return GetInfo(CURLINFO_CONTENT_LENGTH_DOWNLOAD, &value)
+			? (int64_t)value
+			: -1;
+	}
+
 	bool Unpause() noexcept {
 		return ::curl_easy_pause(handle, CURLPAUSE_CONT) == CURLE_OK;
 	}

src/lib/curl/Request.cxx

@@ -140,7 +140,7 @@ CurlRequest::FinishHeaders()
 	state = State::BODY;
 
 	long status = 0;
-	curl_easy_getinfo(easy.Get(), CURLINFO_RESPONSE_CODE, &status);
+	easy.GetInfo(CURLINFO_RESPONSE_CODE, &status);
 
 	handler.OnHeaders(status, std::move(headers));
 }