From a724006854f7364dbf305f84ee440d9664bb6307 Mon Sep 17 00:00:00 2001
From: tastytea <tastytea@tastytea.de>
Date: Wed, 8 Jan 2020 19:55:34 +0100
Subject: [PATCH] Make curl writer non-satatic and add static wrapper.

We need to use the mutex, a class member, from within the writer function.
---
 include/curl_wrapper.hpp | 27 ++++++++++++++++++--
 src/curl_wrapper.cpp     | 53 ++++++++++++++++++++++++++++------------
 2 files changed, 62 insertions(+), 18 deletions(-)

diff --git a/include/curl_wrapper.hpp b/include/curl_wrapper.hpp
index c7bd86e..ddc74fb 100644
--- a/include/curl_wrapper.hpp
+++ b/include/curl_wrapper.hpp
@@ -164,8 +164,31 @@ private:
      *
      *  @since  0.1.0
      */
-    static int writer(char *data, size_t size, size_t nmemb,
-                      string *writerData);
+    size_t writer_body(char *data, size_t size, size_t nmemb);
+
+    /*!
+     *  @brief  Wrapper for curl, because it can only call static member
+     *          functions.
+     *
+     *  <https://curl.haxx.se/docs/faq.html#Using_C_non_static_functions_f>
+     *
+     *  @since  0.1.0
+     */
+    static inline size_t writer_body_wrapper(char *data, size_t sz,
+                                             size_t nmemb, void *f)
+    {
+        return static_cast<CURLWrapper*>(f)->writer_body(data, sz, nmemb);
+    }
+
+    //! @copydoc writer_body
+    size_t writer_header(char *data, size_t size, size_t nmemb);
+
+    //! @copydoc writer_body_wrapper
+    static inline size_t writer_header_wrapper(char *data, size_t sz,
+                                               size_t nmemb, void *f)
+    {
+        return static_cast<CURLWrapper*>(f)->writer_header(data, sz, nmemb);
+    }
 
     /*!
      *  @brief  Setup libcurl connection.
diff --git a/src/curl_wrapper.cpp b/src/curl_wrapper.cpp
index cb047d9..b72e9e9 100644
--- a/src/curl_wrapper.cpp
+++ b/src/curl_wrapper.cpp
@@ -151,17 +151,28 @@ answer_type CURLWrapper::make_request(const http_method &method, string uri,
     return answer;
 }
 
-int CURLWrapper::writer(char *data, size_t size, size_t nmemb,
-                        string *writerData)
+size_t CURLWrapper::writer_body(char *data, size_t size, size_t nmemb)
 {
-    if(writerData == nullptr)
+    if(data == nullptr)
     {
         return 0;
     }
 
-    writerData->append(data, size*nmemb);
+    _curl_buffer_body.append(data, size * nmemb);
 
-    return static_cast<int>(size * nmemb);
+    return size * nmemb;
+}
+
+size_t CURLWrapper::writer_header(char *data, size_t size, size_t nmemb)
+{
+    if(data == nullptr)
+    {
+        return 0;
+    }
+
+    _curl_buffer_headers.append(data, size * nmemb);
+
+    return size * nmemb;
 }
 
 void CURLWrapper::setup_curl()
@@ -180,29 +191,39 @@ void CURLWrapper::setup_curl()
     }
 
     // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg)
-    code = curl_easy_setopt(_connection, CURLOPT_WRITEFUNCTION, writer);
+    code = curl_easy_setopt(_connection, CURLOPT_WRITEFUNCTION,
+                            writer_body_wrapper);
     if (code != CURLE_OK)
     {
-        throw CURLException{code, "Failed to set writer", _curl_buffer_error};
-    }
-
-    // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg)
-    code = curl_easy_setopt(_connection, CURLOPT_HEADERDATA,
-                            &_curl_buffer_headers);
-    if (code != CURLE_OK)
-    {
-        throw CURLException{code, "Failed to set header data",
+        throw CURLException{code, "Failed to set write function",
                 _curl_buffer_error};
     }
 
     // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg)
-    code = curl_easy_setopt(_connection, CURLOPT_WRITEDATA, &_curl_buffer_body);
+    code = curl_easy_setopt(_connection, CURLOPT_WRITEDATA, this);
     if (code != CURLE_OK)
     {
         throw CURLException{code, "Failed to set write data",
                 _curl_buffer_error};
     }
 
+    // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg)
+    code = curl_easy_setopt(_connection, CURLOPT_HEADERFUNCTION,
+                            writer_header_wrapper);
+    if (code != CURLE_OK)
+    {
+        throw CURLException{code, "Failed to set header function",
+                _curl_buffer_error};
+    }
+
+    // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg)
+    code = curl_easy_setopt(_connection, CURLOPT_HEADERDATA, this);
+    if (code != CURLE_OK)
+    {
+        throw CURLException{code, "Failed to set header data",
+                _curl_buffer_error};
+    }
+
     // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg)
     code = curl_easy_setopt(_connection, CURLOPT_USERAGENT,
                             (string("mastorss/") += version).c_str());