POST to Google App Engine Blobstore from CURL easy interface

postBlob.cpp

void postBlob(const std::string& uploadurl, const std::string& blobstring) {

    CURL *easyhandle;
    CURLcode res;

    easyhandle = curl_easy_init();
    if (!easyhandle) {
        throw std::runtime_error("Unable to init curl handle");
    }

    curl_easy_setopt(easyhandle, CURLOPT_URL, uploadurl.c_str());

    struct curl_httppost *post = NULL;
    struct curl_httppost *last = NULL; 

    curl_formadd(&post, 
                 &last, 
                 CURLFORM_PTRNAME, 
                 "formname",            // seems to be unimportant
                 CURLFORM_BUFFER,
                 "thefilename",         // the filename you see in the blobstore viewer
                 CURLFORM_BUFFERPTR,
                 blobstring.c_str(),
                 CURLFORM_BUFFERLENGTH,
                 blobstring.size(),
                 CURLFORM_CONTENTTYPE, 
                 "text/plain",          // set your MIME type 
                 CURLFORM_END);

    // Set the form info  
    curl_easy_setopt(easyhandle, CURLOPT_HTTPPOST, post);
    
    // do the post 
    res = curl_easy_perform(easyhandle); 
    curl_easy_getinfo(easyhandle, CURLINFO_RESPONSE_CODE, &responseCode_);

    // free the post data
    curl_formfree(post);

    if(!easyhandle || res != CURLE_OK) {
        std::err << "Error posting logs: " << curl_easy_strerror(res) << std::endl;
    }
}