C++: Download a file using HTTP GET and store in in a std::string

download.cpp

/**
 * HTTPDownloader.hpp
 *
 * A simple C++ wrapper for the libcurl easy API.
 *
 * Written by Uli Köhler (techoverflow.net)
 * Published under CC0 1.0 Universal (public domain)
 */
#ifndef HTTPDOWNLOADER_HPP
#define HTTPDOWNLOADER_HPP

#include <string>
#include <curl/curl.h>
#include <curl/easy.h>
#include <curl/curlbuild.h>
#include <sstream>
#include <iostream>
/**
 * A non-threadsafe simple libcURL-easy based HTTP downloader
 */
class HTTPDownloader {
public:
    HTTPDownloader();
    ~HTTPDownloader();
    /**
     * Download a file using HTTP GET and store in in a std::string
     * @param url The URL to download
     * @return The download result
     */
    std::string download(const std::string& url);
private:
    void* curl;
};

#endif  /* HTTPDOWNLOADER_HPP */

/**
 * HTTPDownloader.cpp
 *
 * A simple C++ wrapper for the libcurl easy API.
 *
 * Written by Uli Köhler (techoverflow.net)
 * Published under CC0 1.0 Universal (public domain)
 */
#include "Downloader.hpp"

using namespace std;

size_t write_data(void *ptr, size_t size, size_t nmemb, void *stream) {
    string data((const char*) ptr, (size_t) size * nmemb);
    *((stringstream*) stream) << data << endl;
    return size * nmemb;
}

HTTPDownloader::HTTPDownloader() {
    curl = curl_easy_init();
}

HTTPDownloader::~HTTPDownloader() {
    curl_easy_cleanup(curl);
}

string HTTPDownloader::download(const std::string& url) {
    curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
    /* we tell libcurl to follow redirection */
    curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
    curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1); //Prevent "longjmp causes uninitialized stack frame" bug
    curl_easy_setopt(curl, CURLOPT_ACCEPT_ENCODING, "deflate");
    std::stringstream out;
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &out);
    /* Perform the request, res will get the return code */
    CURLcode res = curl_easy_perform(curl);
    /* Check for errors */
    if (res != CURLE_OK) {
        fprintf(stderr, "curl_easy_perform() failed: %s\n",
                curl_easy_strerror(res));
    }
    return out.str();
}