simple https upload from c++ multi-plateform code using libcurl library

sketchab-cpp-libcurl

#include <stdio.h>
#include <string.h>

#include <curl/curl.h>

struct MemoryStruct {
    char *memory;
    size_t size;
};

static size_t
WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp)
{
    size_t realsize = size * nmemb;
    struct MemoryStruct *mem = (struct MemoryStruct *)userp;

    mem->memory = (char *)realloc(mem->memory, mem->size + realsize + 1);
    if (mem->memory == NULL) {
        /* out of memory! */
        printf("not enough memory (realloc returned NULL)\n");
        return 0;
    }

    memcpy(&(mem->memory[mem->size]), contents, realsize);
    mem->size += realsize;
    mem->memory[mem->size] = 0;

    return realsize;
}



int main(int argc, char *argv[])
{
    CURL *curl;
    CURLcode res;

    struct MemoryStruct chunk;

    chunk.memory = (char*)malloc(1);  /* will be grown as needed by the realloc above */
    chunk.size = 0;    /* no data at this point */


    struct curl_httppost *formpost = NULL;
    struct curl_httppost *lastptr = NULL;
    struct curl_slist *headerlist = NULL;
    static const char buf[] = "Expect:";

    curl_global_init(CURL_GLOBAL_ALL);

    /* Fill in the file upload field */
    curl_formadd(&formpost,
        &lastptr,
        CURLFORM_COPYNAME, "fileModel",
        CURLFORM_FILE, "f:\\tmp\\Dog_DemoHead.zip",
        CURLFORM_END);

    curl_formadd(&formpost,
        &lastptr,
        CURLFORM_COPYNAME, "fileNameModel",
        CURLFORM_COPYCONTENTS, "f:\\tmp\\Dog_DemoHead.zip",
        CURLFORM_END);

    curl_formadd(&formpost,
        &lastptr,
        CURLFORM_COPYNAME, "token",
        CURLFORM_COPYCONTENTS, "000000000000000000000000",
        CURLFORM_END);
    curl_formadd(&formpost,
        &lastptr,
        CURLFORM_COPYNAME, "title",
        CURLFORM_COPYCONTENTS, "My title",
        CURLFORM_END);

    curl_formadd(&formpost,
        &lastptr,
        CURLFORM_COPYNAME, "description",
        CURLFORM_COPYCONTENTS, "My description",
        CURLFORM_END);
        




    /* Fill in the submit field too, even if this is rarely needed */
    curl_formadd(&formpost,
        &lastptr,
        CURLFORM_COPYNAME, "submit",
        CURLFORM_COPYCONTENTS, "send",
        CURLFORM_END);

    curl = curl_easy_init();


    if (curl) {

        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, FALSE);

        /* send all data to this function  */
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);

        /* we pass our 'chunk' struct to the callback function */
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&chunk);

        /* some servers don't like requests that are made without a user-agent
        field, so we provide curl */
        curl_easy_setopt(curl, CURLOPT_USERAGENT, "my3dsoftware");

        /* initalize custom header list (stating that Expect: 100-continue is not
        wanted */
        headerlist = curl_slist_append(headerlist, buf);

        /* what URL that receives this POST */        
        //curl_easy_setopt(curl, CURLOPT_URL, "http://api.sketchfab.com/v1/models");
        curl_easy_setopt(curl, CURLOPT_URL, "https://api.sketchfab.com/v1/models");
    
        if ((argc == 2) && (!strcmp(argv[1], "noexpectheader")))
            /* only disable 100-continue header if explicitly requested */
            curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headerlist);
        curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost);

        /* Perform the request, res will get the return code */
        res = curl_easy_perform(curl);
        /* Check for errors */
        if (res != CURLE_OK){
            fprintf(stderr, "curl_easy_perform() failed: %s\n",
            curl_easy_strerror(res));
        }
        else {
           // printf("%lu bytes retrieved\n", (long)chunk.size);
            printf("%s\n", chunk.memory);
        }

        /* always cleanup */
        curl_easy_cleanup(curl);

        /* then cleanup the formpost chain */
        curl_formfree(formpost);
        /* free slist */
        curl_slist_free_all(headerlist);
    }
    return 0;
}