Simple libcurl example (uses autogenerated skeleton)

hackcurl.c

/********* Sample code generated by the curl command line tool **********
 * All curl_easy_setopt() options are documented at:
 * https://curl.se/libcurl/c/curl_easy_setopt.html
 ************************************************************************/

// Pick up Hackaday home page

#include <curl/curl.h>


/* add some custom helper functions */
#include <stdlib.h>  // new header
#include <string.h>  // new header

struct BUFFER
{
  size_t len;
  char *s;
};

struct BUFFER * init_buffer(struct BUFFER *b)
{
  b->len=0;
  b->s=malloc(1);
  if (!b->s) return NULL;
  b->s[0]='\0';
  return b;
}

size_t writefn(void *ptr, size_t size, size_t nmemb, struct BUFFER *b)
{
  size_t nblen=size*nmemb;
  size_t nlen=b->len+nblen;
  b->s=realloc(b->s,nlen+1);
  if (!b->s) return 0;
  memcpy(b->s+b->len,ptr,nblen);
  b->s[nlen]='\0';
  b->len=nlen;
  return nblen;
}
	 


/* back to boilerplate */



int main(int argc, char *argv[])
{
  CURLcode ret;
  CURL *hnd;

  struct BUFFER buff;  // new code
  if (!init_buffer(&buff))  // new code
    {
      fprintf(stderr,"Memory allocation error\n");
      return 98;
    }
  

  hnd = curl_easy_init();
  curl_easy_setopt(hnd, CURLOPT_BUFFERSIZE, 102400L);
  curl_easy_setopt(hnd, CURLOPT_URL, "http://www.hackaday.com");
  curl_easy_setopt(hnd, CURLOPT_USERAGENT, "curl/7.81.0");
  curl_easy_setopt(hnd, CURLOPT_FOLLOWLOCATION, 1L);
  curl_easy_setopt(hnd, CURLOPT_MAXREDIRS, 50L);
  curl_easy_setopt(hnd, CURLOPT_HTTP_VERSION, (long)CURL_HTTP_VERSION_2TLS);
  curl_easy_setopt(hnd, CURLOPT_FTP_SKIP_PASV_IP, 1L);
  curl_easy_setopt(hnd, CURLOPT_TCP_KEEPALIVE, 1L);

  /* Here is a list of options the curl code used that cannot get generated
     as source easily. You may choose to either not use them or implement
     them yourself.

  CURLOPT_WRITEDATA set to a objectpointer
  CURLOPT_INTERLEAVEDATA set to a objectpointer
  CURLOPT_WRITEFUNCTION set to a functionpointer
  CURLOPT_READDATA set to a objectpointer
  CURLOPT_READFUNCTION set to a functionpointer
  CURLOPT_SEEKDATA set to a objectpointer
  CURLOPT_SEEKFUNCTION set to a functionpointer
  CURLOPT_ERRORBUFFER set to a objectpointer
  CURLOPT_STDERR set to a objectpointer
  CURLOPT_HEADERFUNCTION set to a functionpointer
  CURLOPT_HEADERDATA set to a objectpointer

  */

  // custom code here
  curl_easy_setopt(hnd,CURLOPT_WRITEFUNCTION, writefn);
  curl_easy_setopt(hnd,CURLOPT_WRITEDATA,&buff);
  // back to template code

  ret = curl_easy_perform(hnd);
  /* Custom code here */
  if (ret!=CURLE_OK)
    {
      fprintf(stderr,"failure: %s\n",curl_easy_strerror(ret));
      free(buff.s);
      return 99;
    }

  // ok here we have buff containing it all:
  printf("%s\n",buff.s);
  // presumably you really want to write code to parse it now, right...
  
  /* End of custom code */

  curl_easy_cleanup(hnd);
  hnd = NULL;

  return (int)ret;
}
/**** End of sample code ****/