Source Code File 04-03_savememory.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>

/* memory buffer structure */
struct web_data {
    char *buffer;
    size_t size;
};

/* callback function */
static size_t write_mem(
    void *ptr,
    size_t size,
    size_t nmemb,
    void *userdata)
{
    size_t realsize;
    struct web_data *mem;

    realsize = size * nmemb;
    mem = (struct web_data *)userdata;

    mem->buffer = realloc(mem->buffer,
            mem->size + realsize + 1);
    if( mem->buffer==NULL )
    {
        fprintf(stderr,"Memory error\n");
        exit(1);
    }

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

    return(realsize);
}

int main()
{
    CURL *curl;
    CURLcode r;
    char address[] =
        "https://c-for-dummies.com/curl_test.txt";
    struct web_data page;

    /* initialize storage structure */
    page.buffer = malloc(1);
    if( page.buffer==NULL )
    {
        fprintf(stderr,"Memory error\n");
        exit(1);
    }
    page.size = 0;

    /* initialuze curl */
    curl = curl_easy_init();

    /* set options */
    curl_easy_setopt(curl,
            CURLOPT_URL,address);
    curl_easy_setopt(curl,
            CURLOPT_FOLLOWLOCATION,1L);
    curl_easy_setopt(curl,
            CURLOPT_WRITEFUNCTION,write_mem);
    curl_easy_setopt(curl,
            CURLOPT_WRITEDATA,(void *)&page);
    
    /* read the address */
    r = curl_easy_perform(curl);
    if( r != CURLE_OK )
    {
        fprintf(stderr,
                "curl read failed: %s\n",
                curl_easy_strerror(r));
        exit(1);
    }
    
    /* cleanup */
    curl_easy_cleanup(curl);

    /* output results */
    printf("Read %ld bytes:\n", page.size);
    printf("%s",page.buffer);

    return(0);
}
Notes

* Wide version of this code (statements not split)
← 04-02_savedata.c — 05-01_anonftp.c →