curl上传和下载C语言实现

上传

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2021, Daniel Stenberg, , et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ***************************************************************************/
/* 
 * Upload to a file:// URL
 * 
 */
#include 
#include 
#include 
#include 
 
int main(void)
{
  CURL *curl;
  CURLcode res;
  struct stat file_info;
  curl_off_t speed_upload, total_time;
  FILE *fd;
 
  fd = fopen("debugit", "rb"); /* open file to upload */
  if(!fd)
    return 1; /* cannot continue */
 
  /* to get the file size */
  if(fstat(fileno(fd), &file_info) != 0)
    return 1; /* cannot continue */
 
  curl = curl_easy_init();
  if(curl) {
    /* upload to this place */
    curl_easy_setopt(curl, CURLOPT_URL,
                     "file:///home/dast/src/curl/debug/new");
 
    /* tell it to "upload" to the URL */
    curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
 
    /* set where to read from (on Windows you need to use READFUNCTION too) */
    curl_easy_setopt(curl, CURLOPT_READDATA, fd);
 
    /* and give the size of the upload (optional) */
    curl_easy_setopt(curl, CURLOPT_INFILESIZE_LARGE,
                     (curl_off_t)file_info.st_size);
 
    /* enable verbose for easier tracing */
    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
 
    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 {
      /* now extract transfer info */
      curl_easy_getinfo(curl, CURLINFO_SPEED_UPLOAD_T, &speed_upload);
      curl_easy_getinfo(curl, CURLINFO_TOTAL_TIME_T, &total_time);
 
      fprintf(stderr, "Speed: %lu bytes/sec during %lu.%06lu seconds\n",
              (unsigned long)speed_upload,
              (unsigned long)(total_time / 1000000),
              (unsigned long)(total_time % 1000000));
    }
    /* always cleanup */
    curl_easy_cleanup(curl);
  }
  fclose(fd);
  return 0;
}

下载

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2020, Daniel Stenberg, , et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ***************************************************************************/
/* 
 * Download a given URL into a local file named page.out.
 * 
 */
#include 
#include 
#include 
 
#include 
 
static size_t write_data(void *ptr, size_t size, size_t nmemb, void *stream)
{
  size_t written = fwrite(ptr, size, nmemb, (FILE *)stream);
  return written;
}
 
int main(int argc, char *argv[])
{
  CURL *curl_handle;
  static const char *pagefilename = "page.out";
  FILE *pagefile;
 
  if(argc < 2) {
    printf("Usage: %s \n", argv[0]);
    return 1;
  }
 
  curl_global_init(CURL_GLOBAL_ALL);
 
  /* init the curl session */
  curl_handle = curl_easy_init();
 
  /* set URL to get here */
  curl_easy_setopt(curl_handle, CURLOPT_URL, argv[1]);
 
  /* Switch on full protocol/debug output while testing */
  curl_easy_setopt(curl_handle, CURLOPT_VERBOSE, 1L);
 
  /* disable progress meter, set to 0L to enable it */
  curl_easy_setopt(curl_handle, CURLOPT_NOPROGRESS, 1L);
 
  /* send all data to this function  */
  curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, write_data);
 
  /* open the file */
  pagefile = fopen(pagefilename, "wb");
  if(pagefile) {
 
    /* write the page body to this file handle */
    curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, pagefile);
 
    /* get it! */
    curl_easy_perform(curl_handle);
 
    /* close the header file */
    fclose(pagefile);
  }
 
  /* cleanup curl stuff */
  curl_easy_cleanup(curl_handle);
 
  curl_global_cleanup();
 
  return 0;
}

https://curl.se/libcurl/c/fileupload.html
https://curl.se/libcurl/c/url2file.html