curl/docs/examples/sftpget.c

/***************************************************************************
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 *
 * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, 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.
 *
 ***************************************************************************/
/* <DESC>
 * Gets a file using an SFTP URL.
 * </DESC>
 */

#include <stdio.h>

#include <curl/curl.h>

/* define this to switch off the use of ssh-agent in this program */
#undef DISABLE_SSH_AGENT

/*
 * This is an example showing how to get a single file from an SFTP server.
 * It delays the actual destination file creation until the first write
 * callback so that it won't create an empty file in case the remote file
 * doesn't exist or something else fails.
 */

struct FtpFile {
  const char *filename;
  FILE *stream;
};

static size_t my_fwrite(void *buffer, size_t size, size_t nmemb,
                        void *stream)
{
  struct FtpFile *out = (struct FtpFile *)stream;
  if(!out->stream) {
    /* open file for writing */
    out->stream = fopen(out->filename, "wb");
    if(!out->stream)
      return -1; /* failure, can't open file to write */
  }
  return fwrite(buffer, size, nmemb, out->stream);
}


int main(void)
{
  CURL *curl;
  CURLcode res;
  struct FtpFile ftpfile = {
    "yourfile.bin", /* name to store the file as if successful */
    NULL
  };

  curl_global_init(CURL_GLOBAL_DEFAULT);

  curl = curl_easy_init();
  if(curl) {
    /*
     * You better replace the URL with one that works!
     */
    curl_easy_setopt(curl, CURLOPT_URL,
                     "sftp://user@server/home/user/file.txt");
    /* Define our callback to get called when there's data to be written */
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, my_fwrite);
    /* Set a pointer to our struct to pass to the callback */
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &ftpfile);

#ifndef DISABLE_SSH_AGENT
    /* We activate ssh agent. For this to work you need
       to have ssh-agent running (type set | grep SSH_AGENT to check) or
       pageant on Windows (there is an icon in systray if so) */
    curl_easy_setopt(curl, CURLOPT_SSH_AUTH_TYPES, CURLSSH_AUTH_AGENT);
#endif

    /* Switch on full protocol/debug output */
    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);

    res = curl_easy_perform(curl);

    /* always cleanup */
    curl_easy_cleanup(curl);

    if(CURLE_OK != res) {
      /* we failed */
      fprintf(stderr, "curl told us %d\n", res);
    }
  }

  if(ftpfile.stream)
    fclose(ftpfile.stream); /* close the local file */

  curl_global_cleanup();

  return 0;
}