1/***************************************************************************
2 *                                  _   _ ____  _
3 *  Project                     ___| | | |  _ \| |
4 *                             / __| | | | |_) | |
5 *                            | (__| |_| |  _ <| |___
6 *                             \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
9 *
10 * This software is licensed as described in the file COPYING, which
11 * you should have received as part of this distribution. The terms
12 * are also available at https://curl.se/docs/copyright.html.
13 *
14 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
15 * copies of the Software, and permit persons to whom the Software is
16 * furnished to do so, under the terms of the COPYING file.
17 *
18 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19 * KIND, either express or implied.
20 *
21 * SPDX-License-Identifier: curl
22 *
23 ***************************************************************************/
24/* <DESC>
25 * Upload to SFTP, resuming a previously aborted transfer.
26 * </DESC>
27 */
28
29#include <stdlib.h>
30#include <stdio.h>
31#include <curl/curl.h>
32
33/* read data to upload */
34static size_t readfunc(char *ptr, size_t size, size_t nmemb, void *stream)
35{
36  FILE *f = (FILE *)stream;
37  size_t n;
38
39  if(ferror(f))
40    return CURL_READFUNC_ABORT;
41
42  n = fread(ptr, size, nmemb, f) * size;
43
44  return n;
45}
46
47/*
48 * sftpGetRemoteFileSize returns the remote file size in byte; -1 on error
49 */
50static curl_off_t sftpGetRemoteFileSize(const char *i_remoteFile)
51{
52  CURLcode result = CURLE_GOT_NOTHING;
53  curl_off_t remoteFileSizeByte = -1;
54  CURL *curlHandlePtr = curl_easy_init();
55
56  curl_easy_setopt(curlHandlePtr, CURLOPT_VERBOSE, 1L);
57
58  curl_easy_setopt(curlHandlePtr, CURLOPT_URL, i_remoteFile);
59  curl_easy_setopt(curlHandlePtr, CURLOPT_NOPROGRESS, 1);
60  curl_easy_setopt(curlHandlePtr, CURLOPT_NOBODY, 1);
61  curl_easy_setopt(curlHandlePtr, CURLOPT_HEADER, 1);
62  curl_easy_setopt(curlHandlePtr, CURLOPT_FILETIME, 1);
63
64  result = curl_easy_perform(curlHandlePtr);
65  if(CURLE_OK == result) {
66    result = curl_easy_getinfo(curlHandlePtr,
67                               CURLINFO_CONTENT_LENGTH_DOWNLOAD_T,
68                               &remoteFileSizeByte);
69    if(result)
70      return -1;
71    printf("filesize: %lu\n", (unsigned long)remoteFileSizeByte);
72  }
73  curl_easy_cleanup(curlHandlePtr);
74
75  return remoteFileSizeByte;
76}
77
78
79static int sftpResumeUpload(CURL *curlhandle, const char *remotepath,
80                            const char *localpath)
81{
82  FILE *f = NULL;
83  CURLcode result = CURLE_GOT_NOTHING;
84
85  curl_off_t remoteFileSizeByte = sftpGetRemoteFileSize(remotepath);
86  if(-1 == remoteFileSizeByte) {
87    printf("Error reading the remote file size: unable to resume upload\n");
88    return -1;
89  }
90
91  f = fopen(localpath, "rb");
92  if(!f) {
93    perror(NULL);
94    return 0;
95  }
96
97  curl_easy_setopt(curlhandle, CURLOPT_UPLOAD, 1L);
98  curl_easy_setopt(curlhandle, CURLOPT_URL, remotepath);
99  curl_easy_setopt(curlhandle, CURLOPT_READFUNCTION, readfunc);
100  curl_easy_setopt(curlhandle, CURLOPT_READDATA, f);
101
102#ifdef _WIN32
103  _fseeki64(f, remoteFileSizeByte, SEEK_SET);
104#else
105  fseek(f, (long)remoteFileSizeByte, SEEK_SET);
106#endif
107  curl_easy_setopt(curlhandle, CURLOPT_APPEND, 1L);
108  result = curl_easy_perform(curlhandle);
109
110  fclose(f);
111
112  if(result == CURLE_OK)
113    return 1;
114  else {
115    fprintf(stderr, "%s\n", curl_easy_strerror(result));
116    return 0;
117  }
118}
119
120int main(void)
121{
122  const char *remote = "sftp://user:pass@example.com/path/filename";
123  const char *filename = "filename";
124  CURL *curlhandle = NULL;
125
126  curl_global_init(CURL_GLOBAL_ALL);
127  curlhandle = curl_easy_init();
128
129  if(!sftpResumeUpload(curlhandle, remote, filename)) {
130    printf("resumed upload using curl %s failed\n", curl_version());
131  }
132
133  curl_easy_cleanup(curlhandle);
134  curl_global_cleanup();
135
136  return 0;
137}
138