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 */
readfunc(char * ptr,size_t size,size_t nmemb,void * stream)34 static 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 */
sftpGetRemoteFileSize(const char * i_remoteFile)50 static 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
sftpResumeUpload(CURL * curlhandle,const char * remotepath,const char * localpath)79 static 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
main(void)120 int 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
