1 /***************************************************************************
2  *                                  _   _ ____  _
3  *  Project                     ___| | | |  _ \| |
4  *                             / __| | | | |_) | |
5  *                            | (__| |_| |  _ <| |___
6  *                             \___|\___/|_| \_\_____|
7  *
8  * Copyright (C) 1998 - 2019, 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.haxx.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  ***************************************************************************/
22 /* <DESC>
23  * Upload to SFTP, resuming a previously aborted transfer.
24  * </DESC>
25  */
26 
27 #include <stdlib.h>
28 #include <stdio.h>
29 #include <curl/curl.h>
30 
31 /* read data to upload */
readfunc(void * ptr,size_t size,size_t nmemb,void * stream)32 static size_t readfunc(void *ptr, size_t size, size_t nmemb, void *stream)
33 {
34   FILE *f = (FILE *)stream;
35   size_t n;
36 
37   if(ferror(f))
38     return CURL_READFUNC_ABORT;
39 
40   n = fread(ptr, size, nmemb, f) * size;
41 
42   return n;
43 }
44 
45 /*
46  * sftpGetRemoteFileSize returns the remote file size in byte; -1 on error
47  */
sftpGetRemoteFileSize(const char * i_remoteFile)48 static curl_off_t sftpGetRemoteFileSize(const char *i_remoteFile)
49 {
50   CURLcode result = CURLE_GOT_NOTHING;
51   curl_off_t remoteFileSizeByte = -1;
52   CURL *curlHandlePtr = NULL;
53 
54   curlHandlePtr = curl_easy_init();
55   curl_easy_setopt(curlHandlePtr, CURLOPT_VERBOSE, 1L);
56 
57   curl_easy_setopt(curlHandlePtr, CURLOPT_URL, i_remoteFile);
58   curl_easy_setopt(curlHandlePtr, CURLOPT_NOPROGRESS, 1);
59   curl_easy_setopt(curlHandlePtr, CURLOPT_NOBODY, 1);
60   curl_easy_setopt(curlHandlePtr, CURLOPT_HEADER, 1);
61   curl_easy_setopt(curlHandlePtr, CURLOPT_FILETIME, 1);
62 
63   result = curl_easy_perform(curlHandlePtr);
64   if(CURLE_OK == result) {
65     result = curl_easy_getinfo(curlHandlePtr,
66                                CURLINFO_CONTENT_LENGTH_DOWNLOAD_T,
67                                &remoteFileSizeByte);
68     if(result)
69       return -1;
70     printf("filesize: %" CURL_FORMAT_CURL_OFF_T "\n", remoteFileSizeByte);
71   }
72   curl_easy_cleanup(curlHandlePtr);
73 
74   return remoteFileSizeByte;
75 }
76 
77 
sftpResumeUpload(CURL * curlhandle,const char * remotepath,const char * localpath)78 static int sftpResumeUpload(CURL *curlhandle, const char *remotepath,
79                             const char *localpath)
80 {
81   FILE *f = NULL;
82   CURLcode result = CURLE_GOT_NOTHING;
83 
84   curl_off_t remoteFileSizeByte = sftpGetRemoteFileSize(remotepath);
85   if(-1 == remoteFileSizeByte) {
86     printf("Error reading the remote file size: unable to resume upload\n");
87     return -1;
88   }
89 
90   f = fopen(localpath, "rb");
91   if(!f) {
92     perror(NULL);
93     return 0;
94   }
95 
96   curl_easy_setopt(curlhandle, CURLOPT_UPLOAD, 1L);
97   curl_easy_setopt(curlhandle, CURLOPT_URL, remotepath);
98   curl_easy_setopt(curlhandle, CURLOPT_READFUNCTION, readfunc);
99   curl_easy_setopt(curlhandle, CURLOPT_READDATA, f);
100 
101 #ifdef _WIN32
102   _fseeki64(f, remoteFileSizeByte, SEEK_SET);
103 #else
104   fseek(f, (long)remoteFileSizeByte, SEEK_SET);
105 #endif
106   curl_easy_setopt(curlhandle, CURLOPT_APPEND, 1L);
107   result = curl_easy_perform(curlhandle);
108 
109   fclose(f);
110 
111   if(result == CURLE_OK)
112     return 1;
113   else {
114     fprintf(stderr, "%s\n", curl_easy_strerror(result));
115     return 0;
116   }
117 }
118 
main(void)119 int main(void)
120 {
121   const char *remote = "sftp://user:pass@example.com/path/filename";
122   const char *filename = "filename";
123   CURL *curlhandle = NULL;
124 
125   curl_global_init(CURL_GLOBAL_ALL);
126   curlhandle = curl_easy_init();
127 
128   if(!sftpResumeUpload(curlhandle, remote, filename)) {
129     printf("resumed upload using curl %s failed\n", curl_version());
130   }
131 
132   curl_easy_cleanup(curlhandle);
133   curl_global_cleanup();
134 
135   return 0;
136 }
137