How to copy a file in C / C ++ using libssh and sftp

Question

I post here because I need help with some libssh related code .

I read all the official documentation here , but still I don't understand what I need to do if someone can tell me that I would be happy.

Actually I want to copy the file from the client to the remote server, but I don’t understand how to do this with the libssh library and the sftp function in libssh.

The situation is this: the ssh session is open and the sftp session is also open, I can create a file and write it from the client to the server using the built-in lib ssh function.

I did not find an easy way to copy the file from the client to the server using a simple function such as sftp_transfer (sourceFile (e.g. c: \ my document \ hello world.txt), RemoteFile (/ home / user / hello world.txt), right (reading and writing)) ?

Given what I understood from the tutorial, a file is first created in a remote location (server), then it opens this file using this line of code:

file = sftp_open(sftp, "/home/helloworld.txt",access_type,1); 

After that, the file is created on the server, and then it is written to this created file with the buffer:

 const char *helloworld = "Hello, World!\n"; int length = strlen(helloworld); nwritten = sftp_write(file, helloworld, length); 

My question is now, if I have a file, for example, a .doc file, and I want to transfer / download this file from c: \ mydocument \ document.doc for the remote remote server /home/user/document.doc. can i do this with this method?

How can I put this file in the sftp_write () function to send it as helloworld to the sample function?

I may not be good at programming to understand, but I really tried to figure it out, and I was stuck with it.

Thank you in advance for your help.

The following is an example of the code I used for testing:

 // Set variable for the communication char buffer[256]; unsigned int nbytes; //create a file to send by SFTP int access_type = O_WRONLY | O_CREAT | O_TRUNC; const char *helloworld = "Hello, World!\n"; int length = strlen(helloworld); //Open a SFTP session sftp = sftp_new(my_ssh_session); if (sftp == NULL) { fprintf(stderr, "Error allocating SFTP session: %s\n", ssh_get_error(my_ssh_session)); return SSH_ERROR; } // Initialize the SFTP session rc = sftp_init(sftp); if (rc != SSH_OK) { fprintf(stderr, "Error initializing SFTP session: %s.\n", sftp_get_error(sftp)); sftp_free(sftp); return rc; } //Open the file into the remote side file = sftp_open(sftp, "/home/helloworld.txt",access_type,1); if (file == NULL) { fprintf(stderr, "Can't open file for writing: %s\n",ssh_get_error(my_ssh_session)); return SSH_ERROR; } //Write the file created with what into the buffer nwritten = sftp_write(file, helloworld, length); if (nwritten != length) { fprintf(stderr, "Can't write data to file: %s\n", ssh_get_error(my_ssh_session)); sftp_close(file); return SSH_ERROR; } ` 

Answer 1

Open the file in the usual way (using C ++ fstream or C stdio.h ), read its contents into the buffer and pass the buffer to sftp_write .

Something like that:

 ifstream fin("file.doc", ios::binary); if (fin) { fin.seekg(0, ios::end); ios::pos_type bufsize = fin.tellg(); // get file size in bytes fin.seekg(0); // rewind to beginning of file char* buf = new char[bufsize]; fin.read(buf, bufsize); // read file contents into buffer sftp_write(file, buf, bufsize); // write to remote file } 

Please note that this is a very simple implementation. You should probably open the remote file in append mode and then write the data to chunks rather than send one huge amount of data.

Answer 2

I used the following example here .

sftp_read_sync uses an infinite loop to read the file from the server in /path/to/profile from the server path /etc/profile .