Read Bytes from a Remote SFTP File (BinData)

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Demonstrates the Chilkat SFtp.ReadFileBd method, which reads up to a number of bytes from the current position of an open handle and appends them to a BinData. The arguments are the handle, the maximum number of bytes, and the BinData. This example reads in chunks until end-of-file.

Background: For binary files, reading into a BinData preserves the bytes exactly, unlike a text read that decodes through a charset. Because it appends, the chunked read loop accumulates the whole file in the BinData; each pass reads up to the chunk size and the loop repeats until Eof. Fewer bytes than requested can come back near the end of the file, which is normal.

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bool success = false;

//  Demonstrates the SFtp.ReadFileBd method, which reads up to a number of bytes from the current
//  position of an open handle and appends them to a BinData.  The 1st argument is the handle, the
//  2nd is the maximum number of bytes, and the 3rd is the BinData.

Chilkat.SFtp sftp = new Chilkat.SFtp();

//  Connect, authenticate, and initialize the SFTP subsystem.
int port = 22;
success = sftp.Connect("sftp.example.com",port);
if (success == false) {
    Debug.WriteLine(sftp.LastErrorText);
    return;
}

//  Normally you would not hard-code the password in source.  You should instead obtain it
//  from an interactive prompt, environment variable, or a secrets vault.
string password = "mySshPassword";

success = sftp.AuthenticatePw("mySshLogin",password);
if (success == false) {
    Debug.WriteLine(sftp.LastErrorText);
    return;
}

success = sftp.InitializeSftp();
if (success == false) {
    Debug.WriteLine(sftp.LastErrorText);
    return;
}

string handle = sftp.OpenFile("subdir/image.png","readOnly","openExisting");
if (sftp.LastMethodSuccess == false) {
    Debug.WriteLine(sftp.LastErrorText);
    return;
}

//  Read the file in chunks until end-of-file, accumulating the bytes in a BinData.
Chilkat.BinData bd = new Chilkat.BinData();
int chunkSize = 8192;
bool reading = true;
while (reading) {
    success = sftp.ReadFileBd(handle,chunkSize,bd);
    if (sftp.LastReadFailed(handle)) {
        Debug.WriteLine(sftp.LastErrorText);
        return;
    }

    reading = !sftp.Eof(handle);
}

success = sftp.CloseHandle(handle);
if (success == false) {
    Debug.WriteLine(sftp.LastErrorText);
    return;
}

Debug.WriteLine("Read " + Convert.ToString(bd.NumBytes) + " bytes.");

sftp.Disconnect();