Download Bytes from an SFTP Server (BinData)

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Demonstrates the Chilkat SFtp.DownloadBd method, which downloads a remote file and appends its bytes to a BinData. The first argument is the remote file path and the second is the BinData.

Note: This example uses relative local paths, which are resolved against the application's current working directory. Absolute local paths may also be used. Supply the paths appropriate to your own environment.

Background: This brings a remote file straight into memory for hashing, parsing, or handing to another API, with no temporary file on disk. Because it appends, existing bytes in the BinData are preserved — convenient for concatenating several remote files, but a source of surprise if you expected replacement, so clear the BinData first when you want only this file's contents.

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#include <C_CkSFtp.h>
#include <C_CkBinData.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkSFtp sftp;
    int port;
    const char *password;
    HCkBinData bd;

    success = FALSE;

    //  Demonstrates the SFtp.DownloadBd method, which downloads a remote file and appends its bytes
    //  to a BinData.  The 1st argument is the remote file path and the 2nd is the BinData.

    sftp = CkSFtp_Create();

    //  Connect, authenticate, and initialize the SFTP subsystem.
    port = 22;
    success = CkSFtp_Connect(sftp,"sftp.example.com",port);
    if (success == FALSE) {
        printf("%s\n",CkSFtp_lastErrorText(sftp));
        CkSFtp_Dispose(sftp);
        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.
    password = "mySshPassword";

    success = CkSFtp_AuthenticatePw(sftp,"mySshLogin",password);
    if (success == FALSE) {
        printf("%s\n",CkSFtp_lastErrorText(sftp));
        CkSFtp_Dispose(sftp);
        return;
    }

    success = CkSFtp_InitializeSftp(sftp);
    if (success == FALSE) {
        printf("%s\n",CkSFtp_lastErrorText(sftp));
        CkSFtp_Dispose(sftp);
        return;
    }

    //  Download the remote file's bytes into a BinData.  Existing bytes in the BinData are
    //  preserved, so clear it first if you want replacement rather than append behavior.
    bd = CkBinData_Create();
    success = CkSFtp_DownloadBd(sftp,"subdir/image.png",bd);
    if (success == FALSE) {
        printf("%s\n",CkSFtp_lastErrorText(sftp));
        CkSFtp_Dispose(sftp);
        CkBinData_Dispose(bd);
        return;
    }

    printf("Downloaded %d bytes.\n",CkBinData_getNumBytes(bd));

    CkSFtp_Disconnect(sftp);


    CkSFtp_Dispose(sftp);
    CkBinData_Dispose(bd);

    }