Unicode C

SFTP Upload Large File in Parts

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Demonstrates how to split a large file into N parts and then upload each part separately. This technique can be used to potentially avoid limits a SFTP server might impose on upload file size. Unicode C

#include <C_CkSFtpW.h>
#include <C_CkFileAccessW.h>
#include <C_CkBinDataW.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkSFtpW sftp;
    const wchar_t *hostname;
    int port;
    const wchar_t *handle;
    const wchar_t *localFilePath;
    HCkFileAccessW fac;
    int blockSize;
    int numBlocks;
    HCkBinDataW bd;
    int i;

    success = FALSE;

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    sftp = CkSFtpW_Create();

    // Set some timeouts, in milliseconds:
    CkSFtpW_putConnectTimeoutMs(sftp,5000);
    CkSFtpW_putIdleTimeoutMs(sftp,10000);

    // Connect to the SSH server.  
    // The standard SSH port = 22
    // The hostname may be a hostname or IP address.
    hostname = L"sftp.example.com";
    port = 22;
    success = CkSFtpW_Connect(sftp,hostname,port);
    if (success != TRUE) {
        wprintf(L"%s\n",CkSFtpW_lastErrorText(sftp));
        CkSFtpW_Dispose(sftp);
        return;
    }

    // Authenticate with the SSH server.  Chilkat SFTP supports
    // both password-based authenication as well as public-key
    // authentication.  This example uses password authenication.
    success = CkSFtpW_AuthenticatePw(sftp,L"myLogin",L"myPassword");
    if (success != TRUE) {
        wprintf(L"%s\n",CkSFtpW_lastErrorText(sftp));
        CkSFtpW_Dispose(sftp);
        return;
    }

    // After authenticating, the SFTP subsystem must be initialized:
    success = CkSFtpW_InitializeSftp(sftp);
    if (success != TRUE) {
        wprintf(L"%s\n",CkSFtpW_lastErrorText(sftp));
        CkSFtpW_Dispose(sftp);
        return;
    }

    // Open a remote file for writing on the SSH server.
    // If the file already exists, it is overwritten.
    // (Specify "createNew" instead of "createTruncate" to
    // prevent overwriting existing files.)
    handle = CkSFtpW_openFile(sftp,L"big.zip",L"writeOnly",L"createTruncate");
    if (CkSFtpW_getLastMethodSuccess(sftp) != TRUE) {
        wprintf(L"%s\n",CkSFtpW_lastErrorText(sftp));
        CkSFtpW_Dispose(sftp);
        return;
    }

    // We're going to upload the local file "qa_data/zips/big.zip" (a relative local path from our current working directory)
    // to the SFTP server.
    localFilePath = L"qa_data/zips/big.zip";

    // Rather than uploading in one shot, we'll read the local file in chunks
    // and upload a chunk at a time.
    fac = CkFileAccessW_Create();

    success = CkFileAccessW_OpenForRead(fac,localFilePath);
    if (success == FALSE) {
        CkSFtpW_CloseHandle(sftp,handle);
        wprintf(L"%s\n",CkFileAccessW_lastErrorText(fac));
        CkSFtpW_Dispose(sftp);
        CkFileAccessW_Dispose(fac);
        return;
    }

    // If we were to split the local file into 128K chunks, how many chunks (blocks) would
    // we have, including the last partial block?
    blockSize = 131072;
    numBlocks = CkFileAccessW_GetNumBlocks(fac,blockSize);
    wprintf(L"Number of blocks = %d\n",numBlocks);

    bd = CkBinDataW_Create();
    i = 0;
    while (i < numBlocks) {
        // Read the Nth block, which gets appended to the bd.  (which means
        // we must clear the contents of bd before the next iteration)
        success = CkFileAccessW_ReadBlockBd(fac,i,blockSize,bd);
        if (success == FALSE) {
            CkSFtpW_CloseHandle(sftp,handle);
            wprintf(L"%s\n",CkFileAccessW_lastErrorText(fac));
            CkSFtpW_Dispose(sftp);
            CkFileAccessW_Dispose(fac);
            CkBinDataW_Dispose(bd);
            return;
        }

        // Upload this block to the open remote file.
        success = CkSFtpW_WriteFileBd(sftp,handle,bd);
        if (success == FALSE) {
            wprintf(L"%s\n",CkSFtpW_lastErrorText(sftp));
            CkSFtpW_Dispose(sftp);
            CkFileAccessW_Dispose(fac);
            CkBinDataW_Dispose(bd);
            return;
        }

        // Clear the contents for the next iteration.
        CkBinDataW_Clear(bd);

        i = i + 1;
    }

    // Close the local file.
    CkFileAccessW_FileClose(fac);

    // -----------------------------------------------------------------------------
    // This is important.  You must close the handle on the server.
    // Otherwise open handles will accumulate on the server until eventually a limit
    // is reached and the server will fail on a call to OpenFile.
    // -----------------------------------------------------------------------------

    // Close the remote file handle on the server.
    success = CkSFtpW_CloseHandle(sftp,handle);
    if (success != TRUE) {
        wprintf(L"%s\n",CkSFtpW_lastErrorText(sftp));
        CkSFtpW_Dispose(sftp);
        CkFileAccessW_Dispose(fac);
        CkBinDataW_Dispose(bd);
        return;
    }

    wprintf(L"Success.\n");


    CkSFtpW_Dispose(sftp);
    CkFileAccessW_Dispose(fac);
    CkBinDataW_Dispose(bd);

    }