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

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

    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.

    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;
    }

    handle = CkSFtp_openFile(sftp,"subdir/image.png","readOnly","openExisting");
    if (CkSFtp_getLastMethodSuccess(sftp) == FALSE) {
        printf("%s\n",CkSFtp_lastErrorText(sftp));
        CkSFtp_Dispose(sftp);
        return;
    }

    //  Read the file in chunks until end-of-file, accumulating the bytes in a BinData.
    bd = CkBinData_Create();
    chunkSize = 8192;
    reading = TRUE;
    while (reading) {
        success = CkSFtp_ReadFileBd(sftp,handle,chunkSize,bd);
        if (CkSFtp_LastReadFailed(sftp,handle)) {
            printf("%s\n",CkSFtp_lastErrorText(sftp));
            CkSFtp_Dispose(sftp);
            CkBinData_Dispose(bd);
            return;
        }

        reading = !CkSFtp_Eof(sftp,handle);
    }

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

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

    CkSFtp_Disconnect(sftp);


    CkSFtp_Dispose(sftp);
    CkBinData_Dispose(bd);

    }