DataFlex

Read Bytes from a Remote SFTP File (BinData)

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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Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoSftp
    Integer iPort
    String sPassword
    String sHandle
    Variant vBd
    Handle hoBd
    Integer iChunkSize
    Boolean iReading
    String sTemp1
    Integer iTemp1
    Boolean bTemp1

    Move False To iSuccess

    //  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.

    Get Create (RefClass(cComChilkatSFtp)) To hoSftp
    If (Not(IsComObjectCreated(hoSftp))) Begin
        Send CreateComObject of hoSftp
    End

    //  Connect, authenticate, and initialize the SFTP subsystem.
    Move 22 To iPort
    Get ComConnect Of hoSftp "sftp.example.com" iPort To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSftp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  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.
    Move "mySshPassword" To sPassword

    Get ComAuthenticatePw Of hoSftp "mySshLogin" sPassword To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSftp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComInitializeSftp Of hoSftp To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSftp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComOpenFile Of hoSftp "subdir/image.png" "readOnly" "openExisting" To sHandle
    Get ComLastMethodSuccess Of hoSftp To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoSftp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Read the file in chunks until end-of-file, accumulating the bytes in a BinData.
    Get Create (RefClass(cComChilkatBinData)) To hoBd
    If (Not(IsComObjectCreated(hoBd))) Begin
        Send CreateComObject of hoBd
    End
    Move 8192 To iChunkSize
    Move True To iReading
    While iReading
        Get pvComObject of hoBd to vBd
        Get ComReadFileBd Of hoSftp sHandle iChunkSize vBd To iSuccess
        Get ComLastReadFailed Of hoSftp sHandle To bTemp1
        If (bTemp1) Begin
            Get ComLastErrorText Of hoSftp To sTemp1
            Showln sTemp1
            Procedure_Return
        End

        Get ComEof Of hoSftp sHandle To bTemp1
        Move (Not bTemp1) To iReading
    Loop

    Get ComCloseHandle Of hoSftp sHandle To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSftp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComNumBytes Of hoBd To iTemp1
    Showln "Read " iTemp1 " bytes."

    Send ComDisconnect To hoSftp


End_Procedure