PureBasic

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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IncludeFile "CkBinData.pb"
IncludeFile "CkSFtp.pb"

Procedure ChilkatExample()

    success.i = 0

    ;  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.i = CkSFtp::ckCreate()
    If sftp.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ;  Connect, authenticate, and initialize the SFTP subsystem.
    port.i = 22
    success = CkSFtp::ckConnect(sftp,"sftp.example.com",port)
    If success = 0
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

    ;  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.s = "mySshPassword"

    success = CkSFtp::ckAuthenticatePw(sftp,"mySshLogin",password)
    If success = 0
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

    success = CkSFtp::ckInitializeSftp(sftp)
    If success = 0
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

    handle.s = CkSFtp::ckOpenFile(sftp,"subdir/image.png","readOnly","openExisting")
    If CkSFtp::ckLastMethodSuccess(sftp) = 0
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

    ;  Read the file in chunks until end-of-file, accumulating the bytes in a BinData.
    bd.i = CkBinData::ckCreate()
    If bd.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    chunkSize.i = 8192
    reading.i = 1
    While reading
        success = CkSFtp::ckReadFileBd(sftp,handle,chunkSize,bd)
        If CkSFtp::ckLastReadFailed(sftp,handle)
            Debug CkSFtp::ckLastErrorText(sftp)
            CkSFtp::ckDispose(sftp)
            CkBinData::ckDispose(bd)
            ProcedureReturn
        EndIf

        reading = Not CkSFtp::ckEof(sftp,handle)
    Wend

    success = CkSFtp::ckCloseHandle(sftp,handle)
    If success = 0
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        CkBinData::ckDispose(bd)
        ProcedureReturn
    EndIf

    Debug "Read " + Str(CkBinData::ckNumBytes(bd)) + " bytes."

    CkSFtp::ckDisconnect(sftp)


    CkSFtp::ckDispose(sftp)
    CkBinData::ckDispose(bd)


    ProcedureReturn
EndProcedure