Visual FoxPro

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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LOCAL lnSuccess
LOCAL loSftp
LOCAL lnPort
LOCAL lcPassword
LOCAL lcHandle
LOCAL loBd
LOCAL lnChunkSize
LOCAL lnReading

lnSuccess = 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.

loSftp = CreateObject('Chilkat.SFtp')

*  Connect, authenticate, and initialize the SFTP subsystem.
lnPort = 22
lnSuccess = loSftp.Connect("sftp.example.com",lnPort)
IF (lnSuccess = 0) THEN
    ? loSftp.LastErrorText
    RELEASE loSftp
    CANCEL
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.
lcPassword = "mySshPassword"

lnSuccess = loSftp.AuthenticatePw("mySshLogin",lcPassword)
IF (lnSuccess = 0) THEN
    ? loSftp.LastErrorText
    RELEASE loSftp
    CANCEL
ENDIF

lnSuccess = loSftp.InitializeSftp()
IF (lnSuccess = 0) THEN
    ? loSftp.LastErrorText
    RELEASE loSftp
    CANCEL
ENDIF

lcHandle = loSftp.OpenFile("subdir/image.png","readOnly","openExisting")
IF (loSftp.LastMethodSuccess = 0) THEN
    ? loSftp.LastErrorText
    RELEASE loSftp
    CANCEL
ENDIF

*  Read the file in chunks until end-of-file, accumulating the bytes in a BinData.
loBd = CreateObject('Chilkat.BinData')
lnChunkSize = 8192
lnReading = 1
DO WHILE lnReading
    lnSuccess = loSftp.ReadFileBd(lcHandle,lnChunkSize,loBd)
    IF (loSftp.LastReadFailed(lcHandle)) THEN
        ? loSftp.LastErrorText
        RELEASE loSftp
        RELEASE loBd
        CANCEL
    ENDIF

    lnReading = NOT loSftp.Eof(lcHandle)
ENDDO

lnSuccess = loSftp.CloseHandle(lcHandle)
IF (lnSuccess = 0) THEN
    ? loSftp.LastErrorText
    RELEASE loSftp
    RELEASE loBd
    CANCEL
ENDIF

? "Read " + STR(loBd.NumBytes) + " bytes."

loSftp.Disconnect()

RELEASE loSftp
RELEASE loBd