Xbase++

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 nSuccess
LOCAL oSftp
LOCAL nPort
LOCAL cPassword
LOCAL cHandle
LOCAL oBd
LOCAL nChunkSize
LOCAL nReading

nSuccess := 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.

oSftp := CreateObject("Chilkat.SFtp")

//  Connect, authenticate, and initialize the SFTP subsystem.
nPort := 22
nSuccess := oSftp:Connect("sftp.example.com", nPort)
IF (nSuccess == 0)
    ? oSftp:LastErrorText
    oSftp:destroy()
    RETURN
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.
cPassword := "mySshPassword"

nSuccess := oSftp:AuthenticatePw("mySshLogin", cPassword)
IF (nSuccess == 0)
    ? oSftp:LastErrorText
    oSftp:destroy()
    RETURN
ENDIF

nSuccess := oSftp:InitializeSftp()
IF (nSuccess == 0)
    ? oSftp:LastErrorText
    oSftp:destroy()
    RETURN
ENDIF

cHandle := oSftp:OpenFile("subdir/image.png", "readOnly", "openExisting")
IF (oSftp:LastMethodSuccess == 0)
    ? oSftp:LastErrorText
    oSftp:destroy()
    RETURN
ENDIF

//  Read the file in chunks until end-of-file, accumulating the bytes in a BinData.
oBd := CreateObject("Chilkat.BinData")
nChunkSize := 8192
nReading := 1
DO WHILE nReading
    nSuccess := oSftp:ReadFileBd(cHandle, nChunkSize, oBd)
    IF (oSftp:LastReadFailed(cHandle))
        ? oSftp:LastErrorText
        oSftp:destroy()
        oBd:destroy()
        RETURN
    ENDIF

    nReading := .NOT. oSftp:Eof(cHandle)
ENDDO

nSuccess := oSftp:CloseHandle(cHandle)
IF (nSuccess == 0)
    ? oSftp:LastErrorText
    oSftp:destroy()
    oBd:destroy()
    RETURN
ENDIF

? "Read " + Str(oBd:NumBytes) + " bytes."

oSftp:Disconnect()

oSftp:destroy()
oBd:destroy()