Visual FoxPro

Detect End-of-File on a Remote SFTP File

Demonstrates the Chilkat SFtp.Eof method, which returns whether the most recent read for a handle received the SFTP end-of-file status. The only argument is the handle. This example reads until Eof is true.

Background: The timing here is worth understanding: reading exactly through the final byte does not immediately set EOF. The next read succeeds, returns zero bytes, sets the status to SSH_FX_EOF, and only then does Eof report true. That is why the loop tests Eof after each read rather than assuming a short read means the end — a short read can also just be the server returning less than requested.

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LOCAL lnSuccess
LOCAL loSftp
LOCAL lnPort
LOCAL lcPassword
LOCAL lcHandle
LOCAL loSbContent
LOCAL lnChunkSize
LOCAL lnReading
LOCAL lcChunk

lnSuccess = 0

*  Demonstrates the SFtp.Eof method, which returns whether the most recent read for a handle
*  received the SFTP end-of-file status.  The only argument is the handle.

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/data.txt","readOnly","openExisting")
IF (loSftp.LastMethodSuccess = 0) THEN
    ? loSftp.LastErrorText
    RELEASE loSftp
    CANCEL
ENDIF

*  Read until Eof reports the end of the file.  Note that reading exactly through the final byte
*  does not set EOF; the next read returns zero bytes and then Eof becomes true.
loSbContent = CreateObject('Chilkat.StringBuilder')
lnChunkSize = 4096
lnReading = 1
DO WHILE lnReading
    lcChunk = loSftp.ReadFileText(lcHandle,lnChunkSize,"utf-8")
    IF (loSftp.LastReadFailed(lcHandle)) THEN
        ? loSftp.LastErrorText
        RELEASE loSftp
        RELEASE loSbContent
        CANCEL
    ENDIF

    loSbContent.Append(lcChunk)
    lnReading = NOT loSftp.Eof(lcHandle)
ENDDO

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

? loSbContent.GetAsString()

loSftp.Disconnect()

RELEASE loSftp
RELEASE loSbContent