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Check Whether the Last SFTP Read Failed

Demonstrates the Chilkat SFtp.LastReadFailed method, which returns whether the most recent read for a handle failed. The only argument is the handle. A normal end-of-file is not a failure.

Background: A chunked read loop needs to tell three outcomes apart: more data, a clean end-of-file, and an actual error such as a dropped connection or a revoked handle. LastReadFailed isolates the error case — it is false on a normal EOF read (which succeeds with zero bytes) and true for an empty, malformed, or already-closed handle — so the loop can stop cleanly on EOF but bail out with an error message on a genuine failure.

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llSuccess = .F.

//  Demonstrates the SFtp.LastReadFailed method, which returns whether the most recent read for a
//  handle failed.  The only argument is the handle.  A normal end-of-file is NOT a failure.

loSftp = createobject("CkSFtp")

//  Connect, authenticate, and initialize the SFTP subsystem.
lnPort = 22
llSuccess = loSftp.Connect("sftp.example.com",lnPort)
if (llSuccess = .F.) then
    ? loSftp.LastErrorText
    release loSftp
    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.
lcPassword = "mySshPassword"

llSuccess = loSftp.AuthenticatePw("mySshLogin",lcPassword)
if (llSuccess = .F.) then
    ? loSftp.LastErrorText
    release loSftp
    return
endif

llSuccess = loSftp.InitializeSftp()
if (llSuccess = .F.) then
    ? loSftp.LastErrorText
    release loSftp
    return
endif

lcHandle = loSftp.OpenFile("subdir/data.txt","readOnly","openExisting")
if (loSftp.LastMethodSuccess = .F.) then
    ? loSftp.LastErrorText
    release loSftp
    return
endif

llReading = .T.
lnChunkSize = 4096
loBd = createobject("CkBinData")
do while llReading
    llSuccess = loSftp.ReadFileBd(lcHandle,lnChunkSize,loBd)

    //  Distinguish an actual read failure from a normal EOF.  On EOF the read succeeds, returns
    //  zero bytes, and LastReadFailed is .F..
    if (loSftp.LastReadFailed(lcHandle)) then
        ? "Read failed: " + loSftp.LastErrorText
        release loSftp
        release loBd
        return
    endif

    llReading = not loSftp.Eof(lcHandle)
enddo

llSuccess = loSftp.CloseHandle(lcHandle)
if (llSuccess = .F.) then
    ? loSftp.LastErrorText
    release loSftp
    release loBd
    return
endif

? "Read " + str(loBd.NumBytes) + " bytes with no read failures."

loSftp.Disconnect()


release loSftp
release loBd