Visual FoxPro

Read Text at a String Offset from a Remote SFTP File

Demonstrates the Chilkat SFtp.ReadFileText64s method, which is like ReadFileText64 but takes the byte offset as a decimal string. The arguments are the handle, the offset string, the maximum number of bytes, and the charset.

Background: The string-offset read exists for the same reason as its write counterpart: it lets code in languages without convenient 64-bit integers still address positions in very large files by supplying the offset as text. Functionally it is identical to the int64 version.

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LOCAL lnSuccess
LOCAL loSftp
LOCAL lnPort
LOCAL lcPassword
LOCAL lcHandle
LOCAL lcOffset
LOCAL lnNumBytes
LOCAL lcText

lnSuccess = 0

*  Demonstrates the SFtp.ReadFileText64s method, which is like ReadFileText64 but takes the byte
*  offset as a decimal string.  The 1st argument is the handle, the 2nd is the offset string, the
*  3rd is the maximum number of bytes, and the 4th is the charset.

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

*  Supplying the offset as a string is convenient in languages without a native 64-bit integer.
lcOffset = "5000000000"
lnNumBytes = 6
lcText = loSftp.ReadFileText64s(lcHandle,lcOffset,lnNumBytes,"utf-8")
IF (loSftp.LastMethodSuccess = 0) THEN
    ? loSftp.LastErrorText
    RELEASE loSftp
    CANCEL
ENDIF

? lcText

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

loSftp.Disconnect()

RELEASE loSftp