PowerBuilder

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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integer li_rc
integer li_Success
oleobject loo_Sftp
integer li_Port
string ls_Password
string ls_Handle
oleobject loo_Bd
integer li_ChunkSize
integer li_Reading

li_Success = 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.

loo_Sftp = create oleobject
li_rc = loo_Sftp.ConnectToNewObject("Chilkat.SFtp")
if li_rc < 0 then
    destroy loo_Sftp
    MessageBox("Error","Connecting to COM object failed")
    return
end if

//  Connect, authenticate, and initialize the SFTP subsystem.
li_Port = 22
li_Success = loo_Sftp.Connect("sftp.example.com",li_Port)
if li_Success = 0 then
    Write-Debug loo_Sftp.LastErrorText
    destroy loo_Sftp
    return
end if

//  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.
ls_Password = "mySshPassword"

li_Success = loo_Sftp.AuthenticatePw("mySshLogin",ls_Password)
if li_Success = 0 then
    Write-Debug loo_Sftp.LastErrorText
    destroy loo_Sftp
    return
end if

li_Success = loo_Sftp.InitializeSftp()
if li_Success = 0 then
    Write-Debug loo_Sftp.LastErrorText
    destroy loo_Sftp
    return
end if

ls_Handle = loo_Sftp.OpenFile("subdir/image.png","readOnly","openExisting")
if loo_Sftp.LastMethodSuccess = 0 then
    Write-Debug loo_Sftp.LastErrorText
    destroy loo_Sftp
    return
end if

//  Read the file in chunks until end-of-file, accumulating the bytes in a BinData.
loo_Bd = create oleobject
li_rc = loo_Bd.ConnectToNewObject("Chilkat.BinData")

li_ChunkSize = 8192
li_Reading = 1
do while li_Reading
    li_Success = loo_Sftp.ReadFileBd(ls_Handle,li_ChunkSize,loo_Bd)
    if loo_Sftp.LastReadFailed(ls_Handle) then
        Write-Debug loo_Sftp.LastErrorText
        destroy loo_Sftp
        destroy loo_Bd
        return
    end if

    li_Reading = not loo_Sftp.Eof(ls_Handle)
loop

li_Success = loo_Sftp.CloseHandle(ls_Handle)
if li_Success = 0 then
    Write-Debug loo_Sftp.LastErrorText
    destroy loo_Sftp
    destroy loo_Bd
    return
end if

Write-Debug "Read " + string(loo_Bd.NumBytes) + " bytes."

loo_Sftp.Disconnect()


destroy loo_Sftp
destroy loo_Bd