Stdoutread strange behavior

[MattHiggs]

Hello all.  So I have a very peculiar issue.  I have wriiten an autoit script which utilizes an external command line utility called http-ping which, as the name would suggest, is able to determine if the web page associated with a given url is online or not.  Furthermore, it is very similar in functionality to the regular ping command:

Below is a simplified version of the script:

expandcollapse popup

; *** Start added by AutoIt3Wrapper ***
#include <AutoItConstants.au3>
; *** End added by AutoIt3Wrapper ***
#Region ;**** Directives created by AutoIt3Wrapper_GUI ****
#AutoIt3Wrapper_Add_Constants=n
#EndRegion ;**** Directives created by AutoIt3Wrapper_GUI ****
#cs ----------------------------------------------------------------------------

 AutoIt Version: 3.3.15.0 (Beta)
 Author:         myName

 Script Function:
    Template AutoIt script.

#ce ----------------------------------------------------------------------------

; Script Start - Add your code below here
#include <ButtonConstants.au3>
#include <EditConstants.au3>
#include <GUIConstantsEx.au3>
#include <StaticConstants.au3>
#include <WindowsConstants.au3>
#Region ### START Koda GUI section ### Form=
$Form1 = GUICreate("Form1", 336, 301, 192, 124)
$Input1 = GUICtrlCreateInput("", 24, 40, 153, 21)
$Label1 = GUICtrlCreateLabel("website", 48, 8, 91, 28)
GUICtrlSetFont(-1, 14, 400, 0, "MS Sans Serif")
$Button1 = GUICtrlCreateButton("Ping", 200, 40, 73, 25, $BS_NOTIFY)
GUICtrlSetState(-1, $GUI_DISABLE)
$Edit1 = GUICtrlCreateEdit("", 32, 96, 273, 177, BitOR($ES_AUTOVSCROLL,$ES_AUTOHSCROLL,$ES_READONLY,$ES_WANTRETURN))
GUISetState(@SW_SHOW)
#EndRegion ### END Koda GUI section ###

While 1
    If StringRegExp ( GUICtrlRead ( $Input1 ), "^(http|https)://(www\.)?.+\.\w+(/.*)?$" ) = 1 Then
        If GUICtrlGetState ( $Button1 ) = 144 Then
            GUICtrlSetState ( $Button1, $GUI_ENABLE )
        EndIf
    Else
        If GUICtrlGetState ( $Button1 ) = 80 Then
            GUICtrlSetState ( $Button1, $GUI_DISABLE )
        EndIf
    EndIf

    $nMsg = GUIGetMsg()
    Switch $nMsg
        Case $GUI_EVENT_CLOSE
            Exit
        Case $Input1

        Case $Button1
            GUICtrlSetData ( $edit1, "" )
            GUICtrlSetState ( $Button1, $GUI_DISABLE )
            $string = ""
            $proc = Run ( @TempDir & "\httpping.exe " & GUICtrlRead ( $Input1 ), @TempDir, @SW_HIDE, $STDOUT_CHILD )
            Do
                $string = $string & StdoutRead ( $proc )
                GUICtrlSetData ( $Edit1, $string )
            Until Not ProcessExists ( $proc )
            GUICtrlSetState ( $Button1, $GUI_ENABLE )

    EndSwitch
WEnd

As you can see, the script is supposed to set the text of the edit control to the output of the command while the command is running.  But it isn't doing that.  Instead, it is waiting until the command is finished executing (as if I had called Porcesswaitclose) and then updates the edit control with the command's output:

So, to try and troubleshoot what was going on, I modified the script above by changing this line:

$proc = Run ( @TempDir & "\httpping.exe " & GUICtrlRead ( $Input1 ), @TempDir, @SW_HIDE, $STDOUT_CHILD )

To this:

;Input an ip address that is valid for your environment
$proc = Run ( "ping.exe 192.168.2.2", @TempDir, @SW_HIDE, $STDOUT_CHILD )

To see if the regular ping command acted the same way, which, as you can see, it did not:

Why the difference in behavior?  I know that I am using a third party command line tool, but I still would have thought that it would behave similarly to other command line tools......  Any info would be appreciated.  

[BrewManNH]

Add this line after the StdoutRead command and see what the output from the program is.

ConsoleWrite('@@ Debug(' & @ScriptLineNumber & ') : $string = ' & $string & @CRLF & '>Error code: ' & @error & @CRLF) ;### Debug Console

For me, it only sent anything to Stdout after it had finished. Looks like that's the way the program is written.

[jchd]

That depends on the external program using buffered or unbuffered stdout, or I/O streams in general.  It's an option offered at file open in many libraries but for instance C99 considers stream buffering to be implementation-dependant, unless special measures are taken.