write to the stdin

[wbtcpip]

I'm using System to run an external application (let's say ffmpeg for ex)

the gfa help show that System has an option

StdIn h Specifies a handle that will be used as the standard input handle to the process.

how i can write bytes to that handle?

is there a little example?

[(X)]

I asked ChatGPT (Bing) 

Sure! Here’s an example of how to redirect standard input in VB6:
Private Sub Command1_Click()
Dim proc As PROCESS_INFORMATION
Dim start As STARTUPINFO
Dim hPipeRead As Long, hPipeWrite As Long
Dim security As SECURITY_ATTRIBUTES

security.nLength = Len(security)
security.bInheritHandle = 1&
security.lpSecurityDescriptor = 0&

If CreatePipe(hPipeRead, hPipeWrite, security, 0&) Then
start.cb = Len(start)
start.dwFlags = STARTF_USESTDHANDLES Or STARTF_USESHOWWINDOW
start.hStdInput = hPipeRead
start.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE)
start.hStdError = GetStdHandle(STD_ERROR_HANDLE)
start.wShowWindow = SW_HIDE

If CreateProcess(vbNullString, "cmd.exe", ByVal 0&, ByVal 0&, 1&, _
NORMAL_PRIORITY_CLASS, ByVal 0&, vbNullString, start, proc) Then
CloseHandle hPipeRead
WriteToPipe "dir" & vbCrLf, hPipeWrite
WriteToPipe "exit" & vbCrLf, hPipeWrite
CloseHandle hPipeWrite
WaitForSingleObject proc.hProcess, INFINITE
CloseHandle proc.hThread
CloseHandle proc.hProcess
End If
End If
End Sub

Private Sub WriteToPipe(ByVal strData As String, ByVal hPipe As Long)
Dim ret As Long, lngWritten As Long

ret = WriteFile(hPipe, ByVal strData, Len(strData), lngWritten, ByVal 0&)
End Sub
Copy
This code creates a pipe and uses it to redirect the standard input of a new process (in this case cmd.exe). It then writes the commands dir and exit to the pipe. This causes the new process to execute these commands and then exit. Is there anything else you would like to know?

I am not familiar with pipes etc Looks a bit complicated, but, what doesn't at first?...

[(X)]

And in GFA-BASIC 32 for Windows?
OpenW 1

Dim hRead As Handle, hWrite As Handle
Dim security As SECURITY_ATTRIBUTES

security.nLength = Len(security)
security.bInheritHandle = 1&
security.lpSecurityDescriptor = 0&

If CreatePipe(hRead, hWrite, security, 0&) Then
   System "cmd.exe", StdIn hRead
   CloseHandle hRead
   WriteToPipe "dir" & vbCrLf, hWrite
   WriteToPipe "exit" & vbCrLf, hWrite
   CloseHandle hWrite
End If

Do
   Sleep
Until Me Is Nothing

Sub WriteToPipe(ByVal strData As String, ByVal hPipe As Handle)
   Dim ret As Long, lngWritten As Long
   ret = WriteFile(hPipe, ByVal strData, Len(strData), lngWritten, ByVal 0&)
End Sub


SECURITY_ATTRIBUTES is a structure used in the Windows API to specify security information for objects such as pipes and processes. In GFA-BASIC 32 for Windows, you can define it using the Type statement like this:

Type SECURITY_ATTRIBUTES
nLength As Long
lpSecurityDescriptor As Long
bInheritHandle As Long
End Type
This structure has three members: nLength, which specifies the size of the structure; lpSecurityDescriptor, which is a pointer to a security descriptor; and bInheritHandle, which indicates whether the handle to the object can be inherited by child processes.

[(X)]

The code provided appears to mimic opening a command console and typing dir followed by pressing the return key and then typing exit followed by pressing the return key. The code creates a pipe and uses it to redirect the standard input of the cmd.exe process to the read end of the pipe. Then it writes the commands dir and exit to the write end of the pipe, which causes them to be executed by the cmd.exe process.

[wbtcpip]

i guess most of this stuff is not required if i use the command "System" of GB32. System will already return to me an stdin handle. i only wonder how to write to that handle.

[(X)]

Jun 1, 2023 16:00:26 GMT 1 wbtcpip said:

I'm using System to run an external application (let's say ffmpeg for ex)

the gfa help show that System has an option

StdIn h Specifies a handle that will be used as the standard input handle to the process.

how i can write bytes to that handle?

is there a little example?

Can you elaborate on: 'write bytes'?

[(X)]

You can write bytes to the standard input handle of a process launched using the System command in a similar way to how it is done in the code you provided earlier. Here’s an example that shows how to write bytes to the standard input of an external application (in this case ffmpeg) using a pipe:


OpenW 1

Dim hRead As Handle, hWrite As Handle
Dim security As SECURITY_ATTRIBUTES

security.nLength = Len(security)
security.bInheritHandle = 1&
security.lpSecurityDescriptor = 0&

If CreatePipe(hRead, hWrite, security, 0&) Then
System "ffmpeg", StdIn hRead
CloseHandle hRead
WriteToPipe "your data here", hWrite
CloseHandle hWrite
End If

Do
Sleep
Until Me Is Nothing

Sub WriteToPipe(ByVal strData As String, ByVal hPipe As Handle)
Dim ret As Long, lngWritten As Long
ret = WriteFile(hPipe, ByVal strData, Len(strData), lngWritten, ByVal 0&)
End Sub

This code creates a pipe and uses it to redirect the standard input of the ffmpeg process to the read end of the pipe. Then it writes data to the write end of the pipe using the WriteToPipe subroutine. You can modify the "your data here" string to contain the data you want to write to the standard input of the ffmpeg process.

Is this what you were looking for?

[wbtcpip]

yes thank you i will give it a try

[(X)]

What is the byte data you want to send? Is it actual bytes or a string of chars?