Get the stdout of a console process

[FrancoAT]

(First of all,sorry for my poor english)

Hy guys,what i want is simple but i can't do.
I want to create a process using the Windows API and get the output of this process.
For example,i start the ipconfig.exe process with my code and get the output of this process.

Like this:

c:\>ipconfig.exe

//THE OUTPUT OF THE PROCESS
Wireless LAN adapter Wi-Fi:

Connection-specific DNS Suffix . :
IPv4 Address. . . . . . . . . . . : 192.168.0.105
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.0.1

My code

#include <windows.h>
#include <stdio.h>

int main(){

	HANDLE hChildOut = INVALID_HANDLE_VALUE;
	HANDLE hChildIn = INVALID_HANDLE_VALUE;
	
	SECURITY_ATTRIBUTES saAttr; 
	PROCESS_INFORMATION piProcInfo; 
	STARTUPINFO siStartInfo,si;
	BOOL bSuccess = FALSE;   //NON SEI ONDE ENTRA ESSA PORRA
	unsigned char buffer[1000]; 

	saAttr.nLength = sizeof(SECURITY_ATTRIBUTES);  //DEFINE AQUI SASPORRA
	saAttr.bInheritHandle = TRUE; 
	saAttr.lpSecurityDescriptor = NULL;

	// Create a pipe for the child process's STDOUT.
	if ( !CreatePipe(&hChildIn, &hChildOut, &saAttr, 0) ) {
			printf("Failed to create a pipe"); 
	}

	// Ensure the read handle to the pipe for STDOUT is not inherited.
	if ( !SetHandleInformation(hChildOut, HANDLE_FLAG_INHERIT, 0) ){
			printf("Failed to set handle information");
	}

	//ZERA PROCESS INFORMATION
	//ISSO SÓ É PREENCHIDO DEPOIS DO PROCESSO EXECUTADO
	ZeroMemory( &piProcInfo, sizeof(PROCESS_INFORMATION) );

	// Set up members of the STARTUPINFO structure. 
	// This structure specifies the STDIN and STDOUT handles for redirection.
	ZeroMemory( &siStartInfo, sizeof(STARTUPINFO) );  //START INFOS

	siStartInfo.cb = sizeof(STARTUPINFO); 
	siStartInfo.hStdError = hChildOut;
	siStartInfo.hStdOutput = hChildOut;
	siStartInfo.hStdInput = hChildIn;
	siStartInfo.dwFlags |= STARTF_USESTDHANDLES;

	if(!CreateProcess("c:\\windows\\system32\\ipconfig.exe", 
      NULL,     //command line 
      &saAttr,    //process security attributes 
      NULL,     // primary thread security attributes 
      TRUE,     // handles are inherited 
      0,        // creation flags 
      NULL,     // use parent's environment 
      NULL,     // use parent's current directory 
      &siStartInfo,  // STARTUPINFO pointer 
      &piProcInfo)  // receives PROCESS_INFORMATION 

	){

		printf("Seh fodeo %d\n",GetLastError());
		return -1;
	}

	printf("hChildOut handle -> %d\n",hChildOut);

	if( !ReadFile(hChildOut,buffer,500,NULL,NULL) ){

		printf("Error %d\n",GetLastError());
		return -10;
	}

	printf("Saida do processo:\n%s\n",&buffer);

	return 0;
}

Error five means:


ERROR_ACCESS_DENIED
5 (0x5)
Access is denied.

Anyone can help me?

[VictorN]

What API call failed?

[FrancoAT]

ReadFile

[2kaud]

Why not simply use stream redirection? eg

c:\>ipconfig > ipcon.txt

this will create the file ipcon.txt containing the output from the ipconfig command.

[FrancoAT]

This is a clever trick 2kaud,but i want to learn how to use Pipe,indeed using the redirect stream was my first idea,but now i want do with pipe...
I saw in another forum a guy using pipes of windows API with pascal OO ( delphi ),and worked,but my code don't.

[2kaud]

You need to create 2 pipes - one for stdin, one for stdout/stderr. You then use the stdout/write handle for stdout/stderr and the stdin/read handle for stdin.

See http://msdn.microsoft.com/en-us/libr...=vs.85%29.aspx for an example.

[Igor Vartanov]

Creating a Child Process with Redirected Input and Output

[FrancoAT]

I saw all this examples,i Will try again...