Article #15201: How to redirect STDOUT/STDIN

 Question and Answer Database
FAQ201C.txt How to redirect STDOUT/STDIN
Category :Windows API
Platform :All
Product :C++Builder 1.x
Question:
I want to redirect the stdio/stdout of a console app that
I spawn in my Builder app.
Answer:
Here is a snippet of code that illistrates how to do this.
void RunConsoleApp (void){
STARTUPINFO sui;
PROCESS_INFORMATION pi;
SECURITY_ATTRIBUTES sa;
HANDLE hReadPipe, hWritePipe;
char Buffer[4000];
DWORD dwRead;
//setup the stdout
//fist create the sec attrib
sa.nLength = sizeof (SECURITY_ATTRIBUTES);
sa.lpSecurityDescriptor = NULL;
sa.bInheritHandle = true;
//create pipe handles
CreatePipe(&hReadPipe, &hWritePipe, &sa, 2500000);
if (hReadPipe == INVALID_HANDLE_VALUE ||
hWritePipe == INVALID_HANDLE_VALUE){
MessageBox (Handle, "Not a valid Handle for STDOUT", NULL,
MB_OK | MB_ICONEXCLAMATION);
return;
}
//setup the start up info
memset(&sui, 0, sizeof(STARTUPINFO));
sui.cb = sizeof (STARTUPINFO);
sui.dwFlags = STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
sui.wShowWindow = SW_HIDE;
sui.hStdOutput = hWritePipe;
if (!CreateProcess ("console.exe", // pointer to name of executable module, getit fron the open dialog
NULL, // pointer to command line string, have noe so NULL
NULL, // pointer to process security attributes, we don't need to inheriat the handle
NULL, // pointer to thread security attributes
true, // handle inheritance flag
NULL, // creation flags
NULL, // pointer to new environment block
NULL, // pointer to current directory name
&sui, // pointer to STARTUPINFO
&pi // pointer to PROCESS_INFORMATION
)){
MessageBox ((HWND)Handle, "Could not create process", NULL,
MB_OK | MB_ICONEXCLAMATION);
return;
}
CloseHandle(pi.hThread);
WaitForSingleObject(pi.hProcess, 30000);
//read from the pipe and put it in the richedit
bool ReadLoopDone = false;
Memo1->Lines->Clear();
while (!ReadLoopDone){
memset(Buffer, 0, 4000);
ReadFile(hReadPipe,
&Buffer,
sizeof(Buffer),
&dwRead,
NULL);
Memo1->Lines->Add(String(Buffer));
if (dwRead < 4000) ReadLoopDone = true;
}
return;
}
7/2/98 10:32:32 AM

Last Modified: 01-SEP-99