How to pass named pipe into CreateProcess (C++ Windows) - c++

Question

The hierarchy of my project is that I have 3 processes.
Main exe
Middle exe
Worker exe
Main exe will spawn middle exe using createprocess, from there middle exe will spawn worker exe using createprocess as well. Once worker exe is running middle exe terminates.
I would like to be able to pass the output data from worker exe back to main exe.
The way I think is best is to use a named pipe as worker exe's stdout.
In main exe I have this code:
SECURITY_DESCRIPTOR sd;
InitializeSecurityDescriptor(&sd, SECURITY_DESCRIPTOR_REVISION);
SetSecurityDescriptorDacl(&sd, TRUE, static_cast<PACL>(0), FALSE);
SECURITY_ATTRIBUTES sa;
sa.nLength = sizeof(sa);
sa.lpSecurityDescriptor = &sd;
sa.bInheritHandle = FALSE;
HANDLE hPipe = CreateNamedPipe(TEXT("\\\\.\\pipe\\MPipe"),
PIPE_ACCESS_DUPLEX | FILE_FLAG_OVERLAPPED,
PIPE_TYPE_BYTE | PIPE_READMODE_BYTE | PIPE_NOWAIT,
PIPE_UNLIMITED_INSTANCES,
1024 * 4,
1024 * 4,
0,
&sa);
//CreateProcess() code here for middle exe
if (hPipe == NULL || hPipe == INVALID_HANDLE_VALUE) {
MessageBoxA(NULL, "Failed to create pipe", NULL, MB_OK);
}
int count = 0;
while (true) {
if (!ConnectNamedPipe(hPipe, 0)) {
std::this_thread::sleep_for(std::chrono::seconds(20));
count++;
}
if (count > 5)
break;
}
if (count > 5) {
MessageBoxA(NULL, "Failed...", NULL, MB_OK);
}
Then in middle exe I have
memset(&si, 0x00, sizeof(si));
memset(&pi, 0x00, sizeof(pi));
si.cb = sizeof(si);
SECURITY_ATTRIBUTES sa;
sa.nLength = sizeof(sa);
sa.lpSecurityDescriptor = NULL;
sa.bInheritHandle = TRUE;
HANDLE hPipe;
BOOL keepGoing = TRUE;
while(keepGoing){
hPipe = CreateFile(TEXT("\\\\.\\pipe\\MPipe"),
GENERIC_WRITE | GENERIC_READ,
0,
&sa,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL);
if (hPipe == INVALID_HANDLE_VALUE) {
if (GetLastError() == ERROR_PIPE_BUSY) {
MessageBoxA(NULL, "Pipe busy...", NULL, MB_OK);
WaitNamedPipe("\\\\.\\pipe\\MPipe", 2000);
}
else {
MessageBoxA(NULL, "Failed to open pipe for writing", NULL, MB_OK);
break;
}
}
else {
keepGoing = FALSE;
}
}
MessageBoxA(NULL, "Client pipe connected!", NULL, MB_OK);
SetHandleInformation(hPipe, HANDLE_FLAG_INHERIT, 0);
si.hStdError = hPipe;
si.hStdOutput = hPipe;
processFlags = CREATE_SUSPENDED;
CreateProcessW(processPath, commandLine, NULL, NULL, TRUE, processFlags, NULL, NULL, &si, &pi);
For some reason in Main exe it will output "Failed to establish connection..." But in my Middle exe it will output "Client connected!".
I can't figure out why the Middle exe appears to establish a connection but the Main exe doesn't recognize it when ConnectNamedPipe() is called.
Any ideas?