pipecat.c

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

static CALLBACK DWORD read_thread(void *arg)
{
	HANDLE pipe = arg;
	OVERLAPPED ol = { .hEvent = CreateEventW(NULL, TRUE, TRUE, NULL) };

	HANDLE out = GetStdHandle(STD_OUTPUT_HANDLE);
	char outbuf[128];
	for (;;) {
		DWORD r;
		if (!ReadFile(pipe, outbuf, 128, NULL, &ol) && GetLastError() != ERROR_IO_PENDING)
			break;
		if (!GetOverlappedResult(pipe, &ol, &r, TRUE))
			break;
		if (!WriteConsoleA(out, outbuf, r, &(DWORD){0}, NULL) &&
		    !WriteFile(out, outbuf, r, &(DWORD){0}, NULL))
			break;
	}

	CloseHandle(ol.hEvent);
	return 0;
}

int wmain(int argc, wchar_t **argv)
{
	if (argc < 2) {
		fwprintf(stderr, L"usage: %s pipe_name\n", argv[0]);
		return 1;
	}

	HANDLE pipe;
	for (;;) {
		pipe = CreateFileW(argv[1], GENERIC_READ | GENERIC_WRITE, 0, NULL,
			OPEN_EXISTING,
			FILE_FLAG_OVERLAPPED,
			NULL);
		if (pipe && pipe != INVALID_HANDLE_VALUE)
			break;
		if (GetLastError() != ERROR_PIPE_BUSY)
			return 1;
		if (!WaitNamedPipeW(argv[1], NMPWAIT_USE_DEFAULT_WAIT))
			return 2;
	}

	HANDLE thread = CreateThread(NULL, 0, read_thread, pipe, 0, NULL);

	HANDLE in = GetStdHandle(STD_INPUT_HANDLE);
	OVERLAPPED ol = { .hEvent = CreateEventW(NULL, TRUE, TRUE, NULL) };
	char inbuf[128];
	for (;;) {
		DWORD r;
		if (!ReadConsoleA(in, inbuf, 128, &r, NULL) &&
		    !ReadFile(in, inbuf, 128, &r, NULL))
			break;
		if (!WriteFile(pipe, inbuf, r, NULL, &ol) && GetLastError() != ERROR_IO_PENDING)
			break;
		if (!GetOverlappedResult(pipe, &ol, &(DWORD){0}, TRUE))
			break;
	}

	WaitForSingleObject(thread, INFINITE);
	CloseHandle(thread);

	CloseHandle(pipe);
	CloseHandle(ol.hEvent);
	return 0;
}