#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <windows.h>

static char buf[256];

static DWORD read_count;

static HANDLE stdin_h;

static OVERLAPPED stdin_o;

static void die(const char* buf) {

fprintf(stderr, "%s\n", buf);

fflush(stderr);

exit(100);

}

static void overlapped_read(void) {

if (ReadFile(stdin_h, buf, sizeof(buf), NULL, &stdin_o)) {

// Since we start the read operation immediately before requesting a write,

// it should never complete synchronously since no data would be available

die("read completed synchronously");

}

if (GetLastError() != ERROR_IO_PENDING) {

die("overlapped read failed");

}

}

static void write(const char* buf, size_t buf_size) {

overlapped_read();

DWORD write_count;

HANDLE stdout_h = GetStdHandle(STD_OUTPUT_HANDLE);

if (!WriteFile(stdout_h, buf, buf_size, &write_count, NULL)) {

die("overlapped write failed");

}

fprintf(stderr, "%ld", write_count);

fflush(stderr);

}

int main(void) {

HANDLE event = CreateEvent(NULL, FALSE, FALSE, NULL);

if (event == NULL) {

die("failed to create event handle");

}

stdin_h = GetStdHandle(STD_INPUT_HANDLE);

stdin_o.hEvent = event;

write("0", 1);

while (1) {

DWORD result = WaitForSingleObject(event, INFINITE);

if (result == WAIT_OBJECT_0) {

if (!GetOverlappedResult(stdin_h, &stdin_o, &read_count, FALSE)) {

die("failed to get overlapped read result");

}

if (strncmp(buf, "exit", read_count) == 0) {

break;

}

write(buf, read_count);

} else {

char emsg[0xfff];

int ecode = GetLastError();

DWORD rv = FormatMessage(

FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,

NULL,

ecode,

MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),

(LPSTR)emsg,

sizeof(emsg),

NULL);

if (rv > 0) {

snprintf(emsg, sizeof(emsg),

"WaitForSingleObject failed. Error %d (%s)", ecode, emsg);

} else {

snprintf(emsg, sizeof(emsg),

"WaitForSingleObject failed. Error %d", ecode);

}

die(emsg);

}

}

return 0;

}