c++ - Win32 API: how to read the serial, or exit within a timeout if wasn't a data -

i need function read data serial port, or return if no data within time interval. e.g. under gnu/linux bundle poll()orselect()+read(). there way in windows using handle file?

below code illustrate: should work needed, function getoverlappedresult() either buggy, either not documented; instead of number of bytes read @ moment reports nothing(not zero, i.e. if didn't initialized third argument lpnumberofbytestransferred, going contain junk).

//note: `file` argument should opened in non-blocking mode long readdata(handle file, char* buf, long szbuf, int mstimeout){     overlapped readstate = {0};     readstate.hevent = createevent(0, true, false, "☠");     if (!readstate.hevent){         printlasterr();         return -1;     }     unsigned long bytesread = 0; //number of bytes read     if (!readfile(file, buf, szbuf, &bytesread, &readstate)){         //this creates reading event. below waiting complete, , cancel in         //case of timeout.         if (getlasterror() != error_io_pending){             printlasterr();             return -1;         }         //no, can't use here waitforsingleobject(), exiting disregard fact         //is reading still performing, or no more data remains(in case of serial port).         while(1){             std::this_thread::sleep_for(std::chrono::milliseconds( mstimeout ));             unsigned long ret;             puts("result getting");             if (!getoverlappedresult(file, &readstate, &ret, false)                 && getlasterror() != error_io_incomplete){ //error                 printlasterr();                 return -1;             }             printf("result %lu\n",ret);             if(ret == bytesread){//no more bytes read                 return bytesread;             }             bytesread = ret;         }     } else { //completed         printf("bytes read %i\n");         assert(bytesread <= long_max);//we return signed, error         return (long)bytesread;     } } 

call setcommtimeouts after open com port. sets readfile return after interval if no data received. call readfile. no overlap or event or getoverlappedresult needed.