Mail Archives: cygwin/2001/01/28/20:07:39
Any word on this? It would be nice to get this into 1.1.8.
cgf
On Sat, Jan 20, 2001 at 12:01:04PM -0500, Christopher Faylor wrote:
>On Sat, Jan 20, 2001 at 08:56:23AM -0800, Bill Hegardt wrote:
>>Here is a fix for the problem I posted back on January 12th. The
>>problem lies in fhandler_serial.cc
>>
>>The problem is that both the raw_read() and raw_write() functions use
>>the same io_status structure. My fix below
>>creates a local structure called osWrite in the raw_write function. This
>>may not be the best way to solve the
>>problem, but it works. I have built cygwin1.dll, tested it, and the problem
>>is solved. Serial I/O seems solid now.
>>
>>I have a document from Microsoft that explains: "A common mistake in
>>overlapped I/O is to reuse an OVERLAPPED structure
>>before the previous overlapped operation is completed". In my
>>application, one thread was blocked on a read while another
>>thread issued a write on the same handle.
>>
>>My hope is that this fix or something similar will find its
>>way into an upcoming release.
>
>I am willing to apply this, or something like it, but I'd appreciate a
>ChangeLog and a patch. See the "Contributing" link at the Cygwin web
>page for more details.
>
>cgf
>
>>Thanks
>>
>>- Bill
>>
>>----- Cut here ------
>>
>>/* Cover function to WriteFile to provide Posix interface and semantics
>> (as much as possible). */
>>int
>>fhandler_serial::raw_write (const void *ptr, size_t len)
>>{
>> DWORD bytes_written;
>> OVERLAPPED osWrite;
>>
>> memset (&osWrite, 0, sizeof (osWrite));
>> osWrite.hEvent = CreateEvent (&sec_none_nih, TRUE, FALSE, NULL);
>> ProtectHandle (osWrite.hEvent);
>>
>> if (overlapped_armed)
>> PurgeComm (get_handle (), PURGE_TXABORT | PURGE_RXABORT);
>>
>> for (;;)
>> {
>> overlapped_armed = TRUE;
>> if (WriteFile (get_handle(), ptr, len, &bytes_written, &osWrite))
>> break;
>>
>> switch (GetLastError ())
>> {
>> case ERROR_OPERATION_ABORTED:
>> continue;
>> case ERROR_IO_PENDING:
>> break;
>> default:
>> goto err;
>> }
>>
>> if (!GetOverlappedResult (get_handle (), &osWrite, &bytes_written,
>>TRUE))
>> goto err;
>>
>> break;
>> }
>>
>> CloseHandle(osWrite.hEvent);
>>
>> overlapped_armed = FALSE;
>> return bytes_written;
>>
>>err:
>> CloseHandle(osWrite.hEvent);
>> __seterrno ();
>> return -1;
>>}
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