Re: Patch request to qt 5.9.4 (Re: [ANNOUNCEMENT] Qt 5.9.4)

[Tatsuro MATSUOKA <tmacchant2@yahoo.co.jp>]

>>  From: Achim Gratz

>>  To: cygwin
>>  Cc: 
>>  Date: 2019/3/6, Wed 04:24
>>  Subject: Re: Patch request to qt 5.9.4 (Re: [ANNOUNCEMENT] Qt 5.9.4)
>> 
>> T atsuro MATSUOKA writes:
>>>   I contacted with Enrico who tells me the patch that I have shown.
>> 
>>  Yes, but that monkeys around the real problem.  What Yaakov is telling
>>  you is that there are two options and we don't know yet which one we
>>  have to deal with.
>> 
>>  If O_NONBLOCK is needed, but does not work correctly under Cygwin, then
>>  that's a bug in Cygwin.  For this case, Corinna asks you to create an
>>  STC that demonstrates the bug so it can be triaged without having to
>>  work with something as complex as the Qt terminal in Cygwin.
>> 
>>  If on the other hand O_NONBLOCK is in fact not needed and just shows
>>  different behaviour on different systems without a bug in the
>>  implementation being present, then upstream should remove that argument.
>> 
>> 
>>  Regards,
>>  Achim.
> 
> Seeing ML archive that Enrico indicated,
> 
> Re: select() and named pipes
> 
> #include <stdio.h>
> #include <stdlib.h>
> #include <errno.h>
> #include <sys/select.h>
> #include <sys/types.h>
> #include <sys/stat.h>
> #include <fcntl.h>
> #include <unistd.h>
> 
> #define FIFONAME "/tmp/pipe"
> 
> int main(void)
> {
>     int fd;
>     int nsel;
>     fd_set readfds;
>     FD_ZERO(&readfds);
> 
>     if (mkfifo(FIFONAME, 0600) < 0) {
>         perror("mkfifo");
>         exit(1);
>     }
> 
>     fd = open(FIFONAME, O_RDONLY | O_NONBLOCK);
> 
>     if (fd < 0) {
>         perror("open");
>         remove(FIFONAME);
>         exit(2);
>     }
> 
>     FD_SET(fd, &readfds);
>     do {
>         nsel = select(fd + 1, &readfds, 0, 0, 0);
>     } while (nsel == -1 && (errno == EINTR || errno == EAGAIN));
> 
>     if (nsel == -1) {
>         perror("select");
>         exit(3);
>     }
> 
>     if (FD_ISSET(fd, &readfds)) {
>         char buf[100];
>         int status;
>         int count = 0;
>         printf("%d: ", ++count);
>         while ((status = read(fd, buf, sizeof(buf) - 1))) {
>             if (status > 0) {
>                 buf[status] = '\0';
>                 printf("%s", buf);
>             } else if (errno == EAGAIN) {
>                     printf("\n%d: ", ++count);
>             } else {
>                 perror("read");
>                 break;
>             }
>         }
>     }
> 
>     close(fd);
>     remove(FIFONAME);
>     return 0;
> }
> 
> 
> 
> As you wrote this is a issue of Cygwin issue.
> But As long as O_NONBLOCK does not work on Cygwin, Enrico's workaround can 
> be attached for qt.

Apart from Qt maintainer accepts Enrico's patch, I will raise O_NONBLOCK issue by another post.

Tatsuro


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