Tarim <s...@mediaplaygrounds.co.uk> wrote: > I'm now thinking that this is actually a bug in the latest Ubuntu kernel > 3.13.0-65.105-generic where select's FD_ISSET returns true even when > there is no data to read!
This is a kernel bug from a performance standpoint, but the select manpage explicitly documents spurious wakeups as a possibility which userspace must be prepared for. The following patch should fix the problem: ------------------8<------------------ Subject: [PATCH] use non-blocking stdin for interactive mode When accepting keyboard input, it is possible for select() to return a false-positive with spurious wakeups from inside the update_status callback. Using the FIONREAD ioctl in place of select is also a possibility, but may be less portable. --- Downloadable patch: http://80x24.org/spew/1443909787-27821-1-git-send-email-e%4080x24.org/raw In case upstream prefers a pull request: The following changes since commit 7e74b254b2a7c963be0bfce751fc5911fe681c12: Remove hepler script. It's mostly unmaintained, I don't know if anyone but me ever used it. In any case, those who want a custom Debian package should be capable of updating the debian/changelog entry on their own. (2015-02-26 22:48:40 -0500) are available in the git repository at: git://bogomips.org/sox nb-stdin for you to fetch changes up to 62a370a2a01cf1dcc0d5f9b9f49d1515706346cd: use non-blocking stdin for interactive mode (2015-10-03 22:04:50 +0000) ---------------------------------------------------------------- Eric Wong (1): use non-blocking stdin for interactive mode src/sox.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/src/sox.c b/src/sox.c index bab0f45..fdb7616 100644 --- a/src/sox.c +++ b/src/sox.c @@ -1789,6 +1789,18 @@ static int process(void) tcsetattr(fileno(stdin), TCSANOW, &modified_termios); } #endif +#if defined(F_GETFL) && defined(F_SETFL) && defined(O_NONBLOCK) + if (interactive) { + int fd = fileno(stdin); + int flags = fcntl(fd, F_GETFL); + if (flags == -1) { + lsx_warn("error getting flags on stdin descriptor: %s", strerror(errno)); + } else if (!(flags & O_NONBLOCK)) { + if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) + lsx_warn("error setting non-blocking on stdin: %s", strerror(errno)); + } + } +#endif signal(SIGTERM, sigint); /* Stop gracefully, as soon as we possibly can. */ signal(SIGINT , sigint); /* Either skip current input or behave as SIGTERM. */ -- EW ------------------------------------------------------------------------------ _______________________________________________ SoX-devel mailing list SoX-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sox-devel
