kern/184380: [pcm] SNDCTL_DSP_SETFMT accepts unsupported values

[Jan Beich]

>Number:         184380
>Category:       kern
>Synopsis:       [pcm] SNDCTL_DSP_SETFMT accepts unsupported values
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Nov 30 01:20:00 UTC 2013
>Closed-Date:
>Last-Modified:
>Originator:     Jan Beich
>Release:        FreeBSD 11.0-CURRENT amd64
>Organization:
>Environment:
>Description:
According to SNDCTL_DSP_SETFMT documentation if the ioctl() succeeds
the application must check if value was accepted. Unfortunately, our
OSS implementation may return value that's not actually supported.

http://manuals.opensound.com/developer/SNDCTL_DSP_SETFMT.html

At least the following ports check requested format and would assume
AFMT_FLOAT is accepted if built with sys/soundcard.h from opensound.com.

  devel/allegro-devel
  emulators/wine
  multimedia/audacious-plugins
  multimedia/mplayer
  multimedia/vlc

Probably, only Linux accepts AFMT_FLOAT which means apps built with
OSSv4 wouldn't work under linuxulator either.

>How-To-Repeat:
# kern/21073, audio/oss
$ ./dsp-record -b float
Trying    8012 Hz 1 Channel float Format
ioctl(SNDCTL_DSP_SETFMT) failed: Tried 16384, Got 16

# kern/21073, native
$ ./dsp-record -b float | head -1 | vis -m
Trying    8012 Hz 1 Channel float Format
Recording 8012 Hz 1 Channel float Format
=00=00=00=80=FF=FF=FF=7F=FA=FF=FF=7Fx=FF=FF=7F=E4=00=00=80=9B=FE=FF=7F

# audio/oss
$ ./test
0x00000010

# native
$ ./test
0x00004000

$ cat test.c
#include <sys/soundcard.h>

#include <fcntl.h>
#include <stdio.h>

#ifndef AFMT_FLOAT
#define AFMT_FLOAT 0x00004000
#endif

int main()
{
  int fd = open("/dev/dsp", O_RDWR, 0);

  int format = AFMT_FLOAT;
  if (ioctl(fd, SNDCTL_DSP_SETFMT, &format) < 0)
    return 1;

  printf("%0#10x\n", format);

  return 0;
}

>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: