[src/trunk]: src/lib/libossaudio ossv4 mixer API: be extra careful with the i...

[nia <nia%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/0be6ab07bd63
branches:  trunk
changeset: 981567:0be6ab07bd63
user:      nia <nia%NetBSD.org@localhost>
date:      Mon Mar 15 10:58:05 2021 +0000

description:
ossv4 mixer API: be extra careful with the inputs to AUDIO_MIXER_READ.

some drivers (not hdaudio(4), but uaudio(4), eap(4), sb(4), various other
old cards) will return error if a AUDIO_MIXER_VALUE is requested and the
number of channels is not specified as input. this is not documented as
well as it should be, unfortunately.

diffstat:

 lib/libossaudio/ossaudio.c |  9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diffs (44 lines):

diff -r be858cef8f2e -r 0be6ab07bd63 lib/libossaudio/ossaudio.c
--- a/lib/libossaudio/ossaudio.c        Mon Mar 15 07:30:40 2021 +0000
+++ b/lib/libossaudio/ossaudio.c        Mon Mar 15 10:58:05 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ossaudio.c,v 1.65 2020/12/19 12:55:28 nia Exp $        */
+/*     $NetBSD: ossaudio.c,v 1.66 2021/03/15 10:58:05 nia Exp $        */
 
 /*-
  * Copyright (c) 1997, 2020 The NetBSD Foundation, Inc.
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: ossaudio.c,v 1.65 2020/12/19 12:55:28 nia Exp $");
+__RCSID("$NetBSD: ossaudio.c,v 1.66 2021/03/15 10:58:05 nia Exp $");
 
 /*
  * This is an Open Sound System compatibility layer, which provides
@@ -1442,6 +1442,7 @@
                        errno = tmperrno;
                        return retval;
                }
+               mc.type = mdi.type;
                switch (mdi.type) {
                case AUDIO_MIXER_ENUM:
                        if (mv->value >= mdi.un.e.num_mem) {
@@ -1469,6 +1470,7 @@
 #endif
                        break;
                case AUDIO_MIXER_VALUE:
+                       mc.un.value.num_channels = mdi.un.v.num_channels;
                        if (mdi.un.v.num_channels != 2) {
                                for (i = 0; i < mdi.un.v.num_channels; ++i) {
                                        mc.un.value.level[i] = mv->value;
@@ -1512,6 +1514,9 @@
                        return retval;
                }
                mc.dev = mdi.index;
+               mc.type = mdi.type;
+               if (mdi.type == AUDIO_MIXER_VALUE)
+                       mc.un.value.num_channels = mdi.un.v.num_channels;
                retval = ioctl(newfd, AUDIO_MIXER_READ, &mc);
                if (retval < 0) {
                        tmperrno = errno;