[PATCH] amixer: handle simple mixer event errors

nd_mixer_handle_events() can return negative runtime errors while
amixer sevents is monitoring simple mixer events. This was reproduced
during early PipeWire startup, where the handler returned -ENOENT after
snd_mixer_wait() reported a ready event.

The raw control event monitor already reports analogous
snd_hctl_handle_events() errors instead of aborting. Handle simple mixer
event errors the same way so sevents reports the error and keeps
listening instead of hitting an assertion failure.

Fixes: https://github.com/alsa-project/alsa-utils/issues/327

Signed-off-by: Bojan Janjatović <[email protected]>
---
 amixer/amixer.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/amixer/amixer.c b/amixer/amixer.c
index 07e9819..cf3db8e 100644
--- a/amixer/amixer.c
+++ b/amixer/amixer.c
@@ -27,7 +27,6 @@
 #include <ctype.h>
 #include <math.h>
 #include <errno.h>
-#include <assert.h>
 #include <alsa/asoundlib.h>
 #include <poll.h>
 #include <stdint.h>
@@ -1703,7 +1702,8 @@ static int sevents(int argc ATTRIBUTE_UNUSED,
char *argv[] ATTRIBUTE_UNUSED)
  if (res >= 0) {
  printf("Poll ok: %i\n", res);
  res = snd_mixer_handle_events(handle);
- assert(res >= 0);
+ if (res < 0)
+ printf("ERR: %s (%d)\n", snd_strerror(res), res);
  }
  }
  snd_mixer_close(handle);
-- 
2.54.0