Comment 8 for bug 18272

Summary: Fix amixer to reject invalid commands

The patch brings amixer to reject invalid commands, for example: "amixer set
Master,0 nocap" makes no sense, if there is no capture switch at the Master
Mixer Control. It also handles the invalid command, when more than 1 command is
submited. For example: "amixer set Master,0 nocap 50%,50%" does nothing.

Additional it rejects commands like "amixer -c 1 get Line,0 80%,40% unmute cap"
where unnecessary options are submited.

Signed-off-by: Torsten Büchner <email address hidden>

Patch for alsa-utils-1.0.10:

--- amixer.orig.c 2005-09-22 14:47:02.000000000 +0200
+++ amixer.c 2006-01-30 08:01:58.000000000 +0100
@@ -1188,6 +1188,10 @@
   fprintf(stderr, "Specify what you want to set...\n");
   return 1;
  }
+ if (roflag && !(argc < 2)) {
+ fprintf(stderr, "Unknown option: %s\n", argv[1]);
+ return 1;
+ }
  if ((err = snd_mixer_open(&handle, 0)) < 0) {
   error("Mixer %s open error: %s\n", card, snd_strerror(err));
   return err;
@@ -1218,6 +1222,28 @@
   goto __skip_write;
  snd_mixer_selem_get_playback_volume_range(elem, &pmin, &pmax);
  snd_mixer_selem_get_capture_volume_range(elem, &cmin, &cmax);
+ for (idx = 1; idx < argc; idx++) {
+ char *ptr = argv[idx];
+ channels = channels_mask(&ptr, channels);
+ if (*ptr == '\0')
+ continue;
+ dir = dir_mask(&ptr, dir);
+ if (*ptr == '\0')
+ continue;
+ for (chn = 0; chn <= SND_MIXER_SCHN_LAST; chn++) {
+ if (!(channels & (1 << chn)))
+ continue;
+ if ((!strncmp(ptr, "mute", 4) || !strncmp(ptr, "off", 3) || !strncmp(ptr,
"unmute", 6) ||
+ !strncmp(ptr, "on", 2) || !strncmp(ptr, "toggle", 6)) &&
snd_mixer_selem_has_playback_switch(elem)) continue;
+ if ((isdigit(*ptr) || *ptr == '-' || *ptr == '+') &&
snd_mixer_selem_has_playback_volume(elem)) continue;
+
+ if ((!strncmp(ptr, "cap", 3) || !strncmp(ptr, "rec", 3) || !strncmp(ptr,
"nocap", 5) ||
+ !strncmp(ptr, "norec", 5) || !strncmp(ptr, "toggle", 6)) &&
snd_mixer_selem_has_capture_switch(elem)) continue;
+ if ((isdigit(*ptr) || *ptr == '-' || *ptr == '+') &&
snd_mixer_selem_has_capture_volume(elem)) continue;
+ fprintf(stderr, "Setup not available: %s\n",ptr);
+ return 1;
+ }
+ }
  for (idx = 1; idx < argc; idx++) {
   char *ptr = argv[idx], *optr;
   int multi, firstchn = 1;