Bug#222434: Fix amixer to reject invalid commands

[buechi]

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 PROTECTED]>

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;