components/volume.c

   1 /* See LICENSE file for copyright and license details. */
   2 #include <err.h>
   3 #include <fcntl.h>
   4 #include <sys/soundcard.h>
   5 #include <sys/ioctl.h>
   6 #include <stdio.h>
   7 #include <string.h>
   8 #include <unistd.h>
   9
  10 #include "../util.h"
  11
  12 const char *
  13 vol_perc(const char *card)
  14 {
  15         unsigned int i;
  16         int v, afd, devmask;
  17         char *vnames[] = SOUND_DEVICE_NAMES;
  18
  19         afd = open(card, O_RDONLY | O_NONBLOCK);
  20         if (afd == -1) {
  21                 warn("Cannot open %s", card);
  22                 return NULL;
  23         }
  24
  25         if (ioctl(afd, SOUND_MIXER_READ_DEVMASK, &devmask) == -1) {
  26                 warn("Cannot get volume for %s", card);
  27                 close(afd);
  28                 return NULL;
  29         }
  30         for (i = 0; i < LEN(vnames); i++) {
  31                 if (devmask & (1 << i) && !strcmp("vol", vnames[i])) {
  32                         if (ioctl(afd, MIXER_READ(i), &v) == -1) {
  33                                 warn("vol_perc: ioctl");
  34                                 close(afd);
  35                                 return NULL;
  36                         }
  37                 }
  38         }
  39
  40         close(afd);
  41
  42         return bprintf("%d", v & 0xff);
  43 }