components/volume.c

   1 /* See LICENSE file for copyright and license details. */
   2 #if defined(__linux__)
   3 #include <errno.h>
   4 #include <fcntl.h>
   5 #include <sys/soundcard.h>
   6 #include <sys/ioctl.h>
   7 #include <stdio.h>
   8 #include <string.h>
   9 #include <unistd.h>
  10
  11 #include "../util.h"
  12
  13 const char *
  14 vol_perc(const char *card)
  15 {
  16         unsigned int i;
  17         int v, afd, devmask;
  18         char *vnames[] = SOUND_DEVICE_NAMES;
  19
  20         afd = open(card, O_RDONLY | O_NONBLOCK);
  21         if (afd == -1) {
  22                 fprintf(stderr, "open '%s': %s\n", card, strerror(errno));
  23                 return NULL;
  24         }
  25
  26         if (ioctl(afd, SOUND_MIXER_READ_DEVMASK, &devmask) == -1) {
  27                 fprintf(stderr, "ioctl 'SOUND_MIXER_READ_DEVMASK': %s\n", strerror(errno));
  28                 close(afd);
  29                 return NULL;
  30         }
  31         for (i = 0; i < LEN(vnames); i++) {
  32                 if (devmask & (1 << i) && !strcmp("vol", vnames[i])) {
  33                         if (ioctl(afd, MIXER_READ(i), &v) == -1) {
  34                                 fprintf(stderr, "ioctl 'MIXER_READ(%d)': %s\n", i, strerror(errno));
  35                                 close(afd);
  36                                 return NULL;
  37                         }
  38                 }
  39         }
  40
  41         close(afd);
  42
  43         return bprintf("%d", v & 0xff);
  44 }
  45 #endif