components/volume.c

   1 /* See LICENSE file for copyright and license details. */
   2 #include <errno.h>
   3 #include <fcntl.h>
   4 #if defined(__OpenBSD__)
   5 # include <soundcard.h>
   6 #else
   7 # include <sys/soundcard.h>
   8 #endif
   9 #include <sys/ioctl.h>
  10 #include <stdio.h>
  11 #include <string.h>
  12 #include <unistd.h>
  13
  14 #include "../util.h"
  15
  16 const char *
  17 vol_perc(const char *card)
  18 {
  19         unsigned int i;
  20         int v, afd, devmask;
  21         char *vnames[] = SOUND_DEVICE_NAMES;
  22
  23         afd = open(card, O_RDONLY | O_NONBLOCK);
  24         if (afd == -1) {
  25                 fprintf(stderr, "open '%s': %s\n", card, strerror(errno));
  26                 return NULL;
  27         }
  28
  29         if (ioctl(afd, SOUND_MIXER_READ_DEVMASK, &devmask) == -1) {
  30                 fprintf(stderr, "ioctl 'SOUND_MIXER_READ_DEVMASK': %s\n", strerror(errno));
  31                 close(afd);
  32                 return NULL;
  33         }
  34         for (i = 0; i < LEN(vnames); i++) {
  35                 if (devmask & (1 << i) && !strcmp("vol", vnames[i])) {
  36                         if (ioctl(afd, MIXER_READ(i), &v) == -1) {
  37                                 fprintf(stderr, "ioctl 'MIXER_READ(%d)': %s\n", i, strerror(errno));
  38                                 close(afd);
  39                                 return NULL;
  40                         }
  41                 }
  42         }
  43
  44         close(afd);
  45
  46         return bprintf("%d", v & 0xff);
  47 }