components/volume.c

   1 /* See LICENSE file for copyright and license details. */
   2 #include <errno.h>
   3 #include <fcntl.h>
   4 #include <stdio.h>
   5 #include <string.h>
   6 #if defined(__OpenBSD__)
   7         #include <soundcard.h>
   8 #else
   9         #include <sys/soundcard.h>
  10 #endif
  11 #include <sys/ioctl.h>
  12 #include <unistd.h>
  13
  14 #include "../util.h"
  15
  16 const char *
  17 vol_perc(const char *card)
  18 {
  19         size_t i;
  20         int v, afd, devmask;
  21         char *vnames[] = SOUND_DEVICE_NAMES;
  22
  23         if ((afd = open(card, O_RDONLY | O_NONBLOCK)) < 0) {
  24                 fprintf(stderr, "open '%s': %s\n", card, strerror(errno));
  25                 return NULL;
  26         }
  27
  28         if (ioctl(afd, (int)SOUND_MIXER_READ_DEVMASK, &devmask) < 0) {
  29                 fprintf(stderr, "ioctl 'SOUND_MIXER_READ_DEVMASK': %s\n",
  30                         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) < 0) {
  37                                 fprintf(stderr, "ioctl 'MIXER_READ(%ld)': %s\n", i,
  38                                         strerror(errno));
  39                                 close(afd);
  40                                 return NULL;
  41                         }
  42                 }
  43         }
  44
  45         close(afd);
  46
  47         return bprintf("%d", v & 0xff);
  48 }