volume.c

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