dwmbar.c

/*
    gcc dwmbar.c -std=c99 -D_XOPEN_SOURCE=600 -lX11 -lasound -Wall -O3 -o dwmbar 
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <time.h>
#include <alsa/asoundlib.h>
#include <X11/XKBlib.h>

#define DATETIME_BUFFER 8
#define BATTERY_DEVICE "/sys/class/power_supply/BAT1/capacity"
#define ADAPTER_DEVICE "/sys/class/power_supply/ADP1/online"

#define GLYPH_CLOCK    "\uf017"
#define GLYPH_BATTERY  "\uf0e7"
#define GLYPH_VOLUME   "\uf028"
#define GLYPH_WEATHER  "\uf185"
#define GLYPH_KEYBOARD "\uf11c"
#define GLYPH_MAIL     "\uf0e0"

int main (void) {
    const char *keyboardLayouts[] = {"En", "Ru"};
    const char *adapterStatuses[] = {"DC", "AC"};

    time_t timestamp;
    char datetime[DATETIME_BUFFER], output[512];

    Display *display = XOpenDisplay(NULL);
    XkbStateRec xkbState;

    char adapterStatus, batteryStatus[3];
    int adapterDescriptor = open(ADAPTER_DEVICE, O_RDONLY);
    int batteryDescriptor = open(BATTERY_DEVICE, O_RDONLY);

    if (adapterDescriptor == -1 || batteryDescriptor == -1) {
        return EXIT_FAILURE;
    }

    snd_mixer_t *alsa_handle;
    snd_mixer_elem_t *elem;
    snd_mixer_selem_id_t *s_elem;

    snd_mixer_open(&alsa_handle, 0);
    snd_mixer_attach(alsa_handle, "default");
    snd_mixer_selem_register(alsa_handle, NULL, NULL);
    snd_mixer_load(alsa_handle);

    snd_mixer_selem_id_malloc(&s_elem);
    snd_mixer_selem_id_set_index(s_elem, 0);
    snd_mixer_selem_id_set_name(s_elem, "Master");
    elem = snd_mixer_find_selem(alsa_handle, s_elem);

    long int volume, volumeMin, volumeMax, volumePercent;
    snd_mixer_selem_get_playback_volume_range(elem, &volumeMin, &volumeMax);

    while(1) {
        time(&timestamp);
        strftime(datetime, DATETIME_BUFFER, "%H:%M", localtime(&timestamp));
        XkbGetState(display, XkbUseCoreKbd, &xkbState);

        if (pread(adapterDescriptor, &adapterStatus, sizeof(adapterStatus), 0) != sizeof(adapterStatus)) {
            return EXIT_FAILURE;
        }

        if (pread(batteryDescriptor, &batteryStatus, sizeof(batteryStatus), 0) != sizeof(batteryStatus)) {
            return EXIT_FAILURE;
        }

        snd_mixer_handle_events(alsa_handle);
        snd_mixer_selem_get_playback_volume(elem, SND_MIXER_SCHN_MONO, &volume);

        volumePercent = (volume * 100) / volumeMax;

        snprintf(output, 512, 
            "%s %s  %s %ld%%  %s %i%% %s  %s %s",
            GLYPH_KEYBOARD, keyboardLayouts[xkbState.group],
            GLYPH_VOLUME, volumePercent,
            GLYPH_BATTERY, atoi(batteryStatus), adapterStatuses[atoi(&adapterStatus)],
            GLYPH_CLOCK, datetime
        );
        XStoreName(display, DefaultRootWindow(display), output);
        XSync(display, False);

        usleep(300 * 1000);
    }

    close(adapterDescriptor);
    close(batteryDescriptor);

    snd_mixer_selem_id_free(s_elem);
    snd_mixer_close(alsa_handle);

    XCloseDisplay(display);

    return EXIT_SUCCESS;
}